|Block 10: NICU Board Review: Q & A
1. You are evaluating a 3-day-old preterm infant who was born at 26 weeks’ gestation and weighed 800 g. Her blood pressure has dropped acutely, and she has developed seizures. Physical examination demonstrates equal mechanical breath sounds, no heart murmur, hypotonia, a bulging anterior fontanelle, and lethargy. Laboratory evaluation reveals anemia, metabolic acidemia, and hyperglycemia.
Of the following, the MOST likely explanation for these findings is
A. acute pneumothorax
B. intracranial hemorrhage
C. late-onset sepsis
D. patent ductus arteriosus
E. perinatal asphyxia
Preferred Response: B
The clinical presentation of intraventricular hemorrhage (IVH) in the preterm infant can vary from asymptomatic (in up to 75% of cases, usually with a mild-to-moderate grade I to II hemorrhage) to profound hemodynamic, metabolic, and acid-base abnormalities (in the more severe grade III and grade IV (parenchymal hemorrhages). The infant described in the vignette is in a high-risk category for experiencing an IVH due to her extreme prematurity and extremely low birthweight (incidence of 25% to 50%). Her acute instability, bulging fontanelle, lethargy, and seizure coupled with acidosis and anemia are explained best by a severe grade IV IVH. Most such hemorrhages occur in the first 96 hours of postnatal life.
Laboratory data in IVH often document hyperglycemia (an indication of severe stress), anemia (acute decrease in hematocrit), thrombocytopenia (consumption), acidemia (metabolic, reflecting both tissue damage and hypovolemic shock), and hyponatremia indicating inappropriate secretion of antidiuretic hormone.
Managing IVH, or any other intracranial hemorrhage, requires initial stabilization of the airway, control of respiratory function (apnea, hypercarbia, and hypoxia are common), and support of the circulation (packed red blood cell transfusion) as well as correction of acidosis and hyperglycemia. Anticonvulsant therapy with phenobarbital generally is initiated in patients demonstrating seizures. The imaging study of choice for an unstable preterm infant is bedside cranial ultrasonography. For a more mature and stable patient or one for whom subarachnoid or subdural hemorrhage is the principal concern, computed tomography scan of the head is preferred. An investigation into any underlying contributing problems such as sepsis or coagulopathy is necessary. In the face of central nervous system injury, hypercarbia, hypoxia, and hypotension should be avoided.
Acute pneumothorax has been associated with IVH in preterm infants who have respiratory distress. The incidence has declined with the use of surfactant and improved ventilation strategies. The equal breath sounds reported for the infant in the vignette do not suggest a pneumothorax. By definition, late-onset sepsis occurs beyond 3 days after birth. Patent ductus arteriosus (PDA) does not manifest with anemia and a bulging fontanelle. The ligation of a PDA, accompanied by abrupt hemodynamic changes, has been an argued contributory cause to IVH, but this is less of a concern with pharmacologic treatment of the PDA using indomethacin. Perinatal asphyxia is associated with acidemia, seizures, and other problems in the first 24 hours after birth.
2. You are counseling a 23-year-old woman who has diabetes mellitus and has been your patient for the past 18 years. She recently found out that she is pregnant and asks you about potential complications for her unborn child.
Of the following, the MOST likely complications to expect for this woman’s child are
A. hyperacusis, hypercalcemia, hydronephrosis
B. hyperbilirubinemia, hypercalcemia, polydactyly
C. hyperglycemia, hypocalcemia, polysplenia
D. hypoglycemia, hypocalcemia, polycythemia
E. hypogonadism, hypocalcemia, polyuria
Preferred Response: D
Disorders of glucose regulation such as diabetes mellitus may complicate as many as 5% of pregnancies. This includes women who develop diabetes (insulin resistance) during pregnancy, known as gestational diabetes; those who have pre-existing insulin resistance (type 2 diabetes); and those who have pre-existing insulin-dependent diabetes mellitus (IDDM) (type 1 diabetes).
The pregnant woman described in the vignette has IDDM. Risks posed to her developing fetus and newborn are numerous. Postnatal hypoglycemia frequently is encountered in the first 4 to 12 hours in infants of diabetic mothers (IDMs) and is related to macrosomia, an increased metabolic rate, and fetal hyperinsulinemia that takes a few days after birth to diminish. Postnatal hypocalcemia results from the effects of poor late-trimester transfer of calcium across the placenta in pregnancies affected by diabetes, a delay in normal postnatal parathyroid hormone elevation, and poor fetal and neonatal bone mineralization (ie, poor calcium stores). If hypomagnesemia is found in the IDM, it must be corrected to allow normal parathyroid function to resume. Polycythemia (hematocrit >65% [0.65]) represents the fetal response to its increased metabolic rate and a relative fetal hypoxemia in utero when pregnancy is complicated by diabetes and fetal macrosomia. Resultant hyperbilirubinemia needs to be anticipated.
Hyperacusis is not seen in IDMs, whose risk for hearing impairment is similar to that of other newborns requiring intensive care. Hypercalcemia is seen in Williams syndrome, but not in IDMs. Hydronephrosis, seen on prenatal ultrasonography, may be present in a number of highrisk pregnancies, but not IDMs. Polydactyly may be seen in trisomies and some other congenital syndromes but does not occur with greater frequency in IDMs. Polysplenia is seen in defects of left-right asymmetry but does not have an increased incidence in IDMs. Hypogonadism is
characteristic of congenital adrenal hyperplasia, Prader-Willi syndrome, and Turner syndrome; it is not more common in IDMs.
3. You are called to the neonatal intensive care unit to evaluate a newly admitted 34-week gestational age male infant who has respiratory distress. When you arrive, the baby is receiving oxygen supplementation by hood. You note that the baby’s weight, length, and head circumference are all below the 10th percentile. He has excess hair over his forehead, shoulders, and back. In addition, he is very irritable, despite correction of his oxygen saturation to 95%.
