Pediatric Surgery

Vascular Access

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Blood Sampling

Current microtechniques of chemical analysis allow small samples of blood to be taken from children. Capillary tubes can be used for obtaining blood by “heel-stick”. If more blood is needed an antecubital or scalp vein can be used. An assistant will be needed to restrain the child. A 21 or 23 gauge scalp needle (butterfly) with preattached plastic tubing and a small syringe is used to penetrate the skin and enter the vein. Blood will flow immediately and can be aspirated gently by the assistant. Peripheral arterial blood can be sampled in a similar fashion.

Under extreme conditions an experienced physician may use a femoral vein for blood sampling. The child will need to be adequately restrained and the skin prepared with antibacterial solution. The femoral artery is palpated and a small scalp vein needle is inserted just medial to the femoral artery.

Venous Access

Access for infusion therapy can be obtained by percutaneous insertion of steel needles or plastic catheters or by cutdown on peripheral veins. When placing a percutaneous catheter make a small nick in the skin at the insertion site with a separate needle to eliminate skin traction on the plastic catheter and avoid damage to the tip of the catheter. A local anesthetic can be injected to raise a skin wheal at the insertion site. If time allows a topical anesthetic cream can be applied. The needle and plastic catheter are inserted until blood returns. The catheter can then be advanced over the needle into the vein. The catheter is secured by a plastic dressing and tape to allow monitoring of the insertion site and catheter tip site. Phlebitis is the most common complication of peripheral intravenous catheters.

Cutdowns for peripheral venous access are being used less frequently. The cephalic vein at the wrist and the saphenous vein at the ankle are good sites because of their superficial and constant location. Meticulous care should be taken in restraining the extremity and maintaining sterile technique. A vertical incision over the vein provides for greater exposure and the incision can be extended proximally if more length of the vein is needed. A plastic catheter can be placed in the vein by making an oblique venotomy. If the vein is very small the catheter can be passed over a needle. The catheter is secured with absorbable suture and the wound is closed. A sterile dressing is placed and the extremity is immobilized. Peripheral arteries can be cannulated using a similar technique.

Central Venous Access

Central venous access can be obtained by cutdown or percutaneous technique. “PIC” lines or “PCVCs” are small silastic catheters advanced into the central circulation via a peripheral vein. These central lines can be placed with or without ultrasound guidance. These lines cannot be maintained indefinitely but are ideal for several days and up to several weeks. Catheter related sepsis occurs in 2.7-6% of patients with these catheters. Venous thrombosis has been reported in 0.3%.

When short-term, multiple port or large bore access is needed, a percutaneous central line can be placed via the subclavian, external or internal jugular vein. For prolonged parenteral nutrition, blood samplings, or chemotherapy, a tunneled silastic catheter with or without a venous reservoir is preferred. The catheter can be placed with a percutaneous technique or by cutdown utilizing the subclavian, external jugular, internal jugular or saphenous veins. Fluoroscopy should be used during placement of any central line to confirm correct placement. If the subclavian vein has been accessed, a chest x-ray should be obtained to identify an associated pneumothorax or other thoracic complication.

Umbilical Vessel Access

Central venous and arterial access can be obtained through the umbilical cord in a newborn. The distal cord is amputated after the area is prepped with an aseptic solution. The umbilical vein is large and thin-walled and a 5 French plastic catheter can be advanced through the ductus venosus into the right atrium. A 3.5 French soft plastic catheter can be advanced into either of the paired umbilical arteries and positioned in the thoracic or abdominal aorta. The catheter should be positioned above the diaphragm or below the level of the renal arteries. The position of either catheter must be verified by x-ray. Heparin is added to the infusate to prevent thrombosis. Because of the high associated complication rate both of these catheters should be removed as soon as possible.

Intraosseous Access

In emergency situations intravenous access may not be easily or rapidly attainable in an infant or small child. The intraosseous route may be used for infusion of fluid, drugs and blood. Bone marrow needles, short (18-22 gauge) spinal needles or large (14-16 gauge) hypodermic needles can be used. The knee is supported and the tibia prepared with antimicrobial solution. The needle is placed in the midline of the anterior tibia on the flat surface 1-3 cm below the tibial tuberosity. The needle is directed inferiorly at a 60-90% angle and advanced until marrow content is aspirated. The fluid should flow freely into the intramedullary space. The needle is stabilized with a supported dressing to prevent dislodgement. Placement may be checked with a miniature C-arm imaging device.

It is contraindicated to use the intraosseous route in children with diseases of the bone or with ipsilateral extremity fractures. Needle dislodgement with subperiosteal or subcutaneous infiltration of fluid is the most common complication. Compartment syndrome and osteomyelitis have been reported. The infection rate is not higher using this technique. Fears over potential injury to the tibial growth plate have not been substantiated. It is generally advisable to remove an intraosseous needle as soon as possible.

Genetics and Prenatal Diagnosis in Pediatric Surgery

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Serious malformations occur in 1.5% of all births. For half of these children the etiology is unknown; the other half have a documented genetic or teratogenic cause. The importance of prenatal diagnosis lies in its ability to give parents several options. If there are malformations or conditions incompatible with life, the pregnancy can be terminated. If the malformation is correctable at term, surgery can take place after delivery. For some malformations, progressive adverse effects in utero may warrant consideration of early delivery or fetal surgery.

Modern obstetric care includes close monitoring during pregnancy and various prenatal screening-tests, such as alpha-fetoprotein screening and prenatal ultrasonography. Fetal ultrasonography is routinely performed around the 18th gestational week. Occasionally, there are indications for more invasive screening tests, such as chorionic villus sampling, amniocentesis, fetoscopy, fetal sampling, and percutaneous umbilical blood sampling.

Early detection of congenital defects in utero allows for both parental counseling and referral to a perinatal center where further investigation of the condition can be undertaken and monitoring of the high-risk pregnancy can be done. The perinatal center should advise when, where and how delivery will take place. Appropriate centers must have a skilled neonatal intensive care facility and pediatric surgical expertise.

Prenatal Diagnostic Studies and Tests

Chorionic Villus Sampling (CVS)

CVS allows biopsy of fetal cells for chromosomal, enzymatic or DNA analysis in the first trimester (9-12 weeks gestation). Cells are obtained by direct biopsy of chorion, either transcervically or transabdominally, preferably under ultrasound guidance The major disadvantage of this procedure is the associated 3% increased rate of spontaneous abortion. CVS is the preferred prenatal diagnostic test for many high risk conditions (i.e., cystic fibrosis, sickle cell disease, Duchenne’s dystrophy, etc.)

Alpha-Fetoprotein (AFP) Screening

AFP is one of the major proteins in fetal serum. Screening should be offered to women at 16-18 weeks of gestation. AFP in maternal serum is of fetal origin. Increased levels of AFP are found in fetuses with neural tube defects, anencephaly, Turner’s syndrome, omphalocele, sacrococcygeal teratoma, intestinal obstruction and missed abortion. Low AFP levels are observed in intrauterine growth retardation, Trisomy 18, Trisomy 21, and other conditions. However, a normal AFP level does not rule out trisomy. Women with a maternal age exceeding 35 years are at high risk for having babies with Downs Syndrome. Consequently, this group and indeed most pregnant women are now offered assay for both AFP and human chorionic gonadotropin (hCG). Human chorionic gonadotropin levels are frequently elevated in fetuses with Trisomy 21.

Amniocentesis

Amniocentesis involves sampling and analysis of amniotic fluid to detect presence of metabolic disorders and chromosomal defects. Amniocentesis can be safely performed between 12-18 weeks gestation and usually takes 14 days to obtain results. The safety of this procedure is somewhat better than CVS. The risk of miscarriage following amniocentesis is less than 1%.

Fetoscopy and Fetal Sampling

When appropriate, these procedures are performed between 15 and 21 weeks of gestation. Analysis of fetal blood can reveal many conditions including Wiskott-Aldrich syndrome, hemophilia A and B, hemoglobinopathies, alpha 1-antitrypsin deficiency, and chronic granulomatous disease. Conditions in which the genetic defect is not expressed in the amniotic fluid can be discovered by sampling from the skin and liver. Fibroblastic cell culture can be performed to reveal mosaicism. The risk of miscarriage is around 5%.

Percutaneous Umbilical Blood Sampling

Percutaneous aspiration of umbilical cord blood can be safely performed under ultrasound guidance. The blood samples can reveal hematologic abnormalities including isoimmunization. This procedure is usually done between 18 and 20 weeks of gestation. The risk of miscarriage is about 2%. Results of analysis are usually available within 2-3 days.

Prenatal Ultrasound

Sonography is the most important method of fetal screening. It is useful to determine gestational age of the fetus, single or multiple births, the amniotic fluid volume, growth in high risk pregnancies, and a significant number of fetal anomalies. Ultrasonography is the best noninvasive method for determining both functional and anatomic abnormalities in the fetus. Evaluation of amniotic fluid volume is most important. When performed in the 4th month of gestation, the finding of normal amounts of amniotic fluid suggests normal swallowing and renal function. A finding of reduced amniotic fluid volume, or no fluid at all, is a sign of impaired renal function, such as obstruction, multicystic kidneys or renal agenesis. Too much amniotic fluid (more than 2000 ml = polyhydramnios) suggests impaired fetal swallowing (neurologic abnormality, anencephali), proximal alimentary tract obstruction, or compression of the esophagus due to diaphragmatic hernia or congenital lung malformation.

Although a single ultrasound study can provide a wealth of information, serial studies over time can provide even more. Functional evaluation of kidney, heart, and lungs is considerably more accurate with repeated exams.

The heart and the great vessels are easily visualized with ultrasonography or fetal echocardiography. The dynamic function can be evaluated. The four chambers and the two great vessels should be visualized and allows the diagnosis of anomalies such as tetralogy of Fallot, tricuspid atresia, hypoplastic left heart, aortic valve stenosis/ atresia and double outlet right ventricle.

Cerebral malformations, encephaloceles, and hydrocephalus are readily identified by prenatal ultrasound. Intraabdominal structures like hepatic neoplasms (hemangioma), neuroblastoma, enteric duplications and atresias of the gut can also be detected. The differentiation of omphalocele and gastroschisis is especially important because the prognosis in omphalocele is so much worse, compared to gastroschisis, because of the serious associated anomalies and chromosomal defects.

Indications for Prenatal Diagnosis

General Risk Factors

Maternal age more than 35 years (increased risk for fetal chromosomal abnormality). Elevated or reduced serum AFP Increased serum hCG.

Specific Risk Factors

Previous still birth or neonatal death. Previous child with a structural defect or chromosomal abnormality. Structural abnormality in any of the parents. Balanced translocation in any of the parents. Inherited disorders (i.e., cystic fibrosis, metabolic disorders, sex-linked disorders) Medical disease in the mother (i.e., diabetes mellitus) Exposure to teratogens (i.e., ionizing radiation, anticonvulsant medicine, alcohol, etc.) Infections (i.e., rubella, toxoplasmosis, cytomegalovirus)

Treatment of the Fetus

Hydrops fetalis can occur secondary to isoimmunization induced hemolysis. Prenatal treatment of this condition may include erythrocyte transfusion in utero. Transplacental treatment can be administered for cardiac arrhythmias (especially supraventricular tachycardia) leading to hydrops. The most common prenatal treatment used for the fetus is steroid (i.e., glucocorticoid ) administration to increase pulmonary surfactant in the lungs of the preterm infants.

Fetal Surgery

The indication for fetal surgery is malformations that interfere with fetal organ development, which if alleviated would allow normal organogenesis. Pioneering work is now carried out in a few centers for highly selected cases; however, these procedures involve significant risks for both the mother and the fetus (i.e., infection, premature labor, etc.).

Although no large series have proven any long term benefits, work continues (and should continue at a few centers with close supervision) on the use of fetal surgery for:

vesicoamniotic shunt for severe bilateral hydronephrosis with pulmonary hypoplasia
congenital diaphragmatic hernia with prenatal prosthetic patch repair or tracheal plugging
lobectomy for congenital cystic adenomatoid malformation
thoracoamniotic shunt for fetal chylothorax
ventriculoamniotic shunt for severe obstructive hydrocephalus
resection of sacrococcygeal teratoma to prevent cardiac failure secondary to arteriovenous fistula
correction of critical aortic stenosis to prevent severe left ventricular hypoplasia

Anemia

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Unlike many Chapters of this handbook that deal with a specific surgical condition, this short Chapter touches on a physiologic state that has great importance to the surgeon. Anemia denotes a state in which a patient has less than normal hemoglobin. In this situation, decreased oxygen transport may decrease wound healing, may increase cardiac stress during or after surgical event, and may predispose to a variety of postoperative complications. Fortunately, all these anemia problems are less likely in the pediatric patient, but still one must consider carefully the presence of anemia, its probable cause, whether it should be corrected (how and how quickly), and its chance of seriously affecting surgical outcome.

Definition

Generally, anemia is defined as hemoglobin less than 10 grams/deciliter. The normal value for adults and older children is 12-16 grams/deciliter. However, this value may be higher in the newborn and will characteristically fall below this normal range during the first 1-2 months of life.

Physiologic Anemia

Babies rapidly lower their hemoglobin in the neonatal period. Values often fall to the 9-10 g/dl level with corresponding hematocrits of 25-30%. This change is normal and reflects a slow initiation of hematopoesis by the neonatal bone marrow. If surgery is necessary during this period, the surgical and anesthesiological staff must decide whether the transfusion of blood outweighs risks of transfusion and delay of hematopoesis onset.

Iron Deficiency

Iron supplies are transferred to a neonate late in intrauterine life. These supplies may be low in preterm children, just as the supply of other nutrients, vitamins, minerals are low in early children. If there is no compelling reason to correct the anemia quickly, the infant is given iron orally. This is absorbed in the duodenum and proximal jejunum and nicely corrects the problem. Parental iron or transfusion are the alternatives if this deficiency must be corrected quickly.

Hereditary Spherocytosis

This is an autosomal dominant disease process that prevents red cells from assuming their characteristic biconcave shape. The elliptical red blood cells do not move easily through the capillary bed or the pulp of the spleen. Red cells thus entrapped are more rapidly destroyed, resulting in splenomegaly, jaundice, and anemia. The presence of a family history consistent with this disease and the observation of spherocytes and reticulocytes on a peripheral blood smear confirm the diagnosis. Further confirmation involves demonstration of increased cellular fragility in the osmotic fragility test. These children are highly prone to the development of gallstones and concomitant biliary tract disease. Thus, they need full evaluation of those structures if they are coming to splenectomy to control the spherocytosis.

Sickle Cell Anemia

This is the most common inherited disorder of the African American population. Up to 10% of this population is affected. This disease is an autosomal recessive trait and requires the homozygous state for expression of the full-blown disease. Most of these patients have anemia, leukocytosis, jaundice, and perhaps splenomegaly early. By teenage years, the spleen usually shrinks from progressive infarction and fibrosis. However, these children by then often also have biliary stones and biliary tract disease.

In severe forms of this disease, children have painful crises that involve bone pain, severe right and left upper abdominal pain, strokes, and pulmonary infarctions. Many of these children develop osteomyelitis and leg ulcers.

A peripheral smear demonstrates sickle shaped red blood cells, especially when crisis is occurring. However, today most of these children are quickly diagnosed at the time of birth through mandated state screening programs. Hemoglobin electrophoresis confirms the presence of hemoglobin S and indicates the zygosity. Prenatal diagnosis is possible through amniocentesis and DNA analysis.

Although surgeons are not generally asked to manage children with this disease, they are frequently asked to consult for abdominal pain. When surgery is necessary for appendicitis, biliary problems, etc., it is important that the surgeon know how to manage these children to optimize outcome. Preoperative suppressive transfusions, exchange transfusions, meticulous hydration and prevention of hypoxia all are important aspects of preoperative, intraoperative, and postoperative care.

Other Anemias

Diverse other anemic states more rarely come to the attention of pediatric surgeons. Generally, the request is to assist with a complication of the anemia, most often splenomegaly or biliary complications such as cholelithiasis. Care should be used to correct the anemia to the degree possible before operation. If this is not possible, the surgeon must try to optimize care to prevent postoperative complications associated with low red blood volume and decreased oxygen transport.

Immediate Postoperative Care

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The postoperative care of surgical neonates and children begins upon completion of wound closure. The level of postoperative care administered is dependent upon the procedure performed but some general guidelines are provided below. Specific guidelines for postoperative management of many pediatric surgical conditions are provided throughout this handbook.

Wound and Dressing Care

Prior to the removal of the sterile surgical drapes, the skin surrounding the surgical wound is cleansed with warm saline-soaked sponges or lap pads to remove any debris, blood, or prep solutions surrounding the wound. The area is gently padded dry and a sterile towel or dressing is placed over the wound to prevent contamination at the time of drape removal. The type of dressing applied to surgical wounds is selected according to surgeon preference, the type of wound created, and the method of closure. For clean procedures, a dry, sterile dressing (i.e., gauze, steristrips, Opsite®, Tegrederm®) is suitable. Antibiotic ointments and other wound applicants are generally not necessary. To minimize the stress and pain of later dressing removal, dressings are secured in position with the minimal amount of tape or occlusive barrier that achieves coverage of the wound.

Extubation and Transfer

Intraoperative monitoring devices should be left in place until after extubation. A physician member of the surgical team should be present at the time of extubation and assist in the transfer of the pediatric surgical patient to the postanesthesia care unit or appropriate intensive care unit. If respiratory rate or inspiratory tidal volumes are inadequate, the child should be observed in the OR until breathing has improved. Special attention to body temperature and measures to prevent hypothermia after drape removal should be instituted including infrared heating lights, wrapping with warm blankets, and increasing the ambient room temperature.

Postoperative Orders

The postoperative orders are individualized for each patient. In general, outpatient procedures will require only simple postoperative care and specific wound care instructions for the parents. Arrangements for office follow-up visits are discussed. A general outline for writing postoperative orders in postsurgical pediatric patients is provided below.

Admission Order

Specific information regarding the type of bed and/or location within the hospital to which the patient goes after recovery is listed. Arrangements for intensive care unit beds are made preoperatively. If observation status or discharge from the recovery unit is desired, specific instructions regarding wounds, medications, and anticipated clinical course/problems are provided to the parents or primary caregiver.
Attending Physician and Consultants

List the attending physician and all consultants who will participate in the care of the patient. In addition, one specifies which physician(s) and/or service(s) will be the primary providers of postoperative care and orders. The nursing staff must be clearly informed regarding who is contacted for questions about care and for any problems that arise.
Diagnosis

List the primary diagnosis and/or the procedure that has been performed.
Allergies

List any known drug allergies or other sensitivities (i.e., latex, tape, antibiotics, pain medications, etc.)

Admission Weight

The patient’s preoperative weight is specified. This is the weight that is used to calculate medication dosages, fluids, nutritional requirements, etc.

Vital Signs

Provide instructions for the frequency at which vital signs are monitored and recorded. Parameters for changes in vital signs that require notification of the surgical team are clearly specified.

Monitoring Equipment

List any special monitoring devices that are appropriate for postoperative care including pulse oximetry, apnea and/or cardiac monitors, etc.

Ventilator Settings and Respiratory Care

For patients requiring postoperative ventilatory support, specific instructions regarding ventilator mode, tidal volume, peak inspiratory pressure, inspired oxygen concentration, etc. are provided. If other respiratory interventions (i.e., nebulizers, chest physiotherapy, frequent suctioning) are required, specific written orders are made.

Intravenous Fluids

Maintenance and replacement fluid orders are provided.

Diet

Special diets (i.e., clear liquids, general diet) or oral restriction (i.e., NPO) are specified, including orders for initiation of enteral tube feedings when applicable.

Activity

Level of activity and/or restriction (i.e., bedrest, ambulation, etc.) is specified. Physical therapy may be helpful to some hospitalized patients and is initiated when appropriate.

Medications

All medications including doses, routes of administration, and frequencies of administration are recorded clearly and accurately. Analgesic and antiemetic medications are ordered when appropriate. Doses are calculated on a per weight basis.

Wound Care

Special instructions for dressing care or surgical wounds are provided when applicable.

Drains

Drain care orders include specific requests for suction, stripping, frequency of emptying, and quantification of output. Nasogastric tubes are placed to suction or gravity drainage according to attending surgeon preference. Foley catheters are placed to gravity drainage.

Special Studies

Any radiographic exams or follow-up studies are specified, and the radiology department and/or attending radiologist should be notified of all requests. Chest radiographs are obtained in the recovery room or intensive care unit for all patients who remain intubated or who had intraoperative placement of central venous lines or catheters.

Laboratory Tests

Routine laboratory testing is often not necessary in pediatric surgical patients, especially those who have procedures in the surgicenter and are discharged shortly after surgery. Specific laboratory studies are obtained if the results are expected to alter clinical management of the patient. Laboratory tests are often indicated in children who undergo extensive and complicated procedures.

Pain Management

Achieving adequate pain relief is important in children, although children often do not or cannot complain specifically of pain. Pain may adversely affect recovery of infants since painful stimuli may result in decreased arterial saturation and increased pulmonary vascular resistance. Effective pain control allows earlier ambulation and faster recovery in older children.

Local anesthetics administered in the operating room can provide prolonged pain control. Local wound infiltration or regional nerve blocks with bupivicaine (Sensorcaine®) provide pain control for 4-6 hours following an operation. The maximum dose is 3 mg/kg given as a 0.25–0.75% solution.

For larger operations, intravenous narcotics provide excellent pain control. Liberal use of patient controlled analgesia devices and epidural catheters improve postoperative pain control after many abdominal or thoracic operations.

Preoperative Care

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Consultation

Prior to surgery for any patient, surgical consultation occurs. This provides a meeting and introduction between child and surgeon and proceeds to a complete history and physical examination. Since many children meet a surgeon for the first time on referral, the results of a prior history and physical examination are often available. If that is the case the previous findings are reviewed, verified, and further information is sought that may elucidate the diagnosis.

The meeting may be brief but creates the foundation for further interaction between surgeon and child. It is certainly an opportunity for the surgeon to create a friendship, or at least trust, between a frightened child and the person who will ultimately perform surgery. This meeting also is the chance to create communication and trust with anxious parents. Consequently, child and parents must be given adequate opportunity to present their understanding of the diagnosis, raise questions concerning surgery and in-hospital care, and discuss worrisome questions such as pain control, postoperative management, ultimate outcome and long-term results.

If a crowded clinic schedule precludes adequate time to cover all aspects of anticipated surgery, it is quite appropriate to schedule further visits or simply to arrange time for phone conferences with all concerned. Frequently, the surgeon can include other significant family members (grandparents, aunts, and uncles, siblings) by arranging for evening phone conversations.

Since many presurgical patients have already undergone diagnostic testing, it is important to review these tests and share the surgeon’s interpretation with the child and family. Sometimes this entails consultation with other specialists at the children’s hospital (radiologist, pathologists, and pediatric subspecialists). The results of these consultations will generally not be available at the time of the surgical consultation, but the results or discussion can easily be shared with child and family members via phone, e-mail, or fax. Communication at present is one of the easier, but most important, aspects of patient care.

Physical Examination

Abnormal findings on physical examination are often reported to a surgeon prior to the patient encounter. This does not preclude another examination at the time of the consultation visit. Additional findings may be demonstrated, and certainly one wishes to confirm the previously reported findings. Such simple matters as hernias or hydroceles are often confused and need the careful reexamination of the pediatric
surgeon to clarify. In addition, associated findings, well known to the pediatric surgeon, may not be common knowledge to the referring pediatrician or family practitioner. Therefore, a good physical examination is always advisable prior to surgical intervention.

Diagnostic Studies and Laboratory Investigations

The need for diagnostic studies varies from none to extensive. In the case of a child with a reducible inguinal hernia, a good, but simple, physical examination constitutes the best diagnostic study. Further tests, radiographs, blood examinations, etc. are invasive, bothersome, expensive and unwarranted unless there are other findings or complaints. However, the child who presents with severe, recurrent abdominal pain without any physical findings may need extensive studies to demonstrate the causative pathology (or lack thereof). Suffice to say, diagnostic studies are chosen and done that are needed to completely and safely make a diagnosis and sufficient to advise a child and family concerning the need for surgical intervention.

It is clear that a healthy child on a standard diet requires nothing as far as preoperative testing if the surgical problem is simple, can be done under outpatient general anesthetic without hospital stay. For example, a two-year-old child with uncomplicated bilateral inguinal hernias, eating until a few hours before surgery, whose cheeks and lips betray no sign of anemia can and should undergo operative repair without diagnostic testing. Careful questioning of the family history adequately excludes inherited diseases and bleeding dyscrasias. Examination of the child provides all the further information needed to make a correct decision concerning the need for further tests. In contrast, a two-year-old child with previous diagnosis of biliary atresia with unsuccessful Kasai procedure and progressive biliary cirrhosis clearly needs a very complicated and extensive diagnostic evaluation to allow a determination as to whether he can undergo hepatic transplantation.

In summary, the diagnostic regimen is designed to be sufficiently brief or thorough to correctly and adequately identify the surgical problem(s) and formulate the best and safest surgical plan.

