Pediatric Residency Training Program

4

Neonatology

Marta Rogido M.D.

Augusto Sola M.D.

Lee Todd Miller M.D.

  1. Evaluation of the Newborn

Features of the newborn examination that differ from those of children and adolescents include:

  1. General Appearance
  2. Careful observation is necessary to assess spontaneous activity, passive muscle tone, respirations, and abnormal signs, such as cyanosis, intercostal muscle retractions, or meconium staining.
  3. Apgar scoresare a simple, systematic assessment of intrapartum stress and neurologic depression at birth, conducted at 1 and 5 minutes after birth (Table 4-1). A persistently very low Apgar score indicates the need for resuscitation, and scoring should be continued every 5 minutes until a final score of 7 or more is reached.
  4. Skin Examination

Texture differs with gestational age; skin is softer and thinner in premature infants.

  1. Lanugois the thin hair that covers the skin of preterm infants. It is minimally present in term infants.

Table 4-1. Apgar Scoring System*

Score

0

1

2

Heart rate

Absent

< 100/min

> 100/min

Respirations

Absent

Slow, irregular

Good, crying

Muscle tone

Limp

Some flexion

Active motion

Reflex irritability (response to catheter in nose)

No response

Grimace

Cough, sneeze, cry

Color

Blue, pale

Body pink, blue extremities

Completely pink

*Five variables are evaluated at 1 and 5 minutes after birth, and each one is scored from 0 to 2. The final score is the sum of the five individual scores, with 10 representing the optimal score. A persistently very low score indicates the need for resuscitation, and scoring should be continued every 5 minutes until a final score of 7 or more is reached.

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  1. Vernix caseosais a thick, white, creamy material found in term infants; it covers large areas of the skin in preterm infants. It is usually absent in postterm infants.
  2. Coloris pink a few hours after birth, but acrocyanosis (cyanosis of the hands and feet) is very frequent during the first 48–72 hours, and in some infants it can last throughout the first month of life, particularly when the infant is cold. Acrocyanosis and cutis marmorata (mottling of the skin with venous prominence) are frequent intermittent signs of the vasomotor instability characteristic of some infants.
  3. Pallormay be a sign of neonatal asphyxia, shock, sepsis, or anemia.
  4. Jaundice is always abnormal if detected within the first 24 hours of birth.Subsequently, it is frequently seen during the first few days after birth but usually is not associated with serious disease (see section X).
  5. Miliaare very small cysts formed around the pilosebaceous follicles, which appear as tiny, whitish papules that are seen over the nose, cheeks, forehead, and chin. They usually disappear within a few weeks and do not require treatment.
  6. Mongolian spotsare dark blue hyperpigmented macules over the lumbosacral area and buttocks of no pathologic significance. These areas of pigmentation are most frequently seen in Hispanic, Asian, and African American infants.
  7. Pustular melanosisis a benign transient rash characterized by small, dry superficial vesicles over a dark macular base. This rash is more frequently seen in African American infants. Pustular melanosis must be differentiated from viral infections, such as herpes simplex, and from bacterial infections, such as impetigo.
  8. Erythema toxicum neonatorumis a benign rash seen most frequently in the first 72 hours after birth, characterized by erythematous macules, papules, and pustules (resembling “flea bites”) on the trunk and extremities but not on the palms and soles. The rash occurs in about 50% of full-term infants and is found much less frequently in preterm infants. Lesions are filled with eosinophils. No treatment is required.
  9. Nevus simplex(or “salmon patch” or telangiectatic nevus) is the most common vascular lesion of infancy, occurring in 30–40% of newborns and appearing as a pink macular lesion on the nape of the neck (“stork bite”), upper eyelids, glabella, or nasolabial region. It is often transient.
  10. Nevus flammeus, or “port wine stain,”is a congenital vascular malformation composed of dilated capillary-like vessels (a form of capillary hemangioma) that may be located over the face or trunk and may become darker with increasing postnatal age. Those located in the area of the ophthalmic branch of the trigeminal nerve (cranial nerve V-1) may be associated with intracranial or spinal vascular malformations, seizures, and intracranial calcifications (Sturge-Weber syndrome).
  11. Strawberry hemangiomasare benign proliferative vascular tumors occurring in approximately 10% of infants. Often first noticed a few days after birth, they increase in size after birth and usually resolve within 18–24 months. Hemangiomas that compromise the airway or vision require intervention.

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  1. Neonatal acneoccurs in approximately 20% of newborns. It appears after 1–2 weeks of life and is virtually never present at birth. Typically, the lesions are comedones, but inflammatory pustules and papules may be present. No treatment is necessary.
  2. Craniofacial Examination
  3. Head
  4. Microcephaly, or head circumference below the 10th percentile, may be familial but may also be caused by structural brain malformations, chromosomal and malformation syndromes, congenital infections (e.g., cytomegalovirus, toxoplasmosis), or fetal alcohol syndrome.
  5. Caput succedaneumis diffuse edema or swelling of the soft tissue of the scalp that crosses the cranial sutures and usually the midline.
  6. Cephalohematomasare subperiosteal hemorrhages secondary to birth trauma confined and limited by the cranial sutures, usually involving the parietal or occipital bones.
  7. Craniosynostosisis premature fusion of the cranial sutures, which may result in abnormal shape and size of the skull.
  8. Craniotabes are soft areas of the skull with a “Ping-Pong ball” feel. They may occur in the parietal bones and are not related to rickets. They usually disappear within weeks or months.
  9. Earsshould be examined to assess maturity. By term, the ears are firm and have assumed their characteristic shape. The ears should also be inspected for preauricular tags or sinuses and for appropriate shape and location.
  10. Eyes.An abnormal red reflex of the retina may be caused by cataracts, glaucoma, retinoblastoma, or severe chorioretinitis.
  11. Nose.The nose should be examined immediately to rule out unilateral or bilateral choanal atresia. If this is suspected, it can be excluded by passing a nasogastric tube through each nostril.
  12. Mouth
  13. Cleftsof the lip and of the soft and hard palates are easily noted by inspection, but submucous clefts in the soft portion of the palate should be ruled out by digital palpation. These clefts may be isolated or associated with other dysmorphic features.
  14. Micrognathia, a small chin, should be noted. Micrognathia, together with cleft palate, glossoptosis (downward displacement or retraction of the tongue), and obstruction of the upper airway, can be found in Pierre Robin syndrome.
  15. Macroglossiamay suggest Beckwith-Wiedemann syndrome (hemihypertrophy, visceromegaly, macroglossia), hypothyroidism, or a mucopolysaccharidosis.
  16. Neonatalteeth may be seen rarely, usually in the area of the lower incisors.

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  1. Epstein pearlsare small, white epidermoid-mucoid cysts found on the hard palate, which usually disappear within a few weeks.
  2. Neck and Clavicle Examination
  3. Lateral neckcysts or sinuses include branchial cleft cysts and cystic hygromas.
  4. Midline clefts or massesmay be caused by cysts of the thyroglossal duct or by goiter secondary to maternal antithyroid medication or transplacental passage of long-acting thyroid-stimulating antibodies.
  5. Neonatal torticollis, or asymmetric shortening of the sternocleidomastoid muscle, may result from being in a fixed position in utero or from a postnatal hematoma resulting from birth injury.
  6. Edema and webbingof the neck suggest Turner syndrome.
  7. Claviclesshould be examined to rule out fractures, which may occur during delivery, most commonly of large neonates.
  8. Chest Examination
  9. Accessory nipples, which may be present along the anterior axillary or midclavicular lines, may later grow because of the presence of glandular tissue in these areas.
  10. Congenital deformities, such as pectus carinatum(prominent and bulging sternum) and pectus excavatum (depressed sternum), are generally benign. Chest asymmetry, as a result of absence of the formation of ribs or agenesis of the pectoralis muscle (Poland syndrome), may be more serious.
  11. Respiratory Examination

Respiratory distress is diagnosed if tachypnea (respiratory rate > 60 breaths/min), deep respirations, cyanosis, expiratory grunting, or intercostal or sternal retractions are present. Preterm infants breathe irregularly with short, apneic bursts that last less than 5–10 seconds and have no clinical significance (periodic breathing).

