EMBRYOLOGY
Gestational/Embryologic Landmarks
See Table 2-1.
The main source of energy for a growing fetus is carbohydrates.
Germ Layers
See Table 2-2.
Heart
Week 3: Paired heart tubes begin to work.
Week 4:
Primordial atrium is divided into left and right by septa primum and secundum.
Septum primum forms the valve of the foramen ovale, which closes about 3 months after birth.
Failure of the foramen ovale to close results in an atrial septal defect (ASD).
Week 7:
The single ventricle is divided into left and right; prior to that the interventricular foramen communicates between left and right sides.
Failure of the interventricular foramen to close results in a ventricular septal defect (VSD).
Bicuspid aortic valve and VSD are the most common congenital heart defects.
TABLE 2-1. Gestational/Embryologic Landmarks
TABLE 2-2. Summary of Germ Layer Derivatives
Upper portion of fetal body is perfused much better than lower because of the way fetal circulation functions.
Circulation
See Figure 2-1.
Well-oxygenated blood returns from placenta through umbilical vein, where half of it enters the inferior vena cava through the ductus venosus (continuation of the umbilical vein beyond the branching of the left and right portal veins), and the rest enters the hepatic circulation (preferentially through the left portal vein).
FIGURE 2-1. Fetal circulation.
Despite the fact that the umbilical venous blood joins the inferior vena cava prior to entering the right atrium, the streams do not mix substantially. Blood from the artery to vein is preferentially shunted through the foramen ovale to the left atrium, while blood from the lower inferior vena cava, right hepatic circulation, and superior vena cava enters the right ventricle.
The major portion of blood exiting the right ventricle is then shunted to the aorta through the ductus arteriosus because the lungs are collapsed and pulmonary artery pressures are high.
Sixty-five percent of blood in the descending aorta returns to the umbilical arteries for reoxygenation at the placenta; the remainder supplies the inferior part of the body.
After birth, pulmonary artery pressure drops because the lungs expand, reducing flow across the ductus arteriosus and stimulating its closure (usually within first few days of life). (See Figure 2-2.)
Pressure in the left atrium becomes higher than that in the right atrium after birth due to the ↑ pulmonary return, which stimulates closure of the foramen ovale (usually complete by third month of life).
Closure of the ductus arteriosus can be prevented by prostaglandin E1 and facilitated by indomethacin (via inhibition of prostaglandin synthesis).
Failure of kidneys to develop can → oligohydramnios (↓ fluid in the amniotic cavity).
Hemoglobin
Fetal erythropoiesis occurs in the yolk sac (3–8 weeks), liver (6–8 weeks), spleen (9–28 weeks), and then bone marrow (28 weeks onward).
Failure of kidneys to migrate can → ectopic kidneys.
Genitourinary Tract
Metanephri (permanent kidneys) start functioning at 9 weeks; urine is excreted into amniotic cavity.
Initially, kidneys lie in the pelvis; by 8 weeks they migrate into their adult position.
Morphologic sexual characteristics do not develop until 7 weeks’ gestation.
In males, testis-determining factor induces primary sex cords to develop as male gonads, with testosterone production by 8 weeks.
Testicles develop intra-abdominally and then descend through inguinal canals into the scrotum by 26 weeks.
Ovaries are identified by 10 weeks; primary sex cords develop into female gonads with primordial follicles developing prenatally.
A horseshoe kidney gets caught on the inferior mesenteric artery (IMA) during ascent.
Failure of testicle(s) to descend, cryptorchidism, may need to be corrected surgically to prevent progressive dysplasia and may affect fertility.
FIGURE 2-2. Mechanism of ductus arteriosus patency/closure.
Gastrointestinal Tract
By 10 weeks, the midgut returns from the umbilical cord, where it was developing, to the abdominal cavity, while undergoing counterclockwise rotation.
Insufficient rotation of the midgut, called malrotation, can present in neonatal period as intestinal obstruction.
Incomplete separation of foregut and primitive airway can → tracheoesophageal fistula (TEF).
Failure of the intestine to return to the abdominal cavity with intestinal contents remaining at the base of the umbilical cord causes gastroschisis, a full-thickness abdominal wall defect with extruded intestine.
Infants born prior to 30 weeks are given exogenous surfactant to prevent respiratory distress syndrome (RDS). Mom is given steroids.
Lungs
By 24 weeks, primitive alveoli are formed and surfactant production is begun.
