Pediatric Gastroenterology, Hepatology and Nutrition
Core concepts
Know the approach to vomiting (reflux vs pyloric stenosis vs malrotation/volvulus vs raised intracranial pressure), diarrhea (acute infectious vs chronic malabsorptive), and constipation (functional vs Hirschsprung). Recognize pyloric stenosis (projectile nonbilious vomiting, palpable olive, hypochloremic hypokalemic metabolic alkalosis) and malrotation with volvulus (bilious vomiting - surgical emergency). Understand celiac disease (serology with tissue transglutaminase, duodenal biopsy, associated autoimmune disease) and inflammatory bowel disease (differentiate Crohn vs ulcerative colitis). Know neonatal cholestasis (direct hyperbilirubinemia is never physiologic; think biliary atresia, metabolic disease, infection) and the urgency of the Kasai procedure. Understand nutrition: breastfeeding, complementary feeding, iron and vitamin D supplementation, and failure to thrive workup. Recognize intussusception (colicky pain, red currant jelly stool, target sign on ultrasound).
Traps
- Bilious vomiting in a neonate is a surgical emergency until malrotation is excluded.
- Missing pyloric stenosis because the classic olive is not palpable; check electrolytes for hypochloremic alkalosis.
- Treating neonatal direct hyperbilirubinemia as physiologic - it is always pathologic.
- Confusing functional constipation (common, no red flags) with Hirschsprung (delayed meconium, empty rectum, explosive stool).
- Missing celiac because of atypical or extraintestinal presentation.
Worked example / rule of thumb
A 5-week-old with projectile nonbilious vomiting and weight loss: check electrolytes (hypochloremic hypokalemic metabolic alkalosis), obtain ultrasound (thickened pylorus), and correct fluids before pyloromyotomy. Rule of thumb: bilious vomiting = surgical; nonbilious projectile vomiting in a young infant = pyloric stenosis; direct hyperbilirubinemia in a neonate = urgent hepatobiliary workup.