Of the following, this infant’s unusual findings are MOST likely related to prenatal exposure to:
Preferred Response: A
The infant described in the vignette has features consistent with fetal alcohol spectrum disorders (FASDs). FASDs are characterized by a range of recognizable outcomes in infants exposed to alcohol prenatally, the most severe of which is fetal alcohol syndrome (FAS).
FAS includes the presence of specific facial anomalies, such as short palpebral fissures, thin vermilion border of the upper lip, and smooth philtrum, as well as evidence of pre- or postnatal growth restriction (height or weight <10th percentile) and findings consistent with abnormal brain growth (head circumference <10th percentile) or brain development (structural brain anomalies).
Maternal alcohol exposure need not be confirmed to make a diagnosis of FAS, but other syndromes and conditions that have overlapping features should be ruled out. Other categories of FASD include partial FAS with or without confirmed maternal alcohol exposure, alcohol-related birth defects, and alcohol-related neurodevelopmental disorder. Newborns affected by FAS frequently are irritable and tremulous, and although these symptoms suggest neonatal withdrawal, they can continue for months. Infants also can be unusually hirsute (ethnicity always must be considered when judging hirsutism), and this feature typically dissipates over the first 6 postnatal months. Although there is no well-characterized neonatal alcohol withdrawal syndrome, the physician should be alert to signs of drug withdrawal when FASD is suspected due to the frequent concomitant use of alcohol and drugs.
Despite numerous publications describing deleterious effects of cocaine on the developing embryo and fetus, the impact of prenatal cocaine exposure remains uncertain. It is generally accepted that cocaine use in pregnancy increases the likelihood of placental abruption, and there is an increased incidence of sudden infant death syndrome in exposed infants. There also may be an increased risk for genitourinary and limb anomalies. There is no generally agreedupon "cocaine syndrome." Because cocaine often is used in combination with other drugs, cigarettes, and alcohol, it can be difficult to discern what fetal abnormalities are cocaine-related.
Marijuana use in pregnancy is not known to be associated with an increased risk for birth defects, dysmorphic features, or developmental delay in exposed offspring. Methamphetamines have not been shown to increase the risk for birth defects in exposed infants, although decreased birthweight has been reported in some exposed infants. A neonatal withdrawal syndrome that includes abnormal sleep patterns, tremulousness, poor feeding, and increased tone frequently is described. Concern has been raised for neurodevelopmental problems in later years, but further investigation is needed.
The effects of maternal smoking on pregnancy outcome continue to be an active area of study. Cigarette smoking is associated with an increased risk for miscarriage, reduced fetal weight, and abnormal placentation. There may be an increased risk for facial clefting, but cigarette smoking is not otherwise associated with major congenital anomalies.
4. A 5-year-old girl who is new to your practice presents to the clinic for a prekindergarten physical examination. Her primary caretaker, the maternal grandmother, reports that the child’s mother used multiple street drugs throughout her pregnancy as well as medications prescribed for seizure and bipolar disorders. The grandmother is concerned that this child’s speech development is delayed. On physical examination, you note that the girl has wide-spaced eyes, a short nose, and midface hypoplasia.
Of the following, the substance that is MOST likely to be associated with this child’s dysmorphic features is
B. lysergic acid diethylamide (LSD)
Preferred Response: E
The features described for the child in the vignette are most consistent with fetal anticonvulsant syndrome, which can occur following exposure to numerous medications, including phenytoin, carbamazepine, valproate, and phenobarbital. Multiple authors have observed a 10% to 20% incidence of birth defects in infants exposed to phenobarbital in utero. Anomalies include midface hypoplasia, ocular hypertelorism, nail hypoplasia, cleft lip+/-cleft palate, and heart defects as well as developmental delay and pre- and postnatal growth failure. Phenobarbital-exposed newborns may exhibit a withdrawal syndrome that is evidenced by tremulousness and increased activity. Of interest, such infants are likely to have lower serum bilirubin concentrations than nonexposed neonates.
Prenatal exposure to lithium is associated with an increased risk of cardiac malformations (eg, Ebstein anomaly) in the fetus. If the mother takes lithium near term, the exposed neonate may have cyanosis, hypotonia, abnormalities of cardiac rhythm, goiter, hypothyroidism, and nephrogenic diabetes insipidus. Lithium exposure is not associated with dysmorphic features or developmental delays.
Despite popular belief, lysergic acid diethylamide (LSD) generally is not associated with birth defects or withdrawal symptoms in prenatally exposed infants. Although there are isolated case reports of birth defects in exposed neonates, an increased risk for anomalies is not borne out by epidemiologic studies. It is important to note, however, that LSD users often abuse other substances, underscoring the importance of taking an in-depth drug/substance abuse history in pregnant women.
Marijuana use during pregnancy is not known to be associated with an increased incidence of birth defects, dysmorphic features, or developmental delay in exposed offspring, although further study is needed in this regard. Some investigations have shown reduced fetal growth in exposed pregnancies, but this is not confirmed. Prenatally exposed newborns may have tremulousness, increased irritability, and abnormal visual response to light stimulus.
Although there does not appear to be an increase in congenital anomalies associated with methamphetamine use during pregnancy, further study is necessary. There are reports of decreased birthweight in exposed neonates. A neonatal withdrawal syndrome consisting of abnormal sleep patterns, tremulousness, poor feeding, and increased tone has been observed commonly. Once again, it is important to consider polydrug abuse in these instances.
As with all teratogens, the timing of exposure is critical, with the most vulnerable period of embryonic development occurring between 18 and 60 days after conception, during organogenesis. Dosage of the offending agent also is important, as are route of administration, modifying environmental factors, and genetic background of the mother and fetus.