Central Nervous System (CNS)
During week 3, the neural tube is formed on the ectodermal surface.
Neural tube openings (rostral and caudal) are closed by 25–27 days.
By week 5, subdivisions of forebrain, midbrain, and hindbrain are formed.
Failure of caudal neural tube to close completely can result in spina bifida (unfused vertebral arch with or without unfused dura mater and spinal cord), commonly seen in the lumbar area. Failure of the rostral neural tube to close can result in anencephaly.
Lecithin-to-sphingomyelin ratio in the amniotic fluid greater than 3 indicates fetal lung maturity.
PLACENTA
Development
Fetal portion of placenta is formed from chorionic sac.
Maternal portion is derived from endometrium.
Folic acid supplements during pregnancy reduce incidence of neural tube defects.
Transport
Nutrients, electrolytes, water, and gases are diffused or transported across the placenta.
Most drugs pass through placenta and can be detected in fetal plasma (eg, warfarin, morphine, propylthiouracil, and drugs of abuse).
A few substances cannot pass because of their size or charge (eg, heparin); protein hormones (eg, insulin) do not cross placenta.
Maternal α-fetoprotein (AFP) is high in:
Multiple gestations (most common)
Fetal neural tube defects
Gastroschisis
Metabolism
Placenta synthesizes glycogen and cholesterol.
Endocrine Function
Placenta produces β-human chorionic gonadotropin (β-hCG), human chorionic adrenocorticotropic hormone (ACTH), human placental lactogen, and human chorionic somatomammotropin.
Testing urine for β-hCG allows early detection of pregnancy.
PRENATAL DISTURBANCES
Infections
Infants who have experienced an intrauterine infection have a higher-than-average incidence of being small for gestational age, hepatosplenomegaly, congenital defects, microcephaly, and intracranial calcifications.
Maternal AFP is low in trisomies 21 (Down’s) and 18.
TOXOPLASMOSIS
Maternal infection is due to ingestion of oocysts from feces of infected cats and is asymptomatic.
Clinical features in infants include microcephaly, hydrocephalus, intracranial calcifications, chorioretinitis, and seizures.
Incorrect dates is the most common cause for abnormal AFP.
RUBELLA
Congenital rubella syndrome is rare due to the effectiveness of the rubella vaccine.
Maternal infection early in pregnancy can result in congenital rubella syndrome, which includes meningoencephalitis, microcephaly, cataracts, sensorineural hearing loss, and congenital heart disease (patent ductus arteriosus and pulmonary artery stenosis).
Among women infected with toxoplasmosis, only 50% will give birth to an infected neonate.
CYTOMEGALOVIRUS (CMV)
Common—occurs in 1% of newborns.
Newborn disease is associated with primary maternal infection with a 50% chance of infection.
In those affected, only 5% have neurologic deficits.
Infection occurs in 1% of pregnancies with recurrent or reactivated infection.
CMV transmitted intrapartum, through infected blood or through breast milk, is not associated with neurologic deficits.
Clinical features include intrauterine growth retardation (IUGR), low birth weight, petechiae and purpura, jaundice and hepatosplenomegaly, microcephaly, chorioretinitis, and intracranial calcifications.
Late manifestations like learning and hearing deficits can occur in 10% of clinically inapparent infections.
Pregnant women should not change a cat’s litter box, due to risk of toxoplasmosis.
Toxins and Teratogens
ALCOHOL
Most common teratogen.
The amount of alcohol consumed correlates with the severity of spectrum of effects in the neonate, ranging from mild reduction in cerebral function to classic fetal alcohol syndrome (see Figure 2-3).
Incidence of fetal alcohol syndrome is higher in the Native American population because of the higher incidence of alcoholism.
FIGURE 2-3. Fetal alcohol syndrome.
Notice the depressed nasal bridge, flat philtrum, long upper lip, and thin vermillion border. (Reproduced, with permission, from Stoler JM, Holmes LB. Underrecognition of prenatal alcohol effects in infants of known alcohol abusing women. Journal of Pediatrics 135(4):430–436, 1999.)
Clinical manifestations include microcephaly and mental retardation, IUGR, facial dysmorphism (midfacial hypoplasia, micrognathia, shortened nasal philtrum, short palpebral fissures, and a thin vermillion border), renal and cardiac defects, and hypospadias.
COCAINE
Term, 5-lb., 2-day-old infant has irritability, nasal stuffiness, and coarse tremors. He feeds poorly and has diarrhea. Think: Cocaine or heroin withdrawal.
