NBME Pediatrics 3 — Questions and Answers
Question 1: A premature infant born at 28 weeks develops increasing respiratory distress immediately after birth. CXR shows diffuse ground-glass opacities bilaterally. The deficiency responsible is:
- Surfactant (Correct answer)
- Clara cell secretory protein
- Alpha-1 antitrypsin
- Pulmonary IgA
Correct answer: Surfactant
Respiratory distress syndrome in premature infants results from surfactant deficiency, which reduces alveolar surface tension.
Question 2: A 6-week-old male presents with non-bilious projectile vomiting after every feeding. He is hungry immediately after vomiting. Palpation reveals an olive-shaped mass in the epigastrium. Next step?
- Upper GI series
- Abdominal ultrasound (Correct answer)
- CBC and metabolic panel only
- Immediate surgery without imaging
Correct answer: Abdominal ultrasound
Abdominal ultrasound is the gold standard to confirm pyloric stenosis by demonstrating pyloric muscle thickness ≥4 mm and length ≥16 mm.
Question 3: A 2-year-old presents with a barking cough, stridor, and low-grade fever. Neck X-ray shows a 'steeple sign.' Most appropriate initial management?
- IV antibiotics
- Racemic epinephrine nebulization
- Dexamethasone (Correct answer)
- Emergency intubation
Correct answer: Dexamethasone
Dexamethasone is the first-line treatment for croup (laryngotracheitis), reducing subglottic edema and duration of symptoms.
Question 4: A neonate born to a mother with poorly controlled diabetes develops jitteriness, hypotonia, and poor feeding at 2 hours of life. Blood glucose is 28 mg/dL. First step?
- IV D10W bolus (Correct answer)
- Oral formula feeding
- IM glucagon
- Observe and recheck in 1 hour
Correct answer: IV D10W bolus
Symptomatic neonatal hypoglycemia requires immediate IV dextrose bolus (D10W 2 mL/kg) to rapidly restore euglycemia.
Question 5: A 13-year-old girl presents with primary amenorrhea, short stature, webbed neck, and a widely spaced chest with shield-like appearance. Karyotype most likely shows:
- 47,XXX
- 45,X (Correct answer)
- 47,XXY
- 46,XY
Correct answer: 45,X
Turner syndrome (45,X) classically presents with short stature, webbed neck, shield chest, and primary ovarian insufficiency.
Question 6: A 4-month-old is brought in for a well-child visit. Which vaccine is NOT routinely given at this age?
- DTaP
- Hib
- MMR (Correct answer)
- PCV13
Correct answer: MMR
MMR is first administered at 12–15 months; the 4-month visit includes DTaP, Hib, IPV, PCV13, and rotavirus.
Question 7: A 9-year-old male has an elevated ESR, fever, migratory arthritis, and a new heart murmur 3 weeks after untreated strep pharyngitis. Most likely diagnosis?
- Systemic lupus erythematosus
- Juvenile idiopathic arthritis
- Acute rheumatic fever (Correct answer)
- Reactive arthritis
Correct answer: Acute rheumatic fever
Acute rheumatic fever follows group A streptococcal pharyngitis and meets Jones criteria including carditis and migratory arthritis.
NBME Pediatrics 3
A premature infant born at 28 weeks develops increasing respiratory distress immediately after birth.
CXR shows diffuse ground-glass opacities bilaterally.
The deficiency responsible is: