Board study Flashcards

Question

A 10-month-old female infant is brought for a health supervision visit. She was last seen 4 months ago. She has been well since that visit, with no significant illness. She has been feeding well, taking 4 to 5 ounces of formula 4 to 5 times/day plus pureed foods and yogurt. At birth, her weight was at the 30th to 40th percentile; at her previous health supervision visit, her weight was at the 15th to 20th percentile. She says “mama” and “dada,” and is able to pull up to stand but does not crawl. She is followed by cardiology for a heart murmur. The girl’s temperature is 36.5°C, heart rate is 100 beats/min, respiratory rate is 28 breaths/min, blood pressure is 96/45 mm Hg, and oxygen saturation is 100% in room air. Her weight is 7.3 kg (8th percentile) and length is 65 cm (<3rd percentile). She appears pale and is in no apparent distress. There is a 3/6 systolic ejection murmur, lungs are clear to auscultation bilaterally, and her abdomen is soft and nontender with no hepatosplenomegaly. There are no focal neurologic deficits. The remainder of her physical examination findings are normal. Laboratory data are shown: Laboratory Test Result White blood cell count 7,400/µL (7.4 × 109/L) Hemoglobin 3.2 g/dL (32 g/L) Platelet count 314 × 103/µL (314 × 109/L) Mean corpuscular volume 115 fL Neutrophils 22% Lymphocytes 71% Monocytes 7% Reticulocyte 0.8% Absolute reticulocyte count 6 × 103/µL Hemoglobin A 81.6% Hemoglobin A2 2.4% Hemoglobin F 16% Adenosine deaminase 1.98 (reference range, 0.33-0.95 U/g of hemoglobin) Of the following, the MOST appropriate treatment for this girl’s condition is A. erythropoietin administration B. long-term transfusion therapy C. no intervention with continued observation D. single transfusion with continued observation

Answer 1

The girl in the vignette has a history and laboratory findings that are consistent with a pure red blood cell aplasia, most likely Diamond-Blackfan anemia (DBA). This diagnosis is supported by severe macrocytic anemia without reticulocytosis, elevated fetal hemoglobin level, and elevated erythrocyte adenosine deaminase (eADA) level. Her cardiac murmur may be evidence of a congenital heart defect (CHD); there is an increased prevalence of congenital anomalies (eg, cardiac, genitourinary, thumb) in children with DBA. Genetic testing may reveal a mutation in a ribosomal protein, however, not all mutations have been identified. The treatment for DBA is long-term blood transfusion therapy, which is required to support the child’s growth. Leucodepleted red blood cells should be administered to avoid febrile reactions, cytomegalovirus transmission, and human leukocyte antigen (HLA) alloimmunization. It is important to obtain a blood sample for hemoglobin electrophoresis and eADA testing before administering a blood transfusion, as those tests must be performed on the child’s native blood cells and would otherwise not be accurate until 3 months after a blood transfusion. PREP Pearls Diamond-Blackfan anemia is a rare form of pure red blood cell aplasia with severe macrocytic anemia without reticulocytosis, elevated fetal hemoglobin level, and elevated erythrocyte adenosine deaminase level. There is an increased prevalence of congenital anomalies (eg, cardiac, genitourinary, thumb) in children with Diamond-Blackfan anemia. Transient erythroblastopenia of childhood is a form of pure red blood cell aplasia that most often occurs in very young children (typically >1 year of age) after a viral infection. The condition spontaneously resolves within a few weeks.

Answer 2

The adolescent in the vignette has a low positive antinuclear antibody (ANA) titer most likely due to his recent Epstein-Barr virus infection. Low ANA titers (<1:320) are usually not indicative of an autoimmune process, so he should not be referred to a rheumatologist at this time and should not have an ANA profile evaluation performed, unless he exhibits other specific signs of rheumatologic disease. He also does not need to receive corticosteroids for mononucleosis because his symptoms have significantly improved. PREP Pearls Up to one-third of healthy children may have a positive antinuclear antibody titer result. Low antinuclear antibody titers (<1:320) are usually not indicative of an autoimmune process and may be due to viral illnesses, such as mononucleosis or parvovirus.

Answer 3

The girl in the vignette has ingested an unknown amount of mouthwash, which contains ethanol (ethyl alcohol). In addition to beer, wine, and liquor, ethanol is found in a wide variety of household items including hand sanitizer, liquid cough and cold medications, cooking extracts (eg, vanilla), mouthwash, and perfumes/colognes. Because ethanol inhibits hepatic gluconeogenesis, children (especially young children) who ingest ethanol can become profoundly hypoglycemic. Therefore, the best next management step for the girl in the vignette is to obtain a bedside blood glucose level.

Answer 4

Of the response choices, the best next management step after delivery of this neonate will most likely be endotracheal intubation to provide positive-pressure ventilation. The fetal ultrasonography findings are consistent with renal agenesis. Neonates born with bilateral renal agenesis have significant pulmonary hypoplasia resulting from severe oligohydramnios. Fetal urine contributes significantly to the amniotic fluid volume that is needed for fetal lung development. Immediate resuscitative efforts include positive-pressure ventilation through an endotracheal tube. PREP Pearls Fetal urine contributes significantly to amniotic fluid volume. Amniotic fluid is necessary for fetal lung development. Fetal renal agenesis results in severe oligohydramnios which leads to pulmonary hypoplasia.

Answer 5

The adolescent in the vignette had a biphasic asthma response to allergen exposure, with early bronchospasm amenable to bronchodilator treatment followed hours later by a more intense airway inflammatory reaction responsive only to corticosteroids. This biphasic response is characteristic of IgE-mediated allergic asthma. The best next management step for this adolescent is daily and as-needed use of a combined budesonide/formoterol inhaler. A combined inhaled corticosteroid/long-acting β-agonist (ICS/LABA) inhaler used daily and additionally before allergen exposure prevents both early and late responses in those with IgE-mediated allergic asthma. Formoterol is an LABA appropriate for use in asthma management only when combined with an ICS. It is the only LABA with a short enough onset of action to provide acute relief, making it appropriate for as-needed administration (unlike salmeterol). Under the Same Maintenance And Rescue Therapy (SMART) paradigm from the 2020 National Asthma Education and Prevention Program guidelines, the combination of an ICS with formoterol as the LABA is appropriate for both daily maintenance and as-needed treatment. PREP Pearls IgE-mediated allergic asthma is characterized by a biphasic response including early bronchospasm and delayed airway inflammation. The early response in IgE-mediated allergic asthma is amenable to prevention and treatment with bronchodilators, but corticosteroids are the most effective therapy for both prevention and treatment of the delayed inflammatory response. Injectable anti-IgE monoclonal antibodies (eg, omalizumab) can prevent both the early and late phases of allergic asthma by binding circulating IgE and preventing its binding to allergens on mast cells.

Answer 6

It is common for adolescents to have irregular menstrual cycles, especially in the first 2 years after menarche. This phenomenon is due to immaturity of the hypothalamic-pituitary axis, which leads to anovulatory cycles. The interval between menstrual cycles can range from 21 to 45 days; 5% to 10% of girls have intervals shorter than 20 days or longer than 60 days. Prolonged intervals are most commonly seen between the first and second cycle. Bleeding normally occurs for 3 to 7 days. After the initial 2 years, most adolescents begin to have more regular cycles with intervals of 21 to 34 days, typical of adult women.

Answer 7

The boy in the vignette, with known attention-deficit/hyperactivity disorder (ADHD), is exhibiting signs of a learning disability. When he advanced to a higher grade in school, he began to have significant academic difficulty (poor grades, frustration with school, and prolonged time to complete homework despite behaviorally effective treatment with a stimulant medication). Common comorbidities in children with ADHD include learning disabilities, anxiety, depression, and oppositional defiant disorder. To assess the boy for a learning disability, an evaluation that includes both cognitive function and academic achievement should be performed.

Answer 8

The infant in the vignette has prolonged fevers, cytopenia, evidence of inflammation, elevated transaminases, and elevated soluble interleukin 2 (IL-2) receptor levels. This clinical presentation is consistent with hemophagocytic lymphohistiocytosis (HLH). Although seen in all age groups, the highest incidence is in infants younger than 3 months. This condition can be familial or acquired. The most common infectious trigger of acquired HLH is Epstein-Barr virus (EBV), and the most common physical examination finding is splenomegaly (89% of cases).

Answer 9

The boy in the vignette has an intellectual disability. He has a history of developmental delays from a young age, and these impairments have persisted in all areas, including cognitive and adaptive functioning, thus supporting the diagnosis made with the formal school evaluation. The other response choices are not specifically associated with intellectual disability. When a child has school performance concerns, information should be obtained regarding attainment of developmental milestones, social history, birth history, past medical history, and family history (family members with similar difficulties or concerns). For the boy in the vignette, it is unclear from the history provided if his uncle had a reading disability or intellectual disability.

Answer 10

The best next management step for the neonate in the vignette, who has tachypnea, desaturation, and poor feeding, is to initiate treatment with prostaglandin. His physical examination findings are significant for tachycardia, tachypnea, clear lungs, a single second heart sound, and a holosystolic murmur. His chest radiograph demonstrates a right aortic arch and a boot-shaped heart. These findings are concerning for congenital heart disease with insufficient pulmonary blood flow. Prostaglandin needs to be initiated urgently to open the closing ductus arteriosus to increase pulmonary blood flow and increase the oxygen saturation. Echocardiography and electrocardiography will be required to understand the details of his cardiac diagnosis, but they can be performed after the prostaglandin infusion is started. There is no indication for intubation of this child at this time. PREP Pearls Congenital cyanotic heart disease occurs when there is insufficient pulmonary blood flow, intracardiac mixing, or transposition physiology. Prostaglandin infusion maintains patency of the ductus arteriosus. Higher doses are needed when the ductus has closed. The side effects of prostaglandin infusion include apnea, fever, tachycardia, vasodilation, and hypotension.

Answer 11

The adolescent in the vignette has acute transverse myelitis, a disorder of the spinal cord characterized by acute onset of motor, sensory, and sphincter deficits with a range of underlying etiologies. Urinary retention is a common complication, which increases the risk of urinary tract infection. Therefore, of the response choices, the best additional supportive measures in this adolescent’s acute management are bladder ultrasonography and intermittent catheterization. PREP Pearls Acute transverse myelitis is a disorder of the spinal cord characterized by acute onset of motor, sensory, and sphincter deficits with a range of underlying etiologies, most commonly inflammatory or autoimmune. Radicular or back pain may precede the acute onset of neurologic symptoms. Urgent evaluation of suspected transverse myelitis should include spine magnetic resonance imaging (MRI) to exclude cord compression. Most commonly, imaging shows centrally located hyperintensity spanning multiple contiguous vertebral levels; up to 50% have normal findings on MRI. In addition to disease-specific treatment of transverse myelitis with high-dose intravenous corticosteroids or plasma-exchange, supportive management includes bowel and bladder care, deep vein thrombosis prophylaxis, decubitus ulcer prevention, and treatment of autonomic instability.

Answer 12

The most likely diagnosis for the girl in the vignette is a sprain of the anterior talofibular ligament (ATFL). Item C39A illustrates the position of the ATFL, calcaneofibular ligament (CFL) and posterior talofibular ligament (PTFL) on the lateral aspect of the ankle. She had an ankle inversion injury and has tenderness over the anterior aspect of the distal lateral malleolus, where the ligament inserts, and over the ligament itself. Following an ankle sprain, recovery is faster with early mobilization of the ankle. A stirrup style ankle brace (Item C39B) permits dorsiflexion and plantarflexion at the ankle, which allows for a more normal gait, while limiting eversion and inversion. Use of crutches with limited weight-bearing is rarely indicated. Physicians should encourage early mobilization with the use of a less restrictive brace when injured athletes can tolerate it. PREP Pearls Early mobilization after an ankle sprain leads to a faster recovery. The Ottawa ankle rules for obtaining radiographs after an ankle injury have been validated in children.

Answer 13

The infant in the vignette is exhibiting developmental milestones most consistent with a 6-month-old. He responds to his mother, babbles, sits without support, and brings an object to his mouth. PREP Pearls By 6 months of age, infants should be able to sit independently or with their own hands for support. By 6 months of age, infants should babble with vowel sounds and begin to add consonant sounds. By 6 months of age, infants should be able to cross midline to reach for objects.

Answer 14

The child in the vignette had a sore throat 4 weeks before presentation with macroscopic hematuria (tea-colored urine without blood clots), hypertension, and edema. Urinalysis with microscopy shows hematuria and proteinuria favoring a diagnosis of acute poststreptococcal glomerulonephritis (PSGN). PREP Pearls Brown, tea, or cola-colored urine without blood clots favors a glomerular etiology of macroscopic hematuria. Bright red, red, or pink urine with blood clots is suggestive of hematuria originating from the urinary collecting system. A urine that is dipstick test–positive for blood without red blood cells on urine microscopy indicates myoglobinuria (eg, rhabdomyolysis) or hemoglobinuria (eg, intravascular hemolysis). ABP Content Specifications(s) Formulate a differential diagnosis of gross hematuria Plan the appropriate clinical evaluation of gross hematuria Recognize the disorders associated with hematuria

Answer 15

The neonate in the vignette has galactosemia as evidenced by hypoglycemia, hyperbilirubinemia, elevated liver enzymes, and the presence of reducing substances in the urine. The diagnosis of classic galactosemia is made through newborn screening or after the onset of clinical signs and symptoms consistent with the condition. In an untreated neonate, classic galactosemia presents with a life-threatening illness that can involve the liver, brain, and kidney. Neonates are normal at birth; symptoms develop after ingestion of breast milk or standard formula, which leads to accumulation of galactose and its by-products (galactose-1-phosphate, galactitol, and galactonate) in the body. Urea cycle defects present in the neonatal period with hyperammonemia and respiratory alkalosis. Common urea cycle defects include ornithine transcarbamylase deficiency, citrullinemia, and argininosuccinic aciduria.

Answer 16

The infant in the vignette has a clinical presentation that is consistent with a diagnosis of hypertrophic pyloric stenosis (HPS). On abdominal examination of an infant with pyloric stenosis, an “olive-sized” epigastric mass is palpable in 60% to 80% of cases, and peristaltic waves may be visible. PREP Pearls Abdominal examination of an infant with hypertrophic pyloric stenosis may demonstrate a palpable epigastric “olive” or visible peristaltic waves. Hypertrophic pyloric stenosis causes a hypochloremic metabolic alkalosis. Abdominal ultrasonography is the imaging study of choice to diagnose hypertrophic pyloric stenosis. ABP Content Specifications(s) Recognize the acid-base changes associated with pyloric stenosis, and manage appropriately Recognize the clinical features associated with pyloric stenosis, and manage appropriately

Answer 17

The neonate in the vignette has findings consistent with chlamydial conjunctivitis. Neonatal chlamydial infection is acquired during passage through the infected birth canal. Early in the course, chlamydial conjunctivitis can be watery, and later it becomes mucopurulent. There may be swelling of the eyelids and chemosis (swelling and redness of conjunctiva). Eye prophylaxis with erythromycin ointment given at birth is not effective in preventing chlamydial infection. Oral azithromycin or oral erythromycin is the treatment of choice for both chlamydial conjunctivitis and pneumonia in neonates. A single dose of intramuscular ceftriaxone, 50 mg/kg, is recommended for treatment of gonococcal ophthalmia, but is not effective for treatment of a chlamydial infection. Although increased tearing and matting of the eyelashes is commonly seen with nasolacrimal duct obstruction, conjunctival erythema, edema, and swelling are not common. The presence of eyelid swelling and chemosis should prompt further investigation and consideration of treatment for neonatal conjunctivitis. PREP Pearls Chlamydia, an obligate intracellular bacterium, causes the most common sexually transmitted notifiable infection in the United States. Neonates exposed to Chlamydia through an infected birth canal develop conjunctivitis typically 5 to 14 days after birth; chlamydial pneumonia occurs between 3 and 12 weeks of age. The recommended treatment for any form of neonatal chlamydial infection is oral azithromycin or erythromycin

Answer 18

The infant in the vignette is displaying altered mental status, for which the initial management is the ABCs (Airway, Breathing, Circulation) of resuscitation. Assessment and stabilization of the airway is the first step, followed by stabilization of breathing and circulation. The infant in the vignette is cyanotic with poor respiratory effort and a respiratory rate of 8 breaths/min; thus, bag-valve mask ventilation and preparing for intubation is the best next management step. Although obtaining a point-of-care glucose level and administration of intravenous fluids and broad-spectrum antibiotics will be important steps in the infant’s care, addressing the airway and breathing concerns must take priority. PREP Pearls The initial management of altered mental status is the ABCs (Airway, Breathing, Circulation) of resuscitation. The signs and symptoms of altered mental status in a child can range from subtle to overt and vary depending upon the age of presentation. The mnemonic AEIOU TIPS is helpful for remembering the broad differential diagnosis for causes of altered mental status.

Answer 19

The neonate in the vignette has an abnormal newborn screening test with a low thyroxine (T4) and normal thyroid-stimulating hormone (TSH) level. Based on the neonate’s physical examination findings, the next best step in management is to obtain confirmatory serum TSH and free thyroxine (FT4) levels. The most likely diagnosis for this healthy male neonate is congenital thyroxine-binding globulin (TBG) deficiency, a benign X-linked condition. Confirmatory testing would demonstrate normal TSH and FT4 levels. Neonates who have newborn screening performed too soon after birth may have elevated TSH levels, given the expected surge of thyroid hormones that occurs after delivery. In such a case, repeating the newborn screening test may be recommended. However, this would not be true for the neonate in the vignette, as his pattern of thyroid function results is not consistent with the newborn screening test being drawn too soon after birth. PREP Pearls Neonates with an abnormal thyroid newborn screening test result should be evaluated promptly with a physical examination and confirmatory serum thyroid-stimulating hormone and free thyroxine testing. A newborn screening test result showing a low thyroxine and normal thyroid-stimulating hormone level is consistent with thyroxine-binding globulin (TBG) deficiency or, less frequently, central hypothyroidism. The confirmatory serum free thyroxine level distinguishes these conditions (normal in TBG deficiency and low in central hypothyroidism). Thyroxine-binding globulin deficiency is a benign, X-linked condition that does not require treatment.

Answer 20

The clinical scenario described in the vignette is suggestive of a placental abruption with fetal blood loss. The neonate in the vignette is most likely to require a blood transfusion of uncrossmatched O-negative blood. PREP Pearls Most neonates transition to the extrauterine environment without difficulty. Five percent require some form of resuscitation. Anticipation and planning are key components of neonatal resuscitation. Ventilation is the most important step in neonatal resuscitation.