Cocaine readily crosses the placental barrier, placing the fetus at risk. Symptoms of cocaine withdrawal include tremors, high-pitched cry, irritability, excess suck, apnea, and tachycardia, which can become evident within the first 72 hours of life. Opiates also cross the placenta. Tremor and irritability are the common symptoms of opiate withdrawal. Vague autonomic symptoms such as yawning and sneezing are often present.
Causes maternal hypertension and constriction of placental circulation →↓ uterine blood flow and fetal hypoxia.
Associated with a higher risk of spontaneous abortion, placental abruption, fetal distress, meconium staining, preterm birth, IUGR, and low Apgar scores at birth.
Associated with intracranial hemorrhage and necrotizing enterocolitis; cardiac, skull, and genitourinary malformations; and ↑ incidence of sudden infant death syndrome (SIDS).
Cocaine withdrawal in an infant causes irritability, ↑ tremulousness, and poor feeding, as well as ↑ incidence of learning difficulties and attention and concentration deficits later on.
Cocaine use is associated with placental abruption.
NARCOTICS
Heroin and methadone are associated with IUGR, SIDS, and infant narcotic withdrawal syndrome.
Infants of narcotic-abusing mothers should never be given naloxone in the delivery room because it may precipitate seizures.
TOBACCO
Smoking is associated with ↓ birth weight.
PHENYTOIN
Phenytoin is associated with fetal hydantoin syndrome, which includes IUGR, mental retardation, dysmorphic facies, and hypoplasia of nails and distal phalanges.
TETRACYCLINE
Tetracycline causes tooth discoloration and inhibits bone formation.
ISOTRETINOIN (ACCUTANE)
Accutane is associated with hydrocephalus, microtia, micrognathia, and aortic arch abnormalities.
WARFARIN
Warfarin causes abnormal cartilage development, mental retardation, deafness, and blindness.
Warfarin is no longer used in pregnant women due to the advent of low-molecular-weight heparin, which has fewer side effects and is well tolerated.
MATERNAL CONDITIONS
Diabetes
Associated with macrosomia (weight > 4 kg), which can → birth-related injury.
Fetal complications are related to degree of control of maternal diabetes.
Other fetal/neonatal complications include metabolic disorders (hypoglycemia, hypocalcemia, and hypomagnesemia), perinatal asphyxia, respiratory distress syndrome, hyperbilirubinemia, polycythemia and hyperviscosity, and congenital malformations including cardiac, renal, gastrointestinal, neurologic, and skeletal defects.
Elevation of maternal glucose causes elevated fetal glucose, → fetal hyperinsulinism, which can → hypoglycemia in the newborn.
Others
Hypertension and renal and cardiac disease are associated with small-for-gestational-age babies and prematurity.
Maternal lupus is related to first-degree atrioventricular (AV) block in affected infants.
Vascular disease of placenta, caused by maternal illness (such as diabetes or lupus) can → insufficient supply of nutrients to fetus and IUGR.
DELIVERY ROOM
Delivery Room Care
Once the head is delivered, the nose and mouth are suctioned.
Once the whole body is delivered, the newborn is held at the level of the table and the umbilical cord is clamped.
Newborn is then placed under radiant warmer and is dried with warm towels.
Mouth and nose are gently suctioned.
Gentle rubbing of the back or flicking of the soles of the feet, if needed to stimulate breathing.
When the umbilical cord is clamped and cut, absent blood flow within the umbilical vein → the closure of the ductus venosus.
Apgar Scoring
Practical method of assessing newborn infants immediately after birth to help identify those requiring resuscitation on a scale of 0–10. It is not a substitute for assessing the ABCs in neonatal resuscitation.
Assessment at 1 and 5 minutes; further assessments at 10 and 15 minutes may indicate success of resuscitation (see Table 2-3). Resuscitation efforts should not be delayed or interrupted to assign an Apgar score.
A poor Apgar score alone cannot be used to diagnose asphyxia or predict the development of cerebral palsy.
Prophylaxis
Gonococcal and chlamydial eye infection prophylaxis is with erythromycin or tetracycline ointment.
Vitamin K is given intramuscularly (IM) to prevent hemorrhagic disease of the newborn.
Cord Blood/Stem Cells
Blood gas study should be sent if fetal distress is present.
Can be used to test for infant’s blood type.
