LATEST PEDIATRIC GASTROENTEROLOGY
CERTIFICATION EXAM OFFERED BY
AMERICAN BOARD OF PEDIATRICS |
COMPLETE EXAM Q&A WITH RATIONALES
1. A 4-week-old infant presents with progressive,
non-bilious projectile vomiting after feeds. On
examination, the infant is dehydrated and has a
palpable olive-shaped mass in the right upper
quadrant. What is the most likely diagnosis?
A) Hypertrophic pyloric stenosis (HPS)
B) Gastroesophageal reflux disease (GERD)
C) Malrotation with midgut volvulus
D) Duodenal atresia
Correct answer: A
Rationale: HPS presents at 2-8 weeks with
progressive, non-bilious projectile vomiting, olive-
shaped mass, and hypochloremic metabolic
alkalosis. Ultrasound shows thickened pyloric muscle
(>4 mm) and elongated pyloric channel (>16 mm).
2. A 2-year-old child presents with a 2-week history of
intermittent, colicky abdominal pain, vomiting, and
"currant jelly" stools. On examination, a sausage-
,shaped mass is palpated in the right upper quadrant.
What is the most appropriate next step?
A) Air or contrast enema (diagnostic and therapeutic
for intussusception)
B) Upper GI series with small bowel follow-through
C) Abdominal CT scan
D) Emergent laparotomy
Correct answer: A
Rationale: Intussusception (most common in 6-36
months) presents with colicky pain, currant jelly stool
(blood and mucus), and a sausage-shaped mass. Air
enema is both diagnostic and therapeutic
(reduction). If perforation is suspected, do not
perform enema.
3. A 3-year-old child presents with a 1-month history
of chronic diarrhea (6-8 watery stools/day),
abdominal distension, and failure to thrive. Stool is
foul-smelling and floats. The child is irritable. Anti-
tissue transglutaminase (tTG) IgA antibody is
markedly elevated. What is the most likely diagnosis?
A) Celiac disease
B) Cystic fibrosis (CF) (pancreatic insufficiency)
C) Cow's milk protein allergy (CMPA)
,D) Giardiasis (parasitic)
Correct answer: A
Rationale: Celiac disease (gluten-sensitive
enteropathy) presents with chronic diarrhea,
steatorrhea (fat malabsorption, floating stools),
abdominal distension, failure to thrive, and irritability.
Positive tTG IgA (with total IgA) is highly suggestive.
Duodenal biopsy shows villous atrophy.
4. A 2-day-old newborn presents with bilious
vomiting, abdominal distension, and failure to pass
meconium. Abdominal X-ray shows a "double bubble"
sign. What is the most likely diagnosis?
A) Duodenal atresia
B) Malrotation with midgut volvulus
C) Hirschsprung disease
D) Meconium ileus (cystic fibrosis)
Correct answer: A
Rationale: Duodenal atresia (double bubble sign) is
associated with Down syndrome (trisomy 21).
Polyhydramnios is common. Malrotation (B) has a
different X-ray appearance (proximal jejunal
obstruction) and is a surgical emergency.
, 5. A 5-year-old child with a history of cystic fibrosis
(CF) presents with a 2-day history of abdominal pain,
distension, and constipation. Abdominal X-ray shows
a large fecal impaction in the distal ileum (meconium
ileus equivalent, distal intestinal obstruction
syndrome, DIOS). What is the most appropriate initial
treatment?
A) Oral N-acetylcysteine (NAC) and polyethylene
glycol (PEG) 3350 (Golytely)
B) Enema with hyperosmolar contrast (Gastrografin)
(if no signs of perforation)
C) Surgery (laparotomy)
D) Pancreatic enzyme replacement (increase dose)
Correct answer: B
Rationale: DIOS is treated with hyperosmolar enema
(Gastrografin or Hypaque) to soften and mobilize the
meconium. Ensure adequate hydration (risk of fluid
shifts). Oral NAC (A) is also used but enema is first-
line. Surgery for refractory cases.
6. A 4-year-old child presents with a 6-month history
of recurrent abdominal pain (periumbilical),
sometimes associated with vomiting. The child is
otherwise healthy, with normal growth and
development. Physical examination is unremarkable.