Answer 21

The boy in the vignette had onset of watery diarrhea 3 days after exposure to treated (ie, chlorinated, filtrated) recreational water. This presentation is most suggestive of Cryptosporidium parvum gastroenteritis. The incubation period of cryptosporidiosis ranges from 3 to 14 days. Recreational water-associated outbreaks can be caused by a variety of pathogens including Escherichia coli O157:H7, Shigella, norovirus, and Giardia. Sporadic outbreaks of norovirus gastroenteritis are common. However, the incubation period of norovirus infection is short (12 to 24 hours) and characterized by sudden onset of vomiting followed by watery diarrhea. PREP Pearls Cryptosporidium is a leading cause of diarrheal outbreaks associated with exposure to chlorinated recreational water (eg, swimming pools, waterslides). Fecal-oral transmission of Cryptosporidium infection occurs via ingestion of oocysts excreted by infected hosts. Manifestations of cryptosporidiosis include non-bloody, watery diarrhea with abdominal pain, nausea, vomiting, low-grade fever, anorexia, and weight loss; asymptomatic gastrointestinal infection can occur resulting in failure to thrive.

Answer 22

The infant in the vignette with fever, tachypnea, increased work of breathing, and focal crackles on physical examination most likely has community-acquired pneumonia (CAP). Although most CAP in children is caused by viruses, this infant’s focal findings and worsening symptoms make a bacterial etiology more likely. Based on the 2011 Infectious Diseases Society of America (IDSA) guidelines for management of CAP, administration of antibiotics is the best next intervention for this infant with likely bacterial pneumonia. The infant in the vignette appears ill and meets the IDSA guideline criteria for respiratory distress (Item C52A). Admission to the hospital should be considered, and chest radiography would be appropriate; however chest computed tomography is not indicated as a first-line imaging study. Although the infant is in mild distress, he has normal oxygen saturation and does not show signs of imminent respiratory failure; therefore, there is no indication for intubation and mechanical ventilation. However, given his level of distress and the concern for bacterial pneumonia, he does need intervention beyond observation and reevaluation. An important consideration regarding his need for hospital admission is his risk for dehydration, as his mother reports poor oral intake. PREP Pearls Normal respiratory rate varies widely across ages; infants show greater variability than older children. Respiratory rate is a sensitive indicator of illness; abnormal sleeping respiratory rate is the best measure of true dysfunction. Any child with unexplained tachypnea or hypopnea should undergo careful evaluation for underlying illness.

Answer 23

The infant in the vignette, with chronic lung disease related to prematurity, has signs of mild dehydration (mildly sunken anterior fontanelle), and electrolyte abnormalities including hyponatremia, hypokalemia, hypochloremia, and an elevated bicarbonate level. These findings are consistent with a contraction metabolic alkalosis induced by chronic diuretic therapy. Thus, of the response choices, furosemide (used to control excess fluid in the lungs) is the most likely medication to have contributed to this infant’s condition. Furosemide is a loop diuretic that inhibits reabsorption of sodium and chloride in the ascending loop of Henle and the proximal and distal renal tubules by interfering with the chloride-binding co-transport system. Both natriuresis (sodium loss) and diuresis (water loss) result. Diuresis decreases extracellular fluid volume and concentrates extracellular serum bicarbonate, contributing to metabolic alkalosis. Historically, this process was known as “contraction alkalosis,” and the primary mechanism was thought to be due to decreased fluid volume and the resulting concentration of serum bicarbonate. However, newer studies have demonstrated that chloride plays a major role in the development of metabolic alkalosis, and some have suggested that “chloride depletion alkalosis” replace the term “contraction alkalosis” to more accurately reflect the underlying mechanism. PREP Pearls Metabolic alkalosis is often caused by hypochloremia. Infants and children on chronic diuretic therapy with loop diuretics (eg, furosemide) are at risk for developing a chloride depletion alkalosis. Bartter syndrome can cause hypokalemic, hypochloremic, metabolic alkalosis; this diagnosis should be suspected in infants with hyponatremia, hypokalemia, failure to thrive, and dehydration.

Answer 24

Perinatal hepatitis B transmission occurs at the time of labor and delivery. The risk of transmission to the newborn is determined based on the presence of maternal hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg). The presence of HBsAg implies either an acute (<6 months) or chronic (≥6 months) infection in the mother. The presence of HBeAg indicates a high level of transmissibility. For a mother positive for both HBsAg and HBeAg, the risk of perinatal transmission is as high as 90%. For a mother that is only HBsAg positive, the risk is around 30%. Other risk factors associated with high transmissibility include a high viral DNA level >2,000 IU/mL, age <25 and <3 doses of maternal hepatitis B vaccine. Detection of hepatitis B surface antibody (>10 mIU/ML) indicates disease immunity, either from immunization or natural infection. Detection of hepatitis B e antibody along with hepatitis B surface antibody indicates past infection.

Answer 25

The girl in the vignette has evidence of increased intestinal fat losses (steatorrhea and fat-soluble vitamin D deficiency), resulting from fat maldigestion and/or fat malabsorption. Of the response choices, a gluten-free diet is the only treatment for a fat malabsorption disorder. On the basis of the girl’s laboratory and physical examination findings, a diagnosis of celiac disease was suspected. Further testing revealed an elevated tissue transglutaminase IgA antibody level, and findings on endoscopy with biopsy confirmed the diagnosis. A gluten-free diet is the treatment for celiac disease. Albumin infusions are used to treat symptomatic hypoalbuminemia caused by severe protein-losing enteropathy. The albumin level of the girl in the vignette is within the reference range, and an albumin infusion would not address her fat malabsorption and steatorrhea. Lactase enzyme replacement therapy can be used to treat diarrhea that results from malabsorption of lactose, and a low-sugar diet may resolve diarrhea caused by malabsorption of sucrose, but neither treatment would decrease this girl’s fat malabsorption and steatorrhea. PREP Pearls Steatorrhea (Increased fecal fat) occurs when ingested fat is maldigested and/or malabsorbed. Complications of fat maldigestion or malabsorption include diarrhea, abdominal pain, diaper dermatitis in infants and diapered children, weight loss or poor weight gain, and fat-soluble vitamin deficiencies. Treatment of steatorrhea includes identifying and managing the underlying cause while supporting nutrition and growth through adequate caloric intake and fat-soluble vitamin supplementation.

Answer 26

The boy in the vignette has injuries consistent with non-accidental trauma (NAT) or physical abuse (unexplained femur fracture, multiple healed rib fractures). Having trisomy 21 is his most significant risk factor for experiencing physical abuse. Children with developmental disabilities and chronic medical conditions are at increased risk for abuse. One study (Paul) found that children with disabilities are nearly 3 times more likely to be physically abused than children without a disability. Children with mild cognitive disabilities and without motor disabilities were found to be at the highest risk.

Answer 27

The infant in the vignette has an isolated gross motor delay in the setting of predominantly axial hypotonia with preserved reflexes and strength. These examination findings are suggestive of a central etiology for his hypotonia. Magnetic resonance imaging (MRI) of the brain would be an appropriate next step in his diagnostic evaluation to evaluate for cerebral malformations or neuroimaging markers of specific genetic and/or metabolic disorders. The other response choices would be more appropriate when testing for an infant with findings suggestive of hypotonia secondary to a peripheral etiology. In this age group, however, central etiologies are more common than peripheral. The initial diagnostic testing for infants with hypotonia suspected to have a peripheral etiology is focused on time-sensitive and treatable conditions. Evaluation usually includes a serum creatinine kinase (CK) level, SMN1 gene deletion testing, and thyroid studies to evaluate for an underlying myopathy, spinal muscular atrophy, or thyroid disease. If the results of initial laboratory testing are negative, electromyography and nerve conduction studies should be performed for more precise localization within the peripheral nervous system prior to proceeding to targeted disease tests or muscle biopsy. PREP Pearls The signs and symptoms accompanying hypotonia provide important clues for accurate localization, which can encompass any part of the nervous system. In infants, central etiologies of hypotonia are more common than peripheral. Tone, the resistance of the muscle to passive range of motion/stretch, is distinct from strength, the amount of force a muscle group can generate. The presence or absence of weakness can be a helpful localization indicator.

Answer 28

The boy in the vignette had an apparent seizure while exercising. Myoclonic activity associated with an arrhythmia can be mistaken for seizure activity. Seizures can also be associated with dysrhythmia events and can be the initial presenting sign of an underlying channelopathy, such as long QT syndrome. The boy had a sibling who died of sudden infant death syndrome, which can also be the sentinel event for a child with a congenital arrhythmia syndrome. The boy’s personal and family history are very concerning for a genetic heart condition, and he should be evaluated by cardiology prior to clearing him for sports participation. PREP Pearls A history of unexplained seizure activity could signify arrhythmogenic heart disease. A child or adolescent with a well-controlled seizure disorder should be cleared for participation in most sports without qualification.

Answer 29

The infant in the vignette has a large ventricular septal defect with increased pulmonary blood flow, leading to pulmonary edema and tachypnea. Her symptoms are managed with high-dose diuretics to decrease the pulmonary edema. Ultimately, she needs to undergo surgical repair of this lesion. Until then, the pediatrician and pediatric cardiologist can improve her surgical candidacy by maintaining appropriate weight gain. Fortifying the expressed breast milk is the best option to limit fluid intake while maximizing calories. Neither adding an electrolyte solution for hydration nor limiting feeding time to minimize energy use will provide the needed additional calories. Changing the infant’s diet to a 30-kcal/oz formula may result in diarrhea and excessive stool losses. PREP Pearls Children with heart disease have increased caloric needs and often require limitation of fluid intake. Increased caloric density formula or fortified breast milk is often needed for appropriate weight gain in infants with heart disease. A multidisciplinary approach is needed to optimize nutrition and growth for many children with heart disease.

Answer 30

The adolescent boy in the vignette has symptoms consistent with renal colic, macroscopic hematuria with blood clots, and right costovertebral tenderness, favoring a diagnosis of nephrolithiasis. Renal ultrasonography is the first-line imaging modality recommended to detect nephrolithiasis. Advantages of ultrasonography over the other options listed include the avoidance of exposure to ionizing radiation and the potential to detect obstruction in the urinary system. A noncontrast spiral computed tomography (CT) scan is the most sensitive test to diagnose nephrolithiasis, especially in symptomatic patients, however, the significant radiation exposure makes this a less optimal choice. A CT scan with contrast is not commonly recommended as the contrast may decrease the sensitivity for stone detection and extend the time required to perform the test. Renal calculi are often not detected on magnetic resonance imaging. Abdominal radiography has a lower sensitivity and specificity than does ultrasonography and detects only radio-opaque renal stones. PREP Pearls Factors that increase the risk for nephrolithiasis include decreased urine volume, increased solute excretion (calcium, uric acid), and decreased levels of stone inhibitors (citrate, magnesium). Renal and bladder ultrasonography is the first-line imaging modality recommended to diagnose nephrolithiasis in children. A noncontrast spiral computed tomography scan is the most sensitive test to diagnose nephrolithiasis in symptomatic children.

Answer 31

Of the response choices, the most likely diagnosis for the girl in the vignette is trisomy X. Trisomy X or triple X (47,XXX) is a sex chromosome aneuploidy with an incidence of approximately 1 in 1,000 liveborn females. Clinical features are highly variable without clearly defined malformations. Common reported features include: Tall stature Developmental delay: Primarily speech delay; intellectual disability in the mild-to-moderate range (average IQ of 55); learning disabilities in verbal and expressive language Behavior: Conduct disorder, depression, anxiety, autism spectrum disorder, mood disorder PREP Pearls Trisomy X or triple X (47,XXX) is a sex chromosome aneuploidy with highly variable clinical features. The most common features include tall stature, speech delay, and behavioral issues. Triple X syndrome arises when a nondisjunction event results in an extra chromosome X in the embryo; approximately 60% occur during maternal meiosis I and are associated with advanced maternal age.

Answer 32

The clinical presentation of the well-appearing boy in the vignette with a gradual onset of illness characterized by prolonged cough, low-grade fever, malaise, pharyngitis, and bilateral crackles on lung examination is suggestive of atypical pneumonia caused by Mycoplasma pneumoniae. It can be difficult to reliably distinguish bacterial etiologies of community-acquired pneumonia (CAP) from viral etiologies based on clinical findings alone. However, CAP caused by Staphylococcus aureus and Streptococcus pneumoniae is associated with high fever, chills, marked tachypnea, and focal auscultatory findings, which is not consistent with the clinical findings for the boy in the vignette. Atypical infection due to Legionella pneumophila is rare in children, accounting for ≤1% of all pneumonia cases, making this diagnosis unlikely for the boy in the vignette. PREP Pearls Mycoplasma pneumoniae is a frequent cause of upper respiratory tract infection and community-acquired pneumonia in school-aged children, adolescents, and young adults. In ambulatory settings, routine administration of antimicrobial therapy for school-aged children for respiratory tract infection due to suspected Mycoplasma is not indicated. In children with sickle cell disease, trisomy 21, immunodeficiency disorders, and chronic cardiac or pulmonary disease, Mycoplasma pneumoniae can cause severe, complicated pneumonia. In hospitalized children with moderate to severe Mycoplasma pneumoniae pneumonia or other severe manifestations, antimicrobial therapy with a macrolide (eg, azithromycin, clarithromycin) may be indicated.

Answer 33

The child in the vignette has a white pupillary reflex, known as leukocoria (Item C65A). Leukocoria is a concerning finding, suggestive of retinoblastoma (RB; an abnormal growth of retinoblasts), and must be confirmed by an ophthalmologist. The geneticist, radiation oncologist, and pediatric oncologist play a role in caring for a child with RB. However, the specialist who must evaluate the child first and make the diagnosis of RB is the pediatric ophthalmologist. PREP Pearls Leukocoria is the presenting finding in 50% to 60% of cases of retinoblastoma, and new-onset strabismus may be the presenting finding of retinoblastoma. A pediatric ophthalmologist must promptly and thoroughly examine a child with leukocoria to evaluate for retinoblastoma. All children should have screening for a bilateral red reflex at every health supervision visit. The American Academy of Pediatrics guidelines recommend screening from the newborn to 6 months of age, 6 to 12 months of age, 1 to 3 years of age, 4 to 5 years of age, and 6 years and older visits.

Answer 34

The boy in the vignette has displaced, comminuted facial fractures and requires urgent evaluation by a pediatric otolaryngologist. PREP Pearls Comminuted or displaced facial fractures require urgent evaluation by an otolaryngologist. Maxillofacial computed tomography (facial bones including orbits, sinuses, mandible, teeth) is the gold standard imaging modality for facial trauma. For isolated, non-displaced, or minimally displaced facial fractures, conservative management with cold compresses, oral analgesia, and nasal decongestants is appropriate.

Answer 35

The neonate in the vignette most likely has hemorrhagic disease of the newborn, and it is evident from the perinatal history that he did not receive 1 mg intramuscular vitamin K after delivery. To prevent further bleeding, it is important to give this patient vitamin K as soon as possible. If no intravenous line is available, intramuscular injection is an appropriate alternative. Coagulation factor replacement and blood product administration, if needed, can occur later. PREP Pearls Hemorrhagic disease of the newborn due to vitamin K deficiency can be easily prevented with intramuscular injection of 1 mg of vitamin K after birth. Vitamin K deficiency should be strongly considered for a newborn presenting with any form of bleeding, especially those exclusively breastfeeding, those delivered at home, and those who did not receive vitamin K prophylaxis after birth.

Answer 36

The boy in the vignette has newly diagnosed type 1 diabetes, and his blood glucose log demonstrates that he is experiencing elevated blood glucoses in the morning. This pattern is most commonly due to too little (dawn effect) or too much (Somogyi effect) bedtime basal insulin. A blood glucose level checked in the middle of the night (usually between 2-3 AM) can help distinguish between these two effects. An elevated overnight glucose level indicates too little basal insulin, and a low level indicates too much basal insulin. PREP Pearls In type 1 diabetes, elevated morning blood glucose levels may be due to either too little (dawn effect) or too much basal insulin (Somogyi effect). Checking a blood glucose level in the middle of the night (2-3 AM) can help distinguish between the dawn and Somogyi effects. Understanding the pharmacodynamics of insulin analogs is essential for making effective insulin dose adjustments

Answer 37

The boy in the vignette has an incidental radiographic finding of a simple bone cyst, also known as a solitary bone cyst or unicameral bone cyst (UBC). This is a benign pediatric bone tumor representing 3% of primary bone tumor biopsies. Unicameral bone cysts occur most often between ages 4 and 10 years; the etiology remains unknown. Most UBCs are located in the metaphysis of the proximal humerus or femur but can occur in other appendicular or axial bones. They are generally painless and discovered incidentally but can be mildly painful, reflecting a microscopic fracture. Trauma to the area may result in an abrupt pathologic fracture presenting with pain, edema, erythema, warmth, decreased range of motion, and deformity. PREP Pearls The diagnosis of a unicameral bone cyst can be made using radiography; typical features include location in the metaphysis that extends to, but does not cross, the physis; radiolucency with a thin cortical rim; and the pathognomonic sign of the “fallen leaf” fragment representing a portion of fractured cortical bone settling to the dependent part of the fluid-filled cyst. The differential diagnosis of a unicameral bone cyst includes an aneurysmal bone cyst, fibrous dysplasia, and enchondroma. Observation is reasonable for asymptomatic and small unicameral bone cysts. Indications for surgical intervention include persistent pain, recurrent fracture, and prevention of deformity.

Answer 38

The adolescent in the vignette has recently been diagnosed with chronic medical conditions that require daily medications for long-term management. Medication adherence is difficult for adolescents, especially if parents are not monitoring medications closely to increase accountability. The best next step in the management of the girl in the vignette is to assess medication adherence by asking her open-ended questions. For example, “Are you in charge of your own medications?” “Do you ever accidentally forget to take them?” “Do any of them cause you problems?” The physician should not increase or decrease the dosage of her medications until it is assessed if the patient is taking their medications correctly. While referral to hematology for iron infusion therapy may be needed at some point, this step should not occur before open-ended inquiry regarding her medication adherence. PREP Pearls Adherence to medications and medical treatment plans can be challenging for adolescents due to various factors including peer factors, striving for “normalcy,” forgetting the medication, physical well-being (eg, side effect concerns), and parent conflict. Physicians can assess medication adherence with open-ended, nonjudgmental questions. Physicians should participate as team members with parents and adolescents to problem solve how to improve adherence.

