Pediatric Gastroenterology, Hepatology and Nutrition
What to master
Understand bilirubin metabolism and the distinction between unconjugated (hemolysis, Gilbert, Crigler-Najjar) and conjugated (biliary atresia, choledochal cyst, metabolic disease) hyperbilirubinemia. Know neonatal cholestasis red flags: pale stools, dark urine, and conjugated jaundice beyond 2 weeks. Master malabsorption patterns-celiac disease (villous atrophy, anti-tTG), cystic fibrosis (steatorrhea), and lactose intolerance. Know inflammatory bowel disease differences: Crohn (skip lesions, transmural, perianal) versus ulcerative colitis (continuous, mucosal, bloody diarrhea).
Concepts that recur
Gastroesophageal reflux is physiologic in infancy and resolves; GERD implies complications like esophagitis or poor weight gain. Pyloric stenosis presents at 3–6 weeks with projectile nonbilious vomiting and a palpable olive; malrotation with volvulus presents with bilious vomiting-a surgical emergency. Intussusception presents at 6–36 months with colicky pain, currant-jelly stool, and a target sign; air enema is diagnostic and therapeutic. Know Hirschsprung disease (absent ganglion cells, delayed meconium, transition zone on contrast enema). Understand acute liver failure signs-coagulopathy not corrected by vitamin K, encephalopathy, hypoglycemia.
Traps
Examiners use bilious vomiting as a critical discriminator-it is never simple reflux. Another trap is celiac serology while on a gluten-free diet, which can be falsely negative; testing requires gluten exposure. Beware attributing failure to thrive to psychosocial causes before excluding organic disease, and vice versa.
Rule of thumb
Conjugated jaundice at any age is pathologic-in a neonate beyond 2 weeks, exclude biliary atresia urgently with fractionated bilirubin and stool color.