5. A 28-year-old woman who is positive for human immunodeficiency virus and has a history of intravenous drug use delivers a 2,300-g term infant. She had only two prenatal visits, and she was being treated for Chlamydia infection at the time of delivery. Physical examination of the infant reveals facial edema, erythema and scaling of the palms and soles, clear rhinorrhea, and hepatosplenomegaly.
Of the following, the MOST likely cause of this infant’s signs and symptoms is infection with
A. Candida albicans
B. Chlamydia trachomatis
C. Pneumocystis jiroveci
D. Streptococcus agalactiae
E. Treponema pallidum
Preferred Response: E
The newborn described in the vignette has signs of congenital syphilis due to the organism Treponema pallidum. The risk for maternal syphilis is increased in women who are human immunodeficiency virus (HIV)-positive, and the infection may be transmitted vertically in utero to the fetus at any point in the gestation. It also can be transmitted perinatally at delivery. Early physical signs of congenital syphilis include hydrops fetalis, intrauterine growth restriction, hepatosplenomegaly, hemolytic anemia, jaundice, and a maculopapular rash . Radiographic findings include lines of arrested growth, metaphyseal destruction, and periosteal changes (periosteitis) in the long bones. Finally, sensorineural hearing loss, detectable using automated auditory brainstem response technology, may be present.
Maternal HIV infection is associated with a 2% to 25% vertical transmission risk, depending upon maternal disease stage and highly active antiretroviral therapy, infant gestational age, rupture of membranes, and mode of delivery. However, other than potential growth restriction, HIV infection does not manifest acutely in the immediate neonatal period. Appropriate testing for HIV viral particles and early chemoprophylaxis with zidovudine is important in reducing the risk for HIV disease in infancy.
The use of trimethoprim-sulfamethoxazole as prophylaxis against opportunistic infection with Pneumocystis jiroveci (previously known as Pneumocystis carinii), an important cause of pneumonia in those infected with HIV, is recommended beginning at the postnatal age of 6 weeks. However, other than potential growth restriction, HIV infection does not manifest acutely in the immediate neonatal period and does not produce the cutaneous findings exhibited by the infant in the vignette.
Candida albicans infection may be transmitted to the newborn from the mother’s vagina and presents with a diffuse eruption composed of erythematous papules, pustules, and scaling. In extremely low-birthweight newborns (<1,000 g), it may cause significant systemic morbidity and high mortality.
Maternal Chlamydia trachomatis infection that is partially treated may confer risk to the newborn because vertical transmission of this pathogen may occur in 25% to 60% of pregnancies. However, neonatal chlamydial disease manifests primarily as a respiratory (pneumonia) or ocular (conjunctivitis) problem.
Neonatal infection with Streptococcus agalactiae (group B Streptococcus) is a serious and life-threatening condition that may have an early onset (first week after birth) or late onset (1 to 12 weeks after birth). Early-onset disease typically becomes apparent in the first 48 hours after birth and sometimes at delivery. The major clinical signs are those of septicemia, pneumonia, and meningitis; a rash is not typically present. The most fulminant form presents with the newborn in hemodynamic collapse (shock) and hypoxic respiratory failure.
6. You are called to the delivery room to evaluate a term female infant born by precipitous normal spontaneous vaginal delivery to an 18-year-old young woman who received no prenatal care. The mother reports using marijuana and alcohol early in her pregnancy and was seen in the emergency room on two occasions for urinary tract infections. She had several "colds" late in her pregnancy. She lives with her boyfriend and has two dogs, a cat, and a turtle as pets. Physical examination of the infant reveals a 2-kg lethargic, jaundiced infant who has a weak cry, microcephaly, and a distended abdomen. Her liver is palpable 6 cm below the right costal margin, and her spleen is palpable 4 cm below the left costal margin. She has a diffuse petechial rash with areas of purpura on her extremities (Item Q173). Laboratory tests show a peripheral white blood cell count of 10.6x103/mcL (10.6x109/L), hemoglobin of 12.0 mg/dL (120.0 g/L), and platelet count of 60.0x103/mcL (60.0x109/L). The alanine aminotransferase measurement is 300 U/L, and the aspartate aminotransferase value is 420 U/L. Head ultrasonography shows scattered intracerebral calcifications.
Of the following, the MOST rapid test for making the diagnosis in this infant is
A. blood culture
B. cerebrospinal fluid polymerase chain reaction
C. nasopharyngeal viral culture
E. urine culture
Preferred Response: E
The newborn described in the vignette has signs and symptoms suggestive of congenital cytomegalovirus (CMV) infection. CMV is a ubiquitous DNA virus that may be transmitted vertically from mother to infant in utero by transplacental passage of maternal bloodborne virus, at birth by passage through an infected maternal genital tract, or postnatally by ingestion of CMVpositive human milk. Approximately 1% of all liveborn infants are infected in utero and excrete CMV at birth. The risk for infection is greatest during the first half of gestation. In utero fetal infection can occur after maternal primary infection or after reactivation of infection during pregnancy, but sequelae are much more common in infants exposed to maternal primary infection, with 10% having manifestations evident at birth.
Symptomatic congenital CMV disease is characterized by intrauterine growth restriction; jaundice; hepatosplenomegaly; hepatitis; thrombocytopenia with petechiae and purpura; and severe central nervous system involvement that can be characterized by microcephaly, intracerebral calcifications, chorioretinitis, or sensorineural hearing loss.
Viral culture is the test of choice for confirming the diagnosis of congenital CMV infection. The diagnosis is established by isolation of the virus from urine, stool, cerebrospinal fluid (CSF), or saliva in the first 1 to 2 postnatal weeks. CSF polymerase chain reaction testing can be used to detect CMV DNA, but it is less sensitive than viral isolation by culture and is not used routinely. Routine blood culture and nasopharyngeal viral culture are not helpful for detecting CMV. Standard serologic testing is a cumbersome approach to diagnosing congenital CMV disease; serial samples need to be obtained to make the diagnosis clearly. The presence of CMV immunoglobulin M antibodies at birth is highly suggestive of a congenital CMV infection, but a confirmatory urine culture for CMV is recommended to establish the diagnosis definitively.
