Megacolon is characterized by dilation of the colon, which can be caused by several factors.
- Toxic megacolon is the result of inflammation, as in inflammatory bowel disease (ulcerative colitis, Crohn's disease, Salmonella, Cytomegalovirus in HIV patients...). See image.
- Hirsprung's disease (congenital aganglionic megacolon) is a congenital disease caused by the absence of enteric ganglion cells fail to develop; as a result, stool cannot progress through the colon. As the intestines become blocked, infants/children experience constipation, abdominal pain, and vomiting.