Definition of Toxic megacolon:

Toxic megacolon is a life-threatening complication of other intestinal conditions that causes rapid widening (dilation) of the large intestine within 1 to a few days.

Causes, incidence, and risk factors:

Toxic megacolon occurs as a complication of inflammatory bowel disease, such as ulcerative colitis and Crohn' s disease, and infections of the colon. The term "toxic" means that this complication occurs with infection or inflammation.

This is not the same as other forms of megacolon, such as pseudo-obstruction, acute colonic ileus, or congenital colonic dilation. These conditions occur without infection or inflammation.