7. You are called to the newborn nursery to examine a 4-hour-old term infant delivered to a mother who had polyhydramnios. The infant’s Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. The nurse reports that the infant requires frequent oropharyngeal suctioning and displays cyanosis when suctioned. She placed a pulse oximeter on the infant and reports frequent episodes of desaturation from 94% to 70% on room air during the cyanotic episodes. Physical examination reveals an appropriately grown infant who has substantial oral secretions, scattered rales on auscultation, normal S1 and S2 heart sounds, no heart murmur, normal bowel sounds, and no abdominal distention.
Of the following, the MOST important next step is to:
A. insert a feeding tube
B. insert an umbilical arterial catheter
C. measure bedside blood glucose concentration
D. order emergent echocardiography
E. order renal ultrasonography
Preferred Response: A
The newborn described in the vignette displays the classic clinical signs of a tracheoesophageal fistula (TEF) with accompanying esophageal atresia. Attempting to insert an orogastric (OG) feeding tube is the most important next step in evaluating a newborn in whom this diagnosis is suspected. The inability to insert the OG tube confirms esophageal atresia, which can be verified by seeing the tube coiled in the proximal esophageal pouch on chest
radiography. In the presence of esophageal atresia, TEF is confirmed by radiographic examination of the abdomen revealing air in the lower gastrointestinal tract, which could only reach that locale via a fistula between the upper airway and the esophagus distal to any atretic portion.
The intermittent cyanosis exhibited by the newborn may be due to pooling of oral secretions in the hypopharynx, airway obstruction, aspiration of oral secretions through the larynx into the trachea (because the infant cannot swallow these secretions), pneumonitis, or hypoxia resulting from the reflux of gastric contents via the TEF into the tracheobronchial tree. The maternal history of polyhydramnios is a clue to likely swallowing dysfunction or gastrointestinal tract obstruction.
The physical examination and judicious use of diagnostic imaging tools such as plain films and ultrasonography to assess for the presence of vertebral anomalies, anorectal stenosis or atresia, structural heart disease, renal anomalies, and limb anomalies is important in determining if the esophageal atresia or TEF are isolated defects or part of the VACTERL association, which occurs in one third of infants who have esophageal atresia.
TEF and esophageal atresia is a surgical emergency that requires early evaluation for surgical ligation of the TEF to protect the airway. Until surgery is performed, vigilant oropharyngeal suctioning is required, and the newborn’s head should be kept elevated. Some newborns may require tracheal intubation and assisted ventilation. Early insertion of a gastrostomy tube for gastrointestinal decompression and subsequent feeding until such time as the esophagus can be used also is common. Surgical anastomosis of the proximal and distal esophagus may be accomplished as a later procedure.
Measuring bedside glucose concentration is important in newborns who have respiratory distress but should follow evaluation of airway obstruction in the newborn in the vignette. Echocardiography can help in the evaluation of the newborn for structural heart disease, but the documented normal room air saturation of 94% indicates no fixed cardiac shunt or cyanotic lesion, making this test less imperative at this time. Renal ultrasonography is indicated if
VACTERL association is suspected but requires an initial diagnosis of TEF. An umbilical arterial catheter may or may not be indicated, depending on the degree of respiratory distress.
8. A 4-hour-old newborn who weighs 1,890 g and was born at 39 weeks’ gestation has a serum glucose concentration of 25 mg/dL (1.4 mmol/L), resulting in tremors and jitteriness. The child appears to have intrauterine growth restriction and is small for gestational age (SGA), but is not ill and exhibits no dysmorphisms. You admit the infant to the special care nursery and order an intravenous dextrose 10% in water bolus and infusion and some additional laboratory tests. The complete blood count reveals a hemoglobin of 23 g/dL (230 g/L), hematocrit of 68% (0.68), platelet count of 150x103/mcL (150x109/L), and white blood cell count of 7x103/mcL (7x109/L) with a normal differential count.
Of the following, the MOST likely complication for this infant is
Preferred Response: A
Polycythemia is defined as a hematocrit (Hct) of greater than 65% (0.65) and indicates a relative increase in the red blood cell (RBC) mass over the plasma volume of whole blood. An Hct above 65% (0.65) may be associated with hyperviscosity of the blood. Neonatal polycythemia often is referred to as hyperviscosity syndrome. Increases in blood viscosity reduce the flow of blood through the microcirculation, which may result in hypoglycemia, respiratory distress, jitteriness, hypotonia, and feeding problems. A late phenomenon is hyperbilirubinemia as the increased RBC mass breaks down and hemoglobin degradation results in increased bilirubin load for hepatic glucuronidation and excretion.
The infant described in the vignette has two significant risk factors for polycythemia: growth restriction and low birthweight at a term gestation. In utero growth restriction may result from various causes, but maternal or placental disease states that reduce oxygen delivery to the fetus incite release of fetal erythropoietin and result in an increased RBC mass to ensure oxygen-carrying capacity and delivery to fetal tissues. Growth restriction or polycythemia itself may be associated with neonatal hypoglycemia.
Because many clinical signs of the ill neonate are nonspecific, some signs of hypoglycemia clearly overlap with those of polycythemia and warrant urgent intervention. Hypoglycemia must be treated to preserve central nervous system function. If, in the face of polycythemia, hypoglycemia does not improve with intravenous glucose administration, consideration should be given to conducting a partial exchange transfusion with intravenous normal saline to reduce the RBC mass and facilitate improved circulatory flow in the microcirculation. Partial exchange transfusion also may be appropriate to treat symptomatic polycythemia.
Hypercalcemia and hypokalemia are not associated with polycythemia. Hypertension is uncommon in newborns and not related to polycythemia. Hyponatremia is uncommon in polycythemia.
9. You are called to the operative delivery of a 42-weeks’ gestation male following a pregnancy complicated by oligohydramnios and poor fetal growth. Meconium-stained amniotic fluid was noted upon artificial rupture of membranes. Fetal bradycardia resulted in a decision for cesarean delivery. Resuscitation of the infant requires intubation, tracheal suctioning, assisted ventilation, chest compressions, and intravenous epinephrine. Apgar scores are 1, 3, and 5 at 1, 5, and 10 minutes, respectively. You transfer the newborn to the neonatal intensive care unit, where he appears cyanotic, in respiratory distress, and agitated. Systemic blood pressure is 35/17 mm Hg. On 100% oxygen by assisted ventilation, pulse oximetry in the right upper and left lower extremities reveals saturations of 94% and 80%, respectively. You obtain chest radiography.
Of the following, the MOST likely diagnosis is
A. congenital diaphragmatic hernia
B. congenital pneumonia
C. cyanotic congenital heart disease
D. persistent pulmonary hypertension
E. respiratory distress syndrome
Preferred Response: D
The growth restriction, 42-week gestation, oligohydramnios, and depressed condition requiring vigorous resuscitation at birth reported for the newborn in the vignette strongly indicate fetal compromise due to chronic hypoxemia. Although meconium expression does not always equate with fetal stress and may be a normal finding in many term pregnancies, the risk for meconium aspiration must be acknowledged when fetal stress is accompanied by abnormal fetal heart rate findings (bradycardia) and perinatal depression requiring resuscitation.
Viewing and suctioning the trachea is an essential step in this newborn’s resuscitation. Tracheal suctioning may reveal particulate meconium, meconium-stained mucous secretions, or no meconium. The degree of (any) meconium aspiration cannot be determined by delivery room suctioning alone. Clinical, biochemical, and radiographic evaluation must follow for the newborn who has perinatal depression because of the risk for parenchymal lung injury due to aspiration of blood, amniotic fluid, or meconium (meconium aspiration syndrome); meconium obstruction of the small and large airways; air-leak syndromes (pneumothorax, pneumomediastinum); and pulmonary vascular reactivity. The latter is due to hypoxemia and reactive pulmonary vascular constriction, leading to a condition of pulmonary hypertension.
The difference in pre- and postductal arterial oxygen saturations indicates that the newborn in the vignette has a right-to-left shunt and persistent pulmonary hypertension of the newborn (PPHN). The radiograph in the newborn who has PPHN associated with meconium aspiration syndrome reveals generally hyperinflated lung fields, patchy infiltrates, and varying areas of atelectasis and hyperaeration.
Congenital diaphragmatic hernia is a defect in the embryologic closure of the diaphragm in which abdominal contents occupy the thorax and compress lung development. Congenital pneumonia typically is seen in the presence of prolonged rupture of fetal membranes or chorioamnionitis with subsequent neonatal respiratory distress and a lobar or diffuse consolidation. Pneumonia due to group B streptococci may cause respiratory failure in the term newborn and presents a radiographic picture indistinguishable from respiratory distress syndrome due to surfactant deficiency in the preterm infant, in which there are low lung volumes, diffuse ground-glass densities, and air bronchograms. The radiographic appearance of cyanotic congenital heart disease may show cardiomegaly, pulmonary vascular engorgement, or relative pulmonary oligemia.
10. You receive a telephone call from the mother of one of your patients, who tells you that she is 27 weeks pregnant and that her obstetrician has diagnosed a fetal arrhythmia. In discussion with the obstetrician, you learn that the fetal heart rate is 240 beats/min and that there is a 1:1 relationship between the atrial and ventricular contraction.
Of the following, a TRUE statement about this clinical situation is that
A. atrial fibrillation is the most likely cause of the arrhythmia
B. fetal therapy will require umbilical vessel catheterization to deliver medication to the fetus
C. maternal testing for systemic lupus erythematosus should be undertaken
D. preterm delivery should be planned to begin antiarrhythmia therapy
E. the development of fetal hydrops would suggest fetal congestive heart failure
Preferred Response: E
Fetal arrhythmias are common even in healthy fetuses, but can be the source of much parental and physician anxiety. In fact, irregular heart rhythms are detected in about 1% of fetuses, most of which are due to extra-systoles and generally are of little clinical significance. Sustained fetal arrhythmias can be defined as bradycardic or tachycardic.
The most common arrhythmia leading to fetal bradycardia is complete heart block, which may result from abnormalities of the fetal conduction system (especially the atrioventricular junction) in certain types of heterotaxy syndrome, atrioventricular-ventriculoarterial discordance (formerly referred to as Ltransposition), or exposure to maternal antibodies to SS-A/Ro and SS-B/La antigens. The latter are seen most often in maternal autoimmune disorders such as lupus erythematosus.
The atrial tachycardias, such as supraventricular tachycardia, atrial flutter, and atrial fibrillation, may result in cardiac failure that, in the fetus, often manifests as fetal hydrops. Such a nonimmune hydrops likely results from the myopathy that can occur following incessant tachycardia, can be severe, and can lead to fetal demise. When supraventricular tachycardia, the most common of the atrial tachycardias, occurs in the fetus, it frequently is at a rate of 240 beats/min or higher, and there is a direct one-to-one relationship between the atria and the ventricle in terms of conduction. Atrial fibrillation leads to an inconsistent relationship between the atria and ventricle and is decidedly rare in the fetus.
Fetal antiarrhythmic therapy should be undertaken only with an understanding of the underlying electrophysiology of the arrhythmia, fetal-maternal pharmacology, and the pharmacokinetics of the drugs being administered. All antiarrhythmic drugs can cause significant toxicity to both mother and fetus, so the risks and benefits of fetal treatment must be considered carefully before any treatment is begun. When therapy is required to control a fetal tachycardia, such as supraventricular tachycardia, it often can be accomplished with administration of the antiarrhythmic agent to the mother, which is followed by transplacental transfer to the fetus. This can be advantageous compared with other drug delivery options that involve umbilical catheterization or preterm delivery, both of which carry a risk of morbidity in addition to that associated with the arrhythmia.
