Polyps are discrete small raised areas growths in the lining of the bowel. These vary in size from being just a few millimetres in diameter up to 6cm or more. Some polyps are flat while others are attached to the bowel wall by a narrow stalk. They sometimes cause rectal bleeding but often produce no symptoms and are identified during a colonoscopy or other investigation.
There are several different types of polyp and it is necessary for them to be analysed by pathology testing to determine exactly what they are. The commonest are adenomatous and hyperplastic polyps. These may appear identical at colonoscopy, and the distinction can only be made by the pathologist. All bowel cancers begin as polyps, but most polyps do not develop into cancer. Most polyps can be removed during colonoscopy using a wire loop which is placed around the polyp and applying an electrical current to the loop.
Surgery is sometimes needed to remove large polyps, particularly if they are in the rectum. If precancerous polyps are removed, further colonoscopy will be recommended to check for the development of other polyps in the future.