  1. Cardiac Examination

Evaluation should include heart rate (normal is 95–180 beats/min and varies during feeding, sleep, or crying), rhythm, and assessments for murmurs and peripheral pulses.

  1. Diminished femoral pulses.Consider coarctation of the aorta.
  2. Increased femoral pulses.Consider patent ductus arteriosus.
  3. Abdominal Examination
  4. Umbilicus.The umbilical cord should be inspected to confirm the presence of two arteries and one vein and the absence of a urachus (see section I.H.5). The presence of only one umbilical artery may suggest congenital renal anomalies.
  5. Diastasis rectiis the separation of the left and right side of the rectus abdominis at the midline of the abdomen. It is a common condition in newborns, especially in premature and African American infants. No treatment is necessary because the diastasis recti gradually disappears as the infant develops and as the rectus abdominis muscles grow.

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  1. An umbilical herniais caused by the incomplete closure of the umbilical ring. The hernia is noticed as a soft swelling beneath the skin around the umbilicus that often protrudes during crying or straining. Umbilical hernias occur slightly more frequently in African American children. Most close spontaneously and usually no treatment is required. Those that persist beyond 4–5 years of age and those that cause symptoms may require surgical treatment.
  2. Omphalocele and Gastroschisis—see sections XII.C.1 and XII.C.2.
  3. Persistent urachusis the complete failure of the urachal duct to close. This results in a fistula between the bladder and the umbilicus and may present with urine draining from the umbilicus, especially when pressure is applied over the bladder.
  4. Meconium plugis obstruction of the left colon and rectum caused by dense dehydrated meconium. Meconium ileus is the occlusion of the distalileum caused by inspissated (thickened and dried) and viscid meconium, usually secondary to a deficiency of pancreatic enzymes and the resulting abnormally high protein content of intestinal secretions. Meconium plug and meconium ileus, which can be the first manifestations of cystic fibrosis, cause delay in the elimination of meconium, resulting in abdominal distension. Normally, meconium stool is passed within 24 hours after birth in 90% of term infants and within 48 hours in 99%.
  5. Abdominal massesin the neonate may be caused by hydronephrosis (most common), multicystic kidneys, ovarian cysts, or other lesions. If the liver can be palpated on the left side, situs inversus, asplenia, or polysplenia syndrome may be present.
  6. The anusshould be examined for patency. On rare occasions, an imperforate anus may not be visible. Anal patency can be confirmed with careful introduction of either a soft rubber catheter or a rectal thermometer into the anus.
  7. Genitalia Examination

The genitalia should be examined to assess gestational age and to exclude anomalies.

  1. Female genitalia
  2. hypertrophied clitorismay result from virilization from androgen excess associated with virilizing adrenal hyperplasia (see Chapter 6, section III.E). This condition may also be seen in premature infants.
  3. Hydrometrocolposis caused by an imperforate hymen with retention of vaginal secretions. It presents as a small cyst between the labia at the time of birth or as a lower midline abdominal mass during childhood.
  4. Male genitalia
  5. Hypospadiasdescribes the urethral meatus located not in its normal position at the tip of the penis but rather on the ventral surface of the penis in varying locations along the shaft. It is not associated with an increased incidence of associated urinary malformations.
  6. Epispadiasdescribes the urethral meatus located on the dorsal surface of the penis. Epispadias is often associated with bladder extrophy (bladder protrusion from the abdominal wall with exposure of its mucosa).

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  1. Hydroceleis a scrotal swelling caused by fluid accumulation in the tunica vaginalis adjacent to the testis. Although isolated hydroceles usually cause no clinical problems and often resolve spontaneously within a few weeks, some hydroceles are associated with inguinal hernias (see Chapter 3, section IX.C.3).
  2. Cryptorchidism, or undescended testes, may be associated with inguinal hernia, genitourinary malformations, hypospadias, and genetic syndromes. In most males with cryptorchidism, the testes descend spontaneously before 12 months of age. Cryptorchid testes that do not descend by this age are predisposed to future malignancy.
  3. Extremity Examination

The extremities should be examined to detect anatomic and functional abnormalities. The lack of spontaneous movements in the upper extremities may suggest fractures, infection, or brachial plexus injury.

  1. Absence or hypoplasia of the radiusmay be associated with TAR syndrome (thrombocytopenia absent radii), Fanconi anemia, and Holt-Oram syndrome.
  2. Polydactylymay occur as an isolated anomaly or as part of a genetic syndrome.
  3. Edemaof the feet with hypoplastic nails is characteristic of Turner and Noonan syndromes.
  4. Rocker bottom feetis frequently seen in trisomy 18.
  5. The hipsshould be examined for developmental dysplasia of the hips (see Chapter 17, section III.A).
  6. Spine Examination

The spine should be examined for the presence of hair tufts, lipomas, or dimples in the lumbosacral area, which may suggest the presence of spina bifida. If a sacrococcygeal pilonidal dimple is present, a careful attempt to identify the base should be made to rule out a neurocutaneous sinus tract. A myelomeningocele (hernial protrusion of the cord and its meninges through a defect in the vertebral canal) may be present anywhere along the spine and is usually obvious at the time of birth.

  1. Neurologic Examination

Evaluation of muscle tone, level of alertness, and primitive reflexes should be performed (see Chapter 2, Table 2-2).

  1. Abnormalities of Maturity
  2. Preterm Delivery
  3. Definition.preterm delivery occurs less than 37 completed weeks from the first day of the last menstrual period.
  4. Incidence.Preterm delivery occurs in approximately 7% of all births, but this figure varies widely across the United States and throughout the world. The incidence is higher in lower socioeconomic populations and in women who do not receive prenatal care.

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  1. Complications. Premature infantsmay have complications from the time of birth to the first several weeks of life, as presented in Table 4-2.

Table 4-2. Frequent Problems of Preterm Infants

Disrupted mother–father–infant interaction

Perinatal asphyxia

Hypothermia

Hypoglycemia

Hypocalcemia

Respiratory distress syndrome (hyaline membrane disease; surfactant deficiency syndrome)

Fluid and electrolyte abnormalities

Indirect hyperbilirubinemia

Patent ductus arteriosus

Intracranial hemorrhage

Necrotizing enterocolitis

Infections

Retinopathy of prematurity

Bronchopulmonary dysplasia

Anemia

  1. Post-term Delivery
  2. Definition. A post-termdelivery occurs 42 weeks or more from the first day of the last menstrual period.
  3. Complicationsinclude increased incidence of fetal and neonatal morbidity and death from the consequences of placental insufficiency, including severe intrauterine asphyxia, meconium aspiration syndrome, and polycythemia.

III. Growth Abnormalities

  1. Small-for-gestational-age (SGA) infants and intrauterine growth retardation (IUGR)
  2. Definition.Infants that are born weighing below the fifth percentile for corresponding gestational age as a result of IUGR are considered SGA.
  3. Significance.SGA is a sign that intrauterine growth has either stopped or slowed significantly some time during pregnancy.
  4. Etiology. Causes of IUGRare listed in Table 4-3.
  5. Clinical features. Clinical problemsof SGA infants are listed in Table 4-4.
  6. Large-for-gestational-age (LGA) infants
  7. Definition.Newborns are considered LGA if their birth weight is > 90th percentile for their gestational age at birth. These infants should be distinguished from those infants born with high birth weight (birth weight > 4, 000 g). A newborn may be LGA with a birth weight > 90th percentile for the gestational age at birth, without having an absolute birth weight above 4, 000 g.