Pain Management

One of the greatest concerns for child or parents when approaching a surgical event is the problem of postoperative pain control. Most children are not particularly concerned about the technical details of the surgery they will undergo, but they are greatly fearful of the pain that they endure in the postoperative period. Knowledge that this can be controlled in a variety of ways provides some comfort. Knowledge that they will also be in the company of their parents during this period of time is also vitally important.

Consequently, the consultation visit or phone conferences include a thorough discussion of postoperative pain management. Commonly used methods of pain control include intraoperative local anesthetic administration, intravenous narcotics, patient controlled analgesia, caudal blocks, epidural blocks and continuous epidural anesthesia. Although these can all be discussed before the surgical event, it is generally best to provide at least one to two hours in the preanesthetic room so this can be discussed a second time with the anesthesia staff. This is the time of the final decision concerning the exact pain control methods to be used. Since this is often tailored to fit the anesthesia used during the operative event, the anesthesiologist is included in this decision.

Blood Donation

Due to the tremendous information on the hazards of blood transfusion, most parents want to discuss possible transfusion thoroughly. Since transfusion is a rare event, discussion can be limited to acknowledgement that transfusion is most unlikely, and so much so that blood is not routinely prepared for the operation anticipated. In the event that transfusion is a possibility, discussion centers on the use of banked blood versus donor directed blood. This is both a controversial and emotional subject so it is sometimes necessary to involve the director of the blood bank service to fully elucidate the questions posed. Parents must fully understand that blood samples will be necessary from child and donors prior to the surgical date. Furthermore, they need to fully understand that all donor directed blood is subjected to the same testing required for all other blood donations. Finally, parents need to understand that type match does not necessarily predict cross match and that fulfillment of all these requirements requires adequate time before the surgery date.

Presurgical Visitation and Teaching

Most children’s hospitals provide a presurgical visitation and teaching program. These programs allow children to visit all portions of the operative suite prior to surgery. They become familiar with the holding area, the operating room, and the postanesthesia recovery area. They have an opportunity to try on “scrubs”, gowns, masks and caps. The nurses from the various areas answer questions, reassure the children of their parent’s nearness and participation in the entire process, and particularly address concerns about postoperative pain. In our particular hospital, the children conclude the visit by making a mural that is taped to the entry hall wall. As the children pass to the operating rooms, they can look for their previous artwork. We hope it lessens their anxiety and certainly endorse the use of these programs if available.

METABOLIC DISORDERS IN THE NEWBORN INFANT

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HYPERGLYCEMIA

Hyperglycemia may develop in preterm infants, particularly those of very low birth weight who are also SGA. Glucose concentrations may exceed 200–250 mg/dL, particularly in the first few days of life. This transient diabetes-like syndrome usually lasts approximately 1–2 weeks.
Management may include simply reducing glucose intake while continuing to provide supplemental calories with intravenous amino acids and lipids, coupled with small milk feedings by gavage. Insulin infusions intravenously have also been used to permit a larger intravenous glucose intake without hyperglycemia. This is usually reserved for infants in whom it has not been possible to begin any gavage milk feedings and in whom caloric intake in the form of amino acids and lipids is small. However, this approach requires careful direct monitoring of blood glucose concentrations. Hyperglycemia can also be a problem in infants treated with dexamethasone for chronic lung disease.

HYPOCALCEMIA

Calcium concentration in the immediate newborn period decreases in all newborn infants. The concentration in fetal plasma is higher than that of the neonate or adult. Hypocalcemia is usually defined as a total serum concentration less than 7 mg/dL (equivalent to a calcium activity of 3.5 mEq/L), although the physiologically active fraction, ionized calcium, should be measured whenever possible. Ionized calcium is usually normal even when total calcium is as low as 6–7 mg/dL. An ionized calcium of greater than 0.9 µmol/L (1.8 mEq/L; 3.6 mg/dL) is not likely to be detrimental.

Clinical Findings
The clinical signs of hypocalcemia and hypocalcemic tetany include a high-pitched cry, jitteriness, tremulousness, and seizures.
Hypocalcemia tends to occur at two different times in the neonatal period. Early-onset hypocalcemia occurs in the first 2 days of life and has been associated with prematurity, maternal diabetes, asphyxia, and, rarely, maternal hypoparathyroidism. Late-onset hypocalcemia occurs at approximately 7–10 days and is observed in infants receiving modified cow’s milk rather than infant formula (high phosphorus intake) or in infants with hypoparathyroidism or hypomagnesemia. Mothers in third-world countries often have vitamin D deficiency, which can also contribute to late-onset hypocalcemia.

Treatment

A. Oral Calcium Therapy: The oral administration of calcium salts is a preferred method of treatment for chronic forms of hypocalcemia resulting from hypoparathyroidism but is rarely used in early-onset hypocalcemia. Calcium in the form of calcium gluconate can be given as a dilute solution or added to formula feedings several times a day. A dose of 0.5–1 g/kg/d provides approximately 45–90 mg of elemental calcium per kilogram per day. If a 10% solution of calcium gluconate is used, the dose is 5–10 mL/kg/d given in divided doses every 4 hours or every 6 hours.

B. Intravenous Calcium Therapy: Intravenous calcium therapy is usually needed for infants with symptomatic hypocalcemia or an ionized calcium less than 0.9 µmol/L. A number of precautions must be observed when calcium gluconate is given intravenously. The infusion must be given slowly so that there is no sudden increase in calcium concentration of blood entering the right atrium, which could cause severe bradycardia and even cardiac arrest. Furthermore, the infusion must be observed carefully, because an intravenous infiltrate containing calcium can cause full-thickness skin necrosis requiring grafting. For these reasons, intravenous calcium therapy should be given judiciously and through a central venous line if possible. Intravenous administration of 10% calcium gluconate is usually given as a bolus of 100–200 mg/kg over approximately 10–20 minutes, followed by a continuous infusion (0.5–1 g/kg/d) over 1–2 days. Ten percent calcium chloride (20 mg/kg per dose) may result in a larger increment in ionized calcium and greater improvement in mean arterial blood pressure in sick hypocalcemic infants and thus may have a role in the newborn. Note: Calcium salts cannot be added to intravenous solutions that contain sodium bicarbonate because they precipitate as calcium carbonate.

Prognosis
The prognosis is good for neonatal seizures entirely caused by hypocalcemia that is promptly treated.

INBORN ERRORS OF METABOLISM

The individual inborn errors of metabolism are rare, but collectively all such disorders create significant clinical problems. The diseases are considered in detail in Chapter 31, but the diagnoses should be entertained in infants who were initially well that present with sepsis-like syndromes, recurrent hypoglycemia, neurologic syndromes (seizures, altered levels of consciousness), and unexplained acidosis.
In the immediate neonatal period, urea cycle disorders commonly present as altered level of consciousness secondary to hyperammonemia. A clinical clue that supports this diagnosis is hyperventilation with primary respiratory alkalosis. The other major diagnostic category to consider consists of infants with severe acidemia secondary to organic acidemias.

NEUROLOGIC PROBLEMS IN THE NEWBORN INFANT

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SEIZURES

Newborns rarely have well-organized tonic-clonic seizures because of their incomplete cortical organization and a preponderance of inhibitory synapses. The most common type of seizure is characterized by a constellation of findings, including horizontal deviation of the eyes with or without jerking; eyelid blinking or fluttering; sucking, smacking, drooling, and other oral-buccal movements; swimming, rowing, or paddling movements; and apneic spells. Strictly tonic or multifocal clonic episodes are also seen.

Clinical Findings
The differential diagnosis of neonatal seizures is presented in Table 1–28. Most neonatal seizures occur between 12 and 48 hours of age. Later-onset seizures suggest meningitis, benign familial seizures, or hypocalcemia. Information regarding antenatal drug use, the presence of birth asphyxia or trauma, and family history (regarding inherited disorders) should be obtained. Physical examination focuses on neurologic features, other signs of drug withdrawal, concurrent signs of infection, dysmorphic features, and intrauterine growth. Screening workup should include blood glucose, ionized calcium, and electrolytes in all cases. Further workup is dependent on diagnoses suggested by the history and physical examination. If there is any suspicion of infection, a spinal tap should be done. Hemorrhages and structural disease of the CNS can be addressed with real-time ultrasound and CT scan. Metabolic workup should be pursued when appropriate. EEG should be done; the presence of spike discharges must be noted and the background wave pattern evaluated. Not infrequently, correlation between EEG changes and clinical seizure activity is absent.

Treatment
Adequate ventilation and perfusion should be ensured. Hypoglycemia should be treated immediately with a 2 mL/kg infusion of D10W followed by 6 mg/kg/min of D10W (100 mL/kg/d). Other treatments such as calcium or magnesium infusion and antibiotics are indicated to treat hypocalcemia, hypomagnesemia, and suspected infection. Electrolyte abnormalities should be corrected. Phenobarbital, 20 mg/kg intravenously, should be administered to stop seizures. Supplemental doses of 5 mg/kg can be used if seizures persist, up to a total of 40 mg/kg. In most cases, phenobarbital controls seizures. If seizures continue, therapy with phenytoin, sodium valproate, or lorazepam may be indicated. For refractory seizures, a trial of pyridoxine is indicated.

Prognosis
Outcome is related to the underlying cause of the seizure. The outcomes for hypoxic-ischemic encephalopathy and intracranial hemorrhage have been discussed earlier in this chapter. In these settings, seizures that are difficult to control carry a poor prognosis for normal development. Seizures resulting from hypoglycemia, infection of the CNS, some inborn errors of metabolism, and developmental defects also have a high rate of poor outcome. Seizures caused by hypocalcemia or isolated subarachnoid hemorrhage generally resolve without sequelae.

HYPOTONIA

One should be alert to the diagnosis of congenital hypotonia when a mother has polyhydramnios and a history of poor fetal movement.

INTRACRANIAL HEMORRHAGE

1. SUBDURAL HEMORRHAGE
Subdural hemorrhage is related to birth trauma; the bleeding is caused by tears in the veins that bridge the subdural space. Prospective studies relating incidence to specific obstetric complications are not available.
The most common site of subdural bleeding is rupture of superficial cerebral veins with blood over the cerebral convexities. These hemorrhages can be asymptomatic or may cause seizures, with onset on days 2–3 of life, vomiting, irritability, and lethargy. Associated findings include retinal hemorrhages and a full fontanelle. The diagnosis is confirmed by CT scan.
Specific treatment entailing needle drainage of the subdural space is rarely necessary. Most infants survive; 75% are normal on follow-up.

2. PRIMARY SUBARACHNOID HEMORRHAGE
Primary subarachnoid hemorrhage is the most common type of neonatal intracranial hemorrhage. In the term infant, it can be related to trauma of delivery, whereas subarachnoid hemorrhage in the preterm infant is seen in association with germinal matrix hemorrhage. Clinically, these hemorrhages can be asymptomatic or can occur with seizures and irritability on day 2 or, rarely, a massive hemorrhage with a rapid downhill course. The seizures associated with subarachnoid hemorrhage are very characteristic—usually brief, with a normal examination interictally. Diagnosis can be suspected on spinal tap and confirmed with CT scan. Long-term follow-up is uniformly good.

3. NEONATAL STROKE
Focal cerebral ischemic injury can occur in the context of intraventricular hemorrhage in the premature infant and hypoxic ischemic encephalopathy. Neonatal stroke has also been described in the context of underlying disorders of thrombolysis and maternal drug use (cocaine). In some cases, the origin is unclear. The injury often occurs antenatally. The most common clinical presentation of an isolated cerebral infarct is with seizures, and diagnosis can be confirmed with CT scan. The most frequently described distribution is that of the middle cerebral artery.
Treatment is directed at controlling seizures. Long-term outcome is variable, ranging from normal to hemiplegias and cognitive deficits.

RENAL DISORDERS IN THE NEWBORN INFANT

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Renal function depends on postconceptional age. The glomerular filtration rate (GFR) is 20 mL/ min/1.73 m2 in term neonates and 10–13 mL/min/ 1.73 m2 in infants born at 28–30 weeks’ gestation. The velocity of maturation after birth is also dependent on postconceptional age. Creatinine can be used as a clinical marker of GFR. Values in the first month of life are shown in Table 1–27. Creatinine at birth reflects the maternal level and should decrease slowly over the first 3–4 weeks. An increasing serum creatinine is never normal. The ability to concentrate urine and retain sodium is also dependent on gestational age. Infants born at less than 28–30 weeks’ gestation are compromised in this respect and if not observed carefully can become dehydrated and hyponatremic. Preterm infants also have an increased bicarbonate excretion and a low tubular maximum for glucose (approximately 120 mg/dL).

RENAL FAILURE

Renal failure is most commonly seen in the setting of birth asphyxia, hypovolemia, or shock from any cause. The normal rate of urine flow is 1–3 mL/kg/h. After a hypoxic or ischemic insult, acute tubular necrosis may ensue. Typically, there are 2–3 days of anuria or oliguria associated with hematuria, proteinuria, and a rise in serum creatinine. The period of anuria or oliguria is followed by a period of polyuria and then gradual recovery. During the polyuric phase, excessive urine sodium and bicarbonate losses may be seen.
The initial step in management is restoration of the infant’s volume status as needed. Thereafter, restriction of fluids to insensible water loss (40–60 mL/ kg/d) without added electrolytes, plus milliliter-for-milliliter urine replacement, should be instituted. Serum and urine electrolytes and body weights should be followed frequently. These measures should be continued through the polyuric phase. After urine output has been reestablished, urine replacement should be decreased to between 0.5 and 0.75 mL for each milliliter of urine output to see if the infant has regained normal function. If that is the case, the infant can be returned to maintenance fluids.
Finally, many of these infants experience fluid overload and should be allowed to lose enough water through urination to return to birth weight. Hyperkalemia, which may become life-threatening, may occur in this situation despite the lack of added intravenous potassium. If the serum potassium reaches 7–7.5 mEq/L, therapy should be started with glucose and insulin infusion, giving 1 unit of insulin for every 3 g of glucose administered, plus binding resins. Calcium gluconate (100 mg/kg bolus) can also be helpful for arrhythmia resulting from hyperkalemia.
Peritoneal dialysis is occasionally needed for the management of neonatal acute renal failure.

URINARY TRACT ANOMALIES

Abdominal masses in the newborn are most frequently caused by renal enlargement. Most common is a multicystic or dysplastic kidney; congenital hydronephrosis is second in frequency. Chromosomal abnormalities and syndromes with multiple anomalies frequently include renal abnormalities. An ultrasound examination is the first step in diagnosis. In pregnancies associated with oligohydramnios, renal agenesis or obstruction secondary to posterior urethral valves should be considered. Only bilateral disease or disease in a solitary kidney is associated with oligohydramnios, significant morbidity, and death. Such infants will generally also have pulmonary hypoplasia and die from pulmonary rather than renal insufficiency.
Prenatal ultrasonography identifies infants with renal anomalies (most often hydronephrosis) prior to birth. Postnatal evaluation of these infants should include renal ultrasound and a voiding cystourethrogram at about 1 week of age. Until genitourinary reflux is ruled out, these infants should receive antibiotic prophylaxis with low-dose penicillin or ampicillin.

RENAL VEIN THROMBOSIS

Renal vein thrombosis occurs most often in IDMs and in the context of dehydration and polycythemia. Of particular concern is the IDM who is also polycythemic. If fetal distress is superimposed on these problems, prompt reduction in blood viscosity is indicated. Thrombosis usually begins in intrarenal venules and can extend into larger veins. Clinically, there may be an enlarged kidney, with blood and protein in the urine. With bilateral renal vein thrombosis, anuria ensues. Diagnosis can be confirmed with an ultrasound examination that includes Doppler flow studies of the kidneys. Treatment involves correcting the predisposing condition and systemic heparinization for the thrombosis. Use of thrombolytics for this condition is controversial. Prognosis for a full recovery is uncertain. Some infants will go on to develop significant atrophy of the affected kidney and systemic hypertension.

HEMATOLOGIC DISORDERS IN THE NEWBORN INFANT

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BLEEDING DISORDERS

Neonatal coagulation is discussed in Chapter 26. Bleeding in the newborn infant may result from inherited clotting deficiencies (eg, factor VIII deficiency) or acquired disorders—hemorrhagic disease of the newborn, disseminated intravascular coagulation (DIC), liver failure, and thrombocytopenia.

1. HEMORRHAGIC DISEASE IN THE NEWBORN INFANT
Hemorrhagic disease in the newborn infant is caused by the deficiency of the vitamin K–dependent clotting factors (II, VII, IX, and X). Bleeding occurs in 0.25–1.7% of newborns who do not receive vitamin K prophylaxis after birth, generally in the first 5 days to 6 weeks in an otherwise well infant. Sites of ecchymoses and surface bleeding include the gastrointestinal tract, umbilical cord, circumcision site, and nose, although devastating intracranial hemorrhage can occur. Bleeding from vitamin K deficiency is more likely to occur in infants of mothers taking hydantoin anticonvulsants or warfarin and in breastfed infants because of very low amounts of vitamin K in breast milk, with slower and more restricted intestinal colonization. Differential diagnosis includes DIC and hepatic failure, both occurring in ill infants .
Treatment consists of 1 mg of vitamin K subcutaneously or intravenously. Intramuscular injections should be avoided in infants who are bleeding.

2. THROMBOCYTOPENIA
Infants with thrombocytopenia have generalized petechiae (not just on the presenting part) and platelet counts under 150,000/µL (usually < 50,000/µL, may be < 10,000/µL). Neonatal thrombocytopenia can be isolated or may occur in association with a deficiency of clotting factors. The differential diagnosis for thrombocytopenia with distinguishing clinical features is presented in Table 1–25. Treatment of neonatal thrombocytopenia is transfusion of platelets (10 mL/kg of platelets increases the platelet count by approximately 70,000/µL). Indications for transfusion in the term infant are clinical bleeding or a total platelet count less than 10,000–20,000/µL. In the preterm infant at risk for intraventricular hemorrhage, transfusion is indicated for counts less than 40,000–50,000/µL.
Isoimmune thrombocytopenia (analogous to Rh isoimmunization, with a PLA-1-negative mother and PLA-1-positive fetus) requires transfusion of maternal platelets, because 98% of the random population will also be PLA-1-positive. The mother would be the most readily available known PLA-1-negative donor. Treatment with steroids has been disappointing. Treatment with IVIG infusion, 1 g/kg/d for 3 days or until the platelet count has doubled or is over 50,000/µL, is recommended. Antenatal therapy of the mother with IVIG with or without steroids is also beneficial, since 20–30% of infants with isoimmune thrombocytopenia will experience intracranial hemorrhage, half of them before birth.
Infants born to mothers with idiopathic thrombocytopenic purpura are at low risk for serious hemorrhage despite the thrombocytopenia, and treatment is usually unnecessary. If bleeding does occur, a 1- to 2-week course of prednisone, 2 mg/kg/d, is recommended. If severe hemorrhage is present, IVIG can also be used.

ANEMIA

The newborn infant with anemia from acute blood loss presents with signs of hypovolemia (tachycardia, poor perfusion, hypotension), with an initially normal hematocrit that falls after volume replacement. Anemia from chronic blood loss is evidenced by pallor without signs of hypovolemia, with an initially low hematocrit and reticulocytosis.
Anemia can be caused by hemorrhage, hemolysis, or failure to produce red blood cells. Anemia occurring in the first 24–48 hours of life is the result of hemorrhage or hemolysis. Hemorrhage can occur in utero (fetoplacental, fetomaternal, or twin-to-twin), perinatally (cord rupture, placenta previa, incision through placenta at cesarean section), or internally (intracranial hemorrhage, cephalohematoma, ruptured liver or spleen). Hemolysis is caused by blood group incompatibilities, enzyme or membrane abnormalities, infection, and DIC, and is accompanied by significant hyperbilirubinemia.
Initial evaluation should include a review of the perinatal history, assessment of the infant’s volume status, and a complete physical examination. A Kleihaur-Betke test for fetal cells in the mother’s circulation should be done. A complete blood count, blood smear, reticulocyte count, and direct and indirect Coombs tests should be performed. This simple evaluation should suggest a diagnosis in most infants. It is important to remember that hemolysis related to blood group incompatibility will continue for weeks after birth. Serial hematocrits should be followed.

POLYCYTHEMIA

Polycythemia in the newborn is manifested by plethora, cyanosis, mild respiratory distress with tachypnea and oxygen need, hypoglycemia, poor feeding, emesis, and lethargy. The capillary hematocrit is > 68%, the venous hematocrit > 65%.
Elevated hematocrits occur in 2–5% of live births. Although 50% of polycythemic infants are AGA, the prevalence of polycythemia is greater in the SGA and LGA populations. Causes of increased hematocrit include (1) twin-twin transfusion, (2) maternal-fetal transfusion, (3) intrapartum transfusion from the placenta, and (4) chronic intrauterine hypoxia (SGA infants, LGA infants of diabetic mothers).
The consequence of polycythemia is hyperviscosity with decreased perfusion of the capillary beds. Clinical symptomatology can affect several organ systems (Table 1–26). Screening can be done by measuring a capillary (heel stick) hematocrit. If the value is greater than 68%, a peripheral venous hematocrit should be measured. Values greater than 65% should be considered consistent with hyperviscosity.
Treatment is recommended for symptomatic infants. Treatment for asymptomatic infants based strictly on hematocrit is controversial. Definitive treatment is accomplished by an isovolumic partial exchange transfusion with 5% albumin or normal saline, effectively decreasing the hematocrit. The amount to exchange (in milliliters) is calculated using the following formula:

where PVH = peripheral venous hematocrit, DH = desired hematocrit, BV = blood volume, and Wt = weight.

Blood is withdrawn at a steady rate from an umbilical venous line while the replacement solution is infused at the same rate through a peripheral intravenous line over 15–30 minutes. The desired hematocrit value is 50–55%; the assumed blood volume is 80 mL/kg.

INFECTIONS IN THE NEWBORN INFANT

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The fetus and the newborn infant are very susceptible to infections. There are three major routes of perinatal infection: (1) blood-borne transplacental infection of the fetus (eg, cytomegalovirus, rubella, syphilis); (2) ascending infection with disruption of the barrier provided by the amniotic membranes (eg, bacterial infections after 12–18 hours of ruptured membranes); and (3) infection upon passage through an infected birth canal or exposure to infected blood at delivery (eg, herpes simplex, hepatitis B, bacterial infections).
Susceptibility of the newborn infant to infection is related to immaturity of both the cellular and humoral immune systems at birth. This feature is particularly evident in the preterm neonate. Passive protection against some organisms is provided by transfer of IgG across the placenta during the third trimester of pregnancy. Preterm infants, especially those born at less than 30 weeks’ gestation, do not have the benefit of the full amount of this passively acquired antibody.

BACTERIAL INFECTIONS

1. BACTERIAL SEPSIS

Essentials of Diagnosis & Typical Features
Most infants with early-onset sepsis present at <>
Respiratory distress is the most common presenting symptom.
Hypotension, acidemia, and neutropenia are associated clinical findings.
The presentation of late-onset sepsis is more subtle.

General Considerations
The incidence of early-onset (< 5 days) neonatal bacterial infection is 4–5 per 1000 live births. If rupture of the membranes occurs more than 24 hours prior to delivery, the infection rate increases to 1 per 100 live births. If there is early rupture of membranes with chorioamnionitis, the infection rate increases further to 1 per 10 live births. Irrespective of membrane rupture, infection rates are five times higher in preterm than in term infants.

Clinical Findings
Early-onset bacterial infections appear most commonly on day 1 of life, and the majority of cases appear at less than 12 hours. Respiratory distress due to pneumonia is the most common presenting sign. Other features include unexplained low Apgar scores without fetal distress, poor perfusion, and hypotension. Late-onset bacterial infection (at more than 5 days of age) presents in a more subtle manner, with poor feeding, lethargy, hypotonia, temperature instability, altered perfusion, new or increased oxygen requirement, and apnea. Late-onset bacterial sepsis is more often associated with meningitis or other localized infections.
Low total white counts, absolute neutropenia (< 1000/µL), and elevated ratios of immature to mature neutrophils are suggestive of neonatal bacterial infection. Thrombocytopenia is also a common feature. Other laboratory signs are hypoglycemia or hyperglycemia with no change in glucose administration and unexplained metabolic acidosis. In early-onset bacterial infection, pneumonia is invariably present; chest x-ray films show infiltrates, but these infiltrates cannot be distinguished from those resulting from other causes of neonatal lung disease. Definitive diagnosis is made by positive cultures from blood, CSF, and the like.
Early-onset infection is most often caused by group B b-hemolytic streptococci (GBS) and gram-negative enteric pathogens (most commonly E coli). Another organism to consider is Haemophilus influenzae. Late-onset sepsis is caused by coagulase-negative staphylococci (most common in infants with indwelling central venous lines), Staphylococcus aureus, GBS, Enterococcus, Pseudomonas, and other gram-negative organisms.

