Sigmoidoscopy, or “flexible sigmoidoscopy,” lets a physician examine the lining of the rectum and a portion of the colon (large intestine) by inserting a flexible tube about the thickness of your finger into the anus and slowly advancing it into the rectum and lower part of the colon. This procedure evaluates only the lower third of the colon. Sigmoidoscopy is often done without any sedation, although sedation can be used if necessary. Various miniaturized tools can be inserted through the scope to help the doctor obtain samples (biopsies) of the colon and to perform maneuvers to diagnose or treat conditions. Flexible sigmoidoscopy can detect and sometimes treat polyps, rectal bleeding, fissures, strictures, fistulas, foreign bodies, colorectal cancer, and benign and malignant lesions. Flexible sigmoidoscopy is not a substitute for total colonoscopy when it is indicated. The finding of a new, abnormally growing polyp during sigmoidoscopy, for example, is an indication for a colonoscopy to search for additional polyps or cancer. Sigmoidoscopy should not be used for polypectomy unless the entire colon is adequately prepared. This procedure should also not be used with cases of diverticulitis and peritonitis.