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Table 4-3. Causes of Intrauterine Growth Retardation

Type I: Early interference with fetal growth from conception to 24 weeks gestation
   Chromosomal anomalies (trisomy 21, 13–15, 18, and so forth)
   Fetal infections (TORCH)
   Maternal drugs (chronic alcoholism, heroin)
   Maternal chronic illness (hypertension, severe diabetes mellitus)

Type II: Intrauterine malnutrition from 24 to 32 weeks gestation
   Inadequate intrauterine space (multiple pregnancies, uterine tumors, uterine anomalies)
   Placental insufficiency from maternal vascular disease (renal failure, chronic essential hypertension, collagen vascular diseases, pregnancy-induced hypertension)
   Small placenta with abnormal cellularity

Type III: Late intrauterine malnutrition after 32 weeks gestation
   Placental infarct or fibrosis
   Maternal malnutrition
   Pregnancy-induced hypertension
   Maternal hypoxemia (lung disease, smoking)

TORCH = toxoplasmosis, other (syphilis), rubella, cytomegalovirus, herpes simplex virus.

Table 4-4. Clinical Problems of Small-for-Gestational-Age Infants

Perinatal asphyxia

Hypothermia

Hypoglycemia

Polycythemia

Thrombocytopenia

Hypocalcemia

Meconium aspiration syndrome

Intrauterine fetal death

Hypermagnesemia (if mother is treated with magnesium for hypertension or preterm labor)

  1. Etiology. Common causesof increased weight and LGA include maternal diabetes, Beckwith-Wiedemann syndrome, Prader-Willi syndrome (see Chapter 5, section III.A.2), and nesidioblastosis (diffuse proliferation of pancreatic islet cells).
  2. Complications.LGA infants, with or without high birth weight, frequently have hypoglycemia and polycythemia. Inappropriately increased weight for gestational age is often associated with congenital malformations.
  3. Cyanosis
  4. Definition

Cyanosis is bluish discoloration of the skin and mucous membranes that is directly related to the absolute concentration of unoxygenated or reduced hemoglobin (more than 3 g/dL of reduced Hgb in arterial blood, or more than 5 g/dL in capillary blood).

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  1. Clinical significance

In the neonate, cyanosis always constitutes an emergency, requiring immediate diagnosis and treatment.

  1. Etiology

Causes are extensive and include respiratory pathology (e.g., pneumothorax); the “5 T's” of cyanotic congenital heart disease (tetralogy of Fallot, transposition of the great vessels,truncus arteriosus, tricuspid atresia, and total anomalous pulmonary venous connection—see also Chapter 8, section IV); central nervous system pathology (e.g., intraventricular hemorrhage); hematologic disorders (e.g., polycythemia); and metabolic disorders (e.g., hypoglycemia, hypocalcemia, hypothyroidism, and hypothermia).

  1. Evaluation
  2. Initial steps.Evaluation includes a detailed history and physical examination, serum electrolytes with serum glucose, arterial blood gas (ABG; α 100% oxygen test), complete blood count (CBC), and chest radiograph (CXR). At times, cultures, pre- and postductal PaO2 measurements, electrocardiogram, and echocardiogram may be warranted.
  3. 100% oxygen test.ABG is performed after administration of 100% oxygen. The 100% oxygen test helps evaluate whether cyanosis is caused by cardiac or respiratory disease.
  4. Oxygen test in infants with heart disease.In infants with cyanotic congenital heart disease with reduced pulmonary blood flow (e.g., tetralogy of Fallot), administering 100% oxygen increases the PaO2 only slightly, usually less than 10–15 mm Hg. However, in infants with cyanotic congenital heart disease associated with normal or increased pulmonary blood flow (e.g., truncus arteriosus), PaO2 usually increases more than 15–20 mm Hg with 100% oxygen, but levels above 150 mm Hg are unusual.
  5. Oxygen test in infants with lung disease. The PaO2usually increases considerably when 100% oxygen is given, often reaching levels greater than 150 mm Hg. The exception to this rule is that some infants with severe lung disease or with persistent pulmonary hypertension of the newborn (see section VII) may have large right-to-left shunts through the foramen ovale or ductus arteriosus. Therefore, the PaO2 may not increase by more than 10–15 mm Hg with 100% oxygen.
  6. Management

Immediate treatment of cyanosis may be necessary and often includes administration of oxygen and rapid correction of abnormalities of temperature, hematocrit, and glucose and calcium levels. In severely cyanotic infants, intubation and mechanical ventilation may be necessary until a final diagnosis is made and definitive treatment is initiated.

  1. Respiratory Distress
  2. General Concepts

Respiratory problems are among the most significant causes of morbidity and mortality during the neonatal period. Respiratory distress syndrome (RDS; also termed hyaline membrane disease and surfactant deficiency syndrome) in preterm infants and meconium aspiration syndrome (MAS) and persistent pulmonary hypertension of the newborn (PPHN) in full-term infants are the more common pulmonary causes of respiratory distress.

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Clinical features

Manifestations include tachypnea, decreased air entry or gas exchange, retractions (intercostal, subcostal, or suprasternal), grunting, stridor, flaring of the alae nasi, and cyanosis. Many of these signs are nonspecific responses of the newborn to serious illness.

Etiology

Causes are extensive and involve multiple organ systems because many conditions that produce neonatal respiratory distress are not primary diseases of the lungs (Figure 4-1).

  1. Respiratory Distress Syndrome (RDS)
  2. Definition

RDS is the respiratory distress or respiratory insufficiency caused by a lack of surfactant, most frequently in preterm infants.

 

Figure 4-1. Differential diagnosis of respiratory distress in neonates. CNS = central nervous system; RDS = respiratory distress syndrome; BPD = bronchopulmonary dysplasia; MAS= meconium aspiration syndrome; PPHN = persistent pulmonary hypertension of the newborn; TTN = transient tachypnea of the newborn; IDM = infant of diabetic mother.

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  1. Pathophysiology
  2. Pulmonary surfactantis the surface-active material that decreases alveolar surface tension and prevents atelectasis. Although surfactant is first noted at approximately 23–24 weeks gestation, a sufficient quantity is produced only after 30–32 weeks gestation; after this period, the incidence of RDS decreases significantly.
  3. Assessment of fetal lung maturitycan be made by determining the presence of surfactant in amniotic fluid obtained by amniocentesis. A lecithin-to-sphingomyelin (L:S) ratiogreater than 2:1 and the presence of phosphatidylglycerol (a minor phospholipid in surfactant) are indicators of fetal lung maturity.
  4. Epidemiology
  5. Incidence.RDS affects approximately 0.5% of all neonates and is the most frequent cause of respiratory distress in preterm infants. The incidence is higher in white individualsand in males. Risk is higher the younger the gestational age (e.g., 50% have RDS if born before 30 weeks gestation, but only 10% have RDS if born at 35–36 weeks).
  6. Risk factors.The risk of RDS increases with a low L:S ratio, prematurity, a mother with a previous preterm infant with RDS, a mother with diabetes mellitus, neonatal hypothermia, and neonatal asphyxia.
  7. Clinical Features

Infants show increasing respiratory distress during the first 24–48 hours of life, with tachypnea, retractions, expiratory grunting, and cyanosis. Clinical features are more severe and prolonged in preterm infants of less than 31 weeks gestation.

  1. Evaluation

CXR is diagnostic and shows diffuse atelectasis with an increased density in both lungs and a fine, granular, ground-glass appearance of the lungs. The small airways are filled with air and are clearly seen surrounded by the increased density of the pulmonary field, creating air bronchograms.