Treatment
A high index of suspicion is important in the diagnosis and treatment of neonatal infection. Table 1–22 presents guidelines for the evaluation and management of term infants with risk factors or clinical signs of infection. Because the risk of infection is greater in the preterm infant and because respiratory disease is a common sign of infection, any preterm infant with respiratory disease requires blood cultures and broad-spectrum antibiotic therapy for 48–72 hours pending the results of cultures. An examination of CSF should be performed when infection is highly suspected on a clinical basis (eg, associated hypotension, persistent metabolic acidosis, neutropenia). Antibiotic coverage should be directed initially toward suspected organisms. Early-onset sepsis is usually caused by GBS or gram-negative enteric organisms; broad-spectrum coverage, therefore, should include ampicillin plus an aminoglycoside or third-generation cephalosporin—eg, ampicillin, 100 mg/kg/d divided every 12 hours, and gentamicin, 2.5 mg/kg/dose every 12–24 hours (depending on gestational age), or cefotaxime, 100 mg/kg/d divided every 12 hours. Late-onset infections can also be caused by the same organisms, but coverage may need to be expanded to include staphylococci. In particular, the preterm infant with an indwelling line is at risk for infection with coagulase-negative staphylococci, for which vancomycin is the drug of choice in a dosage of 10 mg/kg every 8–24 hours depending on gestational and postnatal ages. Other supportive therapy includes the administration of intravenous immune globulin (500–750 mg/kg) to infants with known overwhelming infection. The duration of treatment for proved sepsis is 10–14 days of intravenous antibiotics. In addition, recombinant human granulocyte colony-stimulating factor (rhG-CSF) is under investigation for treatment of neutropenia in the septic infant. In sick infants, the essentials of good supportive therapy should be provided: intravenous glucose, volume expansion, use of pressors as needed, and oxygen and ventilator support.
Prevention of neonatal GBS infection has been achieved with intrapartum administration of penicillin to selected maternal GBS carriers identified antepartum or intrapartum who have associated risk factors (preterm labor, premature rupture of the membranes before 37 weeks, rupture of the membranes beyond 18 hours at any gestational age, multiple births, maternal fever). If maternal GBS status is unknown, chemoprophylaxis may be indicated for one or more of the risk factors listed above (Figure 1–9). Figure 1–10 presents a suggested strategy for the infant born to a mother who received intrapartum prophylaxis. Some authors also recommend selective neonatal prophylaxis with 50,000 U/kg of penicillin G given intramuscularly if adequate intrapartum treatment has not been given.

2. MENINGITIS
Any newborn with bacterial sepsis is also at risk for meningitis. The incidence is low in infants with early-onset sepsis but much higher in infants with late-onset infection. The workup for any newborn with signs of infection should include a spinal tap. Diagnosis is suggested by a CSF protein greater than 150 mg/dL, glucose less than 30 mg/dL, more than 25 leukocytes/µL, and a positive Gram stain. The diagnosis is confirmed by culture. The most common organisms are GBS and gram-negative enteric bacteria. Although sepsis can be treated with antibiotics for 10–14 days, meningitis should be treated for 21 days. The mortality rate of neonatal meningitis is approximately 25%, with significant neurologic morbidity present in one third of the survivors. Use of dexamethasone has not been studied in neonates.

3. PNEUMONIA
The respiratory system can be infected in utero or upon passage through the birth canal. Early-onset neonatal infection is usually associated with pneumonia. Pneumonia should also be suspected in older neonates with a recent onset of tachypnea, retractions, and cyanosis. In infants already receiving respiratory support, an increase in the requirement for oxygen or ventilator support may indicate pneumonia. Not only common bacteria but also viruses (cytomegalovirus, respiratory syncytial virus, adenovirus, influenza, herpes simplex, parainfluenza) and Chlamydia can cause the disease. In infants with preexisting respiratory disease, intercurrent pulmonary infections may contribute to the ultimate severity of chronic lung disease.

4. URINARY TRACT INFECTION
Infection of the urine is uncommon in the first days of life. Urinary tract infection in the newborn occurs most commonly in association with genitourinary anomalies and is caused by gram-negative enteric pathogens. Urine should be evaluated as part of the workup for late-onset infection. Culture should be obtained either by suprapubic aspiration or bladder catheterization. Antibiotic therapy is continued intravenously for 10–14 days. Evaluation for genitourinary anomalies, starting with an ultrasound examination and a voiding cystourethrogram, should be done subsequently.

5. OTITIS MEDIA
Otitis media occurs in a significant number of long-term nursery occupants. It is particularly common in infants who have had prolonged endotracheal intubation or an indwelling nasogastric feeding tube. Evaluation for infection in such an infant is not complete without an ear examination. Gram-negative enteric pathogens are more commonly found infecting agents in nursery occupants than in outpatients.

6. OMPHALITIS
A normal umbilical cord stump will atrophy and separate at the skin level. A small amount of purulent material at the base of the cord is common but can be minimized by keeping the cord open to air and cleaning the base with alcohol several times a day. The cord can become colonized with streptococci, staphylococci, or gram-negative organisms that can cause local infection. Infections are more common in cords manipulated for venous or arterial lines. Omphalitis is diagnosed when redness and edema develop in the soft tissues around the stump. Local and systemic cultures should be obtained. Treatment is with broad-spectrum intravenous antibiotics. Complications are determined by the degree of infection of the cord vessels and include septic thrombophlebitis, hepatic abscess, necrotizing fasciitis, and portal vein thrombosis. Surgical consultation should be obtained because of the potential for necrotizing fasciitis.

FUNGAL SEPSIS

With the survival of smaller, sicker infants, infection with Candida species has become more common. Infants of low birth weight with central lines who have had repeated exposures to broad-spectrum antibiotics are at highest risk. For infants of birth weight less than 1500 g, colonization rates of 27% have been demonstrated, with many of these infants developing cutaneous lesions. A much smaller percentage (2–5%) develop systemic disease.
Clinical features of fungal sepsis can be indistinguishable from those of late-onset bacterial sepsis but may be more subtle. Thrombocytopenia may be the earliest and only sign. Deep organ involvement (renal, eye, endocarditis) is commonly associated with systemic candidiasis. Treatment is with amphotericin B. In severe infections, flucytosine can be added for synergistic coverage. (See Chapter 38.)
Malassezia furfur is also seen in infants with central lines receiving intravenous fat emulsion. To eradicate this organism, as well as Candida species, it is necessary to remove the indwelling line.

CONGENITAL VIRAL & PARASITIC INFECTIONS

1. CYTOMEGALOVIRUS INFECTION
Cytomegalovirus (CMV) is the most common virus transmitted in utero. The incidence of congenital infection ranges from 0.2% to 2.2% of live births. Transmission of CMV can occur during either primary or reactivated infection in the mother. An important source of infection is children (especially those in a day care setting), who transmit the virus to parents and workers. The incidence of primary infection in pregnancy is 1–4%, with a 40% transplacental transmission rate to the fetus. Of these infants, 85–90% are asymptomatic at birth, whereas 10–15% have clinically apparent disease—hepatosplenomegaly, petechiae, small size for gestational age, microcephaly, direct hyperbilirubinemia, thrombocytopenia, intracranial calcifications, and chorioretinitis. The risk of neonatal disease is higher when the mother acquires the infection in the first half of pregnancy. The incidence of reactivated infection in pregnancy is less than 1%, with an incidence of clinically apparent disease of 0–1%. Diagnosis in the neonate should be confirmed by culture of the virus from urine. Rapid diagnosis is possible with antigen detection techniques and identification of viral DNA by polymerase chain reaction (PCR) testing. Diagnosis can also be confirmed in utero from an amniocentesis specimen. Although experimental and not routinely recommended, ganciclovir therapy has been used in some severely ill neonates.
The mortality rate in patients with symptomatic congenital CMV may be as high as 20%. Sequelae such as hearing loss, mental retardation, delayed motor development, chorioretinitis and optic atrophy, seizures, language delays, and learning disability occur in 90% of symptomatic survivors. The incidence of complications is 5–15% in asymptomatic infants; the most frequent complication is hearing loss, which can be progressive.
Perinatal infection can also occur with acquisition of virus around the time of delivery. These infections are generally asymptomatic and without sequelae. Postnatal infection is usually asymptomatic but can cause hepatitis, pneumonitis, and neurologic illness in compromised seronegative premature infants. The virus can be acquired postnatally through transfusions or ingestion of CMV-infected breast milk. Transfusion risk can be minimized by using frozen, washed red blood cells or CMV antibody-negative donors.

2. RUBELLA
Congenital rubella infection occurs as a result of rubella infection in the mother during pregnancy. The frequency of infection and damage in the fetus is as high as 80% in mothers infected during the first trimester. Fetal infection rates decline in the second trimester before increasing again in the third trimester. Fetal damage generally does not occur in infections acquired after 18 weeks’ gestation. Clinical features of congenital rubella include adenopathy, bone radiolucencies, encephalitis, cardiac defects (pulmonary arterial hypoplasia and patent ductus arteriosus), cataracts, retinopathy, growth retardation, hepatosplenomegaly, thrombocytopenia, and purpura. Affected infants can be asymptomatic at birth but develop clinical sequelae during the first year of life. The diagnosis should be suspected in cases of a characteristic clinical illness in the mother (rash, adenopathy, arthritis) confirmed by serologic testing. Diagnosis can be confirmed by culture of pharyngeal secretions in the baby. Congenital rubella is now rare because prevention is possible with immunization.

3. VARICELLA
Congenital varicella is rare (< 5% after infection acquired during the first or second trimester) but may cause a constellation of findings including limb hypoplasia, cutaneous scars, microcephaly, cortical atrophy, chorioretinitis, and cataracts. Perinatal exposure (5 days before to 2 days after delivery) can cause severe to fatal disseminated varicella in the infant. If maternal varicella develops within this perinatal risk period, 1.25 mL of varicella immune globulin should be given to the newborn. If this has not been done, the illness can be treated with intravenous acyclovir (30 mg/kg/d divided every 8 hours).
Hospitalized premature infants of at least 28 weeks’ gestation whose mothers have no history of chickenpox—and all infants of less than 28 weeks’ gestational age—should receive varicella immune globulin following any postnatal exposure.Susceptible women of childbearing age should be immunized with varicella vaccine.

4. TOXOPLASMOSIS
Toxoplasmosis is caused by the protozoan Toxoplasma gondii. Maternal infection occurs in 0.1– 0.5% of pregnancies and is usually asymptomatic. When primary infection occurs during pregnancy, up to 40% of the fetuses become infected, of whom 15% have severe damage. The sources of transmission include exposure to cat feces and ingestion of raw or undercooked meat. Although the risk of transmission increases to 90% near term, fetal damage is most likely to occur when maternal infection occurs in the second to sixth months of gestation.
Clinical findings include growth retardation, chorioretinitis, seizures, jaundice, hydrocephalus, microcephaly, cerebral calcifications, hepatosplenomegaly, adenopathy, cataracts, maculopapular rash, thrombocytopenia, and pneumonia. The majority of affected infants are asymptomatic at birth but show evidence of damage (chorioretinitis, blindness, low IQ, hearing loss) at a later time. Serologic tests, first for IgG and then for the specific IgM antibody, make the diagnosis. Infants with suspected infection should have an eye examination and CT scan. Organism isolation and PCR tests are also available for diagnosis in the neonate and from amniocentesis specimens.
Treatment of the acutely infected pregnant woman does not prevent transmission to the fetus but reduces the rate of sequelae. Neonatal treatment using pyrimethamine and sulfadiazine with folinic acid can improve long-term outcome. (See Chapter 38.)

PERINATALLY ACQUIRED VIRAL INFECTIONS

1. HERPES SIMPLEX
Herpes simplex virus (HSV) infection is most commonly acquired at the time of birth during transit through an infected birth canal. The mother may have either primary or reactivated secondary infection. Primary maternal infection, because of the high titer of organism and the absence of maternal antibodies, poses the greatest risk to the infant. The risk of neonatal infection with vaginal delivery in this setting is 33–50%. Seventy percent of mothers with primary herpes at the time of delivery are asymptomatic. The risk to an infant born to a mother with recurrent herpes simplex is much lower (< 3–5%). Time of presentation of localized (skin, eye, mouth) or disseminated disease (pneumonia, shock, hepatitis) in the infant is usually 5–14 days of age. CNS disease usually presents at 14–28 days with lethargy and seizures. In about one third of patients, localized skin, eye, and mouth disease is the first indication of infection. In another third, disseminated or CNS disease precedes skin, eye, and mouth findings, whereas the remaining third have disseminated or CNS disease in the absence of skin, eye, and mouth disease. Preliminary diagnosis can be made by scraping the base of a vesicle and finding multinucleated giant cells. Viral culture from vesicles, usually positive in 24–72 hours, makes the definitive diagnosis. In some cases, PCR DNA technology may assist in diagnosis.
Acyclovir (30–60 mg/kg/d given every 8 hours) is the drug of choice for neonatal herpes infection. Treatment improves survival of neonates with CNS and disseminated disease and prevents the spread of localized disease. Prevention is possible by not allowing delivery through an infected birth canal (eg, by cesarean section within 6 hours after rupture of the membranes). However, antepartum cervical cultures are poor predictors of the presence of virus at the time of delivery. Furthermore, given the low incidence of infection in the newborn in secondary maternal infection, cesarean section is not indicated for asymptomatic mothers with a history of herpes. In most settings, cesarean sections are still performed in mothers with active lesions (either primary or secondary) at the time of delivery. Infants born to mothers with a history of HSV infection but no active lesions can be observed closely after birth. Cultures should be obtained and acyclovir treatment initiated only for clinical signs consistent with herpes virus infection. Infants born to mothers with active lesions—irrespective of the route of delivery—should be cultured (eye, oropharynx, umbilicus, rectum) 24 hours after delivery. If the infant is colonized (positive cultures) or if symptoms consistent with herpes infection develop, treatment with acyclovir should be started. In cases of maternal primary infection at the time of vaginal delivery, the infant should be cultured and started on acyclovir pending the results of cultures. The major problem facing perinatologists is the high percentage of asymptomatic primary maternal infection. In these cases, infection in the neonate is currently not preventable. Therefore, any infant who presents at the right age with symptoms consistent with neonatal herpes should be cultured and started on acyclovir pending the results of those cultures.
The prognosis is good for localized skin and mucosal disease that does not progress. The mortality rate for both disseminated and CNS herpes is high, with significant rates of morbidity among survivors despite treatment.

2. HEPATITIS B & C
Infants can be infected with hepatitis B at the time of birth. Clinical illness is rare in the neonatal period, but infants exposed in utero are at high risk of becoming chronic HBsAg carriers, developing chronic active hepatitis and, later, hepatocellular carcinoma. The presence of HBsAg should be determined in all pregnant women. If the result is positive, the infant should receive HBIG and hepatitis B vaccine as soon as possible after birth, followed by two subsequent vaccine doses at 1 and 6 months of age. If HBsAg has not been tested prior to birth in a mother at risk, the test should be run after delivery and hepatitis B vaccine given within 12 hours after birth. If the mother is subsequently found to be positive, HBIG should be given as soon as possible (preferably within 48 hours, but not later than 1 week after birth). Subsequent vaccine doses should be given at 1 and 6 months of age. In premature infants born to HBsAg-positive mothers, vaccine and HBIG should be given at birth, but a three-vaccine hepatitis B series should be given after a weight of 2000 g is attained.
Hepatitis C perinatal transmissions occur in about 5% of infants born to mothers who carry the virus. At the present time, no prevention strategies exist.

3. ENTEROVIRAL INFECTION
Enteroviral infections occur with greatest frequency in the late summer and early fall. Infection is usually acquired in the perinatal period. There is often a history of maternal illness (fever, diarrhea, rash) in the week prior to delivery. The illness appears in the infant in the first 2 weeks of life and is most commonly characterized by fevers, lethargy, irritability, diarrhea, and rash but is not severe. More severe forms occasionally occur, including meningoencephalitis and myocarditis, as well as a disseminated illness with hepatitis, pneumonia, shock, and disseminated intravascular coagulation. Diagnosis can be confirmed by culture (rectum, CSF, blood) or by the more rapid PCR techniques.
There is no therapy of proved efficacy. The prognosis is good for all symptom complexes except severe disseminated disease, which carries a high mortality rate.

4. HIV INFECTION
Human immunodeficiency virus (HIV) can pass transplacentally, can be acquired at the time of delivery, or can be transmitted postpartum via breast milk. The prevalence of HIV infection among women of childbearing age in the United States is 1.5:1000. Transmission of virus occurs in about 30% of births. Administration of zidovudine during pregnancy, intrapartum, and for 6 weeks in the newborn period at a dosage of 2 mg/kg orally four times a day decreases vertical transmission to 8%. Shorter courses of zidovudine are also associated with decreased disease transmission, as is cesarean delivery. The addition of protease inhibitor therapy may further reduce the risk of ante- and intrapartum viral transmission. The risk of transmission is increased in mothers with advanced disease, low CD4 counts, and p24 antigenemia. Prematurity, vaginal delivery, ruptured membranes over 4 hours, and chorioamnionitis also increase the transmission rate. With zidovudine treatment, transmission of virus to the newborn correlates with maternal level of HIV-1 RNA. Diagnosis is based on clinical, immunologic, and serologic findings. Newborns with congenitally acquired HIV are often free of symptoms. Jaundice, neonatal giant cell hepatitis, and thrombocytopenia have been reported at birth. Failure to thrive, lymphadenopathy, hepatosplenomegaly, oral thrush, chronic diarrhea, bacterial infections with common organisms, and an increased incidence of upper and lower respiratory diseases, including lymphoid interstitial pneumonitis, may appear early in life or may be delayed for months to years.
The presence of maternal antibody acquired transplacentally confuses diagnosis in the neonate. The presence of anti-HIV antibody is not diagnostic of infection until after 18 months of age. An infant who is not infected should remain healthy, and the titer of antibody should decline during the first year of life. Diagnosis can be made in infants in the first few months of life by culture or detection of HIV DNA sequences by PCR. These tests should be done at birth and repeated at 1–2 months and 4 months of age. An infant who is age 4 months with no positive culture, PCR, or p24 antigen has a greater than 95% chance of not being infected. Follow-up should document antibody disappearance. An HIV-exposed infant is considered uninfected when there are no physical findings of HIV, immunologic tests are normal, virologic studies are negative, and two HIV antibody tests are negative.
Protection of health care workers is an important issue. Testing should be performed in all pregnant women. Because such testing will fail to identify some infected patients, however, universal precautions should be used. Gloves should be worn during all procedures involving blood and blood-contaminated fluids, intubation, and any invasive procedures using needles. When a splash exposure is possible (eg, in the delivery room), a mask and eye covers should be used.

OTHER INFECTIONS

1. CONGENITAL SYPHILIS
The infant is usually infected in utero by transplacental passage of Treponema pallidum. Active primary and secondary maternal syphilis leads to fetal infection in nearly 100% of infants; latent disease in 40%; and late disease in 10%. Fetal infection is rare at under 18 weeks’ gestation. Fetal infection can result in stillbirth or prematurity. Findings consistent with early congenital syphilis (presentation at under 2 years) include mucocutaneous lesions, lymphadenopathy, hepatosplenomegaly, bony changes, and hydrops. However, in the newborn period, infants are often asymptomatic, so that diagnosis is based on maternal and infant serologic testing and is only presumptive. Later manifestations (at over age 2 years) include Hutchinson disease and mulberry molars, keratitis, chorioretinitis, glaucoma, hearing loss, saddle nose, saber shins, and mental retardation. An infant should be evaluated for congenital syphilis if it is born to a mother with positive nontreponemal tests confirmed by a positive treponemal test but without documented adequate treatment (parenteral penicillin G), including the expected fourfold decrease in nontreponemal antibody titer. Evaluation should include physical examination, a quantitative nontreponemal serologic test for syphilis, CSF examination, long bone x-rays, and antitreponemal IgM. A definitive diagnosis can be made on rare occasions when the organism is identified by dark-field microscopy or pathologic examination of the placenta. Guidelines for therapy are presented in Table 1–23. Infants should be treated for congenital syphilis if they have proved or probable disease, as evidenced by (1) physical or x-ray evidence, (2) quantitative nontreponemal antibody titers four times higher than the mother, (3) elevated CSF protein or cell count or positive VDRL, or (4) a positive antitreponemal IgM test. Asymptomatic infants should be treated if the mother did not receive adequate treatment for syphilis.

2. TUBERCULOSIS
Congenital tuberculosis is rare but may occur in the infant of a mother with hematogenously spread tuberculosis or by aspiration of infected amniotic fluid in cases of tuberculous endometritis. Women with pulmonary tuberculosis are not likely to infect the fetus until after delivery. Postnatal acquisition is the most common mechanism of neonatal infection. Management in these cases is based on the mother’s evaluation.

Mother with a positive skin test and negative chest x-ray, or mother with an abnormal chest x-ray but no evidence of acute disease: Investigate family contacts. Treat the mother with isoniazid (INH).
Mother has an abnormal chest x-ray: Mother and infant should be separated until the mother is evaluated. If active tuberculosis is found, maintain separation until the mother is receiving antituberculosis therapy. Investigate family contacts.
Mother with clinical or x-ray evidence of acute and possibly contagious tuberculosis: Evaluate the infant for congenital tuberculosis (skin test, chest x-ray, lumbar puncture, cultures) and HIV. Treat the mother and infant and separate them until the mother is felt to be noncontagious. If congenital tuberculosis is suspected, multidrug therapy should be initiated.

3. CONJUNCTIVITIS
Neisseria gonorrhoeae may colonize an infant during passage through an infected birth canal. Gonococcal ophthalmitis presents at 3–7 days with purulent conjunctivitis. The diagnosis can be suspected when gram-negative intracellular diplococci are seen on a Gram-stained smear and confirmed by culture. Treatment is with intravenous or intramuscular ceftriaxone, 25–50 mg/kg (not to exceed 125 mg) given once. Prophylaxis at birth is with 1% silver nitrate or 0.5% erythromycin ointment. Infants born to mothers with known gonococcal disease should also receive a single dose of ceftriaxone.
Chlamydia trachomatis is another important cause of conjunctivitis, appearing at 5 days to several weeks of age with congestion, edema, and minimal discharge. The organism is acquired at birth after passage through an infected birth canal. Acquisition occurs in 50% of infants born to infected women, with a 25–50% risk of conjunctivitis. Prevalence in pregnancy is over 10% in some populations. Diagnosis is by isolation of the organism or by rapid antigen detection tests. Treatment is with oral erythromycin (30 mg/kg/d in divided doses every 8–12 hours) for 14 days. Topical treatment alone will not eradicate nasopharyngeal carriage, leaving the infant at risk for the development of pneumonitis. Infants born to mothers with untreated chlamydial infection should also be treated with oral erythromycin.

GASTROINTESTINAL & ABDOMINAL SURGICAL CONDITIONS IN THE NEWBORN INFANT

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ESOPHAGEAL ATRESIA & TRACHEOESOPHAGEAL FISTULA

Essentials of Diagnosis & Typical Features
Polyhydramnios.
Baby with excessive drooling and secretions, choking with attempted feeding.
Unable to pass an orogastric tube to the stomach.

General Considerations
These associated conditions are characterized by a blind esophageal pouch and a fistulous connection between the proximal or distal esophagus (or both) and the airway. In 85% of affected infants, the fistula is between the distal esophagus and the airway. Polyhydramnios is common because of the high level of gastrointestinal obstruction.

Clinical Findings
Infants present in the first hours of life with copious secretions, choking, cyanosis, and respiratory distress. Diagnosis can be confirmed with chest x-ray after careful placement of a nasogastric tube to the point at which resistance is met. On chest x-ray, the tube will be seen in the blind pouch. If a tracheoesophageal fistula is present to the distal esophagus, gas will be present in the bowel. In cases of esophageal atresia without tracheoesophageal fistula, there is no gas in the bowel.

Treatment
The tube in the proximal pouch should be placed on continuous suction to drain secretions and prevent aspiration. The head of the bed should be elevated to prevent reflux of gastric contents through the distal fistula into the lungs. Intravenous glucose and fluids should be provided and oxygen administered as needed. Definitive treatment is by operation and depends on the distance between the segments of esophagus. If the distance is not too great, the fistula can be ligated and the ends of the esophagus anastomosed. In instances in which the ends of the esophagus cannot be brought together, the initial surgery entails fistula ligation and a gastrostomy for feeding. Echocardiography should be performed prior to surgery to rule out a right-sided aortic arch. In those cases, a left-sided thoracotomy would be preferred.

Prognosis
Prognosis is determined primarily by the presence or absence of associated anomalies. Vertebral, anal, cardiac, renal, and limb anomalies are the most likely anomalies to be observed (VACTERL association). Evaluation for associated anomalies should be done early.

INTESTINAL OBSTRUCTION

Essentials of Diagnosis & Typical Features
Infants with high intestinal obstruction present soon after birth with emesis.
Bilious emesis represents a malrotation with midgut volvulus until proved otherwise.
Low intestinal obstruction is characterized by abdominal distention and late onset of emesis.

