The most common indication for operation in Crohn's disease of the colon is:

B. Chronic debility.

DISCUSSION: Crohn's disease of the colon usually leads to operation because of chronic debility and inanition unresponsive to medical therapy. Obstruction, perforation, and bleeding are uncommon complications of colonic Crohn's. While for persons with Crohn's colitis the risk of carcinoma of the colon is four to six times that of a healthy control population, the presence of cancer in the colon is an unusual cause for operation for Crohn's colitis. In fact, most patients with Crohn's have their colons excised before sufficient time has elapsed for cancers to appear. Cancers usually do not appear until 10 years or more after the onset of disease.