There are many conditions that a colonoscopy can detect. One of the main reasons for performing the procedure is to screen for colon cancer, which is the third most common cancer in both men and women. A colonoscopy can detect precancerous polyps, small growths on the inside of the colon that can eventually develop into cancer if left untreated. In addition to detecting cancer and polyps, a colonoscopy can also identify other conditions that affect the colon. These include inflammatory bowel disease (IBD), which includes conditions such as Crohn's disease and ulcerative colitis. A colonoscopy can also detect diverticulitis (which is a condition where small pouches develop in the wall of the colon and become inflamed), hemorrhoids (which are swollen veins in the rectum and anus), and fissures (which are small tears in the lining of the anus).