General Considerations
A history of polyhydramnios is common and the fluid, if bile-stained, can easily be confused with thin meconium staining. The higher the obstruction in the intestine, the earlier the infant will present with vomiting and the less prominent the distention will be. The opposite is true for lower intestinal obstructions. Most obstructions are bowel atresias, believed to be caused by an ischemic event during development. Approximately 30% of cases of duodenal atresia are associated with Down syndrome. Meconium ileus is a distal small bowel obstruction caused by the exceptionally viscous meconium produced by fetuses with cystic fibrosis. Hirschsprung disease is caused by a failure of neuronal migration to the myenteric plexus of the distal bowel so that the distal bowel lacks ganglion cells, causing a lack of peristalsis in that region with a functional obstruction.
Malrotation with midgut volvulus is a surgical emergency that appears in the first days to weeks as bilious vomiting without distention or tenderness. If malrotation is not treated promptly, torsion of the intestine around the superior mesenteric artery will lead to necrosis of the entire small bowel. For this reason, bilious vomiting in the neonate always demands immediate attention and evaluation.

Clinical Findings
Diagnosis of intestinal obstructions depends on plain abdominal radiographs with either upper GI series (high obstruction suspected) or contrast enema (lower obstruction apparent) to define the area of obstruction. Table 1–21 summarizes the findings expected.

All infants with meconium ileus are presumed to have cystic fibrosis. Infants with pancolonic Hirschsprung disease, colon pseudo-obstruction syndrome, or colonic dysgenesis or atresia may also present with meconium impacted in the distal ileum. Definitive diagnosis of cystic fibrosis is by the sweat chloride test (Na+ and Cl{–} concentration > 60 mEq/L) or by genetic testing. Approximately 10– 20% of infants with cystic fibrosis present with meconium ileus. Infants with cystic fibrosis and meconium ileus generally have a normal immunoreactive trypsinogen test because of the associated severe exocrine pancreatic insufficiency in utero.
Any in utero perforation results in meconium peritonitis with residual intra-abdominal calcifications. Many of these are completely healed at birth. If the infant has no signs of obstruction, no further immediate evaluation is needed. A sweat test to rule out cystic fibrosis should be done at a later date.
Low intestinal obstruction may present with delayed stooling (> 24 hours in term infants is abnormal) with mild distention. X-ray findings of gaseous distention should prompt contrast enema to diagnose (and treat) meconium plug syndrome. If no plug is found, the diagnosis may be small left colon syndrome (occurring in IDMs) or Hirschsprung disease. Rectal biopsy will be required to make this diagnosis. Imperforate anus should be apparent on physical examination, although a rectovaginal fistula with a mildly abnormal-appearing anus can occasionally be confused with normal.

Treatment
Nasogastric suction to decompress the bowel, intravenous glucose, fluid and electrolyte replacement, and respiratory support as necessary should be instituted. Antibiotics are usually indicated. The definitive treatment for most of these conditions (with the exception of meconium plug syndrome, small left colon syndrome, and some cases of meconium ileus) is surgery.

Prognosis
Up to 10% of infants with meconium plug syndrome are subsequently found to have cystic fibrosis or Hirschsprung disease. For this reason, some surgeons advocate performance of a sweat chloride test and rectal biopsy in all of these infants before discharge. The infant with meconium plug syndrome who is still symptomatic after contrast enema should have a rectal biopsy.
In cases of duodenal atresia associated with Down syndrome, the prognosis will depend on associated anomalies (eg, heart defects) and the severity of prestenotic duodenal dilation. Otherwise, these conditions usually carry an excellent prognosis after surgical repair.

ABDOMINAL WALL DEFECTS

1. OMPHALOCELE
Omphalocele is a membrane-covered herniation of abdominal contents into the base of the umbilical cord. There is a high incidence of associated anomalies (cardiac, gastrointestinal, chromosomal—eg, trisomy 13). The sac may contain liver and spleen as well as intestine.
Acute management of omphalocele involves covering the defect with a sterile dressing soaked with warm saline to prevent fluid loss, nasogastric decompression, intravenous fluids and glucose, and antibiotics. If the contents of the omphalocele will fit into the abdomen, a primary surgical closure is done. If not, a staged closure is performed, with gradual reduction of the omphalocele contents into the abdominal cavity and a secondary closure. Postoperatively, third-space fluid losses may be extensive; fluid and electrolyte therapy, therefore, must be monitored carefully.

2. GASTROSCHISIS
In gastroschisis, the intestine extrudes through an abdominal wall defect lateral to the umbilical cord. There is no membrane or sac and no liver or spleen outside the abdomen. Gastroschisis is associated with no anomalies except intestinal atresia. The herniation is thought to occur as a rupture through an ischemic portion of the abdominal wall.
Therapy is as described for omphalocele; however, primary closures can be successfully performed more frequently.

DIAPHRAGMATIC HERNIA
This congenital malformation consists of herniation of abdominal organs into the hemithorax (usually left) through a posterolateral defect in the diaphragm. It presents in the delivery room as severe respiratory distress in an infant with poor breath sounds and scaphoid abdomen. The rapidity and severity of presentation—as well as ultimate survival—depend on the degree of pulmonary hypoplasia, which is a result of compression by the intrathoracic abdominal contents in utero. Affected infants are prone to development of pneumothorax.
Treatment includes intubation and ventilation as well as decompression of the gastrointestinal tract with a nasogastric tube. An intravenous infusion of glucose and fluid should be started. Chest x-ray confirms the diagnosis. Surgery to reduce the abdominal contents from the thorax and to close the diaphragmatic defect is performed after the infant is stabilized. The postoperative course is often complicated by severe pulmonary hypertension, requiring therapy with high-frequency ventilation, inhaled NO, or ECMO. The mortality rate for this condition is 50%, with survival dependent on the degree of pulmonary hypoplasia.

GASTROINTESTINAL BLEEDING

Upper Gastrointestinal Bleeding
Upper gastrointestinal bleeding is not uncommon in the newborn nursery. Old blood (coffee-ground material) may be either swallowed maternal blood or infant blood from a bleeding gastric irritation such as gastritis or stress ulcer. Bright red blood from the stomach is most likely acute bleeding, again due to gastritis. Treatment generally consists of gastric lavage (a sample can be sent for Apt testing to determine if it is mother’s or baby’s blood) and antacid medication. If the volume of bleeding is large, intensive monitoring, fluid and blood replacement, and endoscopy are indicated .

Lower Gastrointestinal Bleeding
Rectal bleeding is less common than upper gastrointestinal bleeding in the newborn and is associated with infections (eg, Salmonella acquired from the mother perinatally), milk intolerance (blood streaks with diarrhea), or, in stressed infants, necrotizing enterocolitis. An abdominal x-ray should be obtained to rule out pneumatosis intestinalis (air in the wall of the bowel) or other abnormalities in gas pattern (eg, obstruction). If the x-ray is negative and the examination is benign, a protein hydrolysate or predigested formula (eg, Nutramigen or Pregestamil) should be tried or the mother instructed to avoid all dairy products in her diet if nursing. If the amount of rectal bleeding is large or persistent, endoscopy will be needed.

GASTROESOPHAGEAL REFLUX

All people reflux occasionally, and physiologic regurgitant reflux is extremely common in infants. Reflux is pathologic and should be treated when it results in failure to thrive owing to excessive regurgitation, poor intake due to dysphagia and irritability, apnea or cyanotic episodes (acute life-threatening events), or chronic respiratory symptoms of wheezing and recurrent pneumonias. Diagnosis is clinical, with confirmation by barium swallow or pH probe study.
Initial steps in treatment include prone positioning, with thickened feeds (rice cereal, 1 tbsp/oz of formula) for those with frequent regurgitation and poor weight gain. Gastric acid suppressants such as ranitidine (2 mg/kg twice a day) or cimetidine, along with a prokinetic agent such as metaclopramide (0.1 mg/kg three to four times daily), can also be used (see cautions page 529). Because most infants improve by 12–15 months, surgery is reserved for the most severe cases, especially those with chronic neurologic or respiratory conditions that exacerbate reflux and those who have life-threatening events caused by reflux.

CARDIAC PROBLEMS IN THE NEWBORN INFANT

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STRUCTURAL HEART DISEASE

1. CYANOTIC PRESENTATIONS

Essentials of Diagnosis & Typical Features
Cyanosis, initially without associated respiratory distress.
Failure to increase PaO2 with supplemental oxygen.
Chest x-ray with decreased lung markings suggests right heart obstruction.

General Consideration

The causes of cyanotic heart disease that occurs in the newborn period are transposition of the great vessels (TOGV), total anomalous pulmonary venous return (TAPVR), truncus arteriosus (some types), tricuspid atresia, and pulmonary atresia or critical pulmonary stenosis.

Clinical Findings
Infants with these disorders present with early cyanosis. The hallmark of many of these lesions is cyanosis in an infant without associated respiratory distress. In most of these infants, tachypnea develops over time either because of increased pulmonary blood flow or secondary to metabolic acidemia from progressive hypoxemia. Diagnostic aids include comparing the blood gas or oxygen saturation in room air to that in 100% FIO2. Failure of PaO2 or SaO2 to increase suggests cyanotic heart disease. Other useful aids are chest x-ray, electrocardiography, and echocardiography.
TOGV is the most common form of cyanotic heart disease presenting in the newborn period. Examination generally reveals a systolic murmur and single S2. Chest x-ray shows a generous heart size and a narrow mediastinum with normal or increased lung markings. There is little change in PaO2 or SaO2 with supplemental oxygen. Total anomalous pulmonary venous return, in which venous return is obstructed, presents early with severe cyanosis and tachypnea because the pulmonary venous return is obstructed, resulting in pulmonary edema. The chest x-ray typically shows a small to normal heart size with marked pulmonary edema. Infants with right heart obstruction (pulmonary and tricuspid atresia, critical pulmonary stenosis, and some forms of truncus arteriosus) have decreased lung markings on chest x-ray and, depending on the severity of hypoxia, may develop metabolic acidemia. Those forms with an underdeveloped right heart will have left-sided predominance on electrocardiography. Although tetralogy of Fallot is the most common form of cyanotic heart disease, the obstruction at the pulmonary valve is often not severe enough to result in cyanosis in the newborn. In all cases, diagnosis can be confirmed by echocardiography.

2. ACYANOTIC PRESENTATIONS

Essentials of Diagnosis & Typical Features

Most newborns who present with acyanotic heart disease have left-sided outflow obstruction.
Differentially diminished pulses (coarctation) or decreased pulses throughout (aortic atresia).
Metabolic acidemia.
Chest x-ray showing large heart and pulmonary edema.

General Considerations
Newborn infants who present with serious acyanotic heart disease usually have congestive heart failure secondary to left-sided outflow tract obstruction. Infants with left-to-right shunt lesions (eg, ventricular septal defect) may have murmurs in the newborn period, but clinical symptoms do not occur until pulmonary vascular resistance drops enough to cause significant shunting and subsequent congestive heart failure (usually at 3–4 weeks of age).

Clinical Findings
Infants with left-sided outflow obstruction generally do well the first day or so until the ductus arteriosus—the source of all or some of the systemic flow—narrows. Tachypnea, tachycardia, congestive heart failure, and metabolic acidosis develop. On examination, all of these infants have abnormalities of the pulses. In aortic atresia and stenosis, pulses are all diminished, whereas in coarctation syndromes, differential pulses (diminished or absent in the lower extremities) are evident. Chest x-ray films in these infants show a large heart and pulmonary edema. Diagnosis is confirmed with echocardiography.

3. TREATMENT OF CYANOTIC & ACYANOTIC LESIONS
Early stabilization includes supportive therapy as needed (eg, intravenous glucose, oxygen, ventilation for respiratory failure, pressor support). Specific therapy includes infusions of prostaglandin E1, 0.025–0.1 µg/kg/min, to maintain ductal patency. In some cyanotic lesions (eg, pulmonary atresia, tricuspid atresia, critical pulmonary stenosis) in which lung blood flow is ductus dependent, this improves pulmonary blood flow and PaO2 by allowing shunting through the ductus to the pulmonary artery. In left-sided outflow tract obstruction, systemic blood flow is ductus dependent; prostaglandins improve systemic perfusion and resolve the acidosis. Further specific management—including palliative surgical and cardiac catheterization procedures—is discussed in Chapter 18.

PERSISTENT PULMONARY HYPERTENSION IN THE NEWBORN INFANT

Essentials of Diagnosis & Typical Features
Onset of symptoms on day 1 of life.
Hypoxia with poor response to high concentrations of inspired oxygen.
Right to left shunts through the foramen ovale, ductus arteriosus, or both.
Most often associated with parenchymal lung disease.

General Considerations
Persistent pulmonary hypertension results when the normal decrease in pulmonary vascular resistance after birth does not occur. Most infants so affected are full term or postterm, and many have experienced perinatal asphyxia. Other clinical associations include hypothermia, meconium aspiration syndrome, hyaline membrane disease, polycythemia, neonatal sepsis, chronic intrauterine hypoxia, and pulmonary hypoplasia.
There are three causes of persistent pulmonary hypertension: (1) acute vasoconstriction resulting from perinatal hypoxia, (2) prenatal increase in pulmonary vascular smooth muscle development, and (3) decreased cross-sectional area of the pulmonary vascular bed because of inadequate vessel number. In the first, an acute perinatal event leads to hypoxia and failure of the pulmonary vascular resistance to drop. In the second, abnormal muscularization of the pulmonary resistance vessels results in persistent hypertension after birth. The third category includes infants with pulmonary hypoplasia (eg, diaphragmatic hernia).

Clinical Findings
Clinically, the syndrome is characterized by onset on the first day of life, usually from birth. Respiratory distress is prominent, and PaO2 is usually poorly responsive to high concentrations of inspired oxygen. Many of the infants have associated myocardial depression with resulting systemic hypotension. Echocardiography reveals right-to-left shunting at the level of the ductus arteriosus or foramen ovale (or both). Chest x-ray usually shows lung infiltrates related to associated pulmonary pathology (eg, meconium aspiration, hyaline membrane disease). If the majority of right-to-left shunt is at the ductal level, pre- and postductal differences in PaO2 and SaO2 will be observed.

Treatment
Therapy for persistent pulmonary hypertension involves supportive therapy for other postasphyxia problems (eg, anticonvulsants for seizures, careful fluid and electrolyte management for renal failure). Intravenous glucose should be provided to maintain normal blood sugar, and antibiotics should be administered for possible infection. Specific therapy is aimed at both increasing systemic arterial pressure and decreasing pulmonary arterial pressure to reverse the right-to-left shunting through fetal pathways. First-line therapy includes oxygen and ventilation (to reduce pulmonary vascular resistance) and colloid or crystalloid infusions (10 mL/kg, up to 30 mL/kg) to improve systemic pressure. Ideally, systolic pressure should be greater than 60 mm Hg. With compromised cardiac function, systemic pressors can be used as second-line therapy (eg, dopamine, 5–20 µg/ kg/min; dobutamine, 5–20 µg/kg/min; or both). Metabolic acidemia should be corrected with sodium bicarbonate because acidemia exacerbates pulmonary vasoconstriction. In some cases, a mild respiratory alkalosis may improve oxygenation. Recent studies using the inhaled gas nitric oxide, which is identical or very similar to endogenous endothelium-derived relaxing factor, at doses of 5–20 ppm, have shown it to be a very promising and specific pulmonary vasodilator. In addition, use of high-frequency oscillatory ventilation has proved effective in many of these infants, particularly those with severe associated lung disease.
Infants for whom conventional therapy is failing (poor oxygenation despite maximum support) may require ECMO. The infants are placed on bypass, with blood exiting the baby from the right atrium and returning to the aortic arch after passing through a membrane oxygenator. The lungs are essentially at rest during the procedure, and with resolution of the pulmonary hypertension the infants are weaned from ECMO back to conventional ventilator therapy. This therapy can save infants who might otherwise die but has major side effects that must be considered prior to its institution. The use of ECMO to treat this condition has declined with the advent of high-frequency ventilation and inhaled NO as therapies. Neurodevelopmental outcome among survivors of ECMO is similar to that of infants with persistent pulmonary hypertension managed without the procedure. Approximately 10–15% of survivors have significant neurologic sequelae, with cerebral palsy or cognitive delays. Other sequelae such as chronic lung disease, sensorineural hearing loss, and feeding problems have also been described in this population.

ARRHYTHMIAS
Irregularly irregular heart rates, commonly associated with premature atrial contractions and less commonly with premature ventricular contractions, are noted often in the first days of life of well newborns. These arrhythmias are benign and of no consequence. Clinically significant bradyarrhythmias are seen in association with congenital heart block. Heart block can be seen in an otherwise structurally normal heart (associated with maternal lupus) or with structural cardiac abnormalities.
Treatment is with isoproterenol (starting dose: 0.1 µg/kg/min) to improve cardiac output or with temporary pacing. On electrocardiography, tachyarrhythmias can be either wide complex (eg, ventricular tachycardia) or narrow complex (eg, supraventricular tachycardia). Supraventricular tachycardia is the most common tachyarrhythmia in the neonate and may be a sign of structural heart disease, myocarditis, left atrial enlargement, and aberrant conduction pathways. Acute treatment is ice to the face and, if unsuccessful, adenosine given intravenously at a dose of 75–100 µg/kg. If there is no response, the dose can be increased up to 300 µg/kg. Long-term therapy is with digoxin or propranolol. Digoxin should not be used in cases with Wolff-Parkinson-White syndrome. Cardioversion is rarely needed for supraventricular tachycardia but is needed acutely for hemodynamically unstable ventricular tachycardia.

DISCHARGE & FOLLOW-UP OF THE PREMATURE INFANT

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Hospital Discharge
Medical criteria for discharge of the premature infant includes the ability to maintain temperature in an open crib, nippling all feeds and gaining weight, and the absence of apneic and bradycardiac spells requiring intervention. Infants going home on supplemental oxygen should not desaturate too badly (< 80%) in room air or should demonstrate the ability to arouse in response to hypoxia. Factors such as support for the mother at home and the stability of the family situation play a role in the timing of discharge. Home nursing visits and early physician follow-up can be utilized to hasten discharge.

Follow-Up
With advances in obstetric and maternal care, survival for infants born at less than 28 weeks’ gestation or with birth weights as low as 1000 g is now better than 90%. Eighty percent or more survive at 26–27 weeks’ gestation and birth weights of 800–1000 g. Survival at gestational age 25 weeks and birth weight 700–800 g is nearly 70%, with a considerable drop-off below this level .
These high rates of survival do come with a price in terms of morbidity. Major neurologic sequelae, including cerebral palsy, cognitive delay, and hydrocephalus, is reported in 10–25% of survivors with birth weights under 1500 g. The rate of these sequelae tends to be higher in infants with lower birth weights. In addition to a higher incidence of severe neurologic sequelae, infants with birth weights under 1000 g have an increased rate of lesser disabilities, including learning and behavioral problems. Risk factors for neurologic sequelae include seizures, grade III or IV intracranial hemorrhage, periventricular leukomalacia, severe intrauterine growth restriction, poor early head growth, need for mechanical ventilation, and low socioeconomic class. In addition, maternal fever and chorioamnionitis have been associated with an increased risk of cerebral palsy. Other morbidities in these infants include chronic lung disease and reactive airway disease, resulting in an increased risk from respiratory infections and hospital readmissions in the first 2 years, retinopathy of prematurity, hearing loss, and growth failure. All of these issues require close multidisciplinary outpatient follow-up. Infants with residual lung disease are candidates for monthly palivizumab (Synagis) injections during their first winter after hospital discharge to prevent severe infection with respiratory syncytial virus.

RETINOPATHY OF PREMATURITY

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Retinopathy of prematurity occurs only in the incompletely vascularized retina of the premature infant. The incidence of any acute retinopathy in infants under 1250 g is 66%, whereas only 6% have retinopathy severe enough to warrant intervention. The incidence is highest in babies of the lowest gestational age. The condition appears to be triggered by an initial injury to the developing retinal vessels. Hypoxia, shock, asphyxia, vitamin E deficiency, and light exposure have been associated with this initial injury. After the initial injury, normal vessel development may follow or abnormal vascularization may occur with ridge formation on the retina. The process can still regress at this point or may continue, with growth of fibrovascular tissue into the vitreous associated with inflammation, scarring, and retinal folds or detachment. The disease is graded by stages of abnormal vascular development and retinal detachment (I–V), by the zone of the eye involved (1–3, with zone 1 the posterior region around the macula), and by the amount of the retina involved, in “clock hours” (eg, a detachment in the upper, outer quadrant of the left eye would be defined as affecting the left retina from 12 to 3 o’clock).
Initial eye examination should be performed at 6 weeks of age in infants with a birth weight under 1500 g or in those born at less than 28 weeks’ gestation, as well as in infants over 1500 g with an unstable clinical course. Follow-up is done at 2- to 4-week intervals until the retina is fully vascularized. Infants with zone 1 disease need to be followed at 1- to 2-week intervals. Infants with threshold disease (stage III, zone 1 or 2, in five or more continuous clock hours, with inflammatory changes of “plus” disease) are candidates for laser therapy. Although this treatment does not always prevent retinal detachment, it reduces the incidence of poor outcomes based on visual acuity and anatomic outcomes.

INTRAVENTRICULAR HEMORRHAGE

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Essentials of Diagnosis & Typical Features

Large bleeds are accompanied by hypotension, metabolic acidosis, and altered neurologic status. Smaller bleeds can be asymptomatic.
Routine cranial ultrasound scanning is essential for diagnosis in infants born at less than 32 weeks’ gestation.

General Considerations
Periventricular-intraventricular hemorrhage occurs almost exclusively in premature infants. The incidence is 20–30% in infants born at less than 31 weeks’ gestation and weighing less than 1500 g at birth. The highest incidence is observed in babies of the lowest gestational age (< 26 weeks). Bleeding most commonly occurs in the subependymal germinal matrix (a region of undifferentiated cells). Bleeding can extend into the ventricular cavity. The proposed pathogenesis of bleeding is presented in Figure 1–7. The critical event is probably ischemia with reperfusion injury to the capillaries in the germinal matrix that occurs in the immediate perinatal period. The actual amount of bleeding is also influenced by a variety of factors that affect the pressure gradient across the injured capillary wall. This pathogenetic scheme applies also to intraparenchymal bleeding (venous infarction in a region rendered ischemic) and to periventricular leukomalacia (ischemic white matter injury in a watershed region of arterial supply). Periventricular leukomalacia has a peak incidence in babies born between 28 and 32 weeks’ gestation and appears to be associated with maternal chorioamnionitis.

Clinical Findings
Up to 50% of hemorrhages occur at less than 24 hours of age, and virtually all occur by the fourth day. The clinical syndrome ranges from rapid deterioration (coma, hypoventilation, decerebrate posturing, fixed pupils, bulging anterior fontanelle, hypotension, acidosis, acute drop in hematocrit) to a more gradual deterioration with more subtle neurologic changes to absence of any specific physiologic or neurologic signs.
The diagnosis can be confirmed by real-time ultrasound scan. This can be performed whenever bleeding is clinically suspected. If symptoms are absent, routine scanning should be done at 10–14 days in all infants born at less than 29 weeks’ gestation. Hemorrhages are graded as follows: grade I, germinal matrix hemorrhage only; grade II, intraventricular bleeding without ventricular enlargement; grade III, intraventricular bleeding with ventricular enlargement; and grade IV, any infant with intraparenchymal bleeding. The amount of bleeding is minor (grade I or II) in 75% of infants and major in the remainder.
Follow-up ultrasound examinations are based on the results of the initial scan. Infants with no bleeding or germinal matrix hemorrhage require only a single late scan at age 4–6 weeks to look for periventricular leukomalacia. Any infant with blood in the ventricular system is at risk for posthemorrhagic ventriculomegaly. This is usually the result of impaired absorption of cerebrospinal fluid (CSF), but it can also occur secondary to obstructive phenomena. An initial follow-up scan should be done 1–2 weeks after the initial scan. Infants with intraventricular bleeding and ventricular enlargement should be followed every 7–10 days until ventricular enlargement stabilizes or decreases. Infants without ventriculomegaly should have one additional scan at age 4–6 weeks. In addition, all infants born at 29–32 weeks’ gestation should have at least a late scan (4–6 weeks) to look for ventriculomegaly and periventricular leukomalacia.

Treatment
During acute hemorrhage, supportive treatment (including restoration of volume and hematocrit, oxygenation, and ventilation) should be provided to avoid further cerebral ischemia. Progressive posthemorrhagic hydrocephalus (if it develops) can sometimes be controlled by decreasing the production of CSF (furosemide, 1 mg/kg/d, plus acetazolamide in increasing doses from 25 to 100 mg/kg/d) or by removal of CSF (daily lumbar punctures). The process is usually self-limited and resolves spontaneously; placement of a ventriculoperitoneal shunt is usually not needed. Early treatment with medications or serial spinal taps does not appear to influence whether a shunt will ultimately be needed but may contribute to an improved long-term neurologic outcome.
Although the incidence and severity of intracranial bleeding have decreased in premature infants, strategies to prevent this complication are still needed. Use of antenatal corticosteroids appears to be important in decreasing this complication, and phenobarbital may have a role in the mother who has not been prepared with steroids and is delivering at less than 28 weeks’ gestation. The route of delivery may also play a role, with babies delivered by cesarean section showing a decreased rate of intracranial bleeds, but this issue remains controversial. Postnatal strategies appear less promising, but early indomethacin may have some benefit.

