Hirschsprung Disease Is the absence of parasympathetic ganglion cells in the rectum and colon. May present in neonates or young children. Consider it in any child with constipation, bilious emesis, delayed passage of meconium (after the first 48-72 hrs), abdominal distension, or enterocolitis. Classic physical finding: tight anal sphincter, empty rectal vault, followed by an explosive bowel movement (due to releasing the pressure by loosening the anal sphincter). Definitive Dx made by rectal biopsy. May be complicated by bacterial overgrowth causing enterocolitis.