  1. Management
  2. Supplemental oxygenis necessary.
  3. Continuous positive airway pressure (CPAP), a technique for maintaining end-expiratory airway pressure greater than atmospheric pressure for the spontaneously breathing infant, promotes air exchange. CPAP may be applied via nasal prongs or nasopharyngeal tubes.
  4. Mechanicalventilation may be indicated if hypercarbia and respiratory acidosis develop.
  5. Exogenous surfactantadministered into the trachea is often curative.
  6. Complications
  7. Acute complicationsinclude air leaks (e.g., pneumothorax and pulmonary interstitial emphysema), intraventricular hemorrhage, sepsis, and right-to-left shunt across a patent ductus arteriosus (PDA).
  8. Chronic complications
  9. Bronchopulmonary dysplasia(BPD). This term is often used to describe chronic lung disease (CLD). BPD is defined as progressive pathologic changes in the immature lung affecting both the parenchyma and airways, altering normal lung growth. The diagnosis is based on clinical and radiographic criteria:

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  1. Mechanical ventilationduring the first 2 weeks of life
  2. Clinical signs of respiratory compromise persisting beyond 28 days of life
  3. Need for supplemental oxygenbeyond 28 days of life
  4. Characteristic CXR
  5. Retinopathy of prematurity(see Chapter 18, section VII.)
  6. Prognosis

With aggressive treatment in an intensive care nursery, > 90% of infants with RDS survive.

VII. Persistent Pulmonary Hypertension of the Newborn (PPHN)

  1. Definition

PPHN is any condition, other than congenital heart disease, associated with low blood flow to the lungs after birth. It occurs most frequently in near-term, full-term, or post-term infants.

  1. Etiology

Causes are extensive, but perinatal asphyxia and MAS are most common. The perinatal history is often remarkable for fetal distress.

  1. Pathophysiology

Increased pulmonary vascular resistance results in significant right-to-left shunting through the foramen ovale or ductus arteriosus with resulting hypoxemia.

  1. Clinical Features

Severity is variable, ranging from cyanosis to respiratory failure. PaO2 is often significantly decreased in response to minimal inspired oxygen changes or stimulation, and pre- and postductal PaO2 are notably different.

  1. Evaluation
  2. CXRfindings are variable because of the many causes of this syndrome. Usually, pulmonary vascular markings are decreased initially in infants with idiopathic PPHN not caused by MAS or perinatal asphyxia.
  3. Echocardiogramis important to rule out congenital heart disease and to assess the degree of pulmonary hypertension and right-to-left shunting.
  4. Management
  5. Prevention of hypoxemiais the cornerstone of therapy because hypoxemia is a potent pulmonary vasoconstrictor. Oxygen is the most potent pulmonary vasodilator.
  6. Mechanical ventilationmust be started early if oxygen alone is insufficient.
  7. In severe cases, and for infants who do not respond to usual measures, high-frequency ventilation and extracorporeal membrane oxygenation (ECMO) are generally needed.
  8. Inhaled nitric oxidemay also be of value as a potent pulmonary vasodilator.

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VIII. Meconium Aspiration Syndrome (MAS)

  1. Definition
  2. Meconium(first stools) is a material in the fetal gut that consists of water, mucopolysaccharides, desquamated skin and gastrointestinal mucosal epithelial cells, vernix, bile salts, and amniotic fluid.
  3. MASdescribes an acute respiratory disorder caused by the aspiration of meconium into the airways of the fetus or neonate.
  4. Pathophysiology

Meconium is often passed as a consequence of distress (i.e., hypoxemia) in the fetus at term and becomes more frequent after 42 weeks gestation. The degree of meconium-stained amniotic fluid (MSAF) varies from slightly green to dark green and thick consistency (pea-soup). The MSAF may reach the distal airways and alveoli in utero if the fetus becomes hypoxic and develops gasping or deep respiratory movements, or may occur at the time of birth with the first inspirations.

  1. Clinical Features

Patients with MAS present with signs and symptoms of mild or moderate respiratory distress. Some eventually develop severe respiratory failure with severe hypoxemia and cyanosis.

  1. Evaluation

MAS is suggested by a history of meconium noted at, or before, delivery and the presence of respiratory distress. CXR reveals increased lung volume with diffuse patchy areas of atelectasis and parenchymal infiltrates alternating with hyperinflation. Pneumothorax or pneumomediastinum may occur.

  1. Management

Prevention is of paramount importance. The best approach to MSAF is a combined obstetric and pediatric approach and may include suctioning on the perineum and direct suctioning of the trachea via endotracheal intubation. Generally oxygen is required, and if the MAS is severe, mechanical ventilation or ECMO may be necessary. Complications include PPHN, bacterial pneumonia, and long-term reactive airway disease.

  1. Apnea of Prematurity
  2. Definition

Apnea of prematurity is a respiratory pause without airflow lasting more than 15–20 seconds, or a respiratory pause of any duration if accompanied by bradycardia and cyanosis or oxygen desaturation, as evidenced by pulse oximetry monitoring.

  1. Categories of Apnea
  2. Central apneadescribes a complete cessation of chest wall movements and no airflow.
  3. Apnea secondary to airway obstructiondescribes chest wall movements or respiratory efforts but without airflow. Commonly available apnea monitors do not record obstructive apnea because they continue to detect chest wall movements.
  4. Mixed apneais a combination of central and obstructive apnea and constitutes the most frequent type encountered in preterm infants.

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  1. Etiology

Causes of apnea in preterm infants include neonatal infections, lung disease, hypothermia, hyperthermia, hypoglycemia, seizures, maternal drugs, drug withdrawal, anemia, and gastroesophageal reflux, in addition to idiopathic apnea of prematurity.

Idiopathic Apnea of Prematurity

  1. Incidence.Frequency increases with decreasing gestational age. Incidence is as high as 85% in infants < 28 weeks gestation, and 25% in infants 33–34 weeks gestation.
  2. Clinical features.Idiopathic apnea of prematurity occurs in the absence of any identifiable cause, usually appearing 24 hours after birth and during the first week of life. It usually resolves by postconceptional age of 38–44 weeks (gestational age at birth plus number of weeks of postnatal age).
  3. Management.Idiopathic apnea of prematurity is a diagnosis of exclusion, and therefore a search for underlying causes must be undertaken. Management principles include:
  4. Maintenance of a neutral thermal environment, treatment of hypoxia, and proprioceptive stimulation
  5. Respiratory stimulant medicationsas needed (caffeine or theophylline)
  6. Ventilation as needed (bag and mask as initial management for a severe apneic episode)
  7. CPAP or mechanical ventilation
  8. Neonatal Jaundice
  9. Definition

Jaundice is yellowish discoloration of mucous membranes and skin as a result of increased bilirubin levels. It usually occurs during the first week of life and is most frequently caused by indirect (unconjugated) hyperbilirubinemia that is physiologic in nature. Visible jaundice occurs in the neonate when serum bilirubin levels exceed 5 mg/dL.

  1. Classification of Jaundice
  2. Physiologic jaundice
  3. Definition.This term describes the benign and self-limited indirect hyperbilirubinemia that typically resolves by the end of the first week of life and requires no treatment.
  4. Causes of physiologic jaundice
  5. Increased bilirubin load on hepatocytes
  6. Delayed activity of the hepatic enzyme glucuronyl transferase
  7. Clinical features.Manifestations include jaundice in well-appearing infants and elevated indirect bilirubin levels. Peak serum concentrations in normal full-term infants reach 5–16 mg/dL at around 3–4 days of life and then start to decrease before the first week of life. In preterm infants, the peak bilirubin is reached after 5–7 days and may take 10–20 days before decreasing.

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  1. Nonphysiologic jaundice.This term describes jaundice that is secondary to a pathophysiologic cause and it may be further classified as follows:
  2. Indirect hyperbilirubinemiais an elevated bilirubin in which the conjugated or direct component is < 15% of the total bilirubin level.
  3. Direct hyperbilirubinemiais a conjugated or direct bilirubin level that is > 15% of the total bilirubin level. This is always pathologic in neonates.
  4. Differential Diagnosis of Indirect Hyperbilirubinemia

Possible diagnoses include physiologic jaundice, causes of excessive bilirubin production, causes of impaired clearance of bilirubin from the blood, and causes of defective conjugation of bilirubin by the liver (Figure 4-2). Breastfeeding is associated with higher peak bilirubin levels as compared with formula feeding, and the resulting indirect hyperbilirubinemia is of two types:

  1. Breastfeeding jaundicetypically occurs during the first week of life with increased bilirubin levels and is usually related to suboptimal milk intake. Poor intake leads to weight loss, dehydration, and decreased passage of stool, with resultant decreased excretion of bilirubin in the stool.
  2. Breast milk jaundicetypically occurs after the first week of life and is likely related to breast milk's high levels of β-glucuronidase and high lipase content. Elevated bilirubin is highest in the second and third weeks of life, and lower levels of bilirubin may persist until 10 weeks of life.
 

Figure 4-2. Differential diagnosis of indirect hyperbilirubinemia. RBC = red blood cell; GI = gastrointestinal.

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  1. Differential Diagnosis of Direct Hyperbilirubinemia

Possible diagnoses include obstruction of the hepatobiliary tree, neonatal infection, and metabolic disorders (Figure 4-3).

  1. Evaluation of Hyperbilirubinemia
  2. Jaundice should always be evaluated under the following circumstances:
  3. Jaundice appears at < 24 hours of age.
  4. Bilirubin rises > 5–8 mg/dL in a 24-hour period.
  5. The rate of rise of bilirubin exceeds 0.5 mg/dL per hour (suggestive of hemolysis).
  6. To evaluate indirect hyperbilirubinemia, CBC, reticulocyte count, and smear (for hemolysis) are necessary. Evaluation for sepsis may be indicated.
  7. To evaluate direct hyperbilirubinemia, hepatic ultrasound (to evaluate for choledochal cyst), serologies for viral hepatitis, and radioisotope scans of the hepatobiliary tree are necessary. Evaluation for sepsis may be indicated.
 

Figure 4-3. Differential diagnosis of direct hyperbilirubinemia. EBV = Epstein-Barr virus; TORCH = toxoplasmosis, other (syphilis), rubella, cytomegalovirus, herpes simplex virus.

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  1. Management
  2. Serial bilirubin assessments, observation, and reassuranceare appropriate for physiologic jaundice.
  3. Phototherapy, which creates water-soluble photoisomers of indirect bilirubin that are more readily excreted, may be indicated depending on the infant's gestational maturity, age, bilirubin levels, and risk factors, if present (e.g., blood group incompatibility and suspected sepsis).
  4. Exchange transfusionis performed for rapidly rising bilirubin levels secondary to hemolytic disease.
  5. Complications

include kernicterus and bilirubin encephalopathy.

  1. Indirect bilirubin at sufficiently high concentrations can pass through the blood-brain barrier and produce irreversible damage.
  2. Bilirubin most frequently localizes in the basal ganglia, hippocampus, and some brainstem nuclei.
  3. Clinical featuresinclude choreoathetoid cerebral palsy, hearing loss, opisthotonus, seizures, and oculomotor paralysis.
  4. Infants of Drug-Abusing Mothers
  5. Epidemiology
  6. Incidence.In approximately 10–15% of pregnancies in the United States, fetuses are exposed to illicit drugs while in utero.
  7. Drugs used.Most women who use illicit drugs take multiple drugs. Use of alcohol, cocaine, amphetamines, phencyclidine (PCP), and narcotics may compound the fetal risk in women already using tobacco, caffeine, or prescribed drugs.
  8. Risk factors
  9. Maternal risk factorsinclude inadequate prenatal care, anemia, endocarditis, hepatitis, tuberculosis, HIV, sexually transmitted diseases, low self-esteem, and depression.
  10. Obstetric complicationsassociated with maternal drugs include abruptio placentae, precipitous delivery, and preterm labor and delivery.
  11. Clinical Features

Manifestations vary with the specific drug, some of which cause both intoxication and a withdrawal syndrome. The most common signs are jitteriness and hyperreflexia, together with irritability, tremulousness, feeding intolerance, and excessive wakefulness. Their presence in a neonate should alert the clinician to the possibility of drug exposure, which may be identified by toxicology screens of urine or meconium. Infants born to women using drugs should be identified early in the neonatal period and observed for complications and withdrawal effects.

  1. Mortality rates

range from 3 to 10%, and fetal demise can occur in utero from withdrawal. Causes of mortality include perinatal asphyxia, congenital anomalies, child abuse, and sudden infant death syndrome.

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XII. Surgical Conditions of the Newborn

  1. Esophageal Atresia with Tracheoesophageal Fistula
  2. Epidemiology.This condition occurs in 1:2, 000–3, 000 infants and is often associated with polyhydramnios. The most common type of esophageal atresia (> 90% of cases) involves atresia of the esophagus (proximal pouch) with a distal tracheoesophageal fistula.
  3. Clinical features
  4. History of polyhydramnios
  5. Copious oropharyngeal secretions with increased risk of choking and aspiration pneumonia, particularly if feeding is attempted
  6. Associated malformationsare found in 50% of patients with esophageal atresia and may include congenital heart disease, anorectal, skeletal, or renal malformations, or the VACTERL association (see Chapter 5, section III.A.8).
  7. Evaluation and diagnosis.An oral gastric tube is inserted until it meets resistance. Radiographs show the tube in the upper part of the thorax. In type III, air that has crossed through the distal fistula from the trachea is seen in the stomach.
  8. Management. Surgical repairconsists of closure of the fistula and anastomosis of the two esophageal segments.
  9. Congenital Diaphragmatic Hernia
  10. Overview.The diaphragm develops between the fifth and eighth weeks of gestation. Abnormalities in the development of the diaphragm may allow herniation of the abdominal contents into the thorax, which in turn impairs appropriate growth and maturation of the lungs. Most cases involve the left diaphragm in the posterior and lateral area.
  11. Epidemiology.The incidence is 1:4, 000–5, 000 live births.
  12. Clinical features.The diagnosis may be made by ultrasound in utero (especially when there is a history of polyhydramnios). Newborns present with a scaphoid abdomen (with abdominal contents in the thorax). Severe respiratory insufficiency from pulmonary hypoplasia (abdominal contents within the chest prevents adequate development of the lungs) with severe hypoxemia and acidosis may occur. Breath sounds are decreased, and bowel sounds may be heard in the chest. The condition has a wide spectrum of clinical severity.
  13. Evaluation. Chest radiographsreveal little or no gas in the abdomen, absence of the diaphragmatic dome, significant mediastinal shift to the contralateral side (usually to the right), and bowel loops in the thorax (usually on the left side).
  14. Management.Bag-and-mask ventilation should not be used because this may distend the bowel and increase compression of the lung. Intubation and mechanical ventilation with 100% oxygen should be initiated immediately. Correction of acidosis, hypoxemia, and hypercarbia are paramount. Once the infant is stabilized, management includes surgical reduction of the hernia and closure of the diaphragmatic defect. Fetal surgery is now being performed at some centers for defects identified by prenatal ultrasound.

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  1. Complications.PPHN, pneumothorax, and gastrointestinal complications may develop.
  2. Prognosisis related to the size of the defect, the volume of the hernia inside the thorax, and the duration of the hernia in utero. These factors are associated with the degree of pulmonary hypoplasia and the severity of the clinical presentation. Fetal and neonatal mortality is still high (50% or greater) in infants in whom the condition is diagnosed before 25 weeks gestation.
  3. Abdominal Wall Defects

By the 10th week of gestation, the midgut enters the abdomen. If this process is disturbed, the result is an abdominal wall defect associated with a decrease in intra-abdominal volume. Omphalocele and gastroschisis are the more common defects, both of which require surgical treatment.