Rich in stem cells, which are pleuripotential cells that have potential use in malignancies and gene therapy.
TABLE 2-3. Apgar Scoring
Total out of 10: 7–10 normal newborn; 4–7 may require some resuscitative measures; ≤ 3 require immediate resuscitation.
NURSERY EXAM
General Appearance
Plethora (high hematocrit secondary to chronic fetal hypoxia), jaundice, sepsis and TORCH infections, cyanosis (with congenital heart and lung disease), pallor (anemia, shock, patent ductus arteriosus).
Prenatal infections that most commonly cause birth defects:
TORCH
Toxoplasmosis
Other (hepatitis B, syphilis, varicella-zoster virus)
Rubella
Cytomegalovirus
Herpes simplex virus/human immunodeficiency virus (HSV/HIV)
See Figure 2-4.
Skin
Erythema toxicum is a pustular rash distributed over the trunk, face, and extremities, which resolves over a week.
Mongolian spots are bluish spots present over the buttocks and back that are seen in infants of African, Asian, and Native American descent that tend to fade over a year.
Capillary hemangiomas (“stork bites”) are pink spots over the eyelids, forehead, and back of the neck that tend to fade with time.
See Dermatologic Disease chapter.
Head
Anterior fontanelle closes at 9–12 months.
Large fontanelle is seen in hypothyroidism, osteogenesis imperfecta, and some chromosomal abnormalities.
Absent anterior fontanel is associated with craniosynostosis.
A bulging fontanelle is seen with ↑ intracranial pressure, hydrocephalus, and meningitis.
Face
Mouth—look for cleft lip/palate and macroglossia (large tongue is seen with hypothyroidism, Down’s, and Beckwith-Wiedemann syndrome).
Coarse facial features are associated with mucopolysaccharidoses.
Look for dysmorphic features, including micrognathia, bossing of the forehead, hypertelorism (widely spaced eyes), and low-set ears (Down’s) (see Congenital Malformations and Chromosomal Abnormalities chapter).
Eyes
Check for red reflex with ophthalmoscope. An absent red reflex in one or both eyes signifies blockage of the passageway between the cornea and retina such as associated with cataracts or eye tumor (retinoblastoma).
Look for cataracts, Brushfield spots (salt-and-pepper speckling of the iris seen in Down syndrome), leukocoria (white pupil) with retinoblastoma (rare), and subconjunctival hemorrhage, which can occur after a traumatic delivery.
See Special Organs—Eye, Ear, Nose chapter.
Neck
Inspect for thyroid enlargement and palpate along the sternocleidomastoid for hematoma.
Check for any fistula or tracts, which are associated with branchial closure malformations.
FIGURE 2-4. Head CT consistent with TORCH infection–marked ventricular dilation, extensive encephalomalacia involving both cerebral hemispheres, absent corpus callosum, periventricular calcifications, skull deformity with overriding sutures.
Chest
Symmetry/equality of breath sounds.
Retractions and grunting may signify respiratory distress (nasal flaring, intercostal retractions, use of accessory muscles).
Breasts may be enlarged from the effects of maternal estrogens.
Cardiovascular
Heart rate rhythm, quality of heart sounds, and the presence of a murmur. Murmur in a newborn infant can be due to open ductus arteriosus, but persistent murmur is always pathologic and needs evaluation.
Check pulses and compare brachial with femoral pulse to get an estimate of vascular volume and also to rule out aortic arch obstruction (aortic stenosis, coarctation of aorta), where the femoral pulses will be weak or absent.
Abdomen
Palpate for masses.
Examine umbilicus for omphalocele and gastroschisis.
Inspect the umbilical cord for single umbilical artery (normally two); if present, may indicate congenital anomalies.
Extremities
Check both clavicles for any step off especially in the midclavicular area, where most clavicles fractures occur.
Primitive reflexes (see Growth and Development chapter).
Examine for congenital hip dysplasia.
Acrocyanosis (blue hands and feet only) can be normal in a newborn.
Back
Look for dimples or tufts of hair that may indicate spina bifida.
Papilledema does not occur in infants with open cranial sutures.
Genitalia
Girls may have vaginal bleeding and swollen labia secondary to withdrawal of maternal estrogens.
In boys, palpate for the presence of testicles in scrotum and look for hypo- or epispadias (urethral opening proximal to normal position either on the dorsal or ventral surface).