The fetal heart rate and atrial-ventricular relationship reported for the infant in the vignette is consistent with supraventricular tachycardia that requires close fetal monitoring and serious consideration of maternal administration of antiarrhythmic medication to control the fetal rate and rhythm and avoid fetal congestive heart failure and hydrops.
11. You are examining a 3.5-kg term infant 48 hours after his birth. Results of the physical examination are normal, and you are considering discharging him from the hospital. He is being fed formula from a bottle, and the nurses report intakes of 30 mL every 3 hours. He has wet at least six diapers daily for the past 2 days, but he has not passed any meconium or expressed any stool since birth.
Of the following, the MOST likely diagnosis is
A. ileal atresia
B. imperforate anus
C. meconium ileus
D. meconium plug syndrome
E. neonatal small left colon syndrome
Preferred Response: D
Ninety-five percent of term infants express meconium or pass a stool in the first 24 hours of postnatal life. The infant described in the vignette is term and appropriately grown and has been feeding and voiding well, but he has failed to pass meconium or any stool in the first 2 days of postnatal life. Although he does not have any abdominal distention, emesis, or systemic illness, the pediatric clinician should be concerned about potential bowel, particularly colonic, obstruction.
The most likely explanation for the symptoms described for the infant in the vignette is meconium plug syndrome, which typically is an isolated phenomenon that is not associated with anatomic obstruction (eg, atresia). It occurs commonly in term and preterm infants and may be associated with maternal magnesium sulfate treatment for pre-eclampsia/eclampsia. Meconium plug obstruction generally is related to hypomotility. Clinically, there may be no abdominal findings or a gradual increase in girth but no other signs of illness. Plain radiographs of the abdomen generally provide nonspecific findings, but may show a paucity of gas in the rectosigmoid. A contrast enema characteristically illuminates the plugs of meconium and facilitates their evacuation. On occasion, a firm, paraffin-like formed plug may be expressed spontaneously by affected infants during the second postnatal day. Although some infants who have retained meconium may exhibit a small left colon on contrast enema, colonic motility usually is normal upon evacuation of the meconium plug(s).
Although meconium plug syndrome is the most common cause of delayed passage of stool, the clinician also should consider Hirschsprung disease, a congenital absence of ganglion cells. A failure to pass meconium in the first 24 hours of postnatal life characterizes 95% of affected infants. The area of affected bowel typically is in the rectosigmoid, where a transition zone may be observed on contrast enema, although this finding is less common in neonates. If Hirschsprung disease is considered, diagnostic rectal biopsy should be performed.
The neonatal small left colon syndrome is seen in infants of diabetic mothers and is diagnosed using a contrast enema. The enema may be both diagnostic and therapeutic, as seen in meconium plug syndrome. Gradual feeding and monitoring of the stooling pattern generally results in resolution of the condition over the early weeks of postnatal life.
Imperforate anus occurs in about 1 in 4,000 to 5,000 births, and typically is apparent on physical examination. In some cases, a fistulous tract may exist, and the expression of meconium may occur anywhere along the perineal-scrotal-urethral line. Imperforate anus may be an isolated finding or seen in conjunction with other anomalies such as vertebral malformations, cardiac malformation, tracheoesophageal fistula/esophageal atresia, renal anomalies, and limb malformation (VACTERL association).
Ileal atresia (proximal or distal) occurs as part of a spectrum of jejunal-ileal bowel atresia that likely reflects a mesenteric vascular defect or interruption in development. Its absolute frequency is not well reported, although it commonly is diagnosed prenatally (dilated bowel, polyhydramnios) on obstetric ultrasonography. With a distal obstruction, the newborn may take early feedings well, but becomes ill, with bile-stained emesis and abdominal distention, in the first 24 to 48 postnatal hours. Plain radiographic findings may include multiple stacked loops of airfilled bowel and air-fluid levels.
Meconium ileus is a condition of intestinal obstruction related to thickened, inspissated mucus mixed with meconium that is characteristic of cystic fibrosis and is related to altered chloride and water balance in mucus. The meconium may be beadlike, in small, dense pellets, and even visible on prenatal obstetric ultrasonography. A microcolon may exist distal to the small bowel obstruction. Affected infants may have visible and palpable loops of bowel on examination, in addition to abdominal distention, bilious emesis, and failure to pass meconium in the first 24 to 48 hours of postnatal life. Plain radiographs may reveal a soap-bubble appearance characteristic of meconium stool. A contrast enema may reveal a microcolon and failure to see contrast reflux past the ileocecal valve.
12. A 30-year-old mother who has a history of opiate addiction, which was managed with methadone throughout her pregnancy, asks when you plan to discharge her term newborn, who weighs 2,450 g.
Of the following, the BEST response is at a postnatal age of
A. 24 hours
B. 36 hours
C. 48 hours
D. 5 days
E. 10 days
Preferred Response: D
Maternal opiate use places the newborn at risk for neonatal opiate withdrawal syndrome, often referred to as neonatal abstinence syndrome (NAS). The syndrome is characterized by signs noted and may not become apparent until 5 days after birth. For methadone treated mothers, a higher daily methadone dose may be associated with a greater likelihood of the newborn experiencing NAS.
The infant described in the vignette is term, but is small for gestational age, weighing only 2,450 g, which is defined as low birthweight (LBW). Early discharge (<48 hours after birth) is not recommended for a LBW infant, and some inquiry should be made into the reason for LBW status.
Maternal use of illicit drugs, alcohol, and tobacco can be associated with poor prenatal care and inadequate maternal and fetal weight gain throughout the pregnancy. Unfortunately, pregnant women receiving methadone may be noncompliant with methadone therapy and continue to use illicit drugs during their pregnancy.