  1. Omphaloceleoccurs in approximately 1:6, 000–8, 000 live births. The defect is localized centrally in the abdomen (i.e., through the umbilical ring area), and there is a true hernia sac (abdominal organs are covered with a peritoneal sac). Omphaloceles are frequently associated with other congenital anomalies, including congenital heart defects (most commonly tetralogy of Fallot and atrial septal defects), Beckwith-Wiedemann syndrome, and some chromosomal disorders (trisomy 13 or, less frequently, trisomy 18; see alsoChapter 5, section III.B).
  2. Gastroschisisis a congenital fissure of the anterior abdominal wall, usually located in the right paraumbilical area (i.e., not in the midline). There is no true hernia sac (no peritoneal sac covering), and the bowel is usually the only viscera that herniates. There is no increased association with other congenital anomalies, but there is an increased risk of bowel damage (e.g., ischemia) from exposure of the abdominal contents to the amniotic fluid.
  3. Intestinal Obstruction

Intestinal obstruction may be functional or mechanical, and if mechanical, may be acquired or congenital (see Figure 4-4 for a complete differential diagnosis).

  1. Intestinal atresiais the most common cause of obstruction in the neonatal period. It can occur in the small or large bowel. Intestinal atresias are discussed in Chapter 10, section IV.C.
  2. Meconium ileusis a manifestation of cystic fibrosis during the neonatal period. Abnormal accumulation of intestinal secretions and deficiency of pancreatic enzymes presumably cause increased viscosity of meconium, leading to occlusion of the distal ileum.
  3. Clinical featuresinclude abdominal distension, lack of meconium passage, and vomiting.
  4. Diagnosisis by abdominal radiographs that reveal intestinal distension with minimal air-fluid levels. Air remains trapped in the meconium; thus, there is no definite air-fluid interface. Fine gas bubbles may be seen mixed within meconium, producing a characteristic soap-bubble appearance.

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Figure 4-4. Differential diagnosis of intestinal obstruction in neonates.

  1. Managementoften includes enemas to relieve the obstruction. Early diagnosis and treatment are important to avoid intestinal perforation, meconium peritonitis, and volvulus.
  2. Intestinal malrotationmay be caused by a volvulus (loops of intestine twist if attached to a narrow band of mesentery) with restricted circulation to the rotated (or obstructed) segment, leading to intestinal gangrene. Malrotation and volvulus are discussed in Chapter 10, section IV.B.
  3. Hirschsprung disease.Hirschsprung disease, or congenital aganglionic bowel disease, is caused by a lack of caudal migration of the ganglion cells from the neural crest. It produces contraction of a distal segment of colon, causing obstruction with proximal dilatation.
  4. Incidenceis approximately 1:5, 000 live births. Hirschsprung disease is five times more frequent in male infants, and in 80% of cases there is a family history.
  5. Clinical featuresinclude constipation, vomiting, and abdominal distension.
  6. Diagnosisis by rectal biopsy, revealing absence or paucity of ganglion cells.
  7. Managementincludes resection of the affected segment or colostomy.

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  1. Necrotizing Enterocolitis (NEC)
  2. Epidemiology.NEC is one of the most common surgical conditions in neonates. It is most frequent in preterm infants, with an incidence as high as 8–10% in infants < 30 weeks gestation.
  3. Clinical features.Manifestations include abdominal distension, abdominal tenderness, residual gastric contents, bilious aspirate, bloody stools, and abdominal erythema. Metabolic acidosis and oliguria may be present, and NEC may lead to thrombocytopenia, disseminated intravascular coagulation, and death.
  4. Diagnosis.Classic radiographic findings include abdominal distension, air-fluid levels, thickened bowel walls, pneumatosis intestinalis (air in the bowel wall), and venous portal gas. Pneumoperitoneum is suggestive of perforation.
  5. Management
  6. Medical treatmentincludes bowel rest, no oral feeds, gastric decompression, antibiotics, and parenteral fluids and nutrition. If shock is present, volume infusions and pressors are indicated.
  7. Surgical managementwith exploratory laparotomy is indicated for pneumoperitoneum, presence of a fixed loop on serial radiographs, or a positive paracentesis. Treatment may include resection of necrotic bowel.
  8. Late complications.Intestinal obstruction (e.g., adhesions, strictures), nutritional deficiencies (e.g., malabsorption, short gut syndrome), and cholestasis may occur.

XIII. Hypoglycemia

  1. Definition

Hypoglycemia is serum glucose concentration below 40 mg/dL.

  1. Etiology

Causes are extensive and include:

  1. Conditions that result in insulin excess. Infants of diabetic mothers (IDMs) commonly have transient hypoglycemia.Persistent hypoglycemia may result from insulin-producing tumors or islet cell hyperplasia (nesidioblastosis).
  2. Conditions that result in diminished glucose production or substrate supplyinclude IUGR and preterm infants with limited hepatic glycogen stores and poorly developed gluconeogenesis; stressed infants who have been asphyxiated or with sepsis; infants with inborn errors of metabolism such as galactosemia, hereditary fructose intolerance, and aminoacidopathies; and infants with endocrinopathies such as growth hormone deficiency and panhypopituitarism.
  3. Clinical Features

The neonate may be asymptomatic or may present with diaphoresis, jitteriness, feeding problems, tachycardia, hypothermia, hypotonia, seizures, and, rarely, myocardial infarction.

  1. Management

Treatment is directed at increasing oral feeding, if possible, and if necessary, intravenous glucose.

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XIV. Infants of Diabetic Mothers (IDMs)

  1. Pathophysiology

Maternal hyperglycemia causes fetal hyperglycemia and fetal hyperinsulinemia. This causes increased hepatic glucose uptake and glycogen synthesis, accelerated lipogenesis, augmented protein synthesis, and macrosomia.

  1. Clinical Features
  2. IDMs are large because of increased body fat and visceromegaly, primarily of the liver, adrenals, and heart.
  3. The skeletal length is increased in proportion to weight, but the head and face appear disproportionately small. The umbilical cord and placenta are also enlarged.
  4. IDMs appear plethoric with round facies.
  5. Although IDMs are usually LGA, they may be SGA secondary to placental insufficiency in women with severe diabetic-induced vascular complications.
  6. Complications
  7. IDMs are at considerable risk for the perinatal difficulties summarized in Table 4-5.
  8. Congenital anomalies, such as congenital heart disease, are two to four times more frequent in IDMs than in normal infants.
  9. Small left colon syndromeis a condition occurring exclusively in IDMs, in which infants present with abdominal distension and failure to pass meconium secondary to the decreased caliber of their left colon.

Table 4-5. Clinical Problems of Infants of Diabetic Mothers

Increased risk before and at delivery

   Sudden intrauterine death
   Large for gestational age
   Increased rate of birth trauma
   Increased rate of cesarean section
   Increased risk of asphyxia

Increased risk of common neonatal problems

   Hypoglycemia
   Polycythemia
   Hypocalcemia
   Hypertrophic cardiomyopathy
   Persistent pulmonary hypertension of the newborn
   Respiratory distress syndrome
   Renal vein thrombosis

Increased risk of developing congenital malformations

   Structural heart disease
   Central nervous system
   Musculoskeletal
   Small left colon syndrome
   Caudal regression syndrome (hypoplasia of the sacrum and lower extremities)

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  1. Polycythemia
  2. Definition

Polycythemia is a central venous hematocrit greater than 65%.

  1. Epidemiology

Polycythemia occurs in 2–4% of infants born at sea level.

  1. Etiology

Causes include increased erythropoietin secretion secondary to placental insufficiency, increased red blood cell production by the fetus in response to hypoxemia, or increased placental transfusion from delayed cord clamping.

  1. Clinical features

Manifestations include plethora, poor perfusion, cyanosis, poor feeding, respiratory distress, lethargy, jitteriness, seizures, renal vein thrombosis, and metabolic acidosis. There is an increased risk of NEC.

  1. Management

Treatment includes partial exchange transfusion, in which blood is removed and replaced by the same volume of plasma substitute (normal saline) in a stepwise manner.