SMALL OR LARGE FOR GESTATIONAL AGE
Small for Gestational Age (SGA)
Birth weight less than the tenth percentile for gestational age.
There are two broad categories, early and late onset.
Early onset:
Insult that begins before 28 weeks’ gestational age.
Head circumference and height are proportionally small-sized (symmetric).
Seen in infants born to mothers with severe vascular disease with hypertension, renal diseases, congenital anomalies, infections, and chromosomal abnormalities.
Late onset or asymmetric IUGR.
Occurs with an insult after 28 weeks’ gestational age.
Sparing of the head circumference.
Can occur with multiple gestation and preeclampsia.
Absent breath sounds may signify a tension pneumothorax or atelectasis; bowel sounds in the thorax may indicate congenital diaphragmatic hernia.
Large for Gestational Age (LGA)
Birth weight greater than the 90th percentile for gestational age.
Those at risk are infants of diabetic mothers, postmature infants, and those with Beckwith-Wiedemann syndrome.
Most LGA infants have large parents and are constitutionally large.
Macrosomic infants are those with a birth weight > 4 kg.
Diminished femoral pulses are seen in coarctation of the aorta.
BIRTH TRAUMA
Clavicular Fracture
Most common bone fracture during delivery.
Complete fracture symptoms involve ↓ or absent movement, gross deformity of clavicle, tenderness on palpation, and localized crepitus.
Greenstick (partial) fractures have no symptoms and the diagnosis is made at 7–10 days because of callus formation.
Management is often conservative (pin arm inside sleeve to shirt to ↓ movement).
The most common cause of an abdominal mass in a newborn is an enlarged kidney.
Caput Succedaneum
Area of edema over the presenting portion of the scalp during a vertex delivery.
Associated with bruising and petechiae.
Can cross suture lines.
Layers of the skull can be remebered by this mnemonic:
SCALP
Skin
Cutaneous tissue
Aponeurosis
Loose areolar tissue
Periosteum
Cephalohematoma
Caused by bleeding that occurs below the periosteum of the overlying bone (usually the parietal).
Associated with skull fractures in 5–10%, most often linear.
Contained within the periosteum: does not cross suture lines.
Subgaleal bleed:
Usually associated with delivery trauma or a bleeding disorder.
Always between the aponeurosis and periosteum layers, with bleeding into the loose areolar tissue.
Crosses suture lines and feels very boggy with localization to the dependent area.
Risk factor for significant indirect hyperbilirubinemia in the infant.
Circumcision should be avoided in boys with hypo- or epispadias, as foreskin can be used to repair these defects later on.
Skull Fracture/Epidural Hematoma
Skull fractures are uncommon; most are linear and associated with cephalohematoma. Depressed fractures are often visible and may require surgery.
Epidural hematomas are rare and may require prompt surgical evacuation.
All macrosomic infants should be examined for signs of birth trauma and checked for hypoglycemia.
Molding
Temporary asymmetry of the skull from the overlapping of bones that occurs following prolonged labor and vaginal deliveries.
Normal head shape is regained within a week.
Complete clavicular fractures will → absence of Moro’s reflex.
Klumpke’s Palsy
Involves the lower arm and affects the seventh and eighth cervical and first thoracic nerve roots. The hand is paralyzed and has an absent grasp reflex, causing a “claw hand” deformity.
It is rare to have an isolated Klumpke’s palsy.
Is often accompanied by Horner syndrome.
Caput succedaneum is external to the periosteum and crosses the midline of the skull and suture lines versus a cephalohematoma, which is below the periosteum and does not cross suture lines.
Erb’s Palsy
Erb-Duchenne involves the upper arm and is the most common type.
Involves the fifth and sixth cervical roots, and the arm is adducted and internally rotated, but the grasp reflex is intact (see Figure 2-5).
Brachial plexus injuries can occur during birth when traction is used with shoulder dystocia.
FIGURE 2-5. Erb’s palsy
PERINATAL INFECTIONS
Risk Factors
Rupture of amniotic membranes for 18 hours or more.
Chorioamnionitis.
Intrapartum maternal fever.
Maternal group B Streptococcus (GBS) colonization.
Prematurity.
Maternal UTI with gram-negative organisms is emerging as the common cause due to perinatal GBS prophylaxis.
Degree of functional return in birth brachial plexus injuries depends on the severity of the nerve injury (stretch, rupture, avulsion).
Group B Streptococcus (GBS)
Major cause of severe systemic infection in neonates.