Prognosis
There are no deaths as a result of grade I and grade II hemorrhages, whereas grade III and grade IV hemorrhages carry a mortality rate of 10–20%. Posthemorrhagic ventricular enlargement is rarely seen with grade I hemorrhages but is seen in 54–87% of grade II–IV hemorrhages. Very few of these infants will require a ventriculoperitoneal shunt. Long-term neurologic sequelae are seen no more frequently in infants with grade I and grade II hemorrhages than in preterm infants without bleeding. In infants with grade III and grade IV hemorrhages, severe sequelae occur in 20–25% of cases, mild sequelae in 35% of cases, and no sequelae in 40% of cases. The presence of severe periventricular leukomalacia, large parenchymal bleeds, and progressive ventriculomegaly greatly increases the risk of neurologic sequelae.

ANEMIA IN THE PREMATURE INFANT

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General Considerations
In the premature infant, the hemoglobin reaches its nadir at approximately 8–12 weeks and is 2–3 g/dL lower than that in the term infant. The lower nadir in premature infants appears to be the result of a decreased erythropoietin response to the low red cell mass. Symptoms of anemia include poor feeding, lethargy, increased heart rate, poor weight gain, and perhaps apnea.

Treatment
The decision to transfuse is based on the presence of clinical symptoms. Transfusion is not indicated in an asymptomatic infant simply because of an arbitrary hematocrit number. Most infants become symptomatic if the hematocrit drops below 20%. With risks of transfusion, alternative therapies have been explored. Epoetin alfa, 150–250 units/kg subcutaneously three times per week, has been shown to increase hematocrit and reticulocyte count and to decrease the frequency and volume of transfused blood. This treatment should be reserved for the highest-risk infants (those born at less than 28–30 weeks’ gestation and below 1000–1200 g). For optimal effect, supplemental iron at a dosage of 4–8 mg/kg/d should be given. Treatment should start when infants are taking at least two thirds of their nutrition enterally and should continue through 36 weeks’ postconception.

NECROTIZING ENTEROCOLITIS

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Essentials of Diagnosis & Typical Features

Feeding intolerance with gastric aspirates or vomiting.
Bloody stools.
Abdominal distention and tenderness.
Pneumatosis intestinalis on abdominal x-ray.

General Considerations
Necrotizing enterocolitis is the most common acquired gastrointestinal emergency in the newborn infant; it most often affects preterm infants, with an incidence of 10% in infants of birth weight less than 1500 g. In term infants, it occurs in association with polycythemia, congenital heart disease, and birth asphyxia. The pathogenesis of the disease is a multifactorial interaction between an immature gastrointestinal tract, mucosal injury, and potentially injurious factors in the lumen. Previous intestinal ischemia, bacterial or viral infection, and immunologic immaturity of the gut are thought to play a role in the genesis of the disorder. In up to 20% of affected infants, the only risk factor is prematurity.

Clinical Findings
The most common presenting sign is abdominal distention. Other signs include vomiting or increased gastric residuals, heme-positive stools, abdominal tenderness, temperature instability, increased apnea and bradycardia, decreased urine output, and poor perfusion. The complete blood count may show an increased white blood cell count with an increased band count or, as the disease progresses, absolute neutropenia. Thrombocytopenia is often observed along with stress-induced hyperglycemia and metabolic acidosis. Diagnosis is confirmed by the presence of pneumatosis intestinalis (air in the bowel wall) on x-ray. There is a spectrum of disease, and milder cases may exhibit only distention of bowel loops with bowel wall edema (thickened-appearing walls on x-ray).

Treatment

A. Medical Treatment: Necrotizing enterocolitis is managed by decompression of the gut by nasogastric tube, maintenance of oxygenation, mechanical ventilation if necessary, and intravenous fluids (colloid and normal saline) to replace third-space gastrointestinal losses. Enough fluid should be given to restore a good urine output. Other measures consist of broad-spectrum antibiotics (including anaerobic coverage), close monitoring of vital signs, physical examination, and laboratory studies (blood gases, white blood cell count, platelet count, and x-rays).

B. Surgical Treatment: Indications for surgery are evidence of perforation (free air present on a left lateral decubitus film), a fixed dilated loop of bowel on serial x-rays, abdominal wall cellulitis, or progressive deterioration despite maximal medical support. All of these signs are indicative of necrotic bowel. In the operating room, necrotic bowel is removed and ostomies are created. Reanastomosis is performed after the disease is resolved and the infant is bigger (usually > 2 kg and after 4-6 weeks).

Course & Prognosis
Infants managed either medically or surgically should not be refed until the disease is resolved (normal abdominal examination, resolution of pneumatosis on x-ray), usually in 10–14 days. Nutritional support during this time should be provided by total parenteral nutrition.
Death occurs in 10% of cases. Surgery is needed in less than 25% of cases. Long-term prognosis is determined by the amount of intestine lost. Infants with short bowel require long-term support with intravenous nutrition and therefore have very long hospitalizations. Even for those infants, however, the outcome is favorable because of improved parenteral nutrition formulations. Late strictures—about 3–6 weeks after initial diagnosis—occur in 8% of patients whether treated medically or surgically. Some of these strictures are severe enough to require operative management.

PATENT DUCTUS ARTERIOSUS

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Essentials of Diagnosis & Typical Features

Hyperdynamic precordium.
Widened pulse pressure.
Hypotension.
Presence of a systolic heart murmur in many cases.

General Considerations
Clinically significant patent ductus arteriosus usually presents on days 3–7 as the respiratory distress from hyaline membrane disease is improving. Presentation can be on days 1 or 2, especially in infants born at less than 28 weeks’ gestation and in those who have received surfactant replacement therapy. The signs include a hyperdynamic precordium, increased peripheral pulses, and a widened pulse pressure with or without a systolic heart murmur. Early presentations are sometimes manifested by systemic hypotension without a murmur or hyperdynamic circulation. These signs are often accompanied by an increase in respiratory support. The presence of significant patent ductus arteriosus can be confirmed by echocardiography. Before undertaking medical or surgical ligation, other structural heart disease must be ruled out.

Treatment
The ductus arteriosus is managed by medical or surgical ligation. A clinically significant ductus causing compromise in the infant can be closed (in about two thirds of cases) with indomethacin, 0.1–0.2 mg/kg intravenously every 12–24 hours for three doses. If the ductus reopens, a second course of drug may be utilized. If indomethacin fails to close the ductus or if a ductus reopens a second time, surgical ligation is called for. In some cases, a more prolonged course of indomethacin is being used to prevent recurrences. In addition, in the extremely low-birth-weight infant (< 1000 g) who is at very high risk of developing a symptomatic ductus, a prophylactic strategy starting indomethacin on the first day of life can be used. The major side effect of indomethacin is transient oliguria, which can be managed by fluid restriction until urine output improves. Transient decreases in intestinal and cerebral blood flow caused by indomethacin can be ameliorated by giving the drug as a slow infusion over 1–2 hours. The drug should not be used if the infant is hyperkalemic, if the creatinine is greater than 2 mg/dL, or if the platelet count is less than 50,000/µL.

CHRONIC LUNG DISEASE IN THE PREMATURE INFANT

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Essentials of Diagnosis & Typical Features

Oxygen requirement, respiratory symptoms, and abnormal chest x-ray at age 1 month.
Incidence greatest in infants of the lowest gestational ages.

General Considerations
Chronic lung disease in the premature infant, defined as respiratory symptoms, oxygen requirement, and chest x-ray abnormalities at age 1 month, occurs in about 20% of infants ventilated for surfactant deficiency. The incidence is higher at lower gestational ages. The development of chronic lung disease is a function of lung immaturity at birth and exposure to high oxygen concentrations and ventilator barotrauma. The use of surfactant replacement therapy has, in general, diminished the severity of the chronic lung disease. The mortality rate from this complication is now very low, but significant morbidity still exists secondary to reactive airway symptoms, hospital readmissions during the first 2 years of life for intercurrent respiratory infection, and systemic hypertension.

Treatment
The management of infants who go on to develop chronic lung disease has been enhanced by the use of dexamethasone (0.5 mg/kg) to decrease lung inflammation. Dexamethasone is most effective when started in chronically ventilated infants at age 10 days to 3 weeks. Dosing schedules used have varied from a 5-day course to intermittent 3- to 5-day bursts to an initial 3–5 days at full dose followed by a gradual wean in dosage over 4–6 weeks. Prolonged therapy with systemic corticosteroids has been associated with long-term neurodevelopmental handicaps, growth failure, and cardiomyopathy. Thus shorter courses are used now with greater frequency. Other treatments used in the management of chronic lung disease include diuretics (furosemide [Lasix] 1–2 mg/kg per dose given daily), inhaled b2-adrenergic bronchodilators, and inhaled corticosteroids. After hospital discharge, some of these infants will continue to require oxygen at home. This can be monitored by pulse oximetry with a target SaO2 of 94–96%.

HYALINE MEMBRANE DISEASE

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Essentials of Diagnosis & Typical Features

Tachypnea, cyanosis, and expiratory grunting.
Poor air movement despite increased work of breathing.
Chest x-ray showing hypoexpansion and air bronchograms.

General Considerations
The most common cause of respiratory distress in the preterm infant is hyaline membrane disease. The incidence increases from 5% of infants born at 35–36 weeks’ gestation to more than 50% of infants born at 26–28 weeks’ gestation. This condition is caused by a deficiency of surfactant. Surfactant decreases surface tension in the alveolus during expiration, allowing the alveolus to remain partly expanded and in that way maintaining a functional residual capacity. The absence of surfactant results in poor lung compliance and atelectasis. The infant must expend a great deal of effort to expand the lungs with each breath, and respiratory failure ensues (Figure 1–6).

Clinical Findings
Infants with hyaline membrane disease demonstrate all the clinical signs of respiratory distress. On auscultation, air movement is diminished despite vigorous respiratory effort. Chest x-ray demonstrates diffuse bilateral atelectasis, causing a ground-glass appearance. Major airways are highlighted by the atelectatic air sacs, creating air bronchograms. In the unintubated child, doming of the diaphragm and underexpansion occur.

Treatment
Supplemental oxygen, early intubation and ventilation, and placement of umbilical artery and vein lines are the initial interventions required. A ventilator that can deliver breaths synchronized with the infant’s respiratory efforts (synchronized intermittent mandatory ventilation) should be used if available. High-frequency ventilators are also available for rescue of infants doing poorly on conventional ventilation or who have air leak problems.
Three exogenous surfactants (colfosceril palmitate [Exosurf Neonatal], beractant [Survanta], and calf lung surfactant extract [Infasurf]) are approved in the United States by the Food and Drug Administration for use in infants with hyaline membrane disease. Surfactant replacement therapy, used both in the delivery room as prophylaxis and with established hyaline membrane disease as rescue, decreases the mortality rate in preterm infants and decreases air leak complications of the disease. During the acute course, ventilator settings and oxygen requirements are significantly less in surfactant-treated infants than in control subjects. The dose of the artificial surfactant Exosurf is 5 mL/kg intratracheally, the bovine-derived Survanta is 4 mL/kg, and the calf-derived Infasurf is 3 mL/kg. When the first dose is given in the delivery room to prevent hyaline membrane disease the usual dosing schedule is a total of two or three doses given 8–12 hours apart as long as the infant remains ventilated on over 30–40% inspired oxygen concentration. Rescue surfactant is given as two to four doses 8–12 hours apart. The first dose is administered as soon as possible after birth, preferably before 2–4 hours of age. As the disease process evolves, proteins that inhibit surfactant function leak into the air spaces, making surfactant replacement less effective. The second dose should be administered to infants who continue to require ventilation and more than 30% inspired oxygen concentration. A prophylactic strategy may offer some advantage in those infants born at 26 weeks’ gestation or less. For infants over 26 weeks’ gestation, early rescue therapy (as soon as a diagnosis of surfactant deficiency can be made) is the strategy of choice. The availability of surfactant replacement therapy has encouraged earlier intubation of infants with hyaline membrane disease. Surfactant replacement has also been used with some success in term infants with secondary surfactant deficiency resulting from pneumonia or meconium aspiration.
Antenatal administration of corticosteroids to the mother is an important strategy used by obstetricians to accelerate lung maturation. Infants whose mothers were given corticosteroids more than 24 hours prior to preterm birth have less respiratory distress syndrome and a lower mortality rate. Antenatal corticosteroids and exogenous surfactant administration after birth appear to have a synergistic effect on outcome.

APNEA IN THE PRETERM INFANT

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Essentials of Diagnosis & Typical Features

Respiratory pause of sufficient duration to result in cyanosis or bradycardia.
Most common in infants born at less than 34 weeks’ gestation with onset at less than age 2 weeks.
Methylxanthines (eg, caffeine) provide effective treatment for apnea of prematurity.

General Considerations
In preterm infants, recurrent apneic episodes are a common problem. Apnea is defined as a respiratory pause lasting more than 20 seconds—or any pause accompanied by cyanosis and bradycardia. Shorter respiratory pauses associated with cyanosis or bradycardia also qualify as significant apnea but must be differentiated from periodic breathing, which is common in term as well as preterm infants. Periodic breathing is defined as regularly recurring ventilatory cycles interrupted by short pauses not associated with bradycardia or color change. Although apnea in premature infants is often not associated with a predisposing factor, a variety of processes may precipitate apnea (Table 1–20). These processes should at least be considered before a diagnosis of apnea of prematurity can be established.
Apnea of prematurity is the most frequent cause of apnea. Most apnea of prematurity is mixed apnea characterized by a centrally (brainstem) mediated respiratory pause preceded or followed by airway obstruction. Less common is pure central or pure obstructive apnea. Apnea of prematurity is the result of immaturity of both the central respiratory regulatory centers and protective mechanisms that aid in maintaining airway patency.

Clinical Findings
Onset, typically during the first 2 weeks of life, is gradual, with the frequency of spells increasing over time. Pathologic apnea can be suspected in an infant with a sudden onset of frequent or very severe apneic spells. Apnea presenting from birth or on the first day of life is unusual but can occur in the preterm infant who does not require mechanical ventilation for respiratory distress syndrome. In the term or near-term infant, this presentation can suggest neuromuscular abnormalities of an acute (asphyxia, birth trauma, or infection) or chronic (eg, congenital hypotonia, structural CNS lesion) nature.
The workup depends on the clinical presentation. All infants—regardless of the severity and frequency of apnea—require a minimum screening evaluation, including a general assessment of well-being (eg, tolerance of feedings, stable temperature, normal physical examination), a check of the association of spells with feeding, measurement of PaO2 or SaO2, blood glucose, hematocrit, and a review of the drug history. Infants with severe apnea of sudden onset may require a more extensive evaluation, including a workup for infection. Other specific tests are dictated by relevant signs, for example, evaluation for necrotizing enterocolitis in an infant with apnea and abdominal distention.

Treatment
The physician should first address any underlying cause. If the apnea is due simply to prematurity, treatment is dictated by the frequency and severity of apneic spells. Apneic spells frequent enough to interfere with other aspects of care (eg, feeding), or severe enough to necessitate bag and mask ventilation to relieve cyanosis and bradycardia, require treatment. First-line therapy is with methylxanthines. Caffeine citrate (20 mg/kg as loading dose and then 5–10 mg/kg/d) is the drug of choice because of once-daily dosing and fewer side effects than theophylline (5 mg/kg load; 1–2 mg/kg every 6–12 hours). Side effects of methylxanthines include tachycardia, feeding intolerance, and (with overdosing) seizures. The dose used should be the smallest dose necessary to decrease the frequency of apnea and eliminate severe spells. Desired drug levels are usually in the range of 5–10 µg/mL for theophylline and 10–20 µg/mL for caffeine. Intravenous doxapram infused at a dose of 1 mg/kg/h for 48 hours is effective in some cases of methylxanthine-refractory apnea. Nasal CPAP (continuous positive airway pressure), by treating the obstructive component of apnea, can be effective treatment for some infants. Intubation and ventilation can eliminate symptomatic apneic spells but carries the risks associated with long-term endotracheal intubation.

Prognosis
In the majority of premature infants, apneic and bradycardiac spells cease by 34–37 weeks postconception. The spells tend to disappear by degree of severity; spells that require intervention cease prior to self-resolved episodes. Occasionally the episodes last longer. In infants born at less than 28 weeks’ gestation, episodes may continue past term postconceptual age. Whether to provide home monitoring or outpatient methylxanthine therapy for such infants is controversial. Apneic and bradycardiac episodes in the nursery are not predictors of later SIDS. However, home monitoring in infants still experiencing self-resolving apnea and bradycardia at the time of hospital discharge may be indicated in some cases. The incidence of SIDS is slightly increased in preterm infants. Research in term infants has shown an increased incidence of SIDS in infants who sleep in the prone position. Whether this can be extrapolated to the preterm infant (in particular those with gastroesophageal reflux or persistent respiratory symptoms) is unclear. When possible, a sleeping position on the side (right side down) or, preferably, supine seems prudent unless contraindicated by reflux or respiratory symptoms.

THE PRETERM INFANT

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Premature infants account for the majority of high-risk newborns. The preterm infant faces a variety of physiologic handicaps:

The ability to suck, swallow, and breathe in a coordinated fashion is not achieved until 34–36 weeks’ gestation. Therefore, enteral feedings must be provided by gavage. Furthermore, preterm infants frequently have gastroesophageal reflux and an immature gag reflex, which increases the risk of aspiration of feedings.
Decreased ability to maintain body temperature.
Pulmonary immaturity–surfactant deficiency, often with structural immaturity in infants of less than 26 weeks’ gestation. Their condition is complicated by the combination of noncompliant lungs and a compliant chest wall.
Immature control of respiration, leading to apnea and bradycardia.
Persistent patency of the ductus arteriosus, leading to further compromise of pulmonary gas exchange because of overperfusion of the lungs.
Immature cerebral vasculature, predisposing the infant to subependymal or intraventricular hemorrhage and periventricular leukomalacia.
Impaired substrate absorption by the gastrointestinal tract, compromising nutritional management.
Immature renal function (including both filtration and tubular functions), complicating fluid and electrolyte management.
Increased susceptibility to infection.
Immaturity of metabolic processes, predisposing to hypoglycemia and hypocalcemia.

Delivery Room Care
See Perinatal Resuscitation section, above.

Care in the Nursery

A. Thermoregulation: Maintaining a stable body temperature is a function of heat production and conservation balanced against heat loss. Heat production in response to cold stress can occur through voluntary muscle activity, involuntary muscle activity (shivering), and thermogenesis not caused by shivering. Newborns produce heat mainly through the last of these three mechanisms. This metabolic heat production depends on the quantity of brown fat present, which is very limited in the preterm infant. Heat loss to the environment can occur through the following mechanisms: (1) radiation—transfer of heat from a warmer to a cooler object not in contact; (2) convection—transfer of heat to the surrounding gaseous environment, influenced by air movement and temperature; (3) conduction—transfer of heat to a cooler object in contact; and (4) evaporation—cooling secondary to water loss through the skin. Heat loss in the preterm newborn is accelerated because of a high ratio of surface area to body mass, reduced insulation of subcutaneous tissue, and water loss through the immature skin.
The thermal environment of the preterm neonate must be regulated carefully. The infant can be kept warm in an isolette, in which the air is heated and convective heat loss is minimized. Alternatively, the infant can be kept warm on an open bed with a radiant heat source. Although evaporative and convective heat losses are greater when the radiant warmer is used, this system allows easy access to a critically ill neonate. Ideally, the infant should be kept in a neutral thermal environment (Figure 1–5). The neutral thermal environment allows the infant to maintain a stable core body temperature with a minimum of metabolic heat production through oxygen consumption. The neutral thermal environment for a given infant depends on size, gestational age, and postnatal age. The neutral thermal environment (for either isolette or radiant warmer care) can be obtained by maintaining an abdominal skin temperature of 36.5°C. Generally, when infants reach 1700–1800 g, they can maintain temperature while bundled in a bassinet.

B. Monitoring the High-Risk Infant: Care of the high-risk preterm infant requires sophisticated monitoring techniques. At a minimum, equipment to monitor heart rate, respirations, and blood pressure should be available. Oxygen saturation can be assessed continuously using pulse oximetry. This determination can be correlated with arterial oxygen tension (PaO2) as needed. Transcutaneous PO2 and PCO2 can also be used to assess oxygenation and ventilation. Finally, arterial blood gases, electrolytes, glucose, calcium, bilirubin, and other chemistries must be measured on small volumes of blood. Early in the care of a sick preterm infant, the most efficient way to sample blood for tests as well as to provide fluids and monitor blood pressure is through an umbilical arterial line. Once the infant is stable and the need for frequent blood samples is reduced (usually 4–7 days), the umbilical line should be removed. All indwelling lines are associated with morbidity from thrombosis or embolism, infection, and bleeding.

C. Fluid and Electrolyte Therapy: Fluid requirements in preterm infants are a function of (1) insensible losses (skin and respiratory tract), (2) urine output, (3) stool output (< 5% of total), and (4) others, such as nasogastric losses. In most circumstances, the fluid requirement is determined largely by insensible losses plus urine losses. The major contribution to insensible water loss is evaporative skin loss. The rate of water loss is a function of gestational age (body weight), environment (losses are greater under a radiant warmer than in an isolette), and the use of phototherapy. Respiratory losses are minimal when infants are breathing humidified oxygen. The renal contribution to water requirement is influenced by the decreased ability of the preterm neonate to concentrate the urine and conserve water.
Electrolyte requirements are minimal for the first 24–48 hours until there is excretion in the urine. Basal requirements are as follows: sodium, 3 mEq/ kg/d; potassium, 2 mEq/kg/d; chloride, 2–3 mEq/ kg/d; and bicarbonate, 2–3 mEq/kg/d.
In the infant born before 30 weeks’ gestation , sodium and bicarbonate losses in the urine are frequently elevated, increasing the infant’s requirement for these electrolytes.
Initial fluid management after birth is determined by the infant’s size. Infants weighing more than 1500 g should start at 80–100 mL/kg/d of 10% dextrose in water (D10W), whereas those weighing less should start at 100–120 mL/kg/d of either D10W or 5% dextrose in water (D5W) (infants < 800 g and < 26 weeks’ gestation often become hyperglycemic on D10W). The most critical issue in fluid management is monitoring. Measurements of body weight, urine output, fluid and electrolyte intake, serum and urine electrolytes, and glucose allow fairly precise determinations of the infant’s water, glucose, and electrolyte needs. Parenteral nutrition should be started early and continued until an adequate enteral intake is achieved.

D. Nutritional Support: The average caloric requirement for the growing premature infant is 120 kcal/kg/d. Expected weight gain for the adequately nourished preterm infant is 10–30 g/d.
Infants initially require intravenous glucose infusions to maintain blood glucose concentration in the range of 60–100 mg/dL. Infusions of 5–7 mg/kg/min (approximately 80–100 mL/kg/d of a 10% dextrose solution) are usually needed. Nutritional support in the very low-birth-weight infant generally is started at 24–48 hours of age with parenteral alimentation solutions given either peripherally or centrally via an umbilical vein line or Silastic catheter (Table 1–19). Small-volume trophic feeds with breast milk or 20 kcal/oz premature formula should be started by gavage at 10–25% of the infant’s nutritional needs as soon as possible and slowly advanced to full caloric needs over 3–7 days once the infant is stable. Intermittent bolus feedings are preferred because these appear to stimulate the release of gut-related hormones and may accelerate maturation of the gastrointestinal tract. The more rapid advancement schedule is used for infants weighing over 1500 g and the slowest schedule in the infant weighing less than 1000 g. Note:{ebd} In the extremely low-birth-weight infant (< 1000 g) or the postsurgical neonate, continuous-drip feeds are sometimes better-tolerated.
In general, long-term nutritional support for infants of very low birth weight consists either of breast milk supplemented to increase protein, caloric density, and mineral content or of infant formulas modified for preterm infants. In all of these formulas, protein concentrations (approximately 2 g/dL) and caloric concentrations (approximately 24 kcal/oz) are relatively high. In addition, premature formulas contain some of the fat as medium-chain triglycerides—which do not require bile for emulsification—as an energy source. Increased amounts of calcium and phosphorus are provided to enhance bone mineralization. The infant should be advanced gradually to feedings of higher caloric density after the full volume of either breast milk or formula (20 kcal/oz) is tolerated. Success of feedings is assessed by passage of feeds out of the stomach, abdominal examination free of distention, and normal stool pattern.
When the preterm infant approaches term, the nutritional source for the bottle-fed infant can be changed to a transitional formula (22 kcal/oz) until age 6–9 months. Iron supplementation (2–4 mg/kg/d) is recommended for premature infants, beginning at about age 2 months. This can be provided by iron-supplemented formulas. In some infants, iron supplementation may be indicated earlier. In particular, infants treated with erythropoietin (epoetin alfa) for prevention of anemia of prematurity require supplemental iron at a dosage of 4–8 mg/kg/d.