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Review Questions and Answers

  1. Soon after birth, a term newborn infant presents with increased oral secretions and mild respiratory distress. Which of the following is the most likely diagnosis?

(A). Persistent pulmonary hypertension of the newborn

(B). Pneumonia

(C). Esophageal atresia

(D). Respiratory distress syndrome (surfactant deficiency syndrome)

(E). Diaphragmatic hernia

  1. An abdominal mass is detected on examination of a 2-day-old infant in the newborn nursery. Which of the following is the most likely cause of this abdominal mass?

(A). Ovarian cyst

(B). Hydronephrosis

(C). Wilms' tumor

(D). Multicystic kidney

(E). Hydrometrocolpos

  1. The parents of a 5-day-old term infant notice that he is jaundiced. Your physical examination is remarkable only for scleral icterus and jaundice. The infant's total bilirubin level is 15 mg/dL, with a direct component of 0.4 mg/dL. Which of the following is the most likely diagnosis?

(A). Breastfeeding jaundice

(B). Choledochal cyst

(C). Biliary atresia

(D). Neonatal hepatitis

(E). Breast milk jaundice

  1. You are called to the delivery room to evaluate a newborn infant born at 37 weeks gestation who has an abdominal wall defect noted on delivery. Based on your initial physical examination, you diagnose an omphalocele. Which of the following statements is consistent with this clinical diagnosis?

(A). To rule out gastroschisis definitively, an abdominal computed tomographic scan is necessary.

(B). Compared with gastroschisis, omphalocele is more frequently associated with other congenital malformations.

(C). This abdominal wall defect is just lateral to the umbilicus.

(D). The incidence of bowel obstruction is higher in this infant than in one with gastroschisis.

(E). Omphaloceles may be associated with trisomy 21.

  1. You are evaluating a 3-day-old infant with significant respiratory distress. He was delivered by emergency cesarean section at 42 weeks gestation because of fetal distress. You note that he has an oxygen saturation of 76% in room air that increases to 95% with administration of 100% oxygen. Which of the following statements most accurately supports your suspected diagnosis of persistent pulmonary hypertension of the newborn (PPHN)?

(A). This patient is likely to have an associated cyanotic congenital cardiac defect.

(B). PPHN occurs most frequently in premature infants, but may occur in post-term infants.

(C). PPHN usually resolves spontaneously.

(D). This infant is likely to have significant left-to-right shunting.

(E). Adequate oxygenation is the best preventive measurement and treatment.

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  1. A male infant was born at 32 weeks gestation via cesarean section because of bleeding from placenta previa. Soon after birth, he developed respiratory distress requiring supplemental oxygen and mechanical ventilation. Chest x-ray shows decreased lung volumes and a diffuse ground glass pattern with air bronchograms. Which of the following is the most likely cause of this condition?

(A). Persistent pulmonary hypertension of the newborn (PPHN)

(B). Deficient surfactant

(C). Fluid retention in the lungs

(D). Bronchopulmonary dysplasia

(E). Congenital heart disease

  1. The parents of a term infant diagnosed with physiologic jaundice are very concerned that their child is at risk for brain damage. Which of the following statements regarding the infant's hyperbilirubinemia is most accurate?

(A). Breastfeeding, as compared with formula-feeding, is associated with higher peak serum bilirubin levels.

(B). Serum conjugated bilirubin concentra-tion is the best predictor of bilirubin encephalopathy.

(C). Bilirubin encephalopathy does not occur in healthy term infants.

(D). Increased conjugated (direct) bilirubin levels cause neuronal damage, including choreoathetoid cerebral palsy, hearing loss, and opisthotonus.

(E). This infant's jaundice is expected to peak at 10–14 days of life.

  1. A 2-day-old term male infant is being evaluated before discharge from the nursery. The parents are concerned about a skin rash on his face. As you perform the physical examination, you contemplate skin disorders that are benign as compared with those that may indicate underlying pathology. Which of the following skin findings is most likely to be associated with underlying pathology?

(A). Pustular melanosis

(B). Nevus simplex

(C). Milia

(D). Nevus flammeus

(E). Erythema toxicum neonatorum (ETN)

  1. At a routine health maintenance visit, a 2-week-old infant appears jaundiced. Laboratory evaluation reveals a total bilirubin level of 12.6 mg/dL with a direct bilirubin level of 6.9 mg/dL. Which of the following is the most likely diagnosis?

(A). Breastfeeding jaundice

(B). Breast milk jaundice

(C). Crigler-Najjar syndrome

(D). ABO incompatibility

(E). Choledochal cyst

  1. A female infant born at 30 weeks gestation develops abdominal distension, abdominal tenderness, and bloody stools on the third day of life. Which of the following statements regarding the most likely diagnosis is correct?

(A). The diagnosis is supported by a double-bubble sign on abdominal radiographs.

(B). The diagnosis is supported by pneumatosis intestinalis on abdominal radiographs.

(C). The diagnosis is supported by a soap-bubble appearance on abdominal radiographs.

(D). The infant will ultimately require pancreatic enzyme supplementation.

(E). The diagnosis has an increased association with Down syndrome.

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Questions 11 and 12: The response options for statements 11 and 12 are the same. You will be required to select one answer for each statement in the set.

In each case, select the infant's 1-minute Apgar score.

  1. At 1 minute of life, a newborn's respiratory rate is slow and irregular with a heart rate of 120 beats/min. There is some flexion of her upper and lower extremities; she grimaces when a catheter is placed into her nose; and she appears to be pink and well-perfused, except for some cyanosis of the distal extremities.

(A). 2

(B). 3

(C). 4

(D). 5

(E). 6

(F). 7

(G). 8

  1. At 1 minute of life, a newborn's respiratory rate is slow and irregular with a heart rate of 80 beats/min. There is some flexion of his upper and lower extremities, he does not respond when a catheter is placed into his nose, and he is blue and pale.

(A). 2

(B). 3

(C). 4

(D). 5

(E). 6

(F). 7

(G). 8

Questions 13 and 14: The response options for statements 13 and 14 are the same. You will be required to select one answer for each statement in the set.

For each result of the 100% oxygen test, select the most likely diagnosis.

  1. Almost no improvement in the PaO2(10 mm Hg)

(A). Tetralogy of Fallot

(B). Pneumonia

(C). Respiratory distress syndrome (RDS)

(D). Meconium aspiration syndrome

(E). Truncus arteriosus

  1. A slight improvement in the PaO2(approximately 30 mm Hg)

(A). Tetralogy of Fallot

(B). Pneumonia

(C). Respiratory distress syndrome (RDS)

(D). Meconium aspiration syndrome

(E). Truncus arteriosus

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Answers and Explanations

  1. The answer is C[XII.A.3]. Esophageal atresia, if not detected at birth, is characterized by increased oral secretions as a result of the accumulation of saliva in the proximal esophageal pouch. Respiratory distress may occur if the infant aspirates this saliva. The presence of a distal tracheoesophageal fistula may also result in the passage of gastric contents to the trachea and lung, exacerbating the respiratory problem. Half of children with esophageal atresia have other congenital malformations, such as congenital heart disease. Both pneumonia and persistent pulmonary hypertension of the newborn also present with respiratory distress, but without increased oral secretions. Respiratory distress syndrome occurs less commonly in term infants, and increased oral secretions are not expected. Congenital diaphragmatic hernia usually presents with acute respiratory distress soon after birth in a newborn with a scaphoid abdomen. Bowel sounds can be heard on auscultation of the chest.
  2. The answer is B[I.H.7 and I.I.1.b]. The most likely cause of an abdominal mass detected during the newborn period is of renal origin, with hydronephrosis being the most common cause. In female infants, an ovarian cyst, which is usually a benign tumor, is common, but not as common as hydronephrosis. Wilms' tumor and multicystic kidneys may present as abdominal masses but are also less common causes. Hydrometrocolpos, a retention of vaginal secretions, most commonly presents just after birth as a small cyst located between the labia, although during childhood, it may present as a lower midline abdominal mass.
  3. The answer is A[X.C.1]. Breastfeeding jaundice is typically associated with indirect, or unconjugated, hyperbilirubinemia and is caused by suboptimal milk intake during the first week of life, which causes weight loss, poor hydration, and decreased stool output. The treatment of breastfeeding jaundice is hydration, which typically includes increasing the frequency of breastfeeding, along with observation and serial bilirubin assessments. Breast milk jaundice, which occurs later, after the first week of life, is thought to be associated with high levels of lipase and β-glucuronidase within breast milk. Choledochal cysts, biliary atresia, and neonatal hepatitis are more typical causes direct, or conjugated, hyperbilirubinemia.
  4. The answer is B[XII.C]. Omphalocele is more frequently associated with congenital malformations, such as congenital heart defects, and with genetic conditions such as trisomy 13, and less commonly with trisomy 18, but not with trisomy 21. Omphalocele and gastroschisis are easily distinguished and diagnosed by inspection. An omphalocele occurs centrally through the umbilical ring, whereas gastroschisis is a lateral abdominal wall defect in which the abdominal contents herniate into the amniotic cavity. Because of this difference in clinical presentation, both omphalocele and gastroschisis are diagnosed clinically without the need for radiographic confirmation. In gastroschisis, exposure to the amniotic fluid may cause inflammation of the bowel with subsequent bowel damage and risk of bowel obstruction.
  5. The answer is E[VII.B, VII.C, and VII.F]. One of the most common causes of persistent pulmonary hypertension of the newborn (PPHN) is perinatal asphyxia, resulting in increased pulmonary vascular resistance and significant right-to-left shunting through the foramen ovale or the ductus arteriosus. Oxygen is the most potent vasodilator of pulmonary vessels and, in most cases, increase of both alveolar and arterial partial pressures of O2produces a decrease in pulmonary vascular resistance and reversal of low blood flow to the lungs. By definition, PPHN excludes the presence of congenital heart disease. Left untreated, the hypoxemia caused by PPHN worsens the increased pulmonary vascular resistance, resulting in many cases in irreversible disease and death. In addition, PPHN occurs most commonly in near-term and full-term as well as in post-term infants.
  6. The answer is B[VI.A–H]. Respiratory distress syndrome (RDS), which is most common in premature male infants, is caused by a lack or deficiency of surfactant, with alveolar atelectasis and hypoventilation. Chest x-ray findings usually include a diffuse ground glass pattern with air bronchograms. Pneumonia and sepsis should always be included in the differential diagnosis of RDS because their clinical presentations may be quite similar. Persistent pulmonary hypertension of the newborn (PPHN) is more common in term infants than in premature infants and results most frequently from perinatal asphyxia and meconium aspiration syndrome (MAS). Fluid retention in the lungs may cause respiratory distress, but it is usually mild. The chest x-ray usually shows normal or increased lung volume with increased vascular markings. Bronchopulmonary dysplasia (BPD) is a chronic complication of RDS. Some causes of cyanotic congenital heart disease may cause hypoxemia and respiratory distress after birth; however, the chest x-ray does not show a ground glass appearance, nor air bronchograms.

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  1. The answer is A[X.A–G]. Newborn infants who breastfeed have higher peak serum bilirubin values. However, hyperbilirubinemia alone is not a reason to discontinue breastfeeding. Bilirubin encephalopathy is caused only by nonconjugated (indirect) bilirubin because of the ability of bilirubin to cross the blood-brain barrier. Encephalopathy caused by indirect hyperbilirubinemia does occur in healthy term newborns, and for this reason, high bilirubin levels in this group of infants should not be ignored. Benign physiologic indirect hyperbilirubinemia is expected to peak in term infants at 3–4 days of life and in preterm infants at 5–7 days of life.
  2. The answer is D[I.B.11]. Nevus flammeus or “port wine stain” located over the V-1 branch of the trigeminal nerve may herald Sturge-Weber syndrome, with its associated, and potentially very significant, underlying intracranial vascular malformations and calcifications. Pustular melanosis is a benign rash, characterized by small, dry vesicles over a dark macular base, more frequently seen in African American infants. Nevus simplex is the most common vascular lesion of infancy and is also completely benign and often transient, appearing as a “salmon patch” or “stork bite” on the nape of the neck. Milia are benign very small cysts formed around the pilosebaceous follicles that appear as tiny whitish papules over the nose, cheeks, forehead, and chin. Erythema toxicum neonatorum (ETN) is a benign rash usually present in the first 72 hours of life and seen in approximately 50% of all infants. ETN is characterized by erythematous macules, papules, or pustules on the trunk and extremities.
  3. The answer is E[Figure 4-2 and 4-3]. This infant's presentation with hyperbilirubinemia and a markedly elevated direct bilirubin level is consistent with a choledochal cyst, a disorder that causes obstruction of the biliary tree. Both breastfeeding and breast milk jaundice are characterized by indirect, not direct, hyperbilirubinemia. Crigler-Najjar syndrome, or hereditary deficiency of glucuronyl transferase, would also be expected to result in an indirect, or unconjugated, hyperbilirubinemia. ABO incompatibility would lead to hemolysis with predominantly an elevation of indirect bilirubin.
  4. The answer is B[XII.E]. Necrotizing enterocolitis (NEC) is one of the most common surgical conditions in neonates, occurring most commonly in premature infants. Clinical features include abdominal distension, abdominal tenderness, residual gastric contents, bilious vomiting or bilious nasogastric aspirate, bloody stools, and, at times, abdominal wall erythema. Classic radiographic findings include abdominal distension, air-fluid levels, thickened bowel walls, and pneumatosis intestinalis (air within the bowel wall). In contrast, the double-bubble sign on abdominal radiograph is pathognomonic of duodenal atresia, which classically presents with nonbilious emesis and abdominal distension, but not with bloody stools. The presence of a soap-bubble appearance on abdominal radiographs is characteristic of meconium ileus, a presentation of cystic fibrosis during the neonatal period. Infants with meconium ileus would not be expected to pass bloody stools on the third day of life but may require pancreatic enzyme supplementation if they are ultimately diagnosed with fat malabsorption and cystic fibrosis. There is no known association between Down syndrome and NEC, although there is an association between Down syndrome and duodenal atresia.

11 and 12. The answers are E and B, respectively [Table 4.1]. The Apgar scoring system provides a simple, systematic, and objective assessment of intrapartum stress and neurologic depressions. The female newborn earns 2 points for a heart rate > 100 beats/min, 1 point for slow and irregular respirations, 1 point for having some flexion of the extremities, 1 point for reflex irritability or grimace when a catheter is placed in her nose, and 1 point for her peripheral cyanosis or acrocyanosis, for a total Apgar score of 6 points. The male newborn earns 1 point for a heart rate < 100 beats/min, 1 point for slow and irregular respirations, 1 point for having some flexion of the extremities, 0 points for the absence of reflex irritability when a catheter is placed into his nose, and 0 points for his cyanosis, for a total Apgar score of 3 points.

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13 and 14. The answers are A and E, respectively [IV.D.2]. The 100% oxygen test helps distinguish whether cyanosis is caused by cardiac or respiratory disease. When administered 100% oxygen, infants with primary lung pathology, such as neonatal pneumonia, meconium aspiration syndrome, or respiratory distress syndrome, have a very significant increase in PaO2 levels. In contrast, patients with cyanotic congenital heart disease would not be expected to have such a significant rise in their PaO2 level. Patients with cyanotic congenital heart disease associated with reduced pulmonary blood flow, such as tetralogy of Fallot, would not be expected to respond with any increase of significance in PaO2 level when given 100% oxygen. Those infants with cyanotic congenital heart disease associated with normal or increased pulmonary blood flow, such as truncus arteriosus, may have some increase in the PaO2 level, but nowhere near as much of an increase as that seen in infants with primary pulmonary disease.