Vertical transmission most important route of transmission.
Two patterns of disease:
Early-onset disease (< 1 week of age):
Presents shortly after birth (usually < 12 hours) as sepsis, pneumonia, or meningitis.
Infants < 24 hours of age may not have fever.
Can be associated with persistent pulmonary hypertension of the newborn (PPHN).
Late-onset disease (1 week–3 months): Occurs after the first week of life and most often manifests as bacteremia without a source. The most common focal infection is meningitis (35%) and presents with bulging fontanelle, lethargy, irritability, vomiting, and seizures.
Diagnosis is confirmed by GBS isolation from sterile body fluid (blood, cerebrospinal fluid).
Empiric therapy with ampicillin and gentamicin should be started only if infant is symptomatic (ie, apnea, low temperature, feeding intolerance).
If infant is asymptomatic, monitoring for 48 hours is sufficient since infant will typically show signs of infection within a 48-hour period.
Intrapartum therapy with penicillin G does not prevent late onset disease but protects against early onset disease.
Twenty percent of pregnant women are colonized with GBS. It is recommended that all pregnant women be screened (vaginal, rectal swabs) at 35–37 weeks of gestation, and be given intrapartum antibiotics if positive.
Escherichia coli
Principal cause of gram-negative sepsis and meningitis in newborn.
Commonly colonize genitourinary (GU) and gastrointestinal (GI) tracts.
Risk factors include maternal urinary tract infection (UTI) during last month of pregnancy in addition to previously mentioned risk factors.
Clinical manifestations include sepsis, meningitis, UTI, pneumonia.
Diagnosis is confirmed by E coli isolation from normally sterile body fluids.
Treatment should be based on antibiotic sensitivity data, but a third-generation cephalosporin should be used as an empiric agent.
E. coli infection in the infant is common in infants with galactosemia.
Listeria monocytogenes
Important cause of neonatal sepsis.
Colonizes GU tract.
Clinical manifestations include sepsis and meningitis.
Diagnosis is confirmed by L monocytogenes isolation from sterile body fluid.
Treatment is with penicillin or ampicillin.
Herpes Simplex
Prevalence rate for adults with genital herpes is about 20%.
Risk of neonatal disease is much higher with primary maternal infection (44%), and only 3% for a recurrent one.
Ninety percent of neonatal infection is acquired through infected secretions during birth.
There are three distinct patterns of disease:
Cutaneous disease:
Involves skin, mouth, and eyes.
Vesicular eruptions appear around 7–10 days of life, usually on presenting part.
If not recognized promptly, can progress to disseminated disease.
Encephalitic disease:
Occurs at second to third week of life.
Clinical signs include lethargy, irritability, poor suck, seizures.
Cutaneous lesions may be absent.
Disseminated disease:
Sepsis-like clinical picture (apnea, irritability, hypotonia, hypotension).
Cutaneous lesions may be absent.
Cesarean section is performed for women with primary genital herpes and vaginal lesions in late gestation.
DIAGNOSIS
HSV can be isolated in cell culture from skin lesions or nasopharyngeal swabs.
Polymerase chain reaction (PCR) is a sensitive tool for HSV detection.
TREATMENT
Acyclovir is very effective in treatment of HSV infection.
Course of treatment is often prolonged (21 days) for encephalitic and disseminated forms.
Chlamydia
A 3-week-old infant presents with paroxysmal cough and tachypnea, but no fever; bilateral diffuse crackles, hyperinflation, and patchy infiltrates on x-ray; he had conjunctivitis at 10 days of age. Think: Chlamydia trachomatis.
The incubation period of chlamydial conjunctivitis is between 5 and 14 days; usually manifests later than gonococcal conjunctivitis (occurs 2–5 days after birth). It is commonly acquired from the birth canal during delivery. It is the most common infectious cause of conjunctivitis in the neonates. Generally, gonococcal conjunctivitis usually has a more rapid and progressive course than Chlamydia.
Acquired during passage through the birth canal of an infected mother.
Causes conjunctivitis (few days to several days) and pneumonia (between 3 and 19 weeks).
Characteristic “staccato” cough may not be evident in newborn infants, and may present with frequent apneic episodes.
DIAGNOSIS
Culture.
Erythromycin use has been associated with development of pyloric stenosis.
TREATMENT
Erythromycin orally for 14 days.
Syphilis
Results from transplacental transfer of Treponema pallidum.