Answer 39

The boy in the vignette has severe iron-deficiency anemia (hemoglobin level of 5.5 g/dL [55 g/L]) due to inadequate dietary intake of iron. The best next management step is to give a dose of iron intravenously. Parenteral iron is indicated for children who require a rapid and/or short treatment course, such as the boy in the vignette, and for children who do not tolerate oral iron supplementation or have ongoing blood loss or gastrointestinal disease. The boy in the vignette is hemodynamically stable so he does not require an immediate increase in his hemoglobin level. A transfusion of packed red blood cells would be indicated to rapidly increase the hemoglobin level if the boy had symptoms such as severe fatigue, syncope or near syncope, or significant tachycardia. An intravenous normal saline bolus would be indicated if the boy was hemodynamically unstable. Normal saline boluses should be given with caution in the setting of anemia because the dilutional effect causes worsening of the anemia and decreased oxygen-carrying capacity, and could lead to heart failure. Although dietary changes should be recommended for the boy, his severe anemia necessitates more rapid iron replacement. Oral iron supplementation would also be appropriate for the boy in the vignette. The ferrous form of iron, at a minimum dose of 3 mg/kg/day, is sufficient to replenish iron stores over several months (3 or more). Very high doses of oral iron (eg, 6 mg/kg/day) can cause bowel irritation and constipation, which may lead to decreased adherence. PREP Pearls Parenteral iron is indicated for children with iron deficiency who are hemodynamically stable and require a rapid and/or short treatment course, do not tolerate oral iron supplementation, or have ongoing blood loss or gastrointestinal disease. A packed red blood cell transfusion is indicated for the treatment of symptomatic anemia (eg, severe fatigue, syncope or near syncope, or significant tachycardia). An increase in the reticulocyte percentage is an early indicator of recovery during the treatment of iron-deficiency anemia.

Answer 40

The boy in the vignette has a history and physical examination findings that meet criteria for classic Kawasaki disease (KD). The best next step for him is treatment with 2 mg/kg of intravenous immunoglobulin to reduce the risk of coronary artery aneurysm formation. Although children with KD are treated with acetylsalicylic acid at the time of diagnosis, a dose of 10 mg/kg per day is not adequate. Echocardiography and laboratory evaluation are important to the complete evaluation of KD, but they are not as urgent as the administration of immunoglobulin. PREP Pearls Classic Kawasaki disease is diagnosed when a child has fever for 5 or more days and at least 4 of the following 5 clinical findings: Erythema and cracking of the lips, strawberry tongue, and/or erythema of oral and pharyngeal mucosa Bilateral bulbar conjunctival injection without exudate Maculopapular diffuse erythematous or erythema multiforme-like rash Erythema and edema of the hands and feet in acute phase and/or periungual desquamation in subacute phase Cervical lymphadenopathy (≥1.5-cm diameter), usually unilateral Children with a prolonged fever with fewer than 4 of the classic features may have atypical or incomplete Kawasaki disease; this diagnosis may be supported by laboratory and echocardiographic findings. Treatment of children with Kawasaki disease with 2 mg/kg of intravenous immunoglobulin is required to reduce the incidence of coronary artery aneurysms; acetylsalicylic acid is used to treat inflammation and block platelet function.

Answer 41

The adolescent in the vignette has findings consistent with ulcerative colitis (UC); the constellation of signs, symptoms, and laboratory findings meets the criteria for acute severe colitis (ASC). The initial therapy recommended for ASC includes intravenous corticosteroids and supportive care (including treatment of anemia and nutritional support as clinically warranted).

Answer 42

The girl in the vignette demonstrates features of fetal alcohol spectrum disorder (FASD) including growth restriction, gross motor delay, and the physical findings shown in Item C113A (midface hypoplasia, a relatively smooth philtrum, small palpebral fissures, and a narrow upper lip with a poorly defined “cupid’s bow”). Fetal alcohol spectrum disorder results from maternal alcohol consumption during pregnancy. There is no safe limit for alcohol consumption during pregnancy; FASD can occur with any level of alcohol intake. Both the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommend complete abstinence from alcohol for preconceptional and pregnant women. The clinical features of FASD include: Growth restriction (height and/or weight ≤10%) Dysmorphic features (small palpebral fissures, thin vermillion border, flat nasal bridge, smooth philtrum, railroad track appearance to the ear, hockey stick palmar crease, and midface hypoplasia) Central nervous system abnormalities Congenital cytomegalovirus infection can present with prematurity, intrauterine growth retardation, microcephaly, poor feeding, thrombocytopenia, hepatosplenomegaly, intracranial calcifications, sensorineural hearing loss, and chorioretinitis. While developmental delay may be seen, there are no dysmorphic facial features associated with the condition.

Answer 43

The boy in the vignette is infected with Ascaris lumbricoides, an intestinal roundworm commonly found in locations with tropical climates (eg, Burma). The boy’s symptoms (abdominal pain, anorexia, watery diarrhea), physical examination finding (abdominal distention), and characteristic appearance of the fertilized eggs on microscopic examination of a stool specimen (oval shape surrounded by a thick shell with an external proteinaceous layer) are consistent with A lumbricoides infection.

Answer 44

The child in the vignette meets several of the modified Jones criteria for diagnosing acute rheumatic fever (ARF): arthritis, erythema marginatum, and carditis. To definitively make the diagnosis, however, one needs to also demonstrate evidence of a prior group A streptococcal (GAS) infection. The best test to establish the diagnosis of ARF is antistreptolysin O titer. A C-reactive protein level and echocardiography may be useful in the complete assessment and management of the condition but will not clarify the underlying diagnosis. In general, a rheumatoid factor level is unlikely to be helpful in the diagnosis of knee pain and swelling in a young child and is not recommended to make the diagnosis in this child with a clinical picture suggestive of ARF.

Answer 45

The boy in the vignette has acute cerebellar ataxia, a self-limited, postinfectious disorder primarily affecting children younger than 5 years. Affected children exhibit truncal and gait ataxia, often coming to medical attention due to the inability to stand or sit without support. Dysmetria and titubation (head nodding) while sitting are further evidence of cerebellar dysfunction. Affected children are otherwise well appearing with normal mental status. Symptoms are usually maximal at onset and gradually improve over days to weeks, rarely months. Management is supportive. There is no evidence that immune therapy (eg, corticosteroids or intravenous immunoglobulin [IVIG]) affects outcome. PREP Pearls The differential diagnosis of balance disturbances in childhood is broad and can localize anywhere within the nervous system. A careful history and physical examination are critical for appropriate localization, evaluation, and diagnosis. Ataxia refers to an absence of coordination and can be acute, subacute, or chronic depending on the time course of symptoms. Acute cerebellar ataxia is a self-limited, post-infectious disorder presenting with acute onset of truncal and gait ataxia, often in young children. Treatment is supportive.

Answer 46

The girl in the vignette has Turner syndrome. The best test to reveal her diagnosis is a karyotype, which would show an absent or missing part of a sex chromosome (45,X or a variant). Her short stature, absent breast development, and history of multiple ear infections as an infant are all features of Turner syndrome. Delayed puberty in girls is defined as lack of breast development by age 13 years. In adolescents with delayed puberty, measurement of gonadotropins (luteinizing hormone and follicle-stimulating hormone [FSH]) is indicated to determine whether the pubertal failure is primary (ovarian/testicular) or secondary (hypothalamic-pituitary). In adolescent girls with Turner syndrome, the FSH is often elevated due to primary ovarian failure. The girl in the vignette has a sexual maturing rating of 3 for pubic hair, which is secondary to adrenal androgen production. Bone age radiography is an important part of the evaluation of short stature and delayed puberty. Typically, conditions that delay puberty also delay bone age as estradiol is the primary hormone responsible for growth plate maturation. Although bone age radiography may help in treatment planning for the girl in the vignette, it is not specific enough to determine the etiology of her delayed puberty. A delayed bone age in an otherwise healthy child or adolescent with a normal growth rate aids in the diagnosis of constitutional delay of growth and puberty.

Answer 47

he neonate in the vignette is cyanotic, with a room air oxygen saturation of 78% measured in the right upper and lower extremities. He is comfortably tachypneic with good perfusion. On auscultation, he has clear breath sounds, a single S2, and a continuous murmur. The chest radiograph (Item C120A) shows oligemic lungs without infiltrate, a boot-shaped heart, and a right aortic arch. These findings are consistent with tetralogy of Fallot with pulmonary atresia. Although this diagnosis will need to be confirmed by echocardiography, for this ductal-dependent condition it is important to first initiate prostaglandin infusion to prevent further closure of the patent ductus arteriosus (PDA). The neonate does not have evidence of low cardiac output, so administration of epinephrine is not indicated. He does not have evidence of respiratory failure, so intubation is not indicated. Inhaled nitric oxide would not correct his hypoxemia. The mnemonic 5 Ts and H is helpful for remembering many of the types of cyanotic congenital heart disease: Tetralogy of Fallot Total anomalous pulmonary venous connection Transposition of the great arteries Tricuspid atresia Truncus arteriosus Hypoplastic left heart syndrome

Answer 48

The adolescent in the vignette has findings consistent with left optic neuritis. The swinging flashlight test, also known as the Marcus Gunn pupil test, is performed to detect an afferent pupillary defect. The test is performed by shining a light on one eye for 2 seconds and then alternating the light from eye to eye. Normally, both pupils constrict in response to shining the light on one pupil. If the pupils remain dilated, an afferent pupillary defect is likely, indicating disease of the retina or optic nerve. The adolescent has a lack of pupillary response on the left side with a normal direct and consensual response on the right side, indicating a left afferent pupillary defect. This finding, along with blurring of her left optic disc, makes optic neuritis the most likely diagnosis. The first-line treatment of pediatric optic neuritis is high-dose, pulsed methylprednisolone for 3 to 5 days followed by a taper over 2 weeks. Children and adolescents resistant to steroid therapy may benefit from treatment with intravenous immunoglobulin and plasmapheresis. PREP Pearls Optic neuritis can present with acute vision loss and findings of an afferent pupillary defect with blurring of the optic disc margins. Evaluation of children and adolescents with suspected optic neuritis should include magnetic resonance imaging of the brain and orbits. Optic neuritis can be the initial clinical presentation of demyelinating disorders such as multiple sclerosis.

Answer 49

The girl in the vignette is displaying signs and symptoms of airway obstruction concerning for epiglottitis. The best next step in her management is rapid sequence induction and intubation. Other interventions, such as nebulizer treatments, intravenous corticosteroids or antibiotics, or imaging studies should not be undertaken until a definitive airway is secured. Every effort should be made to keep the child as calm and quiet as possible until the airway is secured. PREP Pearls Epiglottitis is a rare life-threatening condition that results in severe swelling of the epiglottis, which can lead to complete airway obstruction. The clinical presentation of epiglottis is an overtly toxic-appearing child with sudden onset and rapid progression of fever, drooling, stridor, muffled voice, and difficulty swallowing. The classic diagnostic triad, the “3 Ds,” includes drooling, dysphagia, and distress. The critically important first step in the management of a child with suspected epiglottitis is obtaining a definitive and secure airway with an endotracheal tube

Answer 50

The boy in the vignette has a systolic ejection click heard at the right upper sternal border, suggestive of aortic valve pathology, and a family history (paternal grandfather) of aortic valve pathology. Of the response choices, bicuspid aortic valve (BAV) is the most likely diagnosis. He should be evaluated by a pediatric cardiologist; echocardiography is needed to confirm the diagnosis. If there is no significant valve dysfunction or aortic dilation, children with BAV can often play sports and exercise without restriction. PREP Pearls Bicuspid aortic valve, in which the aortic valve develops with only 2 leaflets instead of the normal 3, is one of the most common congenital heart defects. Bicuspid aortic valve occurs in males more than females and can be familial. Individuals with bicuspid aortic valve can develop valve dysfunction (stenosis, regurgitation, or both), aortic dilation, or aortic aneurysm.

Answer 51

Pertussis postexposure prophylaxis with azithromycin is recommended for all close contacts of the index case irrespective of immunization status. Individuals are considered close contacts if they are either household members or asymptomatic persons who had face-to-face exposure within 3 feet of a symptomatic individual in a childcare facility, school, or health care setting. Exposure is defined as direct contact with respiratory, oral, or nasal secretions or sharing the same space with the symptomatic individual for 1 hour or more. Prompt postexposure prophylaxis is recommended, given the high transmission risk (secondary attack rate of 80% in susceptible persons) and effectiveness of azithromycin. Trimethoprim-sulfamethoxazole is reserved for prophylaxis in children who cannot tolerate azithromycin; it is contraindicated in infants younger than 2 months. All exposed individuals should be monitored for symptoms for 21 days. PREP Pearls Pertussis is a highly contagious infection with a typical duration of 6 to 10 weeks. There are 3 stages of pertussis infection: catarrhal (upper respiratory infection symptoms), lasting 1 to 2 weeks; paroxysmal (repeated coughing spells), lasting 2 to 4 weeks; and convalescent (improving cough), lasting 4 to 12 weeks. Household members and close contacts of individuals diagnosed with pertussis infection should receive postexposure prophylaxis with azithromycin, irrespective of their immunization status.

Answer 52

The breastfed neonate in the vignette should start vitamin D supplementation now and iron at age 4 months. Although breast milk provides excellent nutrition during the first year after birth, the vitamin D and iron content in breast milk is not adequate to meet the infant’s nutritional needs.

Answer 53

The male neonate in the vignette most likely has posterior urethral valves (PUVs). This diagnosis is supported by the history of bilateral antenatal hydronephrosis, maternal oligohydramnios, and severe bilateral hydroureteronephrosis with a thick-walled urinary bladder on postnatal renal ultrasonography. The best next step in his evaluation is to perform voiding cystourethrography (VCUG). The VCUG would likely demonstrate the classic findings of a dilated posterior urethra during the voiding phase, trabeculated bladder, and perhaps vesicoureteral reflux (VUR) (Item C126). PREP Pearls Posterior urethral valves are abnormal mucosal folds within the lumen of the posterior urethra that obstruct the flow of urine. Children with suspected posterior urethral valves should have voiding cystourethrography (VCUG) performed. A dilated posterior urethra on VCUG is consistent with the diagnosis. Children with posterior urethral valves are at increased risk of chronic kidney disease, even with prenatal diagnosis and early intervention.

Answer 54

The most likely cause for the hives exhibited by the girl in the vignette is a viral illness. Viral infections cause almost 60% of acute urticaria seen in children, and this girl has clear symptoms of a viral illness. Amoxicillin is a less likely cause of this girl’s urticaria because urticaria caused by amoxicillin usually does not have a delayed onset. Urticaria from food allergies usually presents within 2 hours of exposure. Hypothyroidism, specifically autoimmune hypothyroidism, may predispose some children to urticaria, but in these cases, the urticaria is usually chronic, lasting more than 6 weeks. PREP Pearls The most common cause of acute urticaria in children is a viral infection. The first-line treatment for both acute and chronic urticaria is a nonsedating antihistamine such as cetirizine or loratadine. Children with cold-induced urticaria should be prescribed an epinephrine auto-injector because of the risk of anaphylaxis.

Answer 55

The adolescent in the vignette is demonstrating classic anticholinergic findings (seizure; respiratory depression; dilated pupils; dry, flushed skin; tachycardia; and arrhythmia) caused by an overdose of amitriptyline, a tricyclic antidepressant (TCA). The treatment for TCA-induced, wide complex ventricular tachycardia and resulting hypotension is administration of intravenous sodium bicarbonate, with the goal of raising the serum pH to approximately 7.5. Flumazenil, the antidote for a benzodiazepine overdose, is contraindicated in individuals with TCA overdose as it may induce seizures. Flumazenil should also not be administered to individuals with an unknown ingestion, as it may precipitate seizures in those who are benzodiazepine dependent. PREP Pearls An electrocardiogram should be obtained immediately in a child with suspected or confirmed ingestion of a tricyclic antidepressant. Sodium bicarbonate is the mainstay of treatment in children with tricyclic antidepressant toxicity and should be initiated in any child who is hemodynamically unstable, acidotic, hypotensive, or exhibiting seizure activity or a QRS interval prolongation of more than 100 milliseconds. The goal of sodium bicarbonate therapy for tricyclic antidepressant–induced QRS interval prolongation is to narrow the QRS complex and achieve and maintain a serum pH of 7.5.

Answer 56

The girl in the vignette has acute respiratory failure requiring intubation and mechanical ventilation. Given her ongoing hypoxia despite the provision of 100% FiO2 by the ventilator, equal but diminished breath sounds, and equal chest rise, the best next step in management is to provide manual ventilation with a resuscitation bag via the endotracheal tube to both assess and manage the cause of ventilation failure. Finally, suctioning of the endotracheal tube can alleviate mucus or secretion-related endotracheal tube obstruction. However, given the ongoing significant oxygen desaturations, manual ventilation with a resuscitation bag is indicated before suctioning to attempt to restore normal oxygenation quickly. PREP Pearls When acute hypoxia occurs in mechanically ventilated children, manual ventilation with a resuscitation bag should be performed with 100% FiO2 until the underlying cause of hypoxia can be addressed and corrected. Endotracheal intubation may be required for children with respiratory failure, impending respiratory arrest, or those with neurologic impairment or severely altered mental status where airway protective reflexes cannot be maintained. A common mnemonic used to evaluate and manage a successfully intubated patient who subsequently develops hypoxemia is DOPE: Displacement/Dislodgement of the endotracheal tube, Obstruction of the endotracheal tube, Pneumothorax, and Equipment failure.

Answer 57

The adolescent in the vignette has unilateral cervical lymphadenopathy associated with fever. This clinical scenario, including exposure to kittens, is suggestive of Bartonella henselae infection or “cat-scratch disease.” The adolescent in the vignette has lymphadenopathy, fever, headache, and abdominal pain as well as exposure to kittens, therefore, empiric treatment with azithromycin would be appropriate. Empiric treatment with azithromycin can be considered in situations compatible with this clinical syndrome (eg, acute lymphadenopathy and exposure to kittens). Penicillin, amoxicillin, and first-generation cephalosporins are not recommended for treatment of B henselae. PREP Pearls Cat-scratch disease is a common cause of lymphadenopathy in children, caused by the gram-negative bacillus Bartonella henselae. The majority of Bartonella henselae infections are asymptomatic. The severity of disease varies based on the age and immune status of the host, ranging from regional lymphadenopathy to systemic disseminated infection. Uncomplicated cases of lymphadenopathy due to Bartonella henselae do not require treatment. However, a 5-day course of azithromycin results in reduction of lymph node size and hastens resolution of symptoms.

Answer 58

detailed diet history

Answer 59

The neonate in the vignette is a late preterm infant with severe hyperbilirubinemia. His physical examination findings are consistent with phases 1 to 2 of acute bilirubin neurotoxicity. To prevent further neurologic deterioration and decrease the risk of the long-term neurodevelopmental sequelae of kernicterus, a double volume exchange transfusion should be performed as soon as possible. For this neonate, the total bilirubin level for which exchange transfusion is indicated, is 22.2 mg/dL (379.7 µmol/L); this neonate’s level is well above that (Item C133A). Almost all preterm neonates and approximately 60% of term neonates will develop physiologic jaundice. This jaundice occurs due to catabolism of red blood cells (RBCs) (the half-life of RBCs in neonates is 90 days compared with 120 days in adults), increased RBC volume, immature hepatic conjugation, and delayed establishment of feedings, leading to reduced excretion of bilirubin and increased enterohepatic circulation of bilirubin. Item C133B lists risk factors for severe hyperbilirubinemia in neonates; the neonate in the vignette’s risk factors include gestational age (late preterm), exclusive breastfeeding, and isoimmune hemolytic disease. Phototherapy should continue before and after exchange transfusion but will not rapidly decrease the bilirubin level, which is critical to minimizing the neurotoxic effects of severe hyperbilirubinemia. Intravenous fluid is helpful to address dehydration, if present, but it is not a treatment for hyperbilirubinemia. Partial volume exchange transfusion is performed in neonates with chronic anemia for whom heart failure is a concern and in neonates with symptomatic polycythemia with a central hematocrit greater than 65% to 70% (0.65-0.70); it is not an appropriate treatment for neonatal hyperbilirubinemia. PREP Pearls A high level of bilirubin or an insufficient amount of serum protein to bind the bilirubin leads to circulating free bilirubin, which can easily penetrate the blood–brain barrier. To prevent further neurologic deterioration and decrease the risk of the long-term neurodevelopmental sequelae of kernicterus, a double volume exchange transfusion should be performed as soon as possible when exchange transfusion is indicated. Some risk factors for significant neonatal hyperbilirubinemia include predischarge total serum or transcutaneous bilirubin level close to phototherapy threshold, lower gestational age, exclusive breastfeeding, jaundice observed in the first 24 hours, inherited red blood cell disorders, phototherapy before discharge, hemolysis from any cause, macrosomic infant, and Down syndrome.

Answer 60

The child in the vignette is at a developmental level that is most consistent with that of a 12-month-old. The fine motor development of a 12-month-old child should include the ability to pick things up between thumb and pointer finger, like small bits of food. The gross motor development of a 12-month-old child should include cruising and taking first steps. Often a child this age will stand independently, demonstrating age-appropriate tone and balance, but may not yet be willing to attempt the actual motion of walking. At 15 to 18 months of age we would expect a child to be walking well independently and beginning to run and climb.

Answer 61

The infant in the vignette has chronic diarrhea (duration >14 days) associated with failure to thrive and therefore requires further evaluation. For a child with this clinical presentation, without evidence of secretory diarrhea, upper endoscopy is the best management option. With further evaluation, he was diagnosed with allergic enteropathy. Chronic diarrhea may occur because of the following mechanisms: Osmotic diarrhea: unabsorbed intestinal solutes drive luminal retention of water (via osmotic gradient) Examples: lactose intolerance, exocrine pancreatic insufficiency Diarrhea improves when unabsorbed nutrients are removed from the diet (or in nil per os [NPO] status) Secretory diarrhea: excessive intestinal electrolyte and/or fluid secretion Examples: neuroendocrine tumors (eg, VIPoma, neuroblastoma), congenital chloride diarrhea Diarrhea persists despite NPO status Low stool osmolar gap: Stool Total Osmolarity – 2 × [Stool Na+ + Stool K+] Inflammatory diarrhea: may include both secretory and osmotic mechanisms because intestinal fluid secretion may be excessive and the inflamed bowel may not completely absorb intestinal solutes Examples: infectious diarrhea (excessive intestinal fluid secretion), inflammatory bowel disease, celiac disease, and allergic enteropathy Diarrhea may improve with NPO status Diarrhea caused by dysmotility: occurs because of decreased intestinal transit time Examples: chronic nonspecific diarrhea, irritable bowel syndrome PREP Pearls Chronic diarrhea may be classified based on the mechanism: osmotic, secretory, inflammatory, and dysmotility associated. Infants with chronic diarrhea and failure to thrive require additional evaluation, including blood and stool studies; endoscopic evaluation may be useful to determine the cause.

Answer 62

The girl in the vignette has neurofibromatosis type 1 (NF1). She meets the clinical criteria for NF1 with her optic pathway glioma and at least 6 café au lait macules larger than 5 mm. Neurofibromatosis type 1 is a tumor predisposition syndrome inherited in an autosomal dominant manner with complete penetrance. An example of a NF1 pedigree is shown in Item C136A. Clinical criteria for NF1, recently revised, are below:

Answer 63

Fever, transaminitis, diarrhea, and generalized macular erythematous, blanching, nonpruritic rash, as seen in the infant in the vignette, are common findings in many conditions, including viral infections and medication reactions. However, in the context of a recent blood product (packed red blood cells [PRBCs]) transfusion, transfusion-associated graft-vs-host disease (TA-GVHD) is this infant’s most likely diagnosis. PREP Pearls Transfusion-associated graft-vs-host disease has a high mortality rate. Irradiation of blood products administered to an immunodeficient individual is paramount in preventing transfusion-associated graft-vs-host disease.

Answer 64

The adolescent in the vignette has symptoms and signs of urethral inflammation including dysuria and urethral mucoid discharge. After obtaining urine and oral swabs for nucleic acid amplification testing (NAAT) for Chlamydia trachomatis and Neisseria gonorrhoeae, the best next step in management is to treat him with an antibiotic regimen effective against chlamydia and gonorrhea (eg, doxycycline, orally, and ceftriaxone, intramuscularly). Treatment should begin right away; it should not be held until test results are available. PREP Pearls Urethritis is commonly caused by sexually transmitted infections including gonorrhea and chlamydia. Mycoplasma genitalium causes almost 25% of nongonococcal urethritis cases in the United States. Health care professionals should treat individuals with objective signs of urethral inflammation with antibiotics effective against gonorrhea and chlamydia, even before test results are available.

Answer 65

The adolescent in the vignette has a pectus excavatum chest deformity that is causing him concern about his appearance and exercise capacity. The most common chest wall deformity, pectus excavatum often has a significant negative impact on body image and perceived exercise capacity. Static pulmonary function testing results are rarely abnormal, as is the case for the boy in the vignette. Cardiopulmonary exercise testing may uncover subtle deficits in exercise capacity and is the best test to further evaluate his respiratory function. A lung ventilation-perfusion scan is not indicated for the adolescent in the vignette. Chest wall deformities do not cause ventilation-perfusion mismatch. PREP Pearls Severe chest wall deformities can cause restrictive pulmonary physiology. The severity of the restrictive lung disease is directly related to the complexity of the chest deformity. Pectus excavatum can have a significant negative impact on self-image and perceived exercise capacity; static pulmonary function testing is usually normal. Surgical repair of scoliosis is not likely to improve lung function but can prevent it from worsening.

Answer 66

The infant in the vignette has bathrocephaly resulting from a persistent mendosal suture (Item C140A). This suture usually disappears by the time of birth but when persistent can cause a prominent occiput. Bathrocephaly usually resolves without intervention, so the infant’s mother can be reassured that her son’s head shape will likely normalize. He does not require helmet therapy, referral to neurosurgery, or physical therapy for correction. PREP Pearls Bathrocephaly, which is caused by a persistent mendosal suture and results in a prominent occiput, usually resolves without intervention. Early identification of concerning head shape is crucial so that infants receive treatment before the window of opportunity closes. Craniosynostosis is a rare cause of microcephaly.

Answer 67

The adolescent in the vignette most likely has autosomal dominant polycystic kidney disease (ADPKD). He has multiple cysts visualized on renal ultrasonography and a family history of ADPKD. While he remains asymptomatic, he should be screened with annual blood pressure measurements (to monitor for hypertension) and urinalysis with microscopy (to detect proteinuria and hematuria). Annual blood pressure measurement and urinalysis should be performed for all asymptomatic children with a family history of ADPKD. Serum creatinine values are usually normal in children with ADPKD and kidney function does not typically worsen until adulthood. A computed tomography scan of the brain to screen for cerebral aneurysm is not recommended for asymptomatic children since aneurysmal rupture is extremely rare. Doppler ultrasonography of the liver is helpful in diagnosing portal hypertension secondary to congenital hepatic fibrosis, which is associated with ARPKD. However, hepatic fibrosis is not associated with ADPKD and therefore, liver ultrasonography would not be indicated for the child in the vignette. PREP Pearls Autosomal dominant polycystic kidney disease is the most common inherited kidney disease. Most children with autosomal dominant polycystic kidney disease are asymptomatic and diagnosed incidentally on an imaging study or during screening due to family history. Annual blood pressure measurement and urinalysis (to monitor for proteinuria and hematuria) should be performed for asymptomatic children with a family history of autosomal dominant polycystic kidney disease.

Answer 68

The neonate in the vignette developed fungemia (candidemia) requiring parenteral antifungal therapy. Within 24 hours after starting treatment the neonate appears to have significant nephrotoxicity with acute kidney injury as evidenced by elevated serum blood urea nitrogen and creatinine levels and hypokalemia. Of the response choices, amphotericin B is most likely to cause acute and significant nephrotoxicity. Fluconazole, flucytosine, and micafungin are not associated with kidney injury. PREP Pearls The primary toxic side effect of amphotericin B, including liposomal preparations, is nephrotoxicity. Antifungals may be associated with hepatotoxicity or inhibition of the cytochrome p450 enzyme system, which can result in elevated levels of other medications cleared by the liver. With the exception of flucytosine, therapeutic drug level monitoring is rarely necessary when prescribing antifungal therapy.

Answer 69

The boy in the vignette’s abdominal radiograph shows 3 circular radiopaque foreign bodies that appear to be touching, raising concern that the boy ingested magnets. Because the boy is symptomatic with multiple magnets that have passed through the stomach, the best next step in management is emergency referral for surgical removal. The algorithm for magnet ingestion in children is shown in Item C143. If the magnets were located within the esophagus or stomach, emergency referral for endoscopic removal would be the appropriate next step. Neither close outpatient follow-up with serial abdominal radiography or admission to the hospital for serial abdominal examinations would be appropriate for this child. With ingestion of multiple magnets, he is at risk for bowel injury or perforation if the magnets are not removed promptly.

Answer 70

The infant in the vignette has an annular rash with dusky center following a herpes simplex virus (HSV) gingivostomatitis infection that is suggestive of erythema multiforme (EM). Erythema multiforme is commonly triggered by infections. It is not associated with arthritis; any associated pruritus is mild, not intense; and erythema multiforme is expected to resolve in 2 to 3 weeks, not 24 hours. Erythema multiforme is an immune-mediated, self-limiting disorder involving the skin and mucous membranes. The EM rash is described as annular targetoid plaques with 3 zones: a dusky center, surrounding pallor, and a rim of erythema. The centers of the lesions can become bullous. The lesions symmetrically involve the extremities, trunk, palms, and soles. Individual lesions last for 1 to 2 weeks; transient lesions are more consistent with urticaria. Pruritus, if present, is usually mild, and systemic symptoms such as fever and myalgias may occur especially in those with mucous membrane lesions. PREP Pearls Erythema multiforme is an immune-mediated condition characterized by targetoid lesions on the trunk, extremities, palms, and soles. Infections, especially herpes simplex virus, are a common trigger for erythema multiforme. Erythema multiforme is self-limiting and resolves with supportive care within 2 to 3 weeks.

Answer 71

The infant in the vignette currently requires enteral nutrition support by nasogastric (NG) tube due to inadequate oral intake despite appropriate feeding therapy. Because the medical team anticipates that this level of support will be required for several months, gastrostomy tube (G-tube) placement is indicated. Gastrostomy tube placement is generally recommended when enteral supplementation will be needed for a long period, with recommendations varying from at least 6 weeks to 3 months. The infant’s history of prematurity and previous tracheoplasty do not support a preference for NG or G-tube feeding. Nasogastric feeding is associated with fewer tube-related emergency department visits compared with G-tube feeding, which would be a factor supporting the family’s preference.

Answer 72

The boy in the vignette has a type of ectodermal dysplasia (ED). Children with ED are at high risk for hyperthermia and hyperpyrexia because of their decreased ability to sweat. Anticipatory guidance regarding avoidance of overheating is critically important. PREP Pearls Ectodermal dysplasias are a group of disorders that involve abnormalities in at least 2 ectodermal structures—hair, teeth, nails, or sweat glands. The main clinical features of hypohidrotic ectodermal dysplasia include hypotrichosis, hypodontia, and hypohidrosis. A critical feature of the management of hypohidrosis is avoidance of overheating.

Answer 73

The girl in the vignette has mild to moderate persistent asthma, with symptoms occurring more than twice per week but less than daily. The preferred management for persistent asthma in children 5 years of age and older is daily and as-needed use of a combined inhaler with corticosteroid and formoterol. Combined inhalers containing an inhaled corticosteroid and formoterol (a long-acting β-agonist [LABA]) are appropriate for what is known as the same maintenance and rescue therapy (SMART) approach to asthma management. Formoterol combined with budesonide used with the SMART approach has been well studied in the United States. This combination became the standard of care with the publication of the 2020 National Institutes of Health (NIH) updated asthma treatment guidelines. For children aged 5 years and older with persistent mild or moderate asthma, using an inhaled corticosteroid (ICS) with the long-acting β-agonist (LABA) formoterol as both maintenance and rescue therapy helps to minimize daily steroid exposure while decreasing the likelihood that oral steroids will be needed with exacerbation. The LABA salmeterol has a slower onset of action and is not appropriate for use as a rescue treatment. Item C148A, Item C148B, and Item C148C outline current treatment recommendations for children with asthma. PREP Pearls The most effective treatment for asthma of all severities is an inhaled corticosteroid. Leukotriene modifiers may be used as alternative first-line therapy in young children with mild persistent asthma. A US Food and Drug Administration boxed warning was added to the prescribing information for montelukast regarding the risk for neuropsychiatric adverse effects. Combined inhaled corticosteroids with formoterol are appropriate for the same maintenance and rescue therapy in children and adolescents aged 5 years and older. Long-acting ꞵ-agonists should be used to treat asthma only in conjunction with an inhaled corticosteroid.

Answer 74

The best management strategy for the girl in the vignette is optimization of medical treatment of her atopic dermatitis. Without an obvious correlation between flares of her atopic dermatitis and specific foods, a food elimination diet is not indicated, and food allergy testing in this situation has a high false-positive rate. Current evidence does not support the effectiveness of vitamin supplementation in the management of atopic dermatitis. It will be important to share this information with the girl’s father, and respond respectfully to his questions and concerns to engage him willingly in effective skin care management. PREP Pearls First-line treatment of atopic dermatitis is to optimize medical management before considering dietary modifications. Management of atopic dermatitis must include family education that emphasizes the chronic nature of the condition and the importance of maintenance therapy. Complications of atopic dermatitis include atopic, infectious, and behavioral conditions.

Answer 75

The boy in the vignette has a mechanical heart valve, an indication for endocarditis prophylaxis with antibiotics prior to routine dental cleaning. The regimen recommended by the American Heart Association 2007 guideline is amoxicillin, orally, in a single dose 30 to 60 minutes prior to the procedure. Amoxicillin is the drug of choice because it is well absorbed by the gastrointestinal (GI) tract and has high and sustained serum levels. Item C151 lists alternative antibiotic options for those with a penicillin allergy or inability to take medication orally. The targeted organisms are viridans group streptococci. Clindamycin is an appropriate alternative for those with a penicillin allergy, which the boy in the vignette does not have. Trimethoprim-sulfamethoxazole is not indicated for endocarditis prophylaxis. Not all children with congenital heart disease require endocarditis prophylaxis. Prophylaxis is indicated for children with conditions that confer a high risk of an adverse outcome from infective endocarditis. These conditions include: A prosthetic cardiac valve or prosthetic material used in cardiac valve repair A previous history of endocarditis Specific congenital heart disease (CHD) PREP Pearls Endocarditis prophylaxis is required for children with specific cardiac risk factors (eg, prior history of endocarditis, residual defects, cyanotic disease, or prosthetic material that is not endothelialized). Specific dental procedures and those causing respiratory mucosal injury are the most common indications for endocarditis prophylaxis. Amoxicillin is the antibiotic of choice for endocarditis prophylaxis, administered as a single dose 30 to 60 minutes prior to the procedure.

Answer 76

The best HIV test to order for the adolescent in the vignette is the HIV-1/HIV-2 antigen/antibody combination assay, a fourth-generation immunoassay recommended by the Centers for Disease Control and Prevention (CDC) as the preferred initial screening test. This combination test detects HIV viral protein (p24 antigen) as well as HIV IgM and IgG antibodies to HIV-1 and HIV-2. The test is highly sensitive and specific in identifying individuals in the early stages of HIV infection. The p24 antigen is detectable between weeks 2 and 3 of infection. A non-reactive test result is reported as negative, and no additional testing is recommended unless early HIV infection (acute retroviral syndrome) is suspected. A reactive test is followed up with a supplemental HIV-1/HIV-2 antibody differentiation assay. PREP Pearls The United States Centers for Disease Control and Prevention recommends routine HIV screening at least once for individuals aged 13 to 64 years. Annual HIV screening is recommended for individuals who are at high risk for HIV acquisition. The preferred initial HIV screening test recommended by the Centers for Disease Control and Prevention is the fourth-generation HIV-1/HIV-2 antigen-antibody combination immunoassay performed on serum/plasma.

Answer 77

The girl in the vignette has persistent asymptomatic microscopic hematuria. The most appropriate next step in her evaluation is to order a spot urine calcium:creatinine ratio to evaluate for hypercalciuria. Hypercalciuria, defined as a urine calcium:creatinine ratio of greater than 0.2 mg/mg or calcium excretion of greater than 4 mg/kg daily on 24-hour urine collection, is a risk factor for nephrolithiasis. PREP Pearls Common causes of persistent microscopic hematuria include hypercalciuria, thin basement membrane disease, IgA nephropathy, and sickle cell disease. Initial laboratory evaluation of persistent microscopic hematuria should include urine protein:creatinine ratio, urine calcium:creatinine ratio, urine culture, serum electrolyte levels, renal function tests (blood urea nitrogen and serum creatinine measurement), and hemoglobin electrophoresis (if sickle cell disease is suspected). Children with microscopic hematuria associated with edema, hypertension, or proteinuria should be promptly referred to a pediatric nephrologist.

Answer 78

The infant in the vignette has tachypnea while feeding, hepatomegaly, and a holosystolic murmur at the lower left sternal border. These findings are consistent with a ventricular septal defect (VSD). The flow across an atrial septal defect (ASD) itself does not create a murmur, though the increased flow can result in a fixed split S2 and produce a murmur across the pulmonary valve, which would be heard in mid-systole at the left upper sternal border. Pulmonary valve stenosis would produce a systolic ejection murmur in the pulmonic location. An aortic stenosis murmur would be heard in mid-systole, loudest at the right upper sternal border. PREP Pearls A ventricular septal defect creates a holosystolic murmur heard best at the left lower sternal border. Symptoms and signs of a moderate to large ventricular septal defect include tachypnea, sweating while feeding, tachycardia, and hepatomegaly. A moderate to large ventricular septal defect requires surgical closure and if left open can lead to irreversible pulmonary hypertension (Eisenmenger syndrome)

Answer 79

The girl in the vignette has acrocyanosis caused by thermodysregulation accompanying anorexia nervosa. An 8-kg weight loss in 6 months and low body temperature in an otherwise healthy athletic adolescent makes anorexia nervosa a likely diagnosis. Secondary acrocyanosis is a common finding in anorexia nervosa, occurring in up to 80% of affected individuals. Acrocyanosis is characteristically variable without clearly demarcated margins. Cold exposure is the most common trigger. Asking the girl to provide pictures of her extremities at the time of an episode can confirm the diagnosis. She can be reassured that the cyanosis itself is not threatening to her health; the focus of her care can then shift to treatment of her anorexia nervosa. Methemoglobinemia causes hemoglobin to be oxidized to the ferric (Fe3+) state, which cannot carry oxygen to the peripheral tissues. This pathology results in persistent central cyanosis and low peripheral oxygen saturation. Serum methemoglobin levels above 10% are associated with cyanosis and levels above 20% are associated with dyspnea, tachycardia, and lightheadedness. PREP Pearls Primary acrocyanosis is common and benign. Up to 80% of patients with anorexia nervosa may have acrocyanosis. Raynaud phenomenon is differentiated from acrocyanosis by sharp demarcation of cyanotic skin, pain or discomfort, and a biphasic or triphasic color response (pallor, cyanosis, plethora). Secondary Raynaud phenomenon can be associated with collagen vascular disease and skin breakdown.

Answer 80

The right ear finding for the girl in the vignette is most likely a cholesteatoma, associated with retraction of a portion of the tympanic membrane (TM). A foreign body is more likely to protrude into the ear canal. The head of the stapes is inferior to the location of this girl’s finding. Areas of tympanosclerosis are not usually retracted. PREP Pearls Cholesteatomas are collections of debris that form in retraction pockets of the tympanic membrane, most often secondary to chronic otitis media. If left untreated, cholesteatomas may grow into the middle ear and erode the ossicles. Cholesteatomas may recur after surgical removal, requiring lifelong monitoring.

Answer 81

D PREP Pearls Benign shuddering attacks of infancy is a nonepileptic, self-limited condition of infancy and early childhood characterized by brief shivering movements of the head and upper extremities without alteration of consciousness. Episodes are more frequently noticed during activities such as mealtime, diaper changes, or excitement/frustration. Distinguishing epileptic from nonepileptic conditions in infancy requires careful history with attention to the clinical features of the events, conditions in which they occur, and provoking factors. Video recording of events can be a useful tool for accurate diagnosis. When a diagnosis of benign shuddering attacks is suspected, parental reassurance and education is a critical component of management. Investigative studies, such as neuroimaging, electroencephalography, or laboratory studies are not necessary.

Answer 82

The adolescent in the vignette is considered to have only 1 functional eye because the corrected visual acuity in his left eye is less than 20/40. The American Academy of Pediatrics (AAP) and American Academy of Ophthalmology (AAO) recommend that athletes who are functionally 1-eyed wear protective eyewear for all sports. An eye injury resulting in vision loss in the unaffected eye puts these athletes at risk for significant disability. Because protective eyewear cannot be worn during wrestling, the boy in the vignette should not participate in this sport. Combat sports (eg, martial arts and boxing) are also contraindicated for athletes who are functionally 1-eyed.

Answer 83

The boy in the vignette has the classic symptoms and signs of postviral myositis (benign acute childhood myositis [BACM]), including difficulty walking, calf pain, and calf tenderness after a viral illness. Of the response choices, the best next step in his evaluation is to obtain a creatinine phosphokinase (CPK) level. The CPK level is usually moderately elevated in patients with BACM. This test is useful for excluding other diagnoses and in monitoring recovery. In a well-appearing child with BACM, where close follow-up is feasible, laboratory testing may not be needed. The most dangerous sequela of BACM is rhabdomyolysis, which can lead to myoglobin release and resulting renal failure. Rhabdomyolysis is very rare in children with BACM, and the risk of occurrence does not correlate with the CPK level. Some experts recommend that children with high CPK levels be monitored for dark-colored urine at home and, when noted, use urinalysis to identify myoglobinuria. A reasonable management approach when mild signs and symptoms are present, such as for the boy in the vignette, is observation without laboratory testing as long as follow-up is feasible and anticipatory guidance is provided to return if symptoms worsen or progress, weakness develops, or if dark-colored urine occurs. PREP Pearls Benign acute childhood myositis is an acute myositis that occurs after a viral infection, most often influenza. A child with classic signs and symptoms of benign acute childhood myositis does not require an extensive evaluation. A creatinine phosphokinase level is usually elevated, but rhabdomyolysis is rare. Rheumatological conditions (eg, polymyositis, dermatomyositis, systemic lupus erythematosus, juvenile idiopathic arthritis), and muscular dystrophies should be considered in a child with chronic progressive muscle pain and weakness.

Answer 84

The boy in the vignette has the classic symptoms and signs of postviral myositis (benign acute childhood myositis [BACM]), including difficulty walking, calf pain, and calf tenderness after a viral illness. Of the response choices, the best next step in his evaluation is to obtain a creatinine phosphokinase (CPK) level. The CPK level is usually moderately elevated in patients with BACM. This test is useful for excluding other diagnoses and in monitoring recovery. In a well-appearing child with BACM, where close follow-up is feasible, laboratory testing may not be needed. The most dangerous sequela of BACM is rhabdomyolysis, which can lead to myoglobin release and resulting renal failure. Rhabdomyolysis is very rare in children with BACM, and the risk of occurrence does not correlate with the CPK level. Some experts recommend that children with high CPK levels be monitored for dark-colored urine at home and, when noted, use urinalysis to identify myoglobinuria. A reasonable management approach when mild signs and symptoms are present, such as for the boy in the vignette, is observation without laboratory testing as long as follow-up is feasible and anticipatory guidance is provided to return if symptoms worsen or progress, weakness develops, or if dark-colored urine occurs. PREP Pearls Benign acute childhood myositis is an acute myositis that occurs after a viral infection, most often influenza. A child with classic signs and symptoms of benign acute childhood myositis does not require an extensive evaluation. A creatinine phosphokinase level is usually elevated, but rhabdomyolysis is rare. Rheumatological conditions (eg, polymyositis, dermatomyositis, systemic lupus erythematosus, juvenile idiopathic arthritis), and muscular dystrophies should be considered in a child with chronic progressive muscle pain and weakness.

Answer 85

The boy in the vignette has a clinical constellation of acute follicular conjunctivitis (Item C162A), tender preauricular lymphadenopathy, pharyngitis, and fever, which is most consistent with adenovirus pharyngoconjunctival fever. Adenoviral tonsillitis most often occurs in children younger than 3 years. PREP Pearls Adenovirus is responsible for a wide variety of infections in children, most commonly respiratory and gastrointestinal. Adenovirus pharyngoconjunctival fever presents with follicular conjunctivitis, tender preauricular lymphadenopathy, pharyngitis, and fever. Adenovirus is diagnosed by polymerase chain reaction performed on a nasopharyngeal swab sample; this test is included in the available respiratory multiplex viral panels.

Answer 86

The girl in the vignette most likely has benign paroxysmal vertigo of childhood (BPVC), given her intermittent symptoms and unremarkable physical examination findings. Benign paroxysmal vertigo of childhood is typically a self-limited condition for which observation is recommended. Diagnostic evaluation and referral to neurology are only recommended if symptoms worsen or there is impairment of function. Medication management with anti-emetics or antihistamines may be warranted if episodes are long lasting, which is not yet the case for the girl in the vignette. Although the cause of BPVC is unknown, there is usually a family history of migraine headaches, and children with BPVC may subsequently develop migraines. PREP Pearls Benign paroxysmal vertigo of childhood is the second most common cause of vertigo in children aged 2 to 12 years; the most common cause is middle ear disease. The diagnosis of benign paroxysmal vertigo is based on a history of brief episodes of vertigo associated with vomiting, pallor, nystagmus, ataxia or fearfulness, normal neurologic examination findings, audiometric, and vestibular findings between episodes, symptom-free intervals, and no other attributable disorder. Benign paroxysmal vertigo is a self-limited condition for which the treatment is observation. Referral to neurology for further evaluation and management may be considered for worsening symptoms or impairment of function.

Answer 87

The girl in the vignette has iron-deficiency anemia, the most common cause of anemia in her age group. Her high-volume consumption of cow milk, pica, and pallor support this diagnosis. Laboratory findings consistent with iron-deficiency anemia include a low hemoglobin (Hb) level, low mean corpuscular volume (MCV), low reticulocyte count, high red blood cell distribution width (RDW), high soluble transferrin receptor (sTfR) level, and low ferritin level (the storage form of iron). Anemia of chronic disease or inflammation is associated with a low reticulocyte count, normal RDW, high ferritin level, and low sTfR level. Gastrointestinal blood loss should be considered in the differential diagnosis of any child with iron-deficiency anemia. There may be a poor response to oral iron supplementation if there is a gastrointestinal condition; evaluation by a gastroenterologist for an inflammatory bowel disorder may be indicated. Markers of inflammation that can be helpful in determining the cause of anemia include elevated ferritin level, erythrocyte sedimentation rate, C-reactive protein level, and platelet count.

Answer 88

The most likely effect of care for a neonate under a radiant warmer is hyperthermia. Radiant warmers, while allowing for easy access to neonates, are associated with increased insensible water losses and, if not used properly, can result in significant deleterious effects. PREP Pearls A neutral thermal environment is important for care of newborns. Premature neonates should ideally be cared for in a double-walled incubator. If a radiant warmer is used, care must be taken to ensure that the sensor probe is properly placed and the warmer is placed in automatic mode; careful monitoring of the neonate’s temperature is required.

Answer 89

The boy in the vignette has toxocariasis, a tissue roundworm infection. His signs and symptoms (wheezing, hepatomegaly, anorexia, and weight loss), exposure to dogs and cats, habit of soil pica, and eosinophilia are consistent with infection with the visceral larva migrans form of Toxocara. In Southeast Asia, the seroprevalence of toxocariasis is approximately 34%. In the United States, the seroprevalence is 5%. PREP Pearls Toxocariasis is a parasitic infection caused by 2 species of roundworm (nematode): Toxocara canis and Toxocara cati, parasites of dogs (puppies) and cats (kittens), respectively. Toxocara infection causes disease when larvae migrate to tissues and local immune reactions result in injury. Major symptomatic presentations are visceral larva migrans (young children) and ocular larva migrans (older children and adolescents). The diagnosis of Toxocara is confirmed by Toxocara IgG serologic testing. Stool for ova and parasites are not helpful because the adult worm does not complete its life cycle in the human gastrointestinal tract.

Answer 90

The neonate in the vignette is at risk for sepsis due to a combination of factors, late preterm gestation, maternal fever, and prolonged rupture of membranes (PROM, >18 hours). The best next step in management is to obtain a complete blood cell count, perform a blood culture, and start intravenous ampicillin and gentamicin treatment. Early discharge is not the best option because signs of sepsis may be delayed until 72 hours after birth. Close observation for 48 hours without empiric antibiotics would not be a good choice given this neonate’s multiple risk factors for sepsis. Although normal laboratory evaluation may seem reassuring, the white blood cell counts and inflammatory markers may not be a reliable indicator of sepsis in the first 24 to 48 hours after birth. PREP Pearls Risk factors for early-onset neonatal sepsis include prematurity, evidence of maternal chorioamnionitis, untreated maternal colonization with group B Streptococcus, and prolonged rupture of membranes. Risk stratification algorithms may guide clinicians’ management of neonates at risk for sepsis and reduce the use of unnecessary antibiotics. The use of intrapartum antibiotics has reduced the incidence of early-onset neonatal sepsis.

Answer 91

The neonate in the vignette has isolated right microtia, a malformation of the external ear. Microtia commonly affects both the external ear canal and middle ear, so hearing can be affected. Thus, the best next step is to evaluate this neonate’s hearing with an auditory brainstem response test. This test is recommended soon after birth to evaluate inner ear function. PREP Pearls Neonates with microtia, a malformation of the external ear, should have their hearing evaluated with an auditory brainstem response test soon after birth. Microtia is usually an isolated congenital anomaly. Goldenhar and Treacher-Collins are the most common associated syndromes. Treatment of microtia consists of hearing restoration and external structure reconstruction.

Answer 92

The infant in the vignette most likely has colic. His parents can be reassured that it should improve by the time he is 4 months of age.

Answer 93

The child in the vignette has clinical features concerning for juvenile polyposis syndrome (JPS), evidenced by the presence of 5 or more juvenile polyps in the colon. Because JPS is associated with an increased risk for colorectal cancer, testing and referral to genetics for counseling is recommended for the child and other potentially affected family members. PREP Pearls For a child with fewer than 5 juvenile colonic polyps, endoscopic removal is recommended; repeat colonoscopy is not indicated unless symptoms recur. Children with 5 or more juvenile polyps should be referred for juvenile polyposis syndrome genetic testing. Pediatric polyposis syndromes often require monitoring for extraintestinal malignancies; the involvement of genetic counselors or cancer risk teams is essential.

Answer 94

The boy in the vignette is 18 months old. At this age, expected gross motor skills include walking without holding onto anyone or anything and climbing on and off a couch or chair without help. As the boy can take a few steps but cannot walk without holding onto anyone or anything, he most likely has delayed gross motor skills. His skills in the other developmental domains are appropriate for his age.

Answer 95

The adolescent in the vignette has ascending flaccid paralysis and areflexia without evidence of encephalopathy or myelopathy. This presentation is consistent with Guillain-Barré syndrome (GBS). The diagnosis of GBS is clinical. While diagnostic testing can be used to exclude alternative etiologies or provide additional supportive data, testing results can be normal, especially early in its clinical course. The foundation of treatment is supportive, with close monitoring for evolution to impending respiratory failure. Of the response choices, administration of intravenous immune globulin (IVIG) is the best next management step for this adolescent because of the severity and ongoing progression of her symptoms. Intravenous immune globulin is an immunomodulating therapy that can reduce hospital length of stay and time to ambulation in individuals with GBS. PREP Pearls Guillain-Barré syndrome is an autoimmune, inflammatory, demyelinating polyneuropathy that can have an acute-subacute presentation characterized by ascending symmetric flaccid paralysis and areflexia. Guillain-Barré syndrome is a clinical diagnosis; testing is not required to initiate treatment. While testing can be used to exclude alternative etiologies or provide additional supportive data, results can be normal, especially early in its course. Intravenous immune globulin is an immunomodulating therapy that can shorten hospital length of stay and time to ambulation for individuals with Guillain-Barré syndrome.

Answer 96

The child in the vignette has symptoms of acute severe gastroenteritis, including fevers, vomiting, and dysentery (diarrhea with blood and mucus). The Gram stain and biochemical test characteristics on stool culture suggest infection from a Shigella species. The boy is immunocompromised, with an absolute neutrophil count of 500/μL (0.50 × 109/L). In this situation, intravenous hydration and empiric treatment with intravenous ceftriaxone are recommended while awaiting culture and sensitivity data. Oral amoxicillin is not well absorbed in cases with these clinical findings; therefore, it is not an appropriate treatment option. Rehydration, preferably oral, is the mainstay of management in an otherwise healthy child with mild to moderate symptoms; antibiotics would not be recommended in such cases. PREP Pearls Shigella is the third most common cause of acute bacterial gastroenteritis in the United States after nontyphoidal Salmonella and Campylobacter species. The mainstay of management in an otherwise healthy child with mild to moderate symptoms of Shigella infection is rehydration. Antibiotic therapy is not indicated. Antibiotic therapy is indicated for Shigella infection in an immunocompromised child or a child with severe illness (dysentery and bacteremia). Intravenous ceftriaxone is the treatment of choice.

Answer 97

The boy in the vignette most likely has von Willebrand disease (vWD); this diagnosis is supported by his laboratory findings of an abnormal von Willebrand panel. Item C179 summarizes the different types of vWD. Type 2B is associated with thrombocytopenia, including neonatal thrombocytopenia, and is the most likely diagnosis for the child in the vignette. Desmopressin causes an increase in factor VIII activity, von Willebrand antigen, and ristocetin cofactor activity. Desmopressin is the most common treatment for individuals with type 1 vWD, although not every affected individual has a response. Treatment with desmopressin may cause hyponatremia and therefore requires fluid restriction when used. The infant in the vignette does not have type 1 vWD and would therefore not benefit from this therapy. In addition, in individuals with type 2B vWD, desmopressin can lead to a transient decrease in platelets, which may worsen bleeding. PREP Pearls Von Willebrand factor is a plasma protein that functions as a carrier for factor VIII and helps bind platelets to damaged endothelium. Von Willebrand disease type 2B may be associated with thrombocytopenia Desmopressin is not an appropriate treatment for type 2B von Willebrand disease and may worsen thrombocytopenia.

Answer 98

PREP Pearls Neonates born to mothers who have a history of genital herpes simplex virus infection but do not have active lesions or prodromal genital symptoms (eg, itching or burning) at delivery require only observation for signs of infection. To reduce the risk of vertical transmission, cesarean section should be performed for mothers who have active herpes simplex virus lesions or prodromal genital symptoms (eg, itching or burning) at the time of delivery.

Answer 99

The girl in the vignette has nocturnal enuresis which is likely secondary to sleep-disordered breathing (SDB). Her additional signs and symptoms of SDB include snoring and daytime fatigue. Given her 3+ tonsillar hypertrophy on physical examination, the most appropriate next step in management is referral to an otolaryngologist for consideration of tonsilloadenoidectomy. PREP Pearls Tonsillar and adenoid hypertrophy can lead to sleep-disordered breathing and obstructive sleep apnea. Nocturnal enuresis can be a symptom of sleep-disordered breathing secondary to tonsillar and adenoid hypertrophy. Tonsilloadenoidectomy is an appropriate first-line treatment in otherwise healthy children with obstructive sleep apnea due to documented tonsillar and adenoid hypertrophy.

Answer 100

PREP Pearls Inborn errors of metabolism arise from enzyme deficiencies, which lead to accumulation of toxic substrates and inadequate creation of the product(s) of the enzymatic reaction. Maple syrup urine disease can be identified on newborn screening. Clinical features in an untreated neonate may include maple syrup odor in cerumen and urine, encephalopathy, and central respiratory failure leading to death. Amino acid disorders associated with an abnormal odor include maple syrup urine disease (maple syrup), phenylketonuria (mousy/musty), and isovaleric acidemia (sweaty feet).

Answer 101

The girl in the vignette most likely has chemical urethritis caused by frequent bubble baths. This diagnosis is supported by her symptom of dysuria and the urinalysis results showing microscopic hematuria without pyuria. PREP Pearls Dysuria is a common symptom seen with urinary tract infection, inflammation, irritation, trauma, obstruction, and several systemic illnesses. Chemical urethritis can be caused by detergents, soaps, ointments, and bubble baths.

Answer 102

The radiograph of the boy in the vignette demonstrates a type III (completely displaced) supracondylar fracture. Any significantly displaced fracture in a child warrants immediate assessment for neurovascular compromise with a thorough neurovascular examination of the affected extremity. If the child displays signs of neurovascular compromise, urgent reduction under conscious sedation or general anesthesia is indicated. If there are no signs of neurovascular compromise, the next management steps include orthopedic surgery consultation and placement in a long-arm posterior splint until the specialist is consulted. However, these steps should not be undertaken until both neurologic and vascular status of the extremity is completely assessed. There are 3 types of supracondylar humerus fractures: Type I: Non-displaced or minimally displaced Type II: Displaced with intact posterior cortex Type III: Completely displaced with no cortical contact

Answer 103

The girl in the vignette, with linear growth acceleration, tachycardia, hypertension, goiter, and tremulousness, has hyperthyroidism. Her thyroid-stimulating hormone production would likely be completely suppressed due to thyroid hyperfunction, and her free thyroxine level would be elevated. Elevated levels of thyroid hormone increase linear growth through a direct stimulatory effect on the growth plates and enhanced growth hormone (GH) secretion from the pituitary gland. In contrast, poor linear growth is frequently seen with longstanding hypothyroidism. PREP Pearls Thyroid disease should be considered in the setting of abnormal growth. Thyroid hormone has a direct stimulatory effect on the growth plates and enhances growth hormone secretion from the pituitary gland; poor growth is often seen with longstanding hypothyroidism. The increased growth velocity of hormonally related tall stature can be differentiated from the normal growth velocity of non-hormonal causes of tall stature.

Answer 104

The girl in the vignette exhibits excess mobility of the elbows, knees, and spine. She does not have any joint pain or limitations in her activities. This type of joint mobility is a normal finding in school-aged children. The best next step is to reassure the family about her physical examination findings. She does not need any additional evaluation, treatment, or restriction of her activities. PREP Pearls Joint hypermobility that is not associated with pain or activity limitation is a normal finding in school-aged children. Ehlers-Danlos syndrome, hypermobility type, describes individuals with joint hypermobility, arthralgias, and/or atraumatic joint dislocations, and other criteria, such as skin hyperextensibility, striae, and atrophic scarring. Ehlers-Danlos syndrome, hypermobility type, is diagnosed clinically.

Answer 105

The adolescent male in the vignette has signs and symptoms consistent with carbohydrate malabsorption (watery and acidic stools, bloating, and flatulence). He reports an increase in symptoms after eating lactose-containing foods; thus, lactose intolerance is very likely and can be further investigated with a lactose breath test. Colonoscopy, esophageal pH impedance study, or wheat IgE testing would not be useful to identify lactose intolerance or other causes of carbohydrate malabsorption.

Answer 106

d PREP Pearls Necrotizing fasciitis is a severe, life-threatening pyogenic infection of the subcutaneous tissues and fascia characterized by rapidly progressive spread of infection along the fascial planes, resulting in tissue necrosis and often sepsis. Recent trauma, burns, surgery, and varicella infection are common risk factors for necrotizing fasciitis in children. Necrotizing fasciitis is a surgical emergency. Urgent surgical exploration with aggressive debridement of devitalized tissue is required. Clindamycin is recommended due to its anti-toxin activity and other properties (eg, long postantibiotic effect unaffected by inoculum size compared to penicillin).

Answer 107

The infant in the vignette has laryngomalacia, a dynamic airway obstruction at the level of the larynx. Most infants with laryngomalacia have noisy breathing that is worse when supine and sometimes worse when feeding. This infant has critical laryngomalacia with increased work of breathing that is interfering with feeding and growth. His inspiratory stridor localizes the site of obstruction to above the glottis, and his varying signs and symptoms corroborate a dynamic rather than fixed process. PREP Pearls Upper airway obstruction at or above the glottis is associated with inspiratory stridor; obstruction below the glottis is associated with biphasic or expiratory wheezing. Nasal obstruction in infants (eg, choanal atresia) is life-threatening, as infants are obligate nose breathers. Acute upper airway obstruction at any age is a medical emergency. Airway obstruction can be fixed or dynamic; either type can be worsened by superimposed infection or inflammation.

Answer 108

The neonate in the vignette has distal shaft hypospadias (Item C194A). As in this case, a dorsal hooded prepuce is often seen. Distal shaft hypospadias, which accounts for approximately 90% of cases, is usually surgically repaired at 6 to 12 months of age. Circumcision, if desired, should be deferred because the foreskin tissue may be used in the hypospadias repair. Parents should be reassured that circumcision can be performed at the time of hypospadias repair. Referral to a pediatric urologist is recommended, but an urgent urology consultation is not indicated. The neonate in the vignette’s stretched penile length is normal for age (mean [SD], 3.9 [0.8] cm in term infants), and both testes are descended in a normal scrotum, making a disorder of sexual development (DSD) unlikely; therefore, pelvic ultrasonography and a pediatric endocrinology consultation are not indicated. PREP Pearls Circumcision should be deferred for neonates with hypospadias because the foreskin tissue may be used in the surgical repair. Ninety percent of hypospadias cases are the distal shaft subtype. A neonate with hypospadias and micropenis, with or without undescended testes, should have an evaluation for disorders of sexual development.

Answer 109

Clinical features of trisomy 13 include small for gestational age, failure to thrive, microcephaly, cutis aplasia, cleft palate, holoprosencephaly, and postaxial polydactyly. Tetralogy of Fallot can be seen in trisomy 13. However, the neonate in the vignette has hypocalcemia and an absent thymus; his clinical features make 22q11.2 DS a more likely diagnosis. PREP Pearls 22q11.2 deletion syndrome is characterized by conotruncal heart defects, cleft palate, immune deficiency, dysmorphic facial features, and endocrine abnormalities (eg, hypoparathyroidism leading to hypocalcemia). The diagnostic test of choice for 22q11.2 deletion syndrome is a chromosomal microarray. Fluorescent in situ hybridization for the 22q11.2 critical region is reserved for a critically ill neonate with classic clinical features in whom a rapid turnaround time is required.

Answer 110

The neonate in the vignette has moderate thrombocytopenia (platelet count <50.0 × 103/µL [50.0 × 109/L]) but is otherwise stable with normal physical examination findings. The family history of thrombocytopenia makes neonatal (or fetal) alloimmune thrombocytopenia (NAIT) a likely diagnosis. Head ultrasonography is indicated at this time due to his level of thrombocytopenia and the family history of thrombocytopenia in a previous pregnancy. PREP Pearls Neonatal (fetal) alloimmune thrombocytopenia should be ruled out in any neonate with unexplained, moderate to severe thrombocytopenia. Head ultrasonography should be ordered for a neonate with moderate to severe thrombocytopenia to evaluate for evidence of intracranial bleeding. Neonatal (fetal) alloimmune thrombocytopenia can be more severe and occur earlier in future pregnancies; antenatal treatment may be warranted.

Answer 111

The neonate in the vignette is small for gestational age (SGA), most likely due to maternal smoking during pregnancy. Small for gestational age is defined as a birthweight below the 10th percentile for gestational age. Etiologic factors in SGA include conditions causing placental insufficiency, congenital viral infections, chromosomal and genetic conditions, and toxins such as cigarette smoke, alcohol, and illicit drugs.

Answer 112

The boy in the vignette has a corneal abrasion (Item C202). The most appropriate treatment is application of topical ophthalmic antibiotic ointment or drops to the affected eye until the abrasion is healed. Corneal abrasions are very common in childhood. Typical signs and symptoms include pain, tearing, redness, blurry vision, photophobia, and foreign body sensation. Children may also have mild eyelid swelling or redness resultant from mechanical irritation of rubbing the eye. In infants and very young children the only symptom of a corneal abrasion may be fussiness or excessive crying. PREP Pearls Signs and symptoms of a corneal abrasion include pain, tearing, redness, blurry vision, photophobia, and foreign body sensation; it may present as excessive fussiness or crying in young infants. The treatment of a corneal abrasion is application of topical ophthalmic antibiotic ointment or drops to the affected eye until the abrasion is healed. Tetracaine eye drops should not be prescribed for home use; tetracaine overuse can cause corneal cell death and inhibit corneal healing. Suspected corneal abrasions should be stained with fluorescein, and an examination performed with a cobalt blue light, using a standard ophthalmoscope or a Wood lamp.

Answer 113

The neonate in the vignette has cyanosis, no respiratory distress, low pulse oximetry readings in all extremities, and a systolic ejection murmur in the pulmonic location. These findings are most consistent with pulmonary valve stenosis. If the neonate had aortic valve stenosis, the murmur would be more prominent at the right upper sternal border (aortic valve position), and the right upper extremity saturation would be higher than the lower extremity saturation. Stenosis of either atrioventricular valve (mitral or tricuspid) would result in a diastolic murmur. PREP Pearls The murmur of pulmonary valve stenosis is a middle- to high-pitch systolic ejection murmur best heard at the left upper sternal border. Neonates with critical pulmonary stenosis will be desaturated due to limited pulmonary blood flow and right-to-left shunting, primarily at the atrial level. Neonates with critical and severe pulmonary stenosis should undergo balloon valvuloplasty.

Answer 114

The infant described in the vignette has a history and physical examination findings consistent with infantile atopic dermatitis. Atopic dermatitis (AD) is a chronic skin condition with inflammation presenting as erythema and pruritus that is characterized by exacerbations and remissions. The prevalence of atopic dermatitis is increasing worldwide, especially in better resourced countries; most affected individuals develop the condition during infancy. Atopic dermatitis is grouped under the atopic spectrum of diseases which includes food allergies, allergic rhinitis, and asthma. PREP Pearls Atopic dermatitis is a chronic inflammatory skin condition characterized by exacerbations and remissions. The prevalence of atopic diseases is increasing, especially in better-resourced countries. Genetic predisposition plays a strong role in the development of atopic dermatitis and other allergic conditions.

Answer 115

The adolescent in the vignette has idiopathic intracranial hypertension (IIH; previously known as pseudotumor cerebri); administration of acetazolamide is the best next step in her initial acute management. Idiopathic intracranial hypertension is a syndrome of unknown etiology; it is a diagnosis of exclusion. The pathophysiology is poorly understood. A proposed mechanism is blockage of cerebrospinal fluid (CSF) absorption at the arachnoid villi secondary to cerebral venous hypertension from transverse venous sinus stenosis. PREP Pearls Idiopathic intracranial hypertension is a syndrome of unknown etiology; it is a diagnosis of exclusion. Signs and symptoms of increased intracranial pressure include headache, visual obscurations, pulsatile tinnitus, diplopia, papilledema, cranial nerve VI palsies, and visual field defects. The management of idiopathic intracranial hypertension has 2 goals: 1) preservation of vision and 2) acute symptom relief. A carbonic anhydrase inhibitor (eg, acetazolamide) is the first-line medical therapy in conjunction with weight loss (for children with obesity); surgical intervention is reserved for fulminant presentations or treatment failure. Children and adolescents with idiopathic intracranial hypertension require long-term ophthalmological follow-up with serial ophthalmological examinations that evaluate the fundi, visual acuity, and visual fields.

Answer 116

The girl in the vignette felt something shift in her knee and experienced a rapid onset of pain and swelling after a seemingly mild twisting injury. She has a large effusion and apprehension with patellar motion but no anterior cruciate ligamentous laxity. The most likely diagnosis is a patellar dislocation. PREP Pearls Patellar dislocations and anterior cruciate ligament tears can both present in adolescents with rapid onset of pain and swelling following a twisting knee injury. Knee injury prevention warm-up programs have been shown to reduce rates of knee injury in young athletes. Patella tendon rupture is very uncommon in the pediatric population.

Answer 117

d PREP Pearls Medication errors are the most common adverse event in pediatrics. Disclosure of an adverse event to a patient and family is imperative and should occur at the earliest opportunity. Support and counseling should be provided to the patient, family, and health care practitioner after an adverse event. The practitioner is often the “second victim,” experiencing emotional distress following a patient adverse event.

Answer 118

The adolescent in the vignette developed acute onset of hematemesis, and endoscopy demonstrated acute hemorrhagic erosive gastritis. Of the substances listed, alcohol is most likely to cause these findings. Use of acetaminophen, montelukast, and/or marijuana are not associated with this endoscopic finding. PREP Pearls Symptoms of alcohol-induced gastritis can include nausea, vomiting, abdominal pain, and hematemesis. Alcohol use should be considered in children or adolescents exhibiting nausea, vomiting, abdominal pain, and/or hematemesis. Treatment of alcohol-induced gastritis includes acid suppression and avoidance of alcohol. ABP Content Specifications(s)

Answer 119

The boy in the vignette is being treated with low-dose aspirin for Kawasaki disease. Of the response choices, the best next management step is to administer an inactivated influenza vaccine prior to hospital discharge. Children taking aspirin are at risk for developing Reye syndrome if they contract influenza or varicella infection. Although the risk is minimal, there have been case reports of Reye syndrome associated with Kawasaki disease and aspirin use. The American Heart Association guidelines recommend that infants and children (aged 6 months and older) who are prescribed aspirin receive an inactivated influenza vaccine prior to hospital discharge, if not already vaccinated for the influenza season. Children on long-term aspirin therapy should receive the influenza vaccine annually. Parents of children taking aspirin should be counseled regarding the symptoms of Reye syndrome and advised to seek immediate medical attention if these symptoms develop. PREP Pearls Children taking aspirin are at risk of developing Reye syndrome if they contract influenza or varicella infection. Reye syndrome is characterized by altered mental status associated with significant elevation of liver transaminases and ammonia level. Children with Kawasaki disease who are prescribed aspirin therapy should receive an inactivated influenza vaccine prior to hospital discharge.

Answer 120

The infant in the vignette has a respiratory rate that is at the upper end of the normal range for his age; there are no findings to suggest underlying pathology. The best next step is to reassure the mother that he is not in danger, and schedule follow-up for reevaluation. This scenario is not uncommon and often precipitates an unnecessary referral to a specialist. PREP Pearls There is a broad range of normal respiratory rates with the widest variation in the first 2 years after birth. Multiple factors affect respiratory rate including body temperature, anxiety, metabolic dysfunction, and central neurologic dysfunction.

Answer 121

The infant in the vignette has a left multicystic dysplastic kidney (MCDK) and a normal-functioning right kidney. The best next step in this infant’s management is serial renal ultrasonography to monitor for involution of the MCDK and compensatory hypertrophy of the normal-functioning kidney. PREP Pearls Multicystic dysplastic kidney may be diagnosed on prenatal ultrasonography or incidentally by imaging performed for unrelated conditions or may present as an abdominal mass in the newborn. Renal ultrasonography of a multicystic dysplastic kidney characteristically reveals multiple noncommunicating cysts of different sizes with dysplastic renal parenchyma and an atretic ureter. Serial renal ultrasonography is indicated to monitor for involution of a multicystic dysplastic kidney and compensatory hypertrophy or any abnormalities of the contralateral kidney.

Answer 122

The girl in the vignette is displaying signs and symptoms that cause concern for pericardial tamponade. She has shortness of breath, nonfocal lung examination findings, an abdominal fluid wave, diminished pulses, and distal edema. Chest radiography shows cardiomegaly and a pleural effusion. With her medical history of systemic lupus erythematosus (SLE), and physical examination and imaging findings concerning for serositis (abdominal fluid wave and pleural effusion), pericardial tamponade and pericardial effusion are high on the differential diagnosis list. Of the response choices, the most likely additional finding is a quiet precordium with distant heart sounds. PREP Pearls A high index of suspicion is required to diagnose pericardial tamponade in children. Bedside ultrasonography or echocardiography are useful in detecting pericardial fluid and assessing for tamponade. Risk factors for pericardial tamponade include chest trauma, central venous catheters in or near the heart, recent cardiac surgery, malignancy, collagen vascular disease, severe renal disease, systemic infection with capillary leak, and hypothyroidism. Initial stabilization of individuals with pericardial tamponade requires resuscitation with parenteral boluses of isotonic fluid to maintain cardiac output.

Answer 123

The infant in the vignette has an increasing head circumference and intermittent vomiting, which should raise concern for evolving increased intracranial pressure. With his history of myelomeningocele, these symptoms and signs are concerning for the development of hydrocephalus, a common comorbid condition. Hydrocephalus affects 60% to 95% of children with myelomeningocele, especially with higher-level lesions; ongoing surveillance for the development of signs and symptoms of hydrocephalus is important for prompt recognition and treatment. The most common brain malformation accompanying myelomeningocele is a Chiari II malformation, in which there is downward displacement of part of the brainstem and cerebellum. Symptoms may include dysphagia, choking, hoarseness, stridor, central apnea, disordered breathing, opisthotonus, and in rare cases, sudden death. Many children with this condition are asymptomatic. PREP Pearls Myelomeningocele is a neural tube defect in which a portion of the spinal cord and nerves within the meningeal sac protrude through a defect in the vertebral column. Affected children experience motor and sensory dysfunction below the affected level of the spinal cord, the severity of which varies with the lesion level. Malformations of the brain, spinal cord, soft tissues, and vertebral column can accompany myelomeningocele; Chiari II malformations, hydrocephalus, and malformations of the brain are common. Hydrocephalus is a life-threatening condition which can present with a bulging or tense fontanelle, rapidly accelerating head circumference, lethargy, paralysis of upward gaze (sunsetting eyes), cranial nerve dysfunction, vomiting, headache, and irritability.

Answer 124

The neonate in the vignette has thrombocytopenia absent radius syndrome (TAR). This condition is characterized by severe thrombocytopenia and physical examination findings, including skeletal abnormalities of the upper (Item C216) or lower extremities, short stature, cardiac abnormalities (most commonly septal defects), and characteristic craniofacial features (posteriorly rotated ears, micrognathia, and macrocephaly). Thrombocytopenia absent radius syndrome is a congenital thrombocytopenia that is usually inherited in an autosomal recessive manner. It presents in infancy with thrombocytopenia, which may result in bleeding if not identified and treated promptly. The mainstay of treatment for TAR syndrome is supportive care with platelet transfusions. Irradiated, single-donor platelets should be administered to prevent adverse effects. Because the thrombocytopenia associated with TAR syndrome usually resolves after 1 year of age, definitive treatment with bone marrow transplantation is not warranted. Bone marrow transplantation is the recommended treatment for some congenital causes of thrombocytopenia (eg, congenital amegakaryocytic thrombocytopenia and Wiskott-Aldrich syndrome).

