Snapshot A 2-day-old neonate is noted in the well-baby nursery to have some abdominal distention. He had one episode of bilious vomiting. He is feeding well and does not seem altered. However, his mom is concerned that he has not passed any stool yet. Abdominal radiography shows distended loops of bowel. A barium enema shows a dilated colon with a funnel-shaped transition zone. Pediatric surgery is consulted for biopsy and surgical correction. Introduction Congenital megacolon functional (vs mechanical) intestinal obstruction Pathogenesis absence of ganglion cells/enteric nervous plexus in intestine lack of nerves causes constant contraction failure of neural crest cell migration 99% localized in rectum Genetics associated with mutations in RET gene Associated conditions risk ↑ with Down syndrome risk ↑ with Chagas disease acquired disease as a result of amastigote destruction of ganglion cells Presentation Symptoms bilious vomiting failure to pass meconium in first 48 hours of life chronic constipation large bowel obstruction Physical exam abdominal distention extremely tight anal sphincter no stool in rectal vault Evaluation Gold standard diagnosis rectal suction biopsy lack of ganglionic cells in submucosa Imaging abdominal radiography distended bowel loops lack of air in rectum Differential Diagnosis Imperforate anus Functional constipation Intussusception Duodenal atresia Meconium ileus Treatment Supportive care Surgical resection Prognosis, Prevention, and Complications Prognosis very good overall mortality < 1% normal quality of life in most patients Complications ↑ risk of enterocolitis rupture