Common features include intermittent fever, osteitis and osteochondritis, hepatosplenomegaly, lymphadenopathy, persistent rhinitis (“snuffles”), and a maculopapular rash involving the palms and the soles.
Late manifestations include a saddle nose deformity, saber shins, frontal bossing, Hutchison teeth and mulberry molars, sensorineural, and Clutton’s joints (painless joint effusions).
DIAGNOSIS
Rapid plasma reagin (RPR) titers and the flourescent treponemal antibody-absorption test (FTA-ABS).
Treponemes can also be seen on darkfield microscopy of nasal discharge.
TREATMENT
Penicillin G.
HIV
Up to 25% of pediatric human immunodeficiency virus (HIV) infection results from maternal-fetal vertical transmission.
Transmission from infected breast milk can occur; however, exclusively breast-fed infants have lower transmission rates.
Clinical features in the infant include persistent thrush, lymphadenopathy and hepatosplenomegaly, severe diarrhea, failure to thrive, and recurrent infections.
Strategies to reduce transmission:
Maternal treatment with ZDV during pregnancy.
Consider elective C-section at 38 weeks when feasible.
Mothers who are HIV positive should be advised not to breast-feed due to risk of transmission.
Maternal treatment with zidovudine (ZDV) in the second trimester reduces the rate of transmission by > 70%.
DIAGNOSIS
Detection of p24 antigen in peripheral blood, PCR to detect viral nucleic acid in peripheral blood, and enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies.
TREATMENT
Nutritional support, Pneumocystis jiroveci prophylaxis, antiviral therapy, and anti-infective agents for specific infections.
Delivery room management of a meconium-stained infant consists of nasopharyngeal suctioning before the delivery of the thorax. Infants with respiratory depression require intubation and tracheal suctioning.
SELECTED PROBLEMS IN FULL-TERM INFANTS
Developmental Dysplasia of the Hip (DDH)
Occurs in ∼1 in 800 births.
More common in white females with breech presentation, and is more likely to be unilateral and involve the left hip.
Signs include asymmetry of the skin folds in the groin and shortening of the affected leg.
Evaluation maneuvers:
Ortolani—abduction of the hips by using gentle inward and upward pressure over the greater trochanter.
Barlow—adduct the hips by using the thumb to apply outward and backward pressure; “clunking” of reduction and dislocation are elicited in patients with hip dislocation.
Diagnosis is confirmed by ultrasound. Current American Academy of Pediatrics (AAP) guidelines ask for ultrasound only in female infants with breech presentation and a hip click.
Can be treated with a special brace (Pavlik harness) or sometimes casting. See Musculoskeletal Disease/Orthopedics chapter.
Meconium Ileus/Aspiration
A full-term male infant was born after a prolonged second stage of labor and thick meconium at delivery. He was depressed at birth, requiring intubation and suction of the meconium from below the vocal cords. His condition improved quickly, and he was vigorous at 3 minutes of life. Apgar score was 3 and 7 at 1 and 5 minutes of life, respectively. He was doing well in the well-baby nursery until at 3 hours of life, when he was noted to have dusky episode and was transferred to the special care nursery where his O2 saturation was noted to be 82% breathing room air. He was placed in oxyhood oxygen climbing up to 100% with borderline O2 saturation in the mid-80s. He was intubated and started on mechanical ventilation. His chest x-ray is shown in the figure. What is the likely diagnosis and management of this infant?
The infant described has characteristic meconium aspiration syndrome as seen by nodular appearance of both lung fields on the chest x-ray. He is developing persistent pulmonary hypertension of the newborn (PPHN), management of which includes aggressive ventilation, inhaled nitric oxide, and close monitoring of the gas exchange. An echocardiogram is useful to provide details on the elevated pulmonary pressures as well as to rule out any cardiac defects. Infants are at risk of hypotension and shunting of pulmonary flow via the ductus arteriosus into the systemic circulation resulting in differential O2 saturation in the upper and lower extremities and require pressor support (dopamine, dobutamine, epinephrine) to elevate systemic blood pressure to the level above pulmonary pressure to prevent hypotension and shunting.
Meconium is the first intestinal discharge of a newborn infant and is composed of epithelial cells, fetal hair, mucus, and bile.
Intrauterine stress may cause passage of meconium into the amniotic fluid, which can cause airway obstruction and a severe inflammatory response, → severe respiratory distress known as meconium aspiration syndrome.