Answer 125

The adolescent’s 7-year-old sister is considered severely immunocompromised, because she is a recent hematopoietic stem cell transplant recipient. As she is a member of the adolescent’s household and the exposure to VZV is within 10 days, administration of varicella-zoster immune globulin is recommended at a dose of 125 units per 10 kg, intramuscularly (preferably within 96 hours). If varicella-zoster immune globulin is not available, oral valacyclovir can be administered for 22 days from the time of exposure.

Answer 126

The adolescent in the vignette meets criteria for the diagnosis of obesity with a body mass index (BMI) ≥95th percentile for age and sex. He has evidence of comorbidities, including insulin resistance (acanthosis nigricans) and hypertension. The best next step in his management is to order a fasting glucose level, basic metabolic panel, lipid panel, liver transaminases, and urinalysis to screen for additional comorbidities associated with obesity and hypertension. Current clinical guidelines recommend screening children and adolescents with a BMI ≥95th percentile for diabetes (fasting glucose level, hemoglobin A1c, or 2-hour oral glucose tolerance test), hyperlipidemia (lipid panel), and fatty liver disease (alanine aminotransferase and aspartate aminotransferase levels). A basic metabolic panel and urinalysis is indicated for all adolescents with hypertension.

Answer 127

The neonate in the vignette has gastroschisis, an abdominal wall defect lateral to the umbilicus with exposed bowel. In most cases, this condition will be identified prenatally, and the delivery room staff will be prepared ahead of time to manage the care of the neonate. In addition to providing regular delivery room care, it is critically important to protect the bowel from injury due to fluid loss by keeping it covered with warm, soaked gauze and putting the lower half of the body (from the upper abdomen down) in a bowel bag. Wrapping the bowel in a compression bandage will cause further injury to the bowel. PREP Pearls In a neonate with gastroschisis, it is critically important in the delivery room to protect the exposed bowel from further injury due to fluid loss. Surgical treatment of gastroschisis consists of either primary closure, or a staged approach with silo placement to protect the bowel while it is slowly introduced into the underdeveloped abdomen, and subsequent closure. Gastroschisis may be associated with intestinal atresia.

Answer 128

Of the response choices, the best next step for the adolescent in the vignette is obtaining rapid serum glucose testing and ethanol, acetaminophen, and salicylate levels. The most common laboratory abnormality found in ethanol ingestion, and one requiring urgent treatment, is hypoglycemia. It is important to obtain ethanol and possible coingestant levels rapidly to direct further management. PREP Pearls Alcohol or ethanol intoxication is managed with supportive care and includes rapid evaluation for hypoglycemia, electrolyte derangements, and coingestant levels. Adolescent alcohol use increases the risk of alcohol use disorders as adults, and thus requires early intervention and possible referral to treatment.

Answer 129

The adolescent in the vignette has acute onset of fever, limp, right ankle bony tenderness, and an elevated C-reactive protein (CRP) level after an ankle injury. These signs and symptoms are consistent with acute hematogenous osteomyelitis (AHO). PREP Pearls The initial laboratory evaluation of children with suspected acute hematogenous osteomyelitis should include a C-reactive protein level and blood culture. Magnetic resonance imaging is the imaging modality of choice to confirm the diagnosis. The pathogen most commonly associated with acute hematogenous osteomyelitis in every age group is Staphylococcus aureus (including methicillin-resistant S aureus); group B Streptococcus and Kingella kingae are important pathogens in neonates and young children, respectively. Transition to oral antibiotic therapy is recommended for hospitalized children with suspected or proven acute hematogenous osteomyelitis who have demonstrated a good clinical and laboratory response to initial intravenous antibiotic therapy.

Answer 130

The neonate in the vignette has persistent vomiting, abdominal distention with a palpable bowel loop, and multiple dilated loops of bowel noted on radiography. This presentation is concerning for an intestinal obstruction, even if the emesis is not bilious (green). The contrast enema findings are consistent with Hirschsprung disease (HD); thus, a rectal suction biopsy is indicated as the next diagnostic step, and of the response choices is the test most likely to reveal the diagnosis. For this neonate, the biopsy demonstrated an absence of ganglion cells and confirmed the diagnosis of HD. PREP Pearls Intestinal obstruction should be suspected in neonates with bilious (green) emesis, failure to pass meconium by 24 to 48 hours after birth, abdominal distention, and/or history of maternal polyhydramnios. The absence of 1 or more of these signs and symptoms does not exclude neonatal intestinal obstruction. Initial management steps when a neonatal bowel obstruction is suspected include a thorough physical examination, fluid resuscitation as needed, and urgent pediatric surgical consultation. When intestinal obstruction is suspected, clinically unstable neonates may require urgent operative management without definitive imaging results.

Answer 131

The girl in the vignette has conjunctivitis-otitis syndrome. Non-typeable Haemophilus influenzae is the most common pathogen associated with this syndrome and is therefore the most likely etiology of this girl’s findings. The Haemophilus influenzae childhood vaccine protects against Haemophilus influenzae type b; it does not provide protection against non-typeable Haemophilus influenzae. Oral amoxicillin-clavulanate is the first-line treatment for conjunctivitis-otitis syndrome. PREP Pearls Non-typeable Haemophilus influenzae is the most common etiology of conjunctivitis-otitis syndrome. There is conflicting evidence as to whether children are more likely to have bacterial or viral causes of conjunctivitis; many sources report that bacteria may cause up to 80% of infectious conjunctivitis in children. Both bacterial and viral conjunctivitis are self-limiting conditions. Good hand hygiene is the most effective way to prevent spread.

Answer 132

The girl in the vignette has a bifid uvula and clinical findings suggestive of a submucosal cleft palate (SMCP), including hyper-nasal speech, air escape from her nose, and a palatal ridge. The additional findings of hypertelorism and long face suggest an underlying genetic syndrome such as Loeys-Dietz or DiGeorge syndrome. DiGeorge syndrome is less likely because there is no history of neonatal hypocalcemia or infections due to T-cell defects. The girl in the vignette most likely has Loeys-Dietz syndrome (LDS). PREP Pearls Bifid uvula may be associated with a submucosal cleft palate. Bifid uvula is associated with several genetic syndromes; all children with a bifid uvula should be evaluated for cardiac anomalies. Chronic recurrent ear infections, nasal regurgitation, and velopharyngeal insufficiency are commonly seen in children with submucosal cleft palate.

Answer 133

The adolescent in the vignette is experiencing an acute myelopathy, a neurological emergency requiring urgent neuroimaging to evaluate for spinal cord compression or inflammation. Magnetic resonance imaging (MRI) of the spine with and without contrast is the best test to evaluate the spinal cord and associated structures. The presence of a compressive lesion requires neurosurgical intervention. PREP Pearls Acute spinal cord dysfunction is a neurological emergency requiring careful history, physical examination, and urgent neuroimaging to evaluate for cord compression. Magnetic resonance imaging of the spine with and without contrast is the best test to evaluate the spinal cord and associated structures. Common symptoms and signs of an acute myelopathy include: bilateral motor and/or sensory symptoms, bladder and/or bowel dysfunction, and neck/back pain. In the acute phase, children and adolescents with myelopathy can present with a flaccid paralysis and areflexia below the level of the lesion; this may lead to diagnostic confusion due to the absence of upper motor neuron signs.

Answer 134

PREP Pearls Crotalidae polyvalent immune fab is the standard of treatment for children with pit viper snake bite displaying severe local reactions, systemic symptoms, or rapid progression of symptoms. Initial dosing is 4 to 6 vials. The 2 families of poisonous snakes in the United States are Crotalidae (pit vipers) and Elapidae (eg, coral snakes and cobras). Crotalidae envenomations cause severe local tissue damage and can progress to systemic hematotoxicity (eg, nausea, vomiting, hypotension, coagulation abnormalities); Elapidae envenomations are neurotoxic with little to no local tissue damage.

Answer 135

d The boy in the vignette has no symptoms beyond ear pain, had a recent experience with swimming and water sports, and has otoscopic examination findings (Item C230) typical for otitis externa (external canal edema and debris); this scenario is consistent with a diagnosis of otitis externa. Swimmers have a 5 times increased incidence of otitis externa. The differential diagnosis of an ear canal with this appearance includes otitis media with tympanic membrane rupture, skin conditions such as atopic dermatitis or psoriasis, and a missed foreign body in the canal causing inflammation. PREP Pearls Otitis externa often presents with isolated ear pain after a recent exposure to water (eg, swimming, water sports). Topical combined antibiotic and steroid drops is the first-line treatment of otitis externa. Ototoxic preparations (eg, aminoglycosides) should not be instilled in the ear canal without first visualizing an intact tympanic membrane.

Answer 136

The child in the vignette has a low CD4 cell count because of untreated HIV infection. The presence of acid-fast oocysts in the stool is consistent with cryptosporidiosis. Diarrheal illness from Cryptosporidium species is associated with recreational water parks and contaminated drinking water. In a child with HIV infection, prompt initiation of antiretroviral therapy (eg, dolutegravir, emtricitabine, and tenofovir combination) to improve the CD4 cell count results in resolution of diarrheal symptoms. Treatment is generally not necessary in otherwise healthy children; however, treatment with oral nitazoxanide is considered in children without HIV infection for severe symptoms (>10 loose stools per 24 hours) or persistent symptoms (>2 weeks). PREP Pearls Cryptosporidium is an intracellular parasite responsible for diarrheal illness. Most Cryptosporidium infections are asymptomatic and self-limiting in immunocompetent children. Severe or protracted illness is seen in children with untreated HIV, solid or stem cell transplantation, or immunodeficiency. In a child with HIV infection, prompt initiation of antiretroviral therapy can lead to resolution of diarrhea due to Cryptosporidium.

Answer 137

b The adolescent in the vignette has anemia and multiple risk factors for iron deficiency including a diet deficient in iron-containing foods and heavy monthly menses. However, her hemoglobin level did not improve 1 month after starting an iron supplement. The best next management step is to obtain laboratory testing to evaluate her iron levels to confirm the diagnosis of iron-deficiency anemia. Most likely, the lack of improvement in the adolescent’s hemoglobin level is due to non-adherence with her iron supplement. However, it is important to ensure that there is not an alternative etiology of her anemia before focusing solely on methods to increase her iron intake (eg, a detailed list of iron-containing foods, strategies to improve medication adherence). Decreasing her menstrual flow with an oral contraceptive is unlikely to correct the current iron deficiency when there is poor dietary iron intake.

Answer 138

The adolescent in the vignette has signs and symptoms consistent with bacterial vaginosis (BV). The gold standard test for BV is the Nugent score of a vaginal fluid Gram stain. In clinical practice, BV can be diagnosed by the presence of at least 3 of the following Amsel criteria: Homogeneous, thin vaginal discharge that smoothly coats the vaginal walls Clue cells (vaginal epithelial cells covered with adherent bacteria) on microscopic examination (Item C234A) pH of vaginal fluid >4.5 (normal vaginal pH is 3.8 to 4.3) Fishy odor of vaginal discharge before or after addition of 10% potassium hydroxide (KOH; ie, the whiff test) First-line treatment for bacterial vaginosis is metronidazole orally or intravaginally.

Answer 139

d PREP Pearls During childhood, a total of 6 doses of a pertussis-containing vaccine are recommended: diphtheria, tetanus, pertussis (DTaP) in a 5-dose series, typically at ages 2, 4, 6, and 15 to 18 months, and 4 to 6 years; and 1 dose of tetanus, diphtheria, pertussis (Tdap) at age 11 to 12 years. For children and adolescents aged 7 to 18 years who are not fully vaccinated against tetanus, diphtheria, and pertussis, the preferred first vaccine in the catch-up series is tetanus, diphtheria, pertussis (Tdap).

Answer 140

The neonate in the vignette most likely has bilateral choanal atresia. After delivery, he had no respiratory distress and had normal oxygen saturation levels. He quickly developed oxygen desaturation and respiratory distress when he became quiet and calm. The best next step in his management would be to pass a nasogastric tube through both nares. In the case of bilateral choanal atresia, the physician would be unable to pass the tube through either naris. PREP Pearls Bilateral choanal atresia in a neonate is a medical emergency because neonates are obligate nose breathers. Passage of a nasogastric tube through both nares should be attempted in a neonate with suspected choanal atresia. A neonate with choanal atresia or stenosis should undergo evaluation for associated anomalies, such as those seen in CHARGE syndrome (Coloboma, Heart defects, Atresia or stenosis of the choanae, Retardation of growth and development, Genitourinary anomalies, and Ear anomalies [including hearing loss]).

Answer 141

The adolescent in the vignette is a gymnast and has pain with back extension. Spondylolisthesis is the most likely diagnosis. This condition can usually be identified on plain radiography. If plain radiographs are normal and there is a high degree of suspicion, magnetic resonance imaging (MRI) is the next best option. Computed tomography (CT) and a bone scan may be indicated in the evaluation of back pain due to other etiologies (eg, primary or metastatic bone tumor and injury) but would not be the best imaging options to evaluate the adolescent in the vignette.

Answer 142

The girl in the vignette has recurrent urinary tract infections (UTIs) most likely secondary to bowel bladder dysfunction; therefore, the best next management step is to optimize her bowel regimen. Prophylactic antibiotics will not address her underlying condition (chronic constipation), are unlikely to prevent her UTIs in the long term, and may contribute to antibiotic resistance. Referral to a urologist may be necessary if she continues to have recurrent UTIs after optimization of her bowel regimen. Reassurance alone is inadequate because she is likely to have recurrent UTIs until her chronic constipation is successfully treated. PREP Pearls Bowel and bladder dysfunction resulting in inadequate bladder emptying is a common but underrecognized cause of recurrent urinary tract infections. Renal scarring may occur after recurrent urinary tract infections but does not usually lead to long-term sequelae in the absence of anatomical urinary system abnormalities. If bacteria enter the bloodstream from the urinary tract, urosepsis and meningitis may occur; neonates and immunocompromised children are at higher risk for systemic infection.

Answer 143

The neonate in the vignette has findings consistent with trisomy 13; testing would most likely result in a karyotype of 47,XX, +13. Neonates with trisomy 13 exhibit intrauterine growth restriction and are small for gestational age. Clinical features may include: Midline defects: Cleft lip and/or palate, cyclopia Brain anomalies: Holoprosencephaly, microcephaly Scalp defect: Cutis aplasia Cardiac defects: Atrial septal defect, ventricular septal defect, tetralogy of Fallot, double outlet right ventricle Eye anomalies: Micro-ophthalmia, anophthalmia Hernia: Inguinal, umbilical Renal: Polycystic kidney, hydronephrosis, horseshoe kidney Musculoskeletal: Postaxial polydactyly, congenital talipes equinovarus

Answer 144

PREP Pearls The middle third of the shaft is the most common location of a clavicle fracture; it can be treated conservatively with use of an arm sling, analgesia, and follow-up with a pediatrician. Urgent orthopedic surgery consultation is necessary for an open clavicle fracture, sternoclavicular dislocation, displaced fractures of the distal third of the clavicle, tenting of the skin over the clavicle, or evidence of neurovascular compromise. Fractures of the proximal third of the shaft are the least common type of clavicular fracture and are often associated with serious chest, lung, neck, and vascular injury.

Answer 145

In the vignette, the boy’s signs and symptoms of fever, limp, pain with internal and external rotation of the right hip, leukocytosis, and elevated C-reactive protein (CRP) level support a diagnosis of pyogenic arthritis of the hip joint. The best next step in his evaluation is ultrasonography of the right hip to evaluate for an effusion. If an effusion is detected, the joint should be aspirated as soon as possible to confirm the diagnosis and obtain fluid to send for cell count and culture. A synovial fluid white blood cell count (WBC) of ≥50,000/μL (≥50.0 × 109/L) with neutrophilic predominance is highly suggestive of pyogenic arthritis. Urgent orthopedic consultation, surgical drainage, and irrigation of the hip joint space is required given the risk of aseptic necrosis of the femoral head from increased intra-articular pressure and compromised blood flow. Joint fluid cultures are positive for a bacterial pathogen in 60% of cases. Polymerase chain reaction of the synovial fluid may be positive for fastidious organisms such as Kingella kingae. A blood culture is positive for a bacterial pathogen in 40% of cases of pyogenic arthritis. While results of a blood culture may be helpful in guiding antibiotic treatment, making the diagnosis and surgical draining of a septic joint are the first priority.

Answer 146

The adolescent in the vignette has abdominal pain, a positive Murphy sign (pain associated with palpation of the right upper quadrant during inspiration), and scleral icterus; this clinical scenario is suggestive of choledocholithiasis. Of the response options, obesity is the factor that places the girl at risk for the development of cholelithiasis. Age of menarche, use of nonsteroidal anti-inflammatory drugs, and history of previous appendectomy are not risk factors for the development of cholelithiasis.

Answer 147

The girl in the vignette has impairments in cognitive and adaptive functioning consistent with an intellectual disability and facial features characteristic of fetal alcohol syndrome. The following 3 criteria must be met to diagnose fetal alcohol syndrome: Prenatal and/or postnatal growth deficiency Characteristic facial features including reduced palpebral fissure length, smooth philtrum, and thin upper lip border Neurological or neurobehavioral deficits

Answer 148

The adolescent in the vignette has a painless testicular mass that is increasing in size. Testicular cancer is the most likely diagnosis. Cryptorchidism is a major risk factor for the development of testicular cancer. Infants with cryptorchidism, such as the boy in the vignette who had an orchiopexy at 9 months of age, are up to 8 times more likely to develop testicular cancer even after the testis is placed securely in the scrotum. Cryptorchidism is the risk factor most likely associated with this adolescent’s testicular cancer. It is important to note that premature infants have a high incidence of cryptorchidism. Cerebral palsy, seizure disorder, and urinary incontinence are not associated with an increased risk of developing testicular cancer.

