The course of ulcerative colitis tends to go between periods of active disease (flare-ups) and periods of remission (where there are few or no symptoms). Some people with ulcerative colitis will not experience remission, but instead will have continuous, active disease. About 10% of people have serious complications (such as perforation or massive bleeding) after their first flare-up. Approximately 10% of people never have another flare-up after their first one, which is potentially because the diagnosis of ulcerative colitis was incorrect.
Ulcerative colitis tends to begin in the rectum or the last section of the colon (the sigmoid colon) and may spread up through the rest of the colon. For those who are diagnosed with ulcerative proctitis, where the disease is located only in the rectum, the chance of disease spreading up through the colon is 10% to 30%.
Anywhere from 10% to 40% of patients with ulcerative colitis will require surgery to treat their disease. Surgery always involves the complete removal of the colon; partial removals are not done because the colitis will recur in the portion of the colon that remains.
Colon cancer develops in about 5% of people with ulcerative colitis. The risk of colon cancer is increased after 8 to 10 years of active disease and having more extensive disease (pancolitis).
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