What is the most appropriate next step?
CERTIFICATION EXAM OFFERED BY
AMERICAN BOARD OF PEDIATRICS |
COMPLETE EXAM Q&A WITH RATIONALES
1. A 4-week-old infant presents with progressive,
non-bilious projectile vomiting after feeds. On
examination, the infant is dehydrated and has a
palpable olive-shaped mass in the right upper
quadrant. What is the most likely diagnosis?
A) Hypertrophic pyloric stenosis (HPS)
B) Gastroesophageal reflux disease (GERD)
C) Malrotation with midgut volvulus
D) Duodenal atresia
Correct answer: A
Rationale: HPS presents at 2-8 weeks with
progressive, non-bilious projectile vomiting, olive-
shaped mass, and hypochloremic metabolic
alkalosis. Ultrasound shows thickened pyloric muscle
(>4 mm) and elongated pyloric channel (>16 mm).
2. A 2-year-old child presents with a 2-week history of
intermittent, colicky abdominal pain, vomiting, and
"currant jelly" stools. On examination, a sausage-
,shaped mass is palpated in the right upper quadrant.
What is the most appropriate next step?
A) Air or contrast enema (diagnostic and therapeutic
for intussusception)
B) Upper GI series with small bowel follow-through
C) Abdominal CT scan
D) Emergent laparotomy
Correct answer: A
Rationale: Intussusception (most common in 6-36
months) presents with colicky pain, currant jelly stool
(blood and mucus), and a sausage-shaped mass. Air
enema is both diagnostic and therapeutic
(reduction). If perforation is suspected, do not
perform enema.
3. A 3-year-old child presents with a 1-month history
of chronic diarrhea (6-8 watery stools/day),
abdominal distension, and failure to thrive. Stool is
foul-smelling and floats. The child is irritable. Anti-
tissue transglutaminase (tTG) IgA antibody is
markedly elevated. What is the most likely diagnosis?
A) Celiac disease
B) Cystic fibrosis (CF) (pancreatic insufficiency)
C) Cow's milk protein allergy (CMPA)
,D) Giardiasis (parasitic)
Correct answer: A
Rationale: Celiac disease (gluten-sensitive
enteropathy) presents with chronic diarrhea,
steatorrhea (fat malabsorption, floating stools),
abdominal distension, failure to thrive, and irritability.
Positive tTG IgA (with total IgA) is highly suggestive.
Duodenal biopsy shows villous atrophy.
4. A 2-day-old newborn presents with bilious
vomiting, abdominal distension, and failure to pass
meconium. Abdominal X-ray shows a "double bubble"
sign. What is the most likely diagnosis?
A) Duodenal atresia
B) Malrotation with midgut volvulus
C) Hirschsprung disease
D) Meconium ileus (cystic fibrosis)
Correct answer: A
Rationale: Duodenal atresia (double bubble sign) is
associated with Down syndrome (trisomy 21).
Polyhydramnios is common. Malrotation (B) has a
different X-ray appearance (proximal jejunal
obstruction) and is a surgical emergency.
, 5. A 5-year-old child with a history of cystic fibrosis
(CF) presents with a 2-day history of abdominal pain,
distension, and constipation. Abdominal X-ray shows
a large fecal impaction in the distal ileum (meconium
ileus equivalent, distal intestinal obstruction
syndrome, DIOS). What is the most appropriate initial
treatment?
A) Oral N-acetylcysteine (NAC) and polyethylene
glycol (PEG) 3350 (Golytely)
B) Enema with hyperosmolar contrast (Gastrografin)
(if no signs of perforation)
C) Surgery (laparotomy)
D) Pancreatic enzyme replacement (increase dose)
Correct answer: B
Rationale: DIOS is treated with hyperosmolar enema
(Gastrografin or Hypaque) to soften and mobilize the
meconium. Ensure adequate hydration (risk of fluid
shifts). Oral NAC (A) is also used but enema is first-
line. Surgery for refractory cases.
6. A 4-year-old child presents with a 6-month history
of recurrent abdominal pain (periumbilical),
sometimes associated with vomiting. The child is
otherwise healthy, with normal growth and
development. Physical examination is unremarkable.
What is the most appropriate next step?