Meconium ileus occurs when meconium becomes obstructed in the terminal ileum; presentation is with failure to pass stool, abdominal distention, and vomiting.
Infants with meconium ileus should be tested for cystic fibrosis.
Meconium ileus is the most common presentation of cystic fibrosis in the neonatal period.
Hypoxic/Ischemic Encephalopathy
Hypoxic ischemic encephalopathy is an important cause of permanent damage to the cells of the CNS that occurs secondary to hypoxia (↓ oxygen delivery) and ischemia (↓ blood flow).
Can be caused by maternal conditions (hypertension), placental insufficiency, severe neonatal blood loss, and overwhelming infection.
Neurologic manifestations include hypotonia, coma, and seizures.
It can result in death, cerebral palsy (CP), and mental retardation.
Newer modalities of treatment include selective head cooling or whole body cooling, which are used at several tertiary care neonatal intensive care units (NICUs) in the United States.
Ninety percent of full-term infants pass their first stool within the first 24 hours of life.
Only 10% of patients with cerebral palsy have birth events associated with asphyxia; the cause of the majority of cases of CP remains unknown.
Congenital Diaphragmatic Hernia (CDH)
Associated with chromosomal abnormalities, low birth weight, and IUGR.
Can be diagnosed on prenatal ultrasound (between 16 and 24 weeks).
Signs and symptoms include respiratory distress immediately on delivery, tachypnea, poor breath sounds over affected side of chest (most commonly left), and scaphoid abdomen.
Prenatally diagnosed diaphragmatic hernia in a neonate warrants an exutero intrapartum treatment (EXIT) procedure, where neonatologists and surgeons are present at delivery and infant is intubated and central extracorporeal membrane oxygenation (ECMO) catheters placed at the delivery of the head and neck.
Respiratory distress is a cardinal sign in neonates with CDH.
Jaundice
Common causes of hyperbilirubinemia include ABO incompatibility, breast milk jaundice (see Nutrition chapter), Rh iso-immunization, and infection.
Conjugated hyperbilirubinemia (direct):
When an infant’s direct (conjugated) bilirubin is > 3 mg/dL or more than 20% of the total bilirubin.
Most common causes are idiopathic neonatal hepatitis (diagnosis of exclusion) and biliary atresia.
Unconjugated hyperbilirubinemia (indirect):
When an infant’s indirect (unconjugated) serum bilirubin level is > 10 mg/dL in term infants. Nomograms developed by AAP are used to plot bilirubin levels and to categorize infants into low or high risk group and need for treatment.
Most common cause of neonatal jaundice, seen in up to 50% of neonates.
Secondary to ↑ bilirubin load, defective uptake and conjugation, and impaired excretion into bile.
Physiologic hyperbilirubinemia is seen after the first 24 hours of life, peaks at 3 days, and resolves over 2 weeks.
Kernicterus:
Bilirubin neurotoxicity secondary to persistently elevated bilirubin levels, which exceed albumin-binding capacity of the blood resulting in deposition of bilirubin in the basal ganglia.
This can result in subtle neurologic deficits, hearing loss, profound encephalopathy, and death.
Treatment is initiated to prevent kernicterus.
Phototherapy with blue-green light converts bilirubin in skin to nontoxic isomers that are excreted without conjugation.
Elevated bilirubin levels (12–20 mg/dL) are usually treated with phototherapy.
Exchange transfusion should be considered at higher levels (20–25 mg/dL).
High indirect serum bilirubin levels in the first 24 hours of life are never physiologic.
In neonates there is a cephalopedal progression of jaundice; approximate levels for involvement:
Head and neck: 4–8 mg/dL
Upper trunk: 5–12 mg/dL
Lower trunk and thighs: 8–16 mg/dL
Arms and lower legs: 11–18 mg/dL
Palms and soles: > 15 mg/dL
NEWBORN SCREENING
Neonatal Screening
Available for various genetic, metabolic, hematologic, and endocrine disorders.
All states have screening programs, although specific tests required vary.
Tests performed on heel puncture include those for hypothyroidism, galactosemia, adrenal hyperplasia, cystic fibrosis, phenylketonuria, and other organic acid- and aminoacidopathies.
Early diagnosis of hypothyroidism and treatment with thyroid hormone prior to 3 months of age can greatly improve intellectual outcome.
Auditory Screening
Hearing impairment can affect speech and language development and occurs in 5 in 1000 births.
All infants should be screened with otoacoustic emission hearing testing.