NEONATAL INTENSIVE CARE

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PERINATAL RESUSCITATION

Perinatal resuscitation consists of the steps taken by the obstetrician to support the infant during labor and delivery as well as the traditional resuscitative steps taken by the pediatrician after delivery. Intrapartum support includes maintaining maternal blood pressure with volume expanders if needed, maternal oxygen therapy, positioning the mother to improve placental perfusion, readjusting oxytocin infusions or administering a tocolytic if appropriate, minimizing trauma to the infant (particularly important in infants of very low birth weight), suctioning the nasopharynx upon delivery of the head if meconium is present in the amniotic fluid, obtaining all necessary cord blood samples, and completing an examination of the placenta.
Steps taken by the pediatrician or neonatologist focus on temperature support, initiation and maintenance of effective ventilation, maintenance of perfusion and hydration, and glucose regulation.
A number of conditions associated with pregnancy, labor, and delivery place the infant at risk for birth asphyxia: (1) maternal diseases such as diabetes, pregnancy-induced hypertension, heart and renal disease, and collagen-vascular disease; (2) fetal conditions such as prematurity, multiple births, growth retardation, and fetal anomalies; and (3) labor and delivery conditions, including fetal distress with or without meconium in the amniotic fluid and administration of anesthetics and opioid analgesics.

Physiology of Birth Asphyxia
Birth asphyxia can be the result of several mechanisms: (1) acute interruption of umbilical blood flow (eg, prolapsed cord with cord compression), (2) premature placental separation, (3) maternal hypotension or hypoxia, (4) chronic placental insufficiency, and (5) failure to execute newborn resuscitation properly.
The neonatal response to asphyxia follows a predictable pattern that has been demonstrated in a variety of species (Figure 1–3). The initial response to hypoxia is an increase in frequency of respiration and a rise in heart rate and blood pressure. Respirations then cease (primary apnea) as heart rate and blood pressure begin to fall. This initial period of apnea lasts 30–60 seconds. Gasping respirations (3–6/min) then begin, while heart rate and blood pressure gradually decline. Secondary or terminal apnea then ensues, with further decline in heart rate and blood pressure. The longer the duration of secondary apnea, the greater the risk for hypoxic organ injury. A cardinal feature of the defense against hypoxia is the underperfusion of certain tissue beds (eg, skin, muscle, kidneys, gastrointestinal tract), which allows the perfusion of core organs (ie, heart, brain, adrenals) to be maintained.
The response to resuscitation also follows a predictable pattern. During the period of primary apnea, almost any physical stimulus causes the baby to initiate respirations. Infants in secondary apnea require positive-pressure ventilation. The first sign of recovery is an increase in heart rate, followed by an increase in blood pressure with improved perfusion. The time required for rhythmic, spontaneous respirations to occur is related to the duration of the secondary apnea. As a rough rule, for each 1 minute past the last gasp, 2 minutes of positive-pressure breathing is required before gasping begins, and 4 minutes is required to reach rhythmic breathing. These times can vary depending on the degree and duration of intrauterine asphyxia. Not until some time later do spinal and corneal reflexes return. Muscle tone gradually improves over the course of several hours.

Delivery Room Management
When asphyxia is anticipated, a resuscitation team of two persons should be present—one to manage the airway and one to monitor the heartbeat and provide assistance.

A. Steps in the Resuscitation:

Dry the infant well, and place it under the radiant heat source.
Gently suction the mouth, then the nose.
Quickly assess the infant’s condition. The best criteria are the infant’s respiratory effort (apneic, gasping, regular) and heart rate (> 100 or <>
Infants who are breathing and have heart rates over 100 beats/min usually require no further intervention. Infants with heart rates less than 100 beats/min and apnea or irregular respiratory efforts should be stimulated vigorously. The baby’s back should be rubbed with a towel while oxygen is provided near the baby’s face.
If the baby fails to respond to tactile stimulation within a few seconds, begin bag and mask ventilation, using a soft mask that seals well around the mouth and nose. For the initial inflations, pressures of 30–40 cm H2O may be necessary to overcome surface-active forces in the lungs. Adequacy of ventilation is assessed by observing expansion of the infant’s chest accompanied by an improvement in heart rate, perfusion, and color. After the first few breaths, lower the peak pressure to 15–20 cm H2O. The baby’s chest movement should resemble that of an easy breath rather than a deep sigh. The rate of bagging should be 40–60 breaths per minute.
Most neonates can be resuscitated effectively with a bag and mask. If the infant does not respond to bag and mask ventilation, try to reposition the head (slight extension), reapply the mask to achieve a good seal, consider suctioning the mouth and the oropharynx, and try ventilating with the mouth open. If the infant does not respond within 30 seconds, intubation is appropriate. Failure to respond to intubation and ventilation can result from (1) mechanical difficulties (Table 1–17), (2) profound asphyxia with myocardial depression, and (3) inadequate circulating blood volume. Quickly rule out the mechanical causes listed in Table 1–17. Check to be sure the endotracheal tube passes through the vocal cords. Occlusion of the tube should be suspected when there is resistance to bagging and no chest wall movement. Very few neonates (approximately 0.1%) require either cardiac massage or drugs during resuscitation. Almost all newborns respond to ventilation with 100% oxygen if done effectively.
If mechanical causes are ruled out and the heart rate remains below 80 beats/min and is not increasing after intubation and positive-pressure ventilation for 30 seconds, cardiac compression should be initiated. Simultaneous delivery of chest compressions and positive-pressure ventilation is likely to decrease the efficiency of ventilation. Therefore, chest compressions should be interspersed with ventilation at a 3:1 ratio (90 compressions and 30 breaths per minute).
If drugs are needed (rarely), the drug and dose of choice is epinephrine, 1:10,000 solution, 0.1–0.3 mL/kg given via the endotracheal tube or through an umbilical venous line. Some children and adults who do not respond to standard doses will respond to high-dose epinephrine (ten times the ineffective amount), but the safety and efficacy of such a dose have not been adequately evaluated in the newborn infant and it is thus not currently recommended. Sodium bicarbonate, 1–2 mEq/kg of the neonatal dilution (0.5 mEq/mL), can be used in prolonged resuscitation efforts in which the response to other measures is poor. If volume loss is suspected, 10 mL/kg of a volume expander (5% albumin, normal saline) should be administered through an umbilical vein line.

B. Continued Resuscitative Measures: The appropriateness of continued resuscitative efforts should be reevaluated in an infant who fails to respond to the above efforts. In current practice, resuscitative efforts are made even in apparent stillbirths (ie, infants whose Apgar score at 1 minute is 0–1). Modern resuscitative techniques have led to an increasing survival rate for these infants, with 60% of survivors showing normal development. It is clear from a number of studies that initial resuscitation of these infants should proceed; however, subsequent continued support must depend on response to resuscitation. All studies emphasize that if the Apgar score is not improving markedly over the first 10–15 minutes of life, the mortality rate and the incidence of severe developmental handicaps among survivors are high.

C. Special Considerations:

1. Preterm infants—

Minimizing heat loss improves survival, so prewarmed towels should be available. The environmental temperature of the delivery suite should be raised to > 25°C (especially for infants weighing <>
In the extremely low birth weight infant (<>
Volume expanders and sodium bicarbonate (if needed) should be infused slowly to avoid rapid swings in blood pressure and serum osmolality.

2. Narcotic depression—In the case of opioid administration to the mother during labor, perform the resuscitation as described above. When the baby is stable with good heart rate, color, and perfusion but still has poor respiratory effort, a trial of naloxone (0.1 mg/kg intramuscularly, subcutaneously, intravenously, or intratracheally) is indicated. Naloxone should not be administered in place of positive-pressure ventilation. Naloxone should not be used in the infant of an opioid-addicted mother because it will precipitate withdrawal.

3. Meconium-stained amniotic fluid—

The obstetrician carefully suctions the oropharynx and the nasopharynx after delivery of the head with a suction apparatus attached to wall suction.
The delivery is then completed, and the baby is given to the resuscitation team.
If the baby is active and breathing, requiring no resuscitation, and if obstetric suctioning has been performed, the airway need not be inspected—only further suctioning of the mouth and nasopharynx is required.
The airway of any depressed infant requiring ventilation must be checked and cleared (by passage of a tube below the vocal cords) before positive-pressure ventilation is instituted. Special adapters are available for use with regulated wall suction to allow suction to be applied directly to the endotracheal tube.

4. Universal precautions should always be observed in the delivery room.

Management of the Asphyxiated Infant
Asphyxia is manifested by multiorgan dysfunction, seizures and hypoxic-ischemic encephalopathy, and metabolic acidemia. The infant who has experienced a significant episode of perinatal hypoxia and ischemia is at risk for dysfunction of multiple end organs (Table 1–18). The organ of greatest concern is the brain.
The clinical features of hypoxic-ischemic encephalopathy progress over time: birth to 12 hours, decreased level of consciousness, poor tone, decreased spontaneous movement, periodic breathing or apnea, and possible seizures; 12–24 hours, more seizures, apneic spells, jitteriness, and weakness; after 24 hours, decreased level of consciousness, further respiratory abnormalities (progressive apnea), onset of brainstem signs (oculomotor and pupillary disturbances), poor feeding, and hypotonia.
The severity of clinical signs and the length of time the signs persist correlate with the severity of the insult. Other evaluations helpful in assessing severity in the term infant include electroencephalogram (EEG), computed tomography (CT) scan, and evoked responses. As experience in the use of magnetic resonance imaging (MRI) is gained, this technique may also prove useful. Markedly abnormal EEGs with voltage suppression and slowing evolving into a burst-suppression pattern are associated with severe clinical symptomatology. A CT scan early in the course may demonstrate diffuse hypodensity, whereas later scans may demonstrate brain atrophy and focal ischemic lesions. Visual and somatosensory evoked potentials provide information about function. In most instances, it is not necessary to use all of these tests, but some are obtained to confirm an ominous prognosis. Management is directed at supportive care and treatment of specific abnormalities. Fluids should be restricted initially to 60–80 mL/kg/d; oxygenation should be maintained (with mechanical ventilation if necessary); blood pressure should be supported with judicious volume expansion (if hypovolemic) and pressors; and glucose should be in the normal range of 40–100 mg/dL. Hypocalcemia, coagulation abnormalities, and metabolic acidemia should be corrected and seizures treated with intravenous phenobarbital (20 mg/kg as loading dose, with total initial 24-hour dosing up to 40 mg/kg). Phenobarbital in large doses (40mg/kg intravenously 1–6 hours after the event) given as a neuroprotective therapy is associated with improvement in neurologic outcome with minimal adverse effects on blood pressure, respirations, or blood gases. Other anticonvulsants should be reserved for refractory seizures. The role of hypothermia (in particular, selective head cooling), free oxygen radical scavengers, excitatory amino acid antagonists, and calcium channel blockers in minimizing cerebral injury after asphyxia is under active investigation.

Birth Asphyxia: Long-Term Outcome
Fetal heart rate tracings, cord pH, and 1-minute and 5-minute Apgar scores are imprecise predictors of long-term outcome. Apgar scores of 0–3 at 5 minutes in term infants result in an 8% risk of death in the first year of life and a 1% risk of cerebral palsy among survivors. A 10-minute Apgar score of 0–3 predicts death in the first year in 18% of cases and cerebral palsy among survivors in 5%; at 15 minutes, the rates are 48% and 9%, respectively; and at 20 minutes, 59% and 57%, respectively. The single best predictor of outcome is the severity of clinical hypoxic-ischemic encephalopathy (severe symptomatology carries a 75% chance of death and a 100% rate of neurologic sequelae among survivors). The major sequela of hypoxic-ischemic encephalopathy is cerebral palsy with or without associated mental retardation and epilepsy. Other prognostic features include prolonged seizures refractory to therapy, markedly abnormal EEGs, and CT scans with evidence of major ischemic injury. Other clinical features required to support perinatal hypoxia as the cause of cerebral palsy include the presence of fetal distress prior to birth, a low cord pH of < 7.00, and evidence of other end organ dysfunction.

MULTIPLE BIRTHS

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Twinning has historically occurred as a demographic variation in one of 80 pregnancies (1.25%). The incidence of twinning in the United States in 1990, however, was 2.3% of pregnancies. A clear distinction should be made between dizygotic (fraternal) and monozygotic (identical) twins. Race, maternal parity, and maternal age affect the incidence only of dizygotic twinning. Drugs that induce ovulation, such as clomiphene citrate and gonadotropins, increase the incidence of dizygotic or polyzygotic twinning quite strikingly. Monozygotic twinning can be viewed as a birth defect; the incidence of malformations is also increased in identical twins and may affect only one of the twins. If a defect is found in one, the other should be examined carefully for lesser degrees of the same defect.
Examination of the placenta can help establish the type of twinning: Two amnionic membranes and two chorionic membranes are found in all cases of dizygotic twins and in one third of monozygotic twins; a single chorionic membrane always indicates monozygotic twins.

Complications of Multiple Births

A. Intrauterine Growth Restriction: There is some degree of intrauterine growth restriction in most multiple pregnancies after 34 weeks. If prenatal care is good, however, the growth restriction is rarely significant. There are two exceptions: The first is the monochorial twin pregnancy in which there is an arteriovenous shunt from one twin’s circulation to that of the other (twin-twin transfusion syndrome). The infant on the venous side becomes plethoric and considerably larger than the smaller anemic twin. Morbidity and mortality rates are considerable in twin-twin transfusion syndrome. Discordance in size— birth weights that are significantly different—can also occur when there are separate placentas. One placenta develops poorly, presumably because of a poor implantation site. In this instance, there is no fetal exchange of blood but there is a striking difference in the growth rates of the two infants.

B. Preterm Delivery: Gestation length tends to be inversely related to the number of fetuses. The prematurity tends to increase the mortality or morbidity of twin pregnancies.

C. Obstetric Complications: Polyhydramnios, pregnancy-induced hypertension, premature rupture of membranes, abnormal fetal presentations, and prolapsed umbilical cord occur more frequently in women with multiple fetuses. In general, most of the complications can be avoided or minimized by good obstetric management. Multiple pregnancy should always be identified prenatally with ultrasound examinations; doing so allows the obstetrician and pediatrician or neonatologist to plan management jointly. The neonatal complications are usually related to prematurity. Prolongation of pregnancy, therefore, leads to a significant reduction in neonatal morbidity.
Follow-up studies of twin pregnancies have yielded conflicting results. In general, the studies do not suggest that twinning has a significant effect on later development, especially if prematurity is excluded as a separate risk factor.

INFANTS OF MOTHERS WHO ABUSE DRUGS

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The problem of newborn infants born to mothers who abuse drugs is increasing in all communities. The drugs most commonly abused are tobacco, alcohol, marijuana, and cocaine. Because these mothers may abuse many drugs and give an unreliable history of drug usage, it may be difficult to pinpoint which drug is causing the morbidity seen in a newborn infant. Early hospital discharge makes discovery of these infants based on physical findings and abnormal behavior much more difficult.

1. COCAINE
Cocaine is currently the most commonly abused illicit drug, identified in up to 20–40% of pregnant women on urban delivery services; moreover, cocaine is often used in association with other drugs. The obstetric effects include maternal hypertension, decreased uterine blood flow, fetal hypoxemia, and uterine contractions. The rates of stillbirth, placental abruption, and preterm labor are increased two- to fourfold over nonusers, as is the rate of intrauterine growth restriction. Other effects in the fetus include microcephaly, cerebral infarctions, and congenital malformations caused by vascular infarcts such as intestinal atresia. In high-risk populations (no prenatal care, placental abruptions, and preterm labor), urine toxicology screens should be performed in mothers and infants. Analysis of meconium enhances diagnosis by indicating cumulative drug use prior to delivery.
As with other illegal drugs, cocaine seems to have long-term neurobehavioral effects, but multiple drug use and environmental factors preclude assigning specific effects to cocaine with certainty. The risk of SIDS is increased three to seven times over the risk in nonusers (0.5–1% of exposed infants).

2. OPIOIDS

Essentials of Diagnosis & Typical Features
Irritability, hyperactivity, incessant hunger and salivation.
Vomiting, diarrhea, excessive weight loss.
Tremors, seizures.
Nasal stuffiness, sneezing.
Often IUGR.

Clinical Findings
The withdrawal signs in infants born to mothers who are addicted to heroin or who have been in maintenance methadone programs are similar. The clinical findings in infants born to methadone-maintained mothers may actually be more severe and prolonged than those seen with heroin. Clinical manifestations begin usually within 1–2 days. The clinical picture is typical enough to suggest a diagnosis even if a maternal history of drug abuse has not been obtained, although onset may not occur prior to discharge at 24 hours. Confirmation should be attempted with urine toxicology, but results will be negative unless the last drug dose was within a few days before delivery. Meconium can also be tested for illicit drugs and is more likely to be positive because the substances accumulate throughout pregnancy.

Treatment
Careful observation of the infant is a requirement. If opioid abuse or withdrawal is suspected, the baby is not a candidate for early discharge. Supportive treatment includes swaddling the infant and providing a quiet, dimly lighted environment. In general, specific treatment should be avoided unless the infant has severe symptoms or excessive weight loss. There is no single drug that has been uniformly effective, and the first choice varies among nurseries. The drugs that have been used include phenobarbital at an initial loading dose of 15–20 mg/kg intramuscularly, followed by a maintenance dose of 5 mg/kg/d in two divided doses, usually given orally. Opioids, diazepam, and clonidine have also been used, although the present authors prefer phenobarbital because of its safety and predictability. Treatment can be tapered over several days to a week. Both handling and procedures in the nursery should be kept to a minimum.

Prognosis
These infants demonstrate long-term neurobehavioral handicaps. However, it is difficult to distinguish the effects of in utero drug exposure from those of environmental influences during upbringing. Infants of opioid abusers have a four- to fivefold increased risk of SIDS.

3. ALCOHOL
The effects of alcohol on the fetus and the newborn are roughly proportionate to the degree of ethanol abuse. Fetal growth and development are adversely affected, and infants can experience withdrawal similar to that associated with maternal opioid abuse.
Children with full-blown fetal alcohol syndrome demonstrate postnatal growth deficiency and mild to moderate mental retardation. Those with lesser effects are at increased risk for attention-deficit/hyperactivity disorder and subtle developmental delays.

4. TOBACCO SMOKING
Smoking has been shown to have a negative impact on the growth rate of the fetus. The more the mother smokes, the greater the degree of intrauterine growth restriction. More recently, smoking during pregnancy has been associated with mild neurodevelopmental handicaps. The possible effects of multiple drug abuse apply to this category as well, and the potential interaction of multiple factors on fetal growth and development must be considered.

5. TOLUENE EMBRYOPATHY
Solvent abuse (paint, lacquer, or glue sniffing) is relatively common. The active organic solvent in these agents is toluene. Features attributable to in utero toluene exposure include prematurity, intrauterine growth retardation, microcephaly, craniofacial abnormalities similar to those associated with in utero alcohol exposure (see Table 1–15), nail hypoplasia, and renal anomalies. Long-term effects include postnatal growth deficiency and developmental delay.

6. OTHER DRUGS
There are two categories under which drugs and their effects on the newborn should be considered. In the first category are drugs to which the fetus is exposed because of its exposure to the mother. In many cases these are drugs prescribed for therapy of maternal conditions. The human placenta is relatively permeable, particularly to lipophilic solutes. Whenever possible, drug therapy of the mother should be postponed until after the first trimester. Drugs with potential fetal toxicity include antineoplastics, antithyroid agents, benzodiazepines, warfarin, lithium, angiotensin-converting enzyme inhibitors (eg, captopril, enalapril), and immunosuppressants.
In the second category are drugs the infant acquires from the mother during breast feeding. Most drugs taken by the mother at this time achieve some concentrations in breast milk, although they usually do not present a problem to the infant. If the drug is one that could have adverse effects on the baby, timing breast feeding to coincide with trough concentrations in the mother may be useful. The American Academy of Pediatrics (see second reference below) has reviewed drugs contraindicated in the breast-feeding mother.

BIRTH TRAUMA

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Most birth trauma is associated with difficult delivery, particularly with a large infant, abnormal position, or fetal distress requiring rapid extraction. The most common injuries are soft tissue bruising, fractures (clavicle, humerus, or femur), and cervical plexus palsies, although skull fractures, intracranial hemorrhage (primarily subdural and subarachnoid), and cervical spinal cord injuries can also occur.
Fractures are often diagnosed by the obstetrician, who may feel and hear a snap during delivery. Clavicular fractures may cause decreased spontaneous movement of the arm, with tenderness and crepitus over the area. Humeral or femoral fractures may cause tenderness and swelling over the shaft with a diaphyseal fracture, with limited spontaneous extremity motion in all cases. Epiphyseal fractures are harder to diagnose radiographically owing to the cartilaginous nature of the epiphysis. After 8–10 days, callus appears and is visible on radiographs. Treatment in all cases is gentle handling, with immobilization for 8–10 days: the humerus against the chest with elbow flexed; the femur with a posterior splint from below the knee to the buttock.
Brachial plexus injuries may result from traction as the head is pulled away from the shoulder during delivery. Injury to the C5–C6 roots is most common and results in Erb-Duchenne paralysis. The arm is limp, adducted and internally rotated, extended and pronated at the elbow, and flexed at the wrist (so-called waiter’s tip posture). Grasp is present. If the lower nerve roots (C8–T1) are involved, the hand is flaccid (Klumpke’s palsy). Isolated involvement of these roots is rare. If the entire plexus is injured, the arm and hand are flaccid, with an associated sensory deficit.
Early treatment for brachial plexus injury is conservative, because function usually returns over several weeks. Referral should be made to a physical therapist so that the parents can be instructed on range-of-motion exercises and splinting and for further evaluation if needed. Return of function begins in the deltoid and biceps, with recovery by 3 months in most cases.
Spinal cord injury can occur at birth, especially in difficult breech extractions with hyperextension of the neck, or in midforceps rotations where the body fails to turn with the head. Infants are flaccid, quadriplegic, and without respiratory efforts at birth, although facial movements are preserved. The long-term outlook for such infants is grim.
Facial nerve palsy is sometimes associated with forceps use but more often results from chronic in utero pressure of the baby’s head against the mother’s sacrum. The infant has asymmetric mouth movements and eye closure with poor movement on the affected side. Most cases resolve spontaneously within a few days to 3 weeks.

HEART MURMURS

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Heart murmurs are common in the first days of life and do not usually signify structural heart problems. If a murmur is present at birth, however, it should be considered a valvular problem until proved otherwise because the common benign transitional murmurs (eg, patent ductus arteriosus) are not audible until minutes to hours after birth.
If an infant is pink, well-perfused, and in no respiratory distress and has palpable and symmetric pulses (right brachial pulse no stronger than the femoral pulse), the murmur is most likely transitional. Transitional murmurs are soft (grade 1–3/6), heard at the left upper to midsternal border, and generally loudest during the first 24 hours. If the murmur persists beyond 24 hours, blood pressure in the right arm and a leg should be determined. If there is a difference of more than 15 mm Hg (arm > leg), cardiology consultation should be arranged to evaluate for coarctation of the aorta. If there is no difference, the infant can be discharged home with follow-up in 2–3 days for auscultation and evaluation for signs of congestive failure. If signs of failure or cyanosis are present, the infant should be referred for evaluation without delay. If the murmur persists without these signs, the infant can be referred for elective evaluation at age 2–4 weeks.

RESPIRATORY DISTRESS IN THE TERM NEWBORN INFANT

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Essentials of Diagnosis & Typical Features

Tachypnea, respiratory rate > 60 breaths/min.
Retractions (intercostal, sternal).
Expiratory grunting.
Cyanosis on room air.

General Considerations
Respiratory distress is among the most common symptom complexes seen in the newborn infant. It may result from both noncardiopulmonary and cardiopulmonary causes (Table 1–14). Chest radiography, arterial blood gases, and pulse oximetry are useful in assessing both the cause and the severity of the problem. It is important to consider the noncardiopulmonary causes listed in Table 1–14 because the natural tendency is to focus on the heart and lungs. Most of the noncardiopulmonary causes can be ruled out by the history, physical examination, and a few simple laboratory tests. The evaluation of cardiovascular disorders is discussed in a subsequent section.
The most common pulmonary causes of respiratory distress in the term infant are transient tachypnea, aspiration syndromes, congenital pneumonia, and air leaks.

A. Transient Tachypnea (Retained Fetal Lung Fluid): Respiratory distress is typically present from birth, usually associated with a mild to moderate oxygen requirement (25–50% O2). The infant may be term or near-term, nonasphyxiated, and born following a short labor or cesarean section without labor. Chest x-ray shows perihilar streaking and fluid in interlobar fissures. Resolution usually occurs within 12–24 hours.

