What is "megacolon"

n. 1 (context uncountable English) abnormal dilatation of the colon, not caused by mechanical obstruction. 2 (context countable English) A colon thus enlarged.

n. an abnormal enlargement of the colon; can be congenital (as in Hirschsprung's disease) or acquired (as when children refuse to defecate)

Megacolon is an abnormal dilation of the colon (also called the large intestine). The dilation is often accompanied by a paralysis of the peristaltic movements of the bowel. In more extreme cases, the feces consolidate into hard masses inside the colon, called fecalomas (literally, fecal tumor), which can require surgery to be removed.

A human colon is considered abnormally enlarged if it has a diameter greater than 12 cm in the cecum (it is usually less than 9 cm), greater than 6.5 cm in the rectosigmoid region and greater than 8 cm for the ascending colon. The transverse colon is usually less than 6 cm in diameter.

A megacolon can be either acute or chronic. It can also be classified according to etiology.