The infant described in the vignette probably can be discharged at 5 days if symptoms of NAS have not appeared. Because NAS may not develop until after 48 hours, discharge at or before 48 hours is not appropriate. Because symptoms of NAS appear by 5 days after birth, delaying discharge of an asymptomatic infant until day 10 is not indicated.
13. A term infant is delivered by emergency cesarean section following the acute onset of maternal vaginal bleeding and profound fetal bradycardia. The Apgar scores are 1, 2, and 3 at 1, 5, and 10 minutes, respectively. Resuscitation includes intubation and assisted ventilation, chest compressions, and intravenous epinephrine. The infant is admitted to the neonatal intensive care unit and has seizures 6 hours after birth.
Of the following, a TRUE statement about other organ-system injury that may occur in the infant is that
A. cardiovascular injury is uncommon
B. hypoxic-ischemic encephalopathy usually is an isolated condition
C. liver injury may result in a coagulopathy
D. most infants who have seizures develop cerebral palsy
E. necrotizing enterocolitis does not occur in term infants
Preferred Response: C
The infant described in the vignette required advanced cardiopulmonary resuscitation following a period of fetal bradycardia. In the face of acute maternal vaginal bleeding, perhaps due to placental abruption, placenta previa, or vasa previa, normal placental function was interrupted and fetal hemodynamics altered. The fetal response to asphyxiation characteristically includes a redistribution of cardiac output toward vital organs (eg, brain, heart, adrenal glands) and away from nonvital organ beds (eg, gut, kidneys, skin, bone marrow). As a result, the clinical
manifestations of intrapartum asphyxia include perturbations of multiple organ systems that result from both ischemia and hypoxia. Intrapartum asphyxia can affect various systems:
· Cardiovascular: systemic hypotension, pulmonary hypertension, dilated cardiomyopathy, or myocardial ischemia
· Pulmonary: respiratory distress, surfactant depletion/disruption with capillary-alveolar leak, hypoxic respiratory failure with pulmonary hypertension, or apnea
· Renal: oliguria, acute tubular necrosis, or renal failure
· Gastrointestinal: impaired gastric motility, gastrointestinal hemorrhage, necrotizing enterocolitis (NEC), ischemic hepatitis, or hepatopathy
· Hematopoietic: anemia, thrombocytopenia, coagulopathy
· Metabolic: acidemia, hypoglycemia, hypocalcemia, hypomagnesemia
· Central nervous system: hypoxic-ischemic encephalopathy (HIE), apnea, irritability, jitteriness, abnormalities in neuromuscular tone, seizure, or coma
Following intrapartum asphyxia, it is very rare for HIE to occur as an isolated condition, without evidence of any of the previously noted organ system injuries. Although seizures may be common in the face of hypocalcemia, hypoglycemia, hypoxia, or severe acidosis (pH <7.0), most infants who have a seizure do not develop cerebral palsy.
The cardiovascular abnormalities noted previously are among the most common of organ system injuries in this setting. Intrapartum asphyxia is one of the few settings in which NEC occurs in term infants. The hepatic synthesis of coagulation proteins that may result from hypoxic-ischemic liver injury contribute to coagulopathy.
14. You receive a telephone call from the physician mother of a 1-week-old patient who was born at 24 weeks' gestation. He is being treated in the neonatal intensive care unit and has been stable on the ventilator. She is concerned because when she visited him this morning, his blood pressure was 44/26 mm Hg. His mean arterial pressure was 30 mm Hg. She is worried that his blood pressure is low and that this may be harmful.
Of the following, the MOST accurate statement regarding blood pressure in the preterm infant is that
A. blood pressure values for preterm infants should be compared with those for term infants
B. blood pressure values vary indirectly with gestational age
C. mean arterial pressure should be no less than the corrected gestational age in weeks
D. patent ductus arteriosus narrows the pulse pressure by raising the diastolic pressure
E. systemic hypertension typically occurs coincidentally with pulmonary hypertension
Preferred Response: C
Preterm birth can be associated with a number of morbidities, including hyper- or hypotension. There are well-described normative values for blood pressure in a healthy term newborn, but normal blood pressure values for the preterm infant are much less clear. In fact, there may be no true correct or expected blood pressure for the preterm infant, particularly the child who is born extremely preterm. Blood pressure increases during the first few days and weeks after birth for each gestational age. Neonatologists generally agree that the mean arterial blood pressure for a preterm infant should not be less than the corrected gestational age in weeks.
Thus, for example, a 26-week-gestation infant should have a mean arterial blood pressure in excess of 26 mm Hg. Beyond this simple rule, a given blood pressure value can be considered adequate if there is no evidence of metabolic acidosis, elevated lactate concentration, or inadequate end-organ perfusion.
Just as infant and child blood pressure norms are not compared with adult norms, the normative blood pressure for a term infant is not used to assess the blood pressure of the preterm infant. As noted previously, blood pressure varies directly, not indirectly, with advancing gestational age.
A patent ductus arteriosus widens the blood pressure by allowing blood to be diverted away from the higher-resistance systemic circulation and toward the lower-resistance pulmonary circulation. As this "steal" becomes greater, the diastolic pressure decreases and the pulse pressure (difference between the systolic and diastolic pressure) increases. Finally, systemic hypertension usually does not occur with pulmonary hypertension. In fact, it is not uncommon to note systemic hypotension with pronounced pulmonary hypertension as the failing right ventricle leads to a decrease in cardiac output.
15. An obstetrician calls to tell you she is caring for a woman who is 36 weeks pregnant and has required treatment with propylthiouracil during pregnancy for Graves disease. The mother is worried about the risk of neonatal thyrotoxicosis in the infant and wishes advice.