Answer 149

The infant in the vignette has had 3 episodes that meet criteria for a brief resolved unexplained event (BRUE). Because of the recurrence, duration of >1 minute, and concerning history and physical examination findings, he does not meet criteria for lower-risk BRUE and further evaluation is indicated. Reassurance and follow-up is not appropriate. Potential life-threatening etiologies for his presentation include central nervous system (CNS) abnormalities and abusive head trauma. Thus, the best next step in his management is to obtain computed tomography of the head. A high index of suspicion for nonaccidental trauma should be maintained. Concerning findings include the infant’s fussiness and the bruise on his arm in the context of an otherwise unexplained recurrent potentially life-threatening event. PREP Pearls For infants with new or recurrent episodes of apnea with color change and/or loss of tone, without evidence of an underlying condition, a high index of suspicion must be maintained for non-accidental head trauma. The most common cause of obstructive sleep apnea in children is tonsillar and/or adenoidal hypertrophy. Children with neuromuscular disorders, skeletal dysplasias, and craniofacial anomalies are at high risk for complicated obstructive sleep apnea.

Answer 150

The infant in the vignette has congenital idiopathic talipes equinovarus, commonly called clubfoot (Item C248A). The best next step in management is to refer him to a pediatric orthopedic surgeon for treatment. This condition will not improve without treatment, which should begin as soon as possible, so having him return for reevaluation in 1 month is not the preferred response. Imaging is not routinely recommended for this condition, thus foot and ankle radiographs would not be the appropriate next step. Physical therapy alone will not correct the deformity; timely treatment by a pediatric orthopedic surgeon is required. PREP Pearls Clubfoot is an inward rotational anomaly of the foot at the ankle with an associated increase in the midfoot crease and a shortened calf muscle on the affected side. The mnemonic CAVE is used to describe the features of clubfoot: cavus (high arch), adducted position of the forefoot, hindfoot varus (heel curves in towards the midline), and equinus (ankle stuck in a plantarflexed position). It is important to promptly refer infants with clubfoot to a pediatric orthopedic surgeon.

Answer 151

The adolescent in the vignette has imaging findings consistent with a cerebral arterio-venous malformation (AVM). Arterio-venous malformations are congenital high-flow vascular malformations in which there is a direct connection between the arteries and veins and no intervening capillary bed. The majority of AVMs are caused by sporadic pathologic genetic variants resulting in dysregulated vasculogenesis. However, there are genetic syndromes associated with development of AVMs, most commonly hereditary hemorrhagic telangiectasias. Cavernous malformations (CM) are slow-flow vascular malformations consisting of a tangled, enlarged, abnormal capillary bed without intervening brain parenchyma. Cavernous malformations may be familial or sporadic. Hemorrhage may occur. Common symptoms of CM include headache, seizures, vision changes, and balance problems. On MRI, cavernous malformations have a “popcorn” or “mulberry-like” cluster of tiny blood vessels with surrounding hemosiderin deposits. Unlike AVMs, there is no intervening brain parenchyma. The imaging appearance of the child in the vignette’s vascular lesion is not consistent with a CM. PREP Pearls Arterio-venous malformations are congenital, high-flow, vascular malformations in which there is a direct connection between the arteries and veins and no intervening capillary bed. The majority of arterio-venous malformations are diagnosed incidentally, during a diagnostic evaluation for seizures, headaches, or progressive focal neurological deficits, or acutely, in the setting of intracranial hemorrhage. Manifestations of symptomatic arteriovenous malformations vary based on age, location, size, and the features of the lesion itself.

Answer 152

b Statin therapy (eg, atorvastatin) is recommended for those aged 10 years and older whose LDL cholesterol level remains above goal after lifestyle modification. For those with a family history of cardiovascular disease, 1 high-level risk factor, or 2 or more moderate-level risk factors, the threshold for starting statin therapy is an LDL cholesterol level ≥160 mg/dL (4.1 mmol/L). The treatment goal is an LDL level <130 mg/dL (3.4 mmol/L). For those at higher risk, the threshold for statin treatment is an LDL level ≥130 mg/dL (3.4 mmol/L). The treatment goal is an LDL level <100 mg/dL (2.6 mmol/L). Statins inhibit hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis, resulting in decreased endogenous production of cholesterol, upregulation of LDL receptors in the liver, and increased clearance of LDL cholesterol.

Answer 153

The adolescent in the vignette is experiencing lower abdominal pain during menstruation consistent with dysmenorrhea. Primary dysmenorrhea, menstrual pain in the absence of any underlying pathologic process, is the most common type of dysmenorrhea in adolescents. The first-line treatment of primary dysmenorrhea is a nonsteroidal anti-inflammatory medication (NSAID) such as ibuprofen or naproxen sodium. Pelvic examination with a speculum (with a chaperone present) and testing for sexually transmitted infections should be performed in sexually active adolescents with severe dysmenorrhea.

Answer 154

The adolescent in the vignette has autoimmune adrenalitis, or Addison disease. The history of type 1 diabetes (autoimmune risk factor), new hypoglycemia, fatigue, tachycardia, low blood pressure, and hyperpigmentation in the hand creases are all suggestive of primary adrenal insufficiency. The diagnosis would need to be confirmed by laboratory evaluation. PREP Pearls Additional autoimmune conditions, including autoimmune hypothyroidism and celiac disease, commonly occur in individuals with type 1 diabetes. New onset of celiac disease and Addison disease can cause unexpected hypoglycemia in children and adolescents with type 1 diabetes. Hypoglycemia in children and adolescents with type 1 diabetes is commonly caused by too high of an insulin dose for the basal requirements, carbohydrate intake, and/or activity level.

Answer 155

The child in the vignette has chronic cervical lymphadenopathy. Lymphadenopathy persisting for >6 weeks is considered chronic, 2 to 6 weeks is subacute, and <2 weeks is acute. The best next step in the evaluation of this child’s chronic cervical lymphadenopathy is to obtain a complete blood count, inflammatory markers, and Epstein–Barr virus (EBV), cytomegalovirus (CMV), and Bartonella henselae serology. Ultrasonography of an enlarged lymph node may assist in identifying an abscess, defining the anatomy of the mass, differentiating a malignant versus benign process, and developing strategies for biopsy. Ultrasonography will not determine the specific etiology of lymphadenopathy and is therefore not the best next step in management for the child in the vignette. PREP Pearls Reactive cervical lymphadenopathy from a viral infection is the most common cause of lymphadenopathy in children. Epstein–Barr virus, cytomegalovirus, and Bartonella henselae (cat scratch disease) are common causes of chronic cervical lymphadenopathy in children. Neoplasms are rare in children, but must be considered in the differential diagnosis of chronic lymphadenopathy. Non-Hodgkin lymphoma is more common in children younger than 6 years, and Hodgkin lymphoma is more common in children older than 6 years.

Answer 156

The premature neonate in the vignette has signs of pulmonary overcirculation (prolonged need for mechanical ventilatory support and increased pulmonary vascular markings on chest radiograph) and decreased systemic perfusion (tachycardia, increasing creatinine levels, and feeding intolerance) caused by a patent ductus arteriosus (PDA). PREP Pearls The ductus arteriosus is a blood vessel that anatomically connects the pulmonary artery to the aorta to allow blood to bypass the lungs in fetal life. Nonsteroidal anti-inflammatory drugs (indomethacin and ibuprofen) and acetaminophen decrease synthesis of prostaglandins, leading to vasoconstriction and subsequent closure of a patent ductus arteriosus. There is significant practice variation regarding treatment of a hemodynamically significant persistently patent ductus arteriosus.

Answer 157

The boy in the vignette, with gross motor delay and regression, seizures, hypotonia, exaggerated startle response, and cherry-red spot on his retina, has Tay-Sachs disease (TSD). Tay-Sachs disease is part of a continuum of disorders caused by deficiency of the enzyme β-hexosaminidase A (HEXA), which is needed to break down GM2 ganglioside. In the absence of this enzyme, GM2 ganglioside is aggregated in the lysosomes of brain and nerve cells, leading to the clinical features of the disease. The spectrum of disorders caused by HEXA deficiency includes acute infantile, subacute juvenile, and late-onset TSD. Clinical features expressed depend on the amount of enzyme present. The child in the vignette is seen with acute infantile TSD. PREP Pearls Tay-Sachs disease is an autosomal recessive disorder characterized by gross motor delay, seizures, developmental regression, increased startle response, and a cherry-red spot on the retina. Management of Tay-Sachs disease is supportive with interventional therapies, control of seizures, and nutritional support.

Answer 158

The boy in the vignette experienced a nosebleed that resolved after a brief period of applying pressure. The best next management step is to provide reassurance and discuss conservative measures that include applying pressure in the appropriate location for 5 to 10 minutes without interruption, frequent moisturizing of the nasal mucosa with nasal saline or ointment, humidifying the air in the home, and discouraging nose picking. PREP Pearls Nosebleeds are common in children and most can be treated with conservative management such as applying pressure in the appropriate location for 5 to 10 minutes without interruption, moisturizing the nasal mucosa with nasal saline or ointment, providing humidified air in the home, and discouraging nose picking. The differential diagnosis of epistaxis includes trauma, inflammation, dry air, neoplasms, intranasal drugs, structural abnormalities, and bleeding disorders. Nosebleeds are divided into 2 categories, anterior and posterior, based on the location of the bleeding. Anterior nosebleeds are the most common type and are much easier to visualize and control than posterior nasal bleeds.

Answer 159

The girl in the vignette ingested lye, a caustic alkali, and is displaying signs and symptoms of upper airway edema (mouth and lip swelling, vocal hoarseness) and impending airway compromise (drooling, stridor). The best next management step is endotracheal intubation to secure her airway. PREP Pearls Alkali ingestions cause tissue liquefaction necrosis resulting in greater injury compared to acid ingestions. Symptoms of airway injury due to alkali ingestion, including drooling, mouth pain, lip swelling, and stridor, should raise concern for impending airway compromise; a secure airway should be ensured. Symptomatic, clinically stable children should have esophagogastroduodenoscopy performed within 48 hours of alkali ingestion; current guidelines support a watchful observation period for asymptomatic or minimally symptomatic children.

Answer 160

The boy in the vignette has a respiratory tract infection associated with conjunctivitis, oral mucositis, and rash. This presentation is consistent with Mycoplasma pneumoniae–induced rash and mucositis (MIRM). PREP Pearls Approximately 10% of individuals infected with Mycoplasma pneumoniae develop a nonspecific maculopapular rash. Mycoplasma pneumoniae–induced rash and mucositis (MIRM) is an extrapulmonary manifestation characterized by painful erosive lesions involving 2 or more mucosal sites; skin lesions (eg, target lesions, bullae) may be absent or sparse. Treatment with azithromycin and steroid therapy may shorten the clinical course of Mycoplasma pneumoniae–induced rash and mucositis.

Answer 161

The boy in the vignette has exercise-related respiratory symptoms that are neither relieved nor prevented by the use of an albuterol inhaler. The boy’s symptoms are most consistent with exercise-induced laryngeal obstruction (EILO). The best next step in this boy’s management is to schedule a treadmill exercise provocation test, the best way to reproduce the situation in which he has symptoms and objectively monitor the effect of submaximal exercise on his lung function. If the boy has exercise-induced asthma (EIA), he should have at least partial relief of symptoms or some degree of symptom prevention with the use of an albuterol inhaler, even if his technique is not perfect. Although assessing his inhaler technique would be beneficial, this evaluation would likely delay his diagnosis and appropriate management. PREP Pearls Exercise-induced asthma is characterized by onset several minutes after completion of submaximal exercise and is relieved or prevented by bronchodilator inhalation. A treadmill exercise provocation test is the most appropriate way to document the presence and severity of exercise-induced asthma. Exercise-induced laryngeal obstruction is associated with neck or upper chest tightness and inspiratory stridor or stertor that may be incorrectly interpreted as wheezing. There is a direct relationship between exercise intensity and symptoms, which are not relieved by albuterol.

Answer 162

The boy in the vignette has mild neutropenia (0.212 × 4,800 = ~1,018/μL), as defined by an absolute neutrophil count (ANC) less than 1,500/μL but above 1,000/μL. Neutropenia may be divided into mild (ANC 1,000 to 1,500/μL), moderate (ANC 500 to <1,000/μL), and severe (ANC <500/μL) categories, with some literature including a very severe category (ANC <200/μL).

Answer 163

The physical examination findings of the neonate in the vignette are most consistent with arthrogryposis (also known as arthrogryposis multiplex congenita), a disorder characterized by congenital contractures that affect 2 or more areas of the body. An isolated congenital contracture, such as isolated clubfoot, is not considered arthrogryposis. Arthrogryposis is associated with more than 400 conditions; however, less than half of cases have a known underlying genetic cause. PREP Pearls Arthrogryposis is a disorder characterized by congenital contractures that affect more than 1 area of the body. The clinical features of arthrogryposis result from decreased or absent fetal joint movement in utero. The 2 most common forms of arthrogryposis are amyoplasia (congenital absence or underdevelopment of muscles) and distal arthrogryposis.

Answer 164

The adolescent boy in the vignette has asymptomatic proteinuria, as suggested by the findings of 2+ protein and a urine protein:creatinine ratio (UPCR) of 0.6 mg/mg on random urinalysis. The best next step in his evaluation is to obtain a first morning UPCR to confirm orthostatic proteinuria. If the first morning UPCR is normal (≤0.2 mg/mg), clearance for sports participation can be given. If the first morning UPCR is greater than 0.2 mg/mg, the boy should be referred to a pediatric nephrologist, and clearance for sports participation should be withheld pending that evaluation. PREP Pearls Proteinuria is defined as a urine protein excretion greater than 100 mg/m2 daily or urine protein:creatinine ratio of greater than 0.2 mg/mg on a spot urine sample. In orthostatic proteinuria, a random urine sample will be urine dipstick test positive for protein and the urine protein:creatinine ratio may be greater than 0.2 mg/mg, but on a first morning urine specimen the protein:creatinine ratio will be less than or equal to 0.2 mg/mg. Children with orthostatic proteinuria should have a first morning urinalysis checked at each health supervision visit.

Answer 165

The girl in the vignette has stage I hypertension. Athletes with stage I hypertension can be cleared for participation in all types of sports provided they do not have other conditions that would limit participation. The girl in the vignette can be cleared for both softball and weight lifting. PREP Pearls Young athletes with stage I hypertension can participate in sports without restrictions. Children and adolescents with untreated stage II hypertension should be restricted from sports with a high static component (eg, weight lifting, martial arts, and gymnastics). Criteria for stage I hypertension in children younger than 18 years require blood pressure measurements at or above the 95th percentile but lower than the 95th percentile plus 12 mm Hg.

Answer 166

The boy in the vignette has hypophosphatemic rickets due to X-linked hypophosphatemia (XLH), the most common inherited form of rickets. Children with XLH typically have symptoms and signs of rickets (eg, leg bowing in ambulating children, bone pain, pathologic fractures) and short stature. Dental abscesses are common. X-linked hypophosphatemia is inherited in an X-linked dominant fashion. The mother of the boy in the vignette is likely affected by XLH given her short stature. PREP Pearls The metabolic abnormalities associated with X-linked hypophosphatemia are due to elevated levels of fibroblast growth factor 23 (FGF23), which causes renal phosphate wasting. X-linked hypophosphatemia is characterized by a low phosphate and inappropriately normal 1,25-dihydroxyvitamin D levels; a low serum phosphate level normally stimulates 1α-hydroxylase in the kidney to increase 1,25-dihydroxyvitamin D levels. The traditional treatment of X-linked hypophosphatemia is oral phosphate and calcitriol (1,25-dihydroxyvitamin D) replacement. A monoclonal antibody against FGF23 (burosumab) is available to aid management of the condition.

Answer 167

PREP Pearls The ability to memorize a telephone number is a developmental milestone typical of 5-year-old children. Parents should instruct their children to memorize their telephone number for safety purposes. Language and communication milestones of a 5-year-old include a vocabulary of >2,000 words, complete sentence formation, and sequential storytelling. Imaginative play and creativity emerge at ages 5 to 6 years. tying shoes is a 6 yo thing

Answer 168

PREP Pearls A coagulation profile with mixing studies is helpful in evaluating a child with a suspected bleeding disorder. An individual with hemophilia with bleeding into a joint after trauma may develop a target joint (a joint more likely to have repeated bleeding episodes). Aspirin and nonsteroidal antiinflammatory drugs (eg, ibuprofen) should be avoided in individuals with known or suspected hemophilia due to the antiplatelet effects of these drugs.

Answer 169

The adolescent in the vignette has a history of gradually worsening, activity-related pain and participates in a high-impact sport. Her history and physical examination findings suggest a femur stress fracture. The best next step in her evaluation and management is magnetic resonance imaging (MRI) of the femur. Item C77 is a T2-weighted MRI scan of the femur demonstrating a right femoral neck stress fracture with edema of the inferior aspect of the femoral neck and a subtle fracture line.

Answer 170

The adolescent in the vignette is exhibiting symptoms and signs of increased intracranial pressure (ICP) with worsening headache, blurry vision, paresthesias, papilledema, and abnormal gait. Of the response choices, the best next management step is to obtain magnetic resonance imaging (MRI) of the brain with and without contrast to guide further diagnostic work-up. Head computed tomography (CT) without contrast would also be an appropriate option.

Answer 171

PREP Pearls Black widow spider venom is neurotoxic. Signs and symptoms begin suddenly, and may include nausea, vomiting, pain and pallor at the bite site, paresthesias, tenderness in regional lymph nodes, sweating, abdominal pain, and muscle cramping. Severe signs and symptoms of a black widow spider bite include muscle rigidity, difficulty speaking, ptosis, agitation, hypertension, and respiratory distress. Brown recluse spider venom is a cytotoxin that produces localized effects; systemic symptoms are rare. Treatment is aimed at localized wound care.

Answer 172

bleeding diathesis, commonly Factor 11 deficiency

Answer 173

10 years, 5 years

Answer 174

less than 3

Answer 175

None 4 weeks 8 weeks

Answer 176

they get Ig. If older than 12 months then they get vax

Answer 177

4 weeks; give today or 4-6 weeks

Answer 178

give within 72 hours and up to 120 hours

Answer 179

3 mos apart if under 13, 28 days apart if over 13 yo

Answer 180

They don't need anymore. If 1st dose is given before age 1 you need to wait 4 weeks before second. Between age 1-2 wait 8 weeks. PPSV23 is 8 weeks after last PCV13 if over 2 you need to wait

Answer 181

before 15 weeks and completed by 8 months. Wait 4 weeks in between doses

Answer 182

Tdap administered at age 7–10 years Children age 7–9 years who receive Tdap should receive the routine Tdap dose at age 11–12 years. Children age 10 years who receive Tdap do not need the routine Tdap dose at age 11–12 years. 6 months (as final dose) if first dose of DTaP/DT or Tdap/Td was administered at or after the 1st birthday.

Answer 183

4 weeks between one and two, 8 weeks between two and three

Answer 184

all unimmunized contacts over 12 mos old with no natural h/o varicella should get the vaccine within 3 but up to 5 days after exposure if immunocompromised then they get Ig within 10 days exposure

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