Pediatric Gastroenterology and Hepatology
Domain focus
Pediatric gastroenterology and hepatology tests vomiting, diarrhea and dehydration, constipation, jaundice, and chronic liver disease.
Core rules
- Bilious vomiting is a surgical emergency until malrotation/volvulus is excluded; obtain urgent surgical consultation and imaging.
- Pyloric stenosis: 3–6 weeks, firstborn male, projectile nonbilious vomiting, palpable olive, hypochloremic hypokalemic metabolic alkalosis; diagnosis by ultrasound.
- Acute diarrhea: oral rehydration solution is first-line; give 50–100 mL/kg over 3–4 hours for some dehydration. Continue breastfeeding.
- Conjugated hyperbilirubinemia (direct >1 mg/dL or >20% of total) after 2 weeks is cholestasis and needs urgent evaluation.
- Celiac disease: IgA tissue transglutaminase plus total IgA; confirm with biopsy when appropriate.
Worked example
A 6-week-old boy has projectile vomiting after feeds. He is hungry, has a palpable olive, and labs show Na 132, K 3.1, Cl 88, HCO3 32. Reasoning: nonbilious projectile vomiting with hypochloremic hypokalemic metabolic alkalosis is pyloric stenosis. Obtain ultrasound; correct fluids and electrolytes before pyloromyotomy. Bilious vomiting in the same age group would change the pathway to malrotation.
Traps
- Calling bilious emesis “reflux.”
- Missing dehydration because the child is not lethargic; use weight change, mucous membranes, tears, and urine output.
- Ignoring a direct bilirubin and labeling prolonged jaundice as breast-milk jaundice.