Of the following, a TRUE statement about infants born to mothers who have Graves disease is that
A. approximately 50% of infants have elevated concentrations of thyroid hormones, but only 20% require treatment
B. approximately 50% of infants have symptomatic thyrotoxicosis
C. concentrations of maternal thyroid-stimulating immunoglobulins do not correlate with fetal outcome
D. fewer than 10% of infants have symptomatic thyrotoxicosis
E. infants whose mother’s disease is controlled adequately during pregnancy have a decreased risk of thyrotoxicosis
Preferred Response: D
Transplacental passage of maternal thyroid-stimulating immunoglobulins causes neonatal thyrotoxicosis, a condition that persists as long as sufficient stimulatory immunoglobulin remains in the blood, often for several months. Although up to 17% of infants of mothers who have thyrotoxicosis have laboratory evidence of high thyroid hormone concentrations, 10% or fewer are symptomatic. Symptoms in utero can include increased heart rate and a high output state.
After birth, tachycardia, feeding problems, failure to gain weight, jitteriness, thyrotoxic stare, and persistent jaundice may be seen in severe cases. In general, maternal thyroid-stimulating antibody values correlate with the risk and severity of thyrotoxicosis. However, control of maternal thyrotoxicosis during pregnancy does not reduce the risk of neonatal thyrotoxicosis unless it is associated with decreases in thyroid-stimulating immunoglobulins.
Neonatal thyrotoxicosis has been reported in infants born to women treated with ablative therapy for thyrotoxicosis years before the birth. It is important to remember that because of chronic suppression of thyroid-stimulating hormone in utero and after delivery, infants recovering from neonatal thyrotoxicosis may have prolonged and dangerous secondary hypothyroidism at a few months of age. Therefore, free thyroxine and thyroid-stimulating hormone (TSH) concentrations should be assessed every 3 to 4 weeks after recovery from thyrotoxicosis until TSH values rise to the normal range and free thyroxine values are persistently normal. Occasionally, treatment with thyroxine is necessary for some months if infants develop hypothyroidism.
16. You are called to the newborn nursery to see a 2.1-kg term infant whose bedside glucose screening test value is 30 mg/dL (1.7 mmol/L). The nurse describes the baby as being generally lethargic, jittery with stimulation, and intolerant of oral feeding attempts at 4 hours of age (poor oral suckling and emesis of the small volumes of formula taken). He was born at 41 weeks’ gestation to a mother who had poor weight gain, smoked cigarettes, and had hypertension. The Apgar scores following a vaginal delivery were 6 and 8 at 1 and 5 minutes, respectively. There is
no history of maternal diabetes, illicit drug use, or intrapartum difficulties. On physical examination, the baby’s vital signs are normal except for tachypnea (respiratory rate of 80 breaths/min), with pulse oximetry of 90% on room air. The infant has plethora, acrocyanosis, and generalized low tone. He exhibits rapid, shallow tachypnea, with clear lungs bilaterally on auscultation. There is a soft I/VI systolic murmur along the lower left sternal border and no gallop. Upon stimulation, he has jittery hand movements. Laboratory findings include:
· Serum glucose, 45.0 mg/dL (2.5 mmol/L)
· White blood cell count, 7.0x103/mcL (7.0x109/L) with a normal differential count
· Platelet count, 150.0x103/mcL (150.0x109/L)
· Hematocrit, 70% (0.70)
An arterial blood gas reveals a pH of 7.40, Pao2 of 75 mm Hg, Paco2 of 30 mm Hg, and base excess of -7 mEq/L.
Of the following, the MOST appropriate treatment for this infant’s underlying problem is
A. administration of amphotericin B
B. double-volume exchange transfusion
C. intubation and assisted ventilation
D. partial exchange transfusion
Preferred Response: D
By definition, polycythemia exists when the hematocrit (HCT) is greater than 65% (0.65). This condition occurs in newborns who are small for gestational age, infants of diabetic mothers, the recipient twin in a twin-twin transfusion syndrome-affected pregnancy, or infants who have delayed clamping of the umbilical cord after delivery. The decision to treat polycythemia is contingent upon the presence of symptoms associated with the state of hyperviscosity of the circulating blood conferred upon it by the increased HCT or an HCT of greater than 70%.
Such symptoms include those described for the infant in the vignette. Although blood hyperviscosity also may occur due to markedly elevated white blood cell numbers (generally, >100.0x103/mcL [100.0x109/L]) or with elevations of certain plasma protein fractions, in the newborn, it is almost exclusively related to an increase in the red blood cell mass, as reflected in the HCT.
The treatment of choice for symptomatic polycythemia, as seen in this infant, is a partial exchange transfusion, which reduces the red blood cell mass and maintains a euvolemic state by the administration of crystalloid (eg, normal saline). The partial exchange transfusion is partial in that it removes only a portion of the circulating volume of blood (as opposed to a complete or double-volume exchange transfusion) and replaces (exchanges) it with crystalloid.
The volume of such an exchange is based on the following formula:
Volume of exchange (mL) = [Infant's blood volume] x [Observed HCT-Desired HCT]/Observed HCT
The blood volume of an infant who has polycythemia is 100 mL/kg.
For a 3-kg infant who has an observed HCT of 70% (0.70), the volume of exchange is:
= [3 kg x 100 mL/kg] x [0.70-0.55]/0.70
= 300 mL x 0.15/0.70
= 300 mL x 0.214
= 64 mL
Polycythemia cannot be treated solely with intravenous crystalloid because this fluid leaves the circulatory compartment easily. Because the patient does not have evidence of systemic fungal infection, amphotericin B is not indicated and would not treat polycythemia. The infant in the vignette does not have hypoxemia or hypercarbia that warrants intubation and assisted ventilation. Phototherapy does not treat polycythemia, only the hyperbilirubinemia that follows. A double-volume exchange transfusion is used to treat severe hyperbilirubinemia.48>10th>10th>