B. Aspiration Syndromes: The infant is typically term or near-term, frequently with some fetal distress prior to delivery or depression at delivery. Blood or meconium is usually present in the amniotic fluid, but occasionally the fluid is clear. Respiratory distress is present from birth, in many cases manifested by a barrel chest appearance and coarse breath sounds. An increasing O2 need from pneumonitis may require intubation and ventilation. Chest x-ray shows coarse irregular infiltrates, hyperexpansion, and, in the worst cases, lobar consolidation.
When the amniotic fluid contains meconium or blood, suctioning of the infant’s mouth and nose as the head is delivered and before delivery of the chest is recommended to prevent aspiration of these secretions with the onset of breathing. If the infant is depressed or shows signs of respiratory distress at birth, suctioning of the trachea under direct vision is recommended, especially before commencing resuscitation with positive-pressure ventilation. Although these procedures are recommended, they will not prevent all cases of meconium or blood aspiration. Aspiration often occurs in utero as the stressed infant gasps. Babies with aspirations are at risk of air leak (pneumothorax) because of uneven aeration with segmental overdistention and are at risk for persistent pulmonary hypertension (see Cardiac Problems section, below). Standard treatment includes ventilatory support, antibiotics, and pressor support of systemic blood pressure.

C. Congenital Pneumonia: Infants may be of any gestational age, with or without a maternal history of prolonged rupture of the membranes, chorioamnionitis, or maternal antibiotic administration. Onset of respiratory distress may be at birth or may be delayed for several hours. Chest x-ray may resemble that of retained lung fluid or hyaline membrane disease; rarely, there may be a lobar infiltrate.
The lungs are the most common site of infection in the neonate. Most commonly, infections ascend from the genital tract before or during labor, with the vaginal or rectal flora the most likely infectious agents (group B streptococci, Escherichia coli, Klebsiella). Shock, poor perfusion, and absolute neutropenia (< 2000/mL) provide corroborating evidence for pneumonia. Gram stain of tracheal aspirate may be helpful. Because no signs or laboratory findings can confirm the presence or absence of pneumonia with certainty, all infants with respiratory distress should receive a blood culture and broad-spectrum antibiotic therapy (ampicillin 100 mg/kg in two divided doses and gentamicin 4 mg/kg every 24 hours or 2.5 mg/kg every 12 hours) until the diagnosis of a bacterial infection can be ruled out.

D. Spontaneous Pneumothorax: Respiratory distress (primarily tachypnea) is present from birth, typically not severe, and requires mild to moderate supplemental O2. Breath sounds may be decreased on the affected side; heart tones may be shifted toward the opposite side and may be distant. Chest x-ray will show pneumothorax or pneumomediastinum.
This entity occurs in 1% of all deliveries. The risk is increased by manipulations such as positive-pressure ventilation in the delivery room. Treatment usually consists of supplemental O2 and watchful waiting. Breathing 100% O2 for a few hours may accelerate reabsorption of the extrapulmonary gas by creating a diffusion gradient for nitrogen across the surface of the lung (nitrogen washout technique). This is effective only if the infant was breathing room air or O2 at low concentration at the time of the pneumothorax. Drainage by needle thoracentesis or tube thoracostomy is occasionally required. There is a small increased risk of renal abnormalities associated with spontaneous pneumothorax. Therefore, a careful physical examination of the kidneys and observation of urine output are indicated. If pulmonary hypoplasia with pneumothorax is suspected, renal ultrasound would also be indicated.

E. Other Pulmonary Causes: The other pulmonary causes of respiratory distress are fairly rare. Bilateral choanal atresia should be suspected if there is no air movement when the infant breathes through the nose. These infants present in the delivery room with good color and heart rate while crying but become cyanotic and bradycardiac when they quiet down and resume normal breathing. Other causes of upper airway obstruction are usually characterized by some degree of stridor or poor air movement despite good respiratory effort. Pleural effusions can be suspected in hydropic infants (eg, those with erythroblastosis fetalis). Space-occupying lesions cause a shift of the mediastinum and asymmetric breath sounds and would be apparent on chest x-ray.

Treatment
Whatever the cause, the cornerstone of treatment of neonatal respiratory distress is provision of adequate supplemental oxygen to maintain a PaO2 of 60–70 mm Hg and a saturation by pulse oximetry (SpO2) of 92–96%. PaO2 levels less than 50 mm Hg are associated with pulmonary vasoconstriction, which can exacerbate hypoxemia, whereas those greater than 100 mm Hg may increase the risk of oxygen toxicity without additional benefit. Oxygen should be warmed, humidified, and delivered through an air blender. Concentration should be measured with a calibrated oxygen analyzer. An umbilical or peripheral arterial line should be placed in any infant requiring more than 45% FIO2 by 4–6 hours of life to allow frequent blood gas determinations. Noninvasive monitoring with a pulse oximeter should be used.
Other supportive treatment includes intravenous provision of glucose and water. Unless infection can be unequivocally ruled out, blood cultures should be obtained and broad-spectrum antibiotics started. Volume expansion (normal saline; 5% albumin) can be given in infusions of 10 mL/kg over 30 minutes for low blood pressure, poor perfusion, and metabolic acidosis. Sodium bicarbonate (1–2 mEq/kg) is indicated for treatment of documented metabolic acidosis that has not responded to oxygen, ventilation, and volume. Specific workup should be pursued as indicated by the history and physical findings. In most cases, a chest x-ray study, blood gas measurements, complete blood count, and blood glucose allow a diagnosis.
Intubation and ventilation should be undertaken for signs of respiratory failure (PaO2 <> 60 mm Hg). Peak pressures should be adequate to produce chest wall expansion and audible breath sounds (usually 18–24 cm H2O). Positive end-expiratory pressure (4–6 cm H2O) should also be used. Ventilation rates of 20–50 breaths per minute are usually required. The goal is to maintain a PaO2 of 60–70 mm Hg and a PaCO2 of 40–50 mm Hg.

Prognosis
Most of the respiratory conditions affecting the term infant are acute and resolve in the first several days. Meconium aspiration syndrome and congenital pneumonia are associated with significant long-term pulmonary morbidity (chronic lung disease) and mortality (approximately 10–20%). Mortality rates in these disorders have been reduced by use of high-frequency ventilation, inhaled nitric oxide to treat pulmonary hypertension, and extracorporeal membrane oxygenation (ECMO).

HYPOGLYCEMIA

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Essentials of Diagnosis & Typical Features

Defined as blood glucose <>
LGA, SGA, preterm, and stressed infants at risk.
May be asymptomatic.
Infants can present with lethargy, poor feeding, irritability, or seizures.

General Considerations
Blood glucose concentration in the fetus is approximately 15 mg/dL less than the maternal glucose concentration. Glucose concentration normally decreases in the immediate postnatal period, with concentrations below 40–45 mg/dL being considered indicative of hypoglycemia. By 3 hours, the glucose concentration in normal-term babies stabilizes between 50 and 80 mg/dL. After the first few hours of life, concentrations below 40–45 mg/dL should be considered abnormal. The two most commonly encountered groups of term newborn infants at high risk for neonatal hypoglycemia are IDMs and IUGR infants.

Infants of Diabetic Mothers
The IDM has abundant glucose stores in the form of glycogen and fat but develops hypoglycemia because of hyperinsulinemia induced by maternal and fetal hyperglycemia. Other tissues also grow abnormally in utero, probably as a consequence of increased flow of nutrients from the maternal circulation. The result is a macrosomic infant who is at increased risk for trauma during delivery. Other problems related to the in utero metabolic environment include a cardiomyopathy (asymmetric septal hypertrophy), which can present as a murmur with or without cardiac failure and respiratory distress, and, more rarely, microcolon, which presents as low intestinal obstruction. Infants whose mothers have diabetes at conception are also at increased risk for congenital anomalies probably related to first-trimester glucose control. Other neonatal problems include a hypercoagulable state and polycythemia, a combination that predisposes the infant to large venous thromboses (eg, renal vein thrombosis). Finally, these infants are somewhat immature for their gestational age and are at increased risk for hyaline membrane disease, hypocalcemia, and hyperbilirubinemia.

Intrauterine Growth Restricted Infants
The IUGR infant has reduced glucose stores in the form of glycogen and body fat and therefore is prone to hypoglycemia despite relatively appropriate endocrine adjustments at birth. In addition to hypoglycemia, marked hyperglycemia and a transient diabetes mellitus–like syndrome may occasionally develop, particularly in the very preterm SGA infant. These problems can usually be handled by adjusting glucose intake, though insulin is sometimes needed transiently.

Other Causes of Hypoglycemia
Hypoglycemia occurs with disorders associated with islet cell hyperplasia (Beckwith-Wiedemann syndrome [macroglossia, omphalocele, macrosomia],erythroblastosis fetalis, nesidioblastosis), inborn errors of metabolism (glycogen storage disease, galactosemia), and endocrine disorders (panhypopituitarism, other deficiencies of counterregulatory hormones). It may also occur as a complication of birth asphyxia, hypoxia, or other stresses, including bacterial and viral sepsis. Premature infants are also at risk for hypoglycemia because of decreased glycogen stores.

Clinical Findings
The signs of hypoglycemia in the newborn infant are relatively nonspecific and may be subtle: lethargy, poor feeding, irritability, tremulousness, jitteriness, apnea, and seizures. The disorder is most severe and resistant to treatment if due to hyperinsulinemia. Cardiac failure may occur in severe cases, particularly in IDMs with cardiomyopathy. Infants with hyperinsulinemic states can experience the onset of hypoglycemia very early (within the first 30–60 minutes of life).
Blood glucose can be measured by heel stick using a bedside glucometer. All infants at risk should be screened, including IDMs, IUGR infants, premature infants, and any infant with symptoms that could be due to hypoglycemia. All low or borderline values should be confirmed by direct measurement of blood glucose concentration determined in the laboratory. It is important to continue surveillance of glucose concentration until the baby has been on full enteral feedings without intravenous supplementation for a 24-hour period. Relapse of hypoglycemia thereafter is unlikely.
Infants with hypoglycemia requiring intravenous glucose infusions for more than 5 days should be evaluated for the less common causes of hypoglycemia. This workup should include evaluation for inborn errors of metabolism, hyperinsulinemic states, and deficiencies of counterregulatory hormones.

Treatment
Therapy is based on provision of glucose either enterally or intravenously. Table 1–13 presents suggested treatment guidelines. In hyperinsulinemic states, boluses of glucose should be avoided and a higher glucose infusion rate used. After initial correction with a bolus of D10W, 2 mL/kg, glucose infusion should be increased gradually as needed from a starting rate of 6 mg/kg/min. Finally, in both IDMs and IUGR infants, those with high hematocrits and hypoglycemia are most likely to show clinical signs of hypoglycemia. In such infants, both the hypoglycemia and the polycythemia should be treated—with intravenous glucose infusion and partial exchange transfusion, respectively.

Prognosis
The prognosis of hypoglycemia is good if therapy is prompt. CNS sequelae are seen in infants with neonatal seizures resulting from hypoglycemia.

COMMON PROBLEMS IN THE TERM NEWBORN INFANT

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NEONATAL JAUNDICE

General Considerations
Jaundice is a common neonatal problem. Sixty-five percent of newborns develop clinical jaundice with a bilirubin level above 5 mg/dL during the first week of life. From an evolutionary standpoint, hyperbilirubinemia ought to confer some biologic advantage if it occurs so often. Bilirubin is a potent antioxidant and peroxyl scavenger that may help the newborn, who is deficient in most antioxidant substances such as vitamin E, catalase, and superoxide dismutase, to avoid oxygen toxicity in the days after birth. Hyperbilirubinemia can also be toxic, with high levels resulting in an encephalopathy known as kernicterus.

Metabolism of Bilirubin
Heme (iron protoporphyrin) is broken down by heme oxygenase to iron, which is conserved; carbon monoxide, which is exhaled; and biliverdin, which is then further metabolized to bilirubin by the enzyme bilirubin reductase. Each 1 g of hemoglobin breakdown results in the production of 34 mg of bilirubin (1 mg/dL = 17.2 µmol/L of bilirubin). Bilirubin is carried bound to albumin to the liver, where, in the presence of the enzyme uridyldiphosphoglucuronyl transferase (UDPGT; glucuronyl transferase), it is taken up by the hepatocyte and conjugated with two glucuronide molecules. The conjugated bilirubin is then excreted through the bile to the intestine. In the presence of normal gut flora, the conjugated bilirubin is metabolized further to stercobilins and excreted in the stool. In the absence of gut flora—and with slow intestinal motility, as in the first few days of life—the conjugated bilirubin remains in the intestinal lumen, where a mucosal enzyme (b-glucuronidase) can cleave off the glucuronide molecules, leaving unconjugated bilirubin to be reabsorbed (the enterohepatic circulation of bilirubin).

Bilirubin Toxicity
The exact mechanism by which bilirubin is toxic to cells is not known. It is assumed that if the amount of lipid-soluble unconjugated bilirubin exceeds the available binding sites on albumin, there will then be “free” bilirubin that can enter neurons and damage them. The blood-brain barrier probably plays an important role in protecting an individual from brain damage, but its integrity is impossible to measure clinically. It is not known whether there is a level of bilirubin above which brain damage would always occur even in a healthy individual.
The syndrome of bilirubin encephalopathy was well described in the era before exchange transfusion as treatment for Rh isoimmunization (see below). The pathologic correlate is known as kernicterus, named for the yellow staining of the subthalamic nuclei (kerns) seen at autopsy. The early symptoms of bilirubin encephalopathy consist of lethargy, hypotonia, and poor sucking, progressing to hypertonia, opisthotonos, and a high-pitched cry. Long-term sequelae include athetoid cerebral palsy, sensorineural deafness, limitation of upward gaze, and dental dysplasia. Whether or not bilirubin causes more subtle neurologic abnormalities remains debatable.
Bilirubin encephalopathy is very rare with current neonatal management. The only infant in which a specific bilirubin level (20 mg/dL [344 µmol/L] and above) has been associated with an increased risk of kernicterus is the Rh-isoimmunized infant. This observation—and the management strategy of keeping bilirubin under 20 mg/dL with exchange transfusion if needed—has been extended to other neonates with hemolytic disease despite an absence of data on the risk. The risk of bilirubin encephalopathy is probably very small for term infants without hemolysis even at bilirubin levels of 25 mg/dL (430 µmol/L). Premature infants are probably at some increased risk because of associated illnesses that may affect the integrity of the blood-brain barrier and reduced albumin levels. For this reason, a lower level of bilirubin is generally assumed to represent the “exchange level” in these infants and is usually determined arbitrarily based on the infant’s birth weight and gestational age. One common approach is to use 1% of the birth weight in grams as the exchange level in mg/dL (eg, 12 mg/dL for a 1200-g infant)—down to a low of 10 mg/dL. Many other approaches exist as well.

Causes of Unconjugated Hyperbilirubinemia
The causes of unconjugated hyperbilirubinemia can be grouped into two main categories: overproduction of bilirubin and decreased conjugation of bilirubin (Table 1–9).

A. Increased Bilirubin Production: Increased production of bilirubin results from an increased rate of red blood cell destruction (hemolysis) due to the presence of maternal antibodies against fetal cells (Coombs test–positive), abnormal red cell membrane shape (ie, spherocytosis), or abnormal red cell enzymes (ie, glucose-6-phosphate dehydrogenase [G6PD] deficiency). Antibodies can be directed against the major blood group antigens (the type A or type B infant of a type O mother) or the minor antigens (the Rh system: D, E, C, d, e, c, Kell, Duffy, and so on).

1. Antibody-mediated hemolysis (Coombs test–positive)—ABO blood group incompatibility is common, usually not severe, and can accompany any pregnancy in a type O mother. The severity is not predictable because of variability in the amount of naturally occurring anti-A or anti-B IgG antibodies in the mother. Although 20% of pregnancies are the appropriate “set-ups” for ABO incompatibility (mother O, baby A or B), only about 33% of such infants are Coombs test–positive and only about 20% of these develop excessive jaundice. In addition to hyperbilirubinemia in the first days of life, these infants may develop a significant anemia over the first several weeks and on occasion may need to be transfused at a few weeks of age.
Rh isoimmunization is much less common and increases in severity with each immunized pregnancy because of an increased maternal IgG antibody production each time. Most Rh disease can be prevented by administering high-titer Rho(D) immune globulin to an Rh-negative woman after any invasive procedure during pregnancy as well as after any miscarriage, abortion, or delivery of an Rh-positive infant. In severe cases, erythroblastosis fetalis (hydrops or generalized edema with heart failure related to severe anemia in the fetus) occurs, often resulting in fetal or neonatal death without appropriate antenatal intervention. In less severe cases, hemolysis is the main problem, with resultant hyperbilirubinemia and anemia. The cornerstone of antenatal management once isoimmunization has been diagnosed is transfusion of the fetus with Rh-negative cells, either directly into the umbilical vein via percutaneous cordocentesis or into the fetal abdominal cavity. Following delivery, phototherapy is usually started immediately, with exchange transfusion (see below) as needed. A 500 mg/kg dose of intravenous immune globulin (IVIG) given to the infant as soon after delivery as the diagnosis is made has been shown to decrease the need for exchange transfusion. Ongoing hemolysis will still occur until all maternal antibody is gone; therefore, these infants need to be followed carefully over the first 2 months for development of anemia severe enough to require transfusion. The role of erythropoietin therapy in treating late anemia is under investigation.

2. Nonimmune hemolysis (Coombs test– negative)—Hereditary spherocytosis is the most common red cell membrane defect, resulting in hemolysis because of decreased red cell deformability. These infants may have hyperbilirubinemia severe enough to require exchange transfusion. Mild to moderate splenomegaly may be present. Diagnosis is suspected by peripheral blood smear and confirmed by red cell osmotic fragility study. A family history of anemia, jaundice, and gallstones may be elicited.
G6PD deficiency is the most common red cell enzyme defect resulting in hemolysis and should be suspected in a male (it is X-linked) of African, Mediterranean, or Asian descent, particularly when the onset of jaundice is later than usual.

3. Nonhemolytic increased bilirubin production—Enclosed hemorrhage, such as cephalohematoma, intracranial hemorrhage, or extensive bruising in the skin, can lead to jaundice as the red blood cells are broken down and removed. Polycythemia leads to jaundice by increased red cell mass, with increased numbers of cells reaching senescence daily. Ileus, either paralytic or mechanical, related to a bowel obstruction, leads to hyperbilirubinemia secondary to increased enterohepatic circulation.

B. Decreased Rate of Conjugation:

1. UDPGT deficiency–Crigler-Najjar syndrome type I (complete deficiency, autosomal recessive) and type II (partial deficiency, autosomal dominant) present as excessive and prolonged neonatal jaundice, but both forms are very rare.

2. Gilbert syndrome is a mild autosomal dominant disorder affecting 3–6% of the population and characterized by decreased hepatic UDPGT levels. Mild unconjugated hyperbilirubinemia without other liver function abnormalities occurs after puberty. The possible relationship of this disorder to exaggerated neonatal jaundice is under investigation.

C. Hyperbilirubinemia Caused by Unknown or Multiple Factors:

1. Physiologic jaundice—The contributing factors to physiologic jaundice include UDPGT inactivity at birth, a relatively high red cell mass even in the nonpolycythemic neonate, and an absence of intestinal flora, with initially slow intestinal motility leading to an active enterohepatic circulation of bilirubin. For jaundice to be physiologic rather than pathologic, the following criteria should be satisfied: (1) clinical jaundice appears after 24 hours of age; (2) total bilirubin rises by less than 5 mg/dL (86 µmol/L) per day; (3) peak bilirubin occurs at 3–5 days of age, with a total bilirubin of no more than 15 mg/dL (258 µmol/L); and (4) clinical jaundice is resolved by 1 week in the term infant and by 2 weeks in the preterm infant. Hyperbilirubinemia outside of these parameters—or jaundice that requires treatment—is not physiologic and must be evaluated further (see below).

2. High altitude—Infants at 3100 m (10,000 ft) have twice the incidence of bilirubin over 12 mg/dL (206 µmol/L) as infants at 1600 m (5200 ft) and four times that of infants at sea level: 39% versus 16% versus 8%, respectively. Possible mechanisms include increased bilirubin production secondary to increased hematocrit and decreased clearance caused by hypoxemia.

3. Racial differences—Asians are more likely than whites or blacks to have a bilirubin greater than 12 mg/dL (206 µmol/L): 23% versus 10–13% versus 4%, respectively.

4. Prematurity—Premature infants frequently have poor enteral intake, delayed stooling, and increased enterohepatic circulation. Even at 37 weeks’ gestation, they are four times more likely than at 40 weeks to have a bilirubin greater than 13 mg/dL (224 µmol/L).

5. Breast feeding and jaundice—There are two syndromes of jaundice associated with breast feeding: breast milk jaundice and breast feeding–associated jaundice (“lack-of-breast-milk jaundice”).

Breast milk jaundice is an uncommon syndrome of prolonged unconjugated hyperbilirubinemia believed to be caused by a prolonged increased enterohepatic circulation of bilirubin in some breast-fed infants, perhaps related to increased free fatty acids in the milk. The presence of moderate unconjugated hyperbilirubinemia for 6–8 weeks in a thriving infant without evidence for hemolysis, hypothyroidism, or other disease strongly suggests this diagnosis. The hyperbilirubinemia peaks at 10–15 days of age, with a maximal level of 10–30 mg/dL (172–516 µmol/L), and declines slowly by 3–12 weeks of age. If nursing is interrupted for 24–48 hours, the bilirubin level falls quickly and will not rebound to the same level when nursing is resumed. This is indicated only if the hyperbilirubinemia is severe.
Breast feeding–associated jaundice, also known as “lack-of-breast-milk jaundice,” is a common entity. Breast-fed infants have a higher incidence (9%) of bilirubin over 13 mg/dL (224 µmol/L) than formula-fed infants (2%) and are more likely to have bilirubin over 15 mg/dL (258 µmol/L) than formula-fed infants: 2% versus 0.3%. The pathogenesis appears to be decreased enteral intake and increased enterohepatic circulation. No increase in bilirubin production is seen, as measured by carbon monoxide exhalation. Although rarely associated with bilirubin encephalopathy, this type of jaundice should be considered a sign of failure to establish an adequate milk supply and should prompt specific inquiries into this possibility (Table 1–10). If inadequate intake is present, the infant should receive supplementation with formula if needed, and the mother should be instructed to nurse more frequently and to pump her breasts with an electric breast pump every 2 hours to enhance milk production. A consultation with a certified lactation specialist should be considered, because many physicians feel inadequately prepared to handle these situations. Because hospital discharge of normal newborns occurs before the milk supply is established, a follow-up visit 2–3 days after discharge is of obvious importance.
These two entities may sometimes overlap in the same infant, because prolonged jaundice is common in breast-fed infants (20–30%), and many of those infants with high bilirubin levels in the first days also persist longest.
Prolonged Hyperbilirubinemia: Causes of prolonged hyperbilirubinemia include hemolytic disease, breast milk jaundice, Crigler-Najjar syndrome, bowel obstruction, congenital hypothyroidism, and galactosemia. Galactosemia generally presents with hepatomegaly in an ill-appearing, often septic infant, and the hyperbilirubinemia is usually mixed.

Evaluation of Hyperbilirubinemia
Clinical jaundice appears at a bilirubin level of 5 mg/dL (86 µmol/L) and appears first on the head, progressing down the chest and abdomen as the level increases. By the time jaundice is noted on the distal extremities, the level is likely to be at least 15 mg/dL (258 µmol/L). When checking serum bilirubin levels, the level should be assessed based on the age in hours at which the sample was obtained. Infants with a total serum bilirubin greater than the 95th percentile for age in hours have a 40% risk of developing subsequent significant hyperbilirubinemia (Figure 1–2). Infants who develop clinical jaundice on the first day of life—or who develop excessive jaundice—require evaluation. The minimal evaluation consists of a feeding and elimination history, weight (and comparison with birth weight), examination for any source of excessive heme breakdown, and laboratory evaluation for blood type, Coombs testing, complete blood count with smear, and total bilirubin level. A G6PD test should be considered if the infant is a male of African, Asian, or Mediterranean racial background, particularly if the jaundice presents later than usual. A fractionated bilirubin level should be obtained if the infant appears acutely ill, if jaundice is prolonged, or if the infant has dark urine with light stools.
Because of large interlaboratory variability, serial bilirubin levels should be obtained from a single laboratory whenever possible to make interpretation more accurate.
Treatment of Hyperbilirubinemia

A. Protoporphyrins: Tin and zinc protoporphyrin or mesoporphyrin (Sn-PP, Zn-PP; Sn-MP, Zn-MP) are inhibitors of heme oxygenase, the enzyme that begins the catabolism of heme (iron protoporphyrin). Studies are under way involving a single injection of these substances shortly after birth to prevent the formation of bilirubin. Although early results are promising, these drugs are still experimental.

B. Phototherapy: Phototherapy is used most commonly, because it is relatively noninvasive and safe. Light at a wavelength absorbed by bilirubin (blue or white spectrum) is used. The unconjugated bilirubin in the skin is converted by such light to a stereoisomer compound that is water soluble and able to be excreted in the bile without conjugation. A minimum of 10–12 µW/cm2 irradiance is required, and efficacy is dose dependent. The dose can be raised by increasing the body surface area exposed to the light and by moving the lights closer to the baby. Fiberoptic blankets are effective. The infant’s eyes should be shielded from the light to prevent damage to retinal cells. A frequent side effect of phototherapy is diarrhea, which is managed by feeding a non-lactose-containing formula for the duration of the treatment.
Phototherapy is started when the bilirubin level is approximately 5 mg/dL (86 µmol/L) lower than the exchange level for that infant (eg, at levels of 15–18 mg/dL [258–310 µmol/L] for a term infant), depending also on the infant’s age. Guidelines for the use of phototherapy in the term infant with and without ABO incompatibility are shown in Table 1–11 and Table 1–12. Although phototherapy has been shown to decrease the likelihood of exchange transfusion, the long-term benefits of its use in infants with less severe jaundice are unknown.

C. Exchange Transfusion: Double-volume exchange transfusion (approximately 160–200 mL/kg body weight) remains necessary in the rare case of hemolysis resulting from Rh isoimmunization, ABO incompatibility, or hereditary spherocytosis. In addition to decreasing the bilirubin level by approximately 50% acutely, the exchange also removes nearly 80% of the sensitized or abnormal red blood cells and offending antibody so that ongoing hemolysis will be decreased. The procedure is invasive and not without risk. The risk of mortality is greatest in the smallest, most immature, and otherwise unstable infants, but sudden death during the procedure can occur in any infant. Because of the rarity of the procedure and its inherent risk, it should be performed very cautiously, preferably at a referral center.
For the typical exchange transfusion, the umbilical vein is catheterized, and reconstituted whole blood with a hematocrit of approximately 50% is used in aliquots of 8–10 mL per pass. Hypocalcemia occurs during the procedure because of binding to the citrate-phosphate-dextrose anticoagulant and needs to be corrected periodically. Hypoglycemia is common following the procedure and requires close monitoring. Thrombocytopenia occurs because of the removal of platelets. The entire procedure should take 1–2 hours and should be performed using aseptic technique.

EARLY DISCHARGE OF THE NEWBORN INFANT

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The trend for several years has been toward shorter hospital stays for well mothers and infants, with typical stays in 1997 of 24 hours following a normal vaginal delivery and 48–72 hours following a cesarean section. Although there has been a growing backlash against early discharge, culminating in the United States in the passage of the Newborns’ and Mothers’ Health Protection Act (effective January 1, 1998), it is unlikely that the typical length of stay for the normal newborn will increase substantially. Discharge at 24–36 hours of age appears safe and appropriate for most infants if there are no contraindications (Table 1–7) and a follow-up visit at 48–72 hours after discharge is ensured. Most infants with severe cardiorespiratory disorders and infections are identified in the first 6 hours of life. The exception would be the infant treated with intrapartum antibiotic prophylaxis for maternal group B streptococcal colonization or infection. The Centers for Disease Control and American Academy of Pediatrics (AAP) have recommended that these infants be observed in hospital for 48 hours because of the possibility of “partial treatment” with delayed onset of symptoms of infection. Other problems such as jaundice and difficulties in breast feeding typically occur after 48 hours and can usually be dealt with on an outpatient basis provided good follow-up has been arranged.
The AAP recommends a follow-up visit within 48–72 hours for any newborn discharged before 48 hours of age. Infants who are small or slightly premature—especially if breast feeding—are at particular risk for inadequate intake. Suggested guidelines for the follow-up interview and physical examination are presented in Table 1–8. The optimal timing of discharge must be determined in each case based on medical, social, and financial factors.

CIRCUMCISION
Circumcision is an elective procedure to be performed only in healthy, stable infants. The procedure probably has medical benefits, including prevention of phimosis, paraphimosis, balanoposthitis, and urinary tract infection. Later benefits include decreased incidence of cancer of the penis, cervical cancer (in partners of circumcised men), and sexually transmitted diseases (including HIV). Most parents decide on circumcision for nonmedical reasons. The risks of the procedure include local infection, bleeding, removal of too much skin, and urethral injury. The combined incidence of these complications is less than 1%. Local anesthesia (dorsal penile nerve block or circumferential ring block with 1% lidocaine without epinephrine) or topical application of an anesthetic cream (eg, lidocaine-prilocaine cream) are safe and effective and should always be used. Techniques that allow visualization of the glans throughout the procedure (eg, using Plastibell and Gomco clamp) are preferred to a blind technique (eg, using Mogen clamp) because occasional amputation of the glans can occur with the latter technique. Circumcision is contraindicated in infants with genital abnormalities (eg, hypospadias). Coagulation screen should be performed prior to the procedure in infants with a family history of bleeding disorders.

HEARING SCREENING
Normal hearing is critical to normal language development. Significant bilateral hearing loss is present in 1–3 infants per 1000 in the well nursery and in 2–4 infants per 100 in the neonatal intensive care unit population. All infants should be screened for hearing loss by auditory brainstem evoked responses or evoked otoacoustic emissions as early as possible. Primary care providers and parents need to be advised of the possibility of hearing loss and offered ready referral in suspect cases.

CARE OF THE WELL NEWBORN INFANT

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The primary responsibility of the level 1 nursery is care of the well infant. This includes promoting mother-infant bonding, establishing feeding, and teaching the techniques of newborn care. Surveillance of the infant is a key function of the staff; they must be alert for the signs and symptoms of illness, including temperature instability, change in activity, refusal to feed, pallor, cyanosis, early or excessive jaundice, tachypnea and respiratory distress, delayed (beyond 24 hours) passage of first stool or voiding of urine, and bilious vomiting. Several preventive measures are undertaken routinely in the normal newborn nursery.
Eye prophylaxis to prevent gonococcal ophthalmia is routinely administered within 1 hour after birth with either erythromycin ointment or silver nitrate 1% drops. Because of the severe chemical conjunctivitis caused by silver nitrate, erythromycin is preferred.
Vitamin K, 1 mg, is given intramuscularly or subcutaneously within 4 hours after birth to prevent hemorrhagic disease of the newborn. The area to be injected must be cleansed thoroughly before injection to prevent infection.
Hepatitis B vaccine and hepatitis B immune globulin (HBIG) are administered if the mother is known to be surface antigen-positive. If maternal HBsAg status is unknown at birth, the vaccine should be given. The mother’s blood should be tested and HBIG given at less than 7 days of age if the test is positive.
Cord blood is collected on all infants at birth and used for blood typing and Coombs testing if the mother is type O or Rh-negative. Cord blood is useful also for other tests, such as toxicology screens.
Rapid glucose testing should be performed in infants at risk for hypoglycemia (eg, infants of diabetic mothers [IDMs]; preterm, SGA, LGA, or stressed infants). Values less than 40 mg/dL should be confirmed by laboratory blood glucose testing and treated. Hematocrit should be measured at age 3–6 hours in infants at risk for or those who have symptoms of polycythemia or anemia.
The state-sponsored newborn genetic screen (for inborn errors of metabolism such as phenylketonuria [PKU], galactosemia, sickle cell disease, hypothyroidism, and cystic fibrosis) is performed just prior to discharge, after 24–48 hours in hospital if possible. In many states, a repeat test is required at 8–14 days of age because the PKU test is often falsely negative when obtained at under 48 hours of age. Not all state-mandated screens include the same panel of diseases. In infants with prolonged hospital stays, the test should be performed by 1 week of age.
Infants should be positioned supine or lying on the right side with the dependent arm forward to minimize the risk of sudden infant death syndrome (SIDS).

FEEDING THE WELL NEWBORN INFANT
Indications that the baby is ready for feeding include (1) alertness and vigor, (2) absence of abdominal distention, (3) good bowel sounds, and (4) normal hunger cry. All of these usually occur within 6 hours after birth, but fetal distress or traumatic delivery may prolong this period.
The healthy term infant should be allowed to feed every 2–5 hours on demand. The first feeding usually occurs by 3 hours of life, often as early as in the delivery room. Breast milk or formula (20 kcal/oz) can be given. For formula-fed babies, the volume generally increases from 0.5–1 oz per feeding initially to 1.5–2 oz per feeding on day 3. By day 3, the average term newborn takes in about 100 mL/kg/d of milk.
Although a wide range of infant formulas can satisfy the nutritional needs of most neonates, breast milk is the standard on which formulas are based (see also Chapter 10). The distribution of calories in human milk is 55% fat, 38% carbohydrate, and 7% protein, with a whey-to-casein ratio of 60:40, allowing easy protein digestion. Despite the low concentrations of several vitamins and minerals, their bioavailability is high. All of the necessary nutrients, vitamins, minerals, and water are provided by human milk for the first 6 months of life except vitamin K (thus, 1 mg intramuscularly is administered at birth), vitamin D (200–300 IU/d if minimal sunlight exposure), fluoride (0.25 mg/d after 6 months if water supply not fluoridated), and vitamin B12 (0.3–0.5 mg/d if the mother is a strict vegetarian). Other advantages of breast milk include (1) the presence of immunologic, antimicrobial, and anti-inflammatory factors, including IgA, cellular, and protein or enzymatic components that decrease the incidence of upper respiratory and gastrointestinal infections in infancy; (2) the possibility that breast feeding may decrease the frequency and severity of childhood eczema and asthma; (3) promotion of mother-infant bonding; and (4) evidence that breast milk as a nutritional source improves neurodevelopmental outcomes.
Although approximately 55% of mothers in the United States initiate breast feeding, only 20% continue to breastfeed at 6 months. Hospital practices that facilitate the successful initiation of breast feeding include rooming-in, nursing on demand, and avoiding the use of pacifiers and supplemental formula (unless medically indicated). The nursery staff must be cognizant of problems associated with breast feeding and be able to provide help and support for mothers in the hospital. It is essential that an experienced professional observe and assist with at least one feeding to document good latch-on, important in preventing the common breast-feeding problems of sore nipples, unsatisfied babies, engorgement, poor milk supply, and excessive hyperbilirubinemia (“lack-of-breast-milk jaundice”).

EXAMINATION AT BIRTH

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The extent of the newborn physical examination depends on the condition of the infant and the environment in which the examination is being performed. In the delivery room, the examination consists largely of observation plus auscultation of the chest and inspection for congenital anomalies and birth trauma. Major congenital anomalies are present in 1.5% of live births and account for 20–25% of perinatal and neonatal deaths. Because the infant is recovering from the stress of birth, the examination should not be extensive. The Apgar score (Table 1–5) should be recorded at 1 and 5 minutes of age. In the case of severely depressed infants, a 10-minute score should also be recorded. Although the 1- and 5-minute Apgar scores have almost no predictive value for long-term outcome, serial scores do provide a useful shorthand description of the severity of perinatal depression and the quality of the resuscitative efforts pursued.
The color of the skin is a useful indicator of cardiac output. Because there is normally a high blood flow to the skin, any stress that triggers a catecholamine response produces fairly dramatic changes in skin color secondary to changes in the distribution of the cardiac output and perfusion of the skin. Cyanosis and pallor are two signs reflecting inadequate oxygenation and skin blood flow.
The skeletal examination immediately after delivery serves two purposes: (1) to detect any obvious congenital anomalies and (2) to detect signs of birth trauma, particularly in LGA infants or those born after a protracted second stage of labor—in whom a fractured clavicle or humerus might be found.
The umbilical cord should be examined for the number of vessels. Normally, there are two arteries and one vein. In 1% of deliveries (5–6% of twin deliveries), the cord has only two vessels: an artery and a vein. The latter may be considered a minor anomaly and, as with other minor anomalies, carries a slightly increased risk of associated defects. The placenta is usually examined by the physician delivering it. Small placentas are always associated with small infants. The placental examination emphasizes the identification of membranes and vessels—particularly in multiple gestations—as well as the presence and severity of placental infarcts or evidence of clot (placental abruption) on the maternal side.

GENERAL EXAMINATION IN THE NURSERY
It is important that the examiner have warm hands and a gentle approach. Start with observation, then auscultation of the chest, and then palpation of the abdomen. Examination of the eyes, ears, throat, and hips should be done last, since these maneuvers are most disturbing to the infant. The heart rate should range from 120 to 160 beats/min and the respiratory rate from 30 to 60/min; blood pressure is affected by perinatal asphyxia and the need for mechanical ventilation more so than by gestational age or birth weight. Systolic blood pressure on day 1 ranges from 50 to 70 mm Hg and increases steadily during the first week of life. Note: An irregularly irregular heart rate, usually caused by premature atrial contractions, is common. This irregularity should resolve in the first days of life and is not of pathologic significance.

Skin
Observe for bruising, petechiae (common over the presenting part), meconium staining, and jaundice. Peripheral cyanosis is commonly present when the extremities are cool or the infant is polycythemic. Generalized cyanosis merits immediate evaluation. Pallor may be caused by acute or chronic blood loss or by acidosis. In dark-skinned infants, pallor and cyanosis should be assessed in the oral region and nail beds. Plethora suggests polycythemia. Note vernix caseosa (a whitish, greasy material covering the body that decreases as term approaches) and lanugo (the fine hair covering the preterm infant’s skin). Dry skin with cracking and peeling of the superficial layers is common in postterm infants. Edema may be generalized (hydrops) or localized (eg, on the dorsum of the feet in Turner syndrome). Check for birthmarks such as capillary hemangiomas (lower occiput, eyelids, forehead) and mongolian spot (bluish-black pigmentation over the back and buttocks). Milia—small white keratogenous cysts—can be found scattered over the cheeks, forehead, nose, and nasolabial folds. Miliaria (blocked ducts of sweat glands) occurs in intertriginous areas and on the face or scalp. It can appear as small vesicles (crystallina), small erythematous papules (rubra), or pustules. Erythema toxicum is a benign rash characterized by fleeting erythematous papules and pustules filled with eosinophils. Pustular melanosis leaves pigmented macules when the pustules rupture. The pustules are noninfectious but contain neutrophils. Jaundice presenting in the first 24 hours is considered abnormal and should be evaluated (see Neonatal Jaundice section, below).

Head
Check for cephalohematoma (a swelling over one or both parietal bones contained within suture lines) and caput succedaneum (edema over the presenting part that crosses suture lines). Subgaleal hemorrhages (beneath the scalp) are uncommon but can lead to extensive blood loss into this large potential space with resultant hypovolemic shock. Skull fractures may be linear or depressed and may be associated with cephalohematoma. Check the size and presence of the fontanelles. The anterior fontanelle varies from 1 to 4 cm in any direction, whereas the posterior fontanelle should be less than 1 cm. A third fontanelle is a bony defect along the sagittal suture in the parietal bones and may be a feature of certain syndromes such as trisomy 21. Sutures should be freely mobile. Craniosynostosis is a prematurely fused suture.

Face
Odd facies may be associated with a specific syndrome. Bruising from birth trauma (especially with face presentation) and forceps marks should be identified. Face presentation may be associated with considerable soft tissue swelling around the nose and mouth, causing considerable distortion. Facial nerve palsy is observed when the infant cries; the unaffected side of the mouth moves normally, giving a distorted grimace.

Eyes
Subconjunctival hemorrhages are seen frequently as a result of the birth process. Less commonly, a corneal tear may occur, presenting as a clouded cornea. Ophthalmologic consultation is indicated in such cases. Extraocular movements should be assessed. Occasional uncoordinated eye movements are common, but persistent irregular movements are abnormal. The iris should be inspected for abnormalities such as Brushfield spots (trisomy 21) and colobomas. Examine for the red reflex of the retina. Leukokoria can be caused by glaucoma (cloudy cornea), cataract, or tumor (retinoblastoma). Infants at risk for chorioretinitis (congenital viral infection) should undergo a formal retinal examination with pupils dilated prior to nursery discharge or as an outpatient.

Nose
Examine the nose for size and shape. In utero compression can cause deformities. Because babies under age 1 month are obligate nose breathers, any nasal obstruction (eg, bilateral choanal atresia or stenosis) can cause respiratory distress. Unilateral choanal atresia can be diagnosed by occluding each naris. Purulent nasal discharge at birth suggests congenital syphilis.

Ears
Malformed or malpositioned (low-set or posteriorly rotated) ears are often associated with other congenital anomalies. The tympanic membranes should be visualized.

Mouth
Epithelial (Epstein) pearls are retention cysts along the gum margins and at the junction of the hard and soft palates. Natal teeth may be present and sometimes need to be removed to avoid the risk of aspiration. Check the integrity and shape of the palate; rule out cleft lip and cleft palate. A small mandible and tongue with cleft soft palate is seen with Pierre-Robin syndrome and can result in respiratory difficulty as the tongue occludes the airway. A prominent tongue can be seen in trisomy 21 and Beckwith-Wiedemann syndrome. Excessive drooling suggests esophageal atresia.

Neck
Redundant skin or webbing is seen in Turner syndrome. Sinus tracts may be seen as remnants of branchial clefts. Check for masses: midline (thyroid), anterior to the sternocleidomastoid (branchial cleft cysts), within the sternocleidomastoid (hematoma, torticollis), and posterior to the sternocleidomastoid (cystic hygroma).

Chest & Lungs
Check for fractured clavicles (crepitus, bruising, and tenderness). Increased anteroposterior diameter (barrel chest) can be seen with aspiration syndromes. Check air entry bilaterally and the position of the mediastinum and heart tones. Decreased breath sounds with respiratory distress and a shift in the mediastinum suggests pneumothorax (tension) or a space-occupying lesion (eg, diaphragmatic hernia). With pneumomediastinum, the heart sounds are muffled. Expiratory grunting and decreased air entry are observed in hyaline membrane disease. Rales are not of clinical significance at this age.

Heart
Examination of the heart is described in detail in Chapter 18. Note: Murmurs are commonly present in the first hours and are most often benign. Severe congenital heart disease in the newborn infant may be present with no murmur at all. The two most common presentations of heart disease in the newborn infant are cyanosis and congestive heart failure with abnormalities of pulses. In hypoplastic left heart and critical aortic stenosis, pulses are diminished at all sites. In aortic coarctation and interrupted aortic arch, pulses are diminished in the lower extremities.

Abdomen
Check for softness, distention, and bowel sounds. If polyhydramnios was present or excessive oral secretions are noted, pass a soft catheter into the stomach to rule out esophageal atresia. Palpate for kidneys—most abdominal masses in the newborn infant are associated with kidney disorders (eg, multicystic or dysplastic, hydronephrosis). When the abdomen is relaxed, normal-sized kidneys may be felt but are not prominent. A markedly scaphoid abdomen plus respiratory distress suggests diaphragmatic hernia. Absence of abdominal musculature (prune belly syndrome) may occur in association with renal abnormalities. Check the size of the liver and the spleen. These organs are superficial and discernible by light palpation in the newborn infant. The outline of a distended bladder may be seen and palpated above the pubic symphysis.

Genitalia & Anus
Male and female genitals show characteristics according to gestational age (see Table 1–2). In the female during the first few days, a whitish vaginal discharge with or without blood is normal. Check the patency and location of the anus.

Skeleton
Check for obvious anomalies, for example, the absence of a bone, clubfoot, fusion or webbing of digits, and extra digits. Examine for hip dislocation by attempting to dislocate the femur posteriorly and then abducting the legs to relocate the femur. Look for extremity fractures and for palsies (especially brachial plexus injuries). Rule out myelomeningoceles and other spinal deformities (eg, scoliosis). Arthrogryposis (multiple joint contractures) results from chronic limitation of movement in utero, which may result from lack of amniotic fluid or from a congenital neuromuscular disease.

Neurologic Examination
Normal newborns are endowed with a set of reflexes that facilitate survival (eg, rooting and sucking reflexes), as well as sensory abilities (eg, hearing and smell) that allow them to recognize their mother within a few weeks of birth. Although the retina is well developed at birth, visual acuity is poor (20/400) because of a relatively immobile lens. Acuity improves rapidly over the first 6 months, with fixation and tracking well developed by 2 months.
In examining the newborn, observe resting tone (normal-term newborns should exhibit flexion of the upper and lower extremities) and spontaneous movements. Look for symmetry of movements. Extension of extremities should result in spontaneous recoil to the flexed position. Assess the character of the cry; a high-pitched cry may be indicative of disease of the central nervous system (CNS) (eg, hemorrhage). Hypotonia and a weak cry are indicative of systemic disease or a congenital neuromuscular disorder. Check for newborn reflexes:

Sucking reflex in response to a nipple or the examiner’s finger in the mouth. This reflex is observed by 14 weeks’ gestation.
Rooting reflex: Head turns to the side of a facial stimulus. This reflex develops by 28 weeks’ gestation.
Traction response: The infant is pulled by the arms to a sitting position. Initially, the head lags, then with active flexion comes to the midline briefly before falling forward.
Palmar grasp with placement of the examiner’s finger in the palm. This reflex develops by 28 weeks’ gestation and disappears by age 4 months.
Deep tendon reflexes: Several beats of ankle clonus and an upgoing Babinski reflex may be normal.
Placing: Rub the dorsum of one foot on the underside of a surface. The infant will flex the knee and bring the foot up.
Moro (startle) reflex: Hold the infant and support the head. Allow the head to drop 1–2 cm suddenly. The arms will abduct at the shoulder and extend at the elbow. Adduction will follow. The hands show a prominent spreading or extension of the fingers. This reflex develops by 28 weeks’ gestation (incomplete) and disappears by age 3 months.
Tonic neck reflex: Forcibly turn the infant’s head to one side, and the arm and leg on that side extend while the opposite arm and leg flex (“fencing position”). This reflex disappears by age 8 months.

EVALUATION OF THE NEWBORN INFANT

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HISTORY

Taking the history in newborn medicine involves three key areas: (1) the medical history of the mother and father, including a relevant genetic history; (2) the history pertaining to the mother’s previous pregnancies; and (3) the history of the current pregnancy, including antepartum and intrapartum events.
The mother’s medical history should include any chronic medical conditions, medications taken during pregnancy, unusual dietary habits, smoking history, occupational exposures to chemicals or infections of potential risk to the fetus, and pertinent aspects of the social history that may suggest increased risks for parenting problems and child abuse. Family illnesses with genetic implications should be sought. The past pregnancy history should include maternal age, gravidity and parity, blood type, and pregnancy outcomes. The current obstetric history should include documentation and results of procedures such as ultrasound, amniocentesis, screening tests (eg, HBsAg, antibody screen, serum AFP, HIV), and antepartum tests of fetal well-being (eg, biophysical profiles or nonstress tests). Information should be sought regarding pregnancy-related illnesses in the mother such as urinary tract infection, pregnancy-induced hypertension or preeclampsia-eclampsia, vaginal bleeding, and preterm labor. Peripartum events of importance include duration of ruptured membranes, maternal fever, fetal distress or meconium-stained amniotic fluid, type of delivery (vaginal or cesarean section), anesthesia and analgesia used, reason for operative or forceps delivery, and condition of the infant at birth, including any resuscitation needed and Apgar scores.

ASSESSMENT OF GROWTH & GESTATIONAL AGE
It is important to know an infant’s gestational age because its behavior and anticipated problems can be predicted on this basis. Accurate recall of the date of the last menstrual period is the best indicator of gestational age. Other obstetric observations, such as fundal height, time of auscultation of fetal heartbeat with a stethoscope, and early ultrasound examination, provide supporting information. A postnatal examination can also be used because fetal physical characteristics and neurologic development progress in predictable fashion. Table 1–2 lists the physical and neurologic criteria to be examined. The upper panel is the neuromuscular examination, assessing primarily muscle tone and strength. The lower panel catalogs a variety of physical characteristics. Adding the scores assigned to each characteristic yields a total score that corresponds to the gestational age.

Disappearance of the anterior vascular capsule of the lens is also helpful in determining gestational age. At 27–28 weeks’ gestation, the lens capsule is covered by vessels; by 34 weeks, this vascular plexus is completely atrophied. Foot length, measured carefully from the heel to the tip of the longest toe, also correlates with gestational age in appropriately grown infants. The foot measures 4.5 cm at 25 weeks’ gestation and increases by 0.25 cm/wk until term.
By convention, unless the physical examination indicates a gestational age more than 2 weeks different (in either direction) from the obstetric dates, the gestational age is as assigned by the dates. The birth weight and gestational age must be plotted on an appropriate standard to determine if the infant’s weight is appropriate for gestational age (AGA), small for gestational age (SGA) or intrauterine growth restricted (IUGR), or large for gestational age (LGA) (Figure 1–1). Birth weight and gestational age distributions vary from one population to the next depending on factors such as those listed in Table 1–3. Whenever possible, standards should be prepared from data derived from the local population, but when such information is not available any regional standard may be used. The birth weight–gestational age distribution of an infant is a screening tool that should be supplemented by clinical data confirming a tentative diagnosis of intrauterine growth restriction or excessive fetal growth. These data include not only the clinical features of the infant determined during the physical examination but also factors such as the size of the parents and the birth weight–gestational age distribution of infants previously born to the parents.

The fact that SGA infants have fewer problems (such as respiratory distress syndrome) than AGA infants of the same birth weight but a lower gestational age has led to the common misconception that SGA infants have accelerated maturation. SGA infants, when compared to AGA infants of the same gestational age, actually have increased morbidity and mortality rates.
Knowledge of a baby’s birth weight in relation to gestational age is also helpful in anticipating neonatal problems. LGA babies are at risk for birth trauma, hypoglycemia, polycythemia, congenital anomalies, cardiomyopathy, hyperbilirubinemia, and hypocalcemia. SGA babies are at risk for fetal distress during labor and delivery, polycythemia, hypoglycemia, and hypocalcemia.