Why do polyps get bigger?
A polyp, or more strictly speaking, the particular type of polyp called an adenoma, starts out as a tiny bump on the surface of the bowel. Some polyps remain very small throughout their lives while others continue to enlarge. Most polyps remain benign throughout life but about one in 10 will turn into cancer. Experts believe that all malignancies of the bowel begin as benign polyps; so removing benign polyps can prevent the development of cancer.

Do polyps cause symptoms?
Polyps usually do not cause symptoms, and most people will never know if they have them. Occasionally they can cause bleeding from the rectum. Sometimes polyps produce an excess of mucus, which can be noticed in the stool after a bowel movement. Very occasionally a polyp can grow so large as to cause a blockage of the bowel but unless this occurs, polyps do not cause pain.

What tests confirm the presence of polyps?
Polyps can be detected either by colonoscopy or by a barium enema x-ray. Both methods require the bowel to be as clear as possible before the procedure so you will be asked to follow a special diet as well as take laxatives. Both techniques also involve a small tube being passed through the rectum. In the case of a barium enema this is to allow a liquid to be passed into the bowel that will show up on x-rays. In a colonoscopy, a soft flexible tube is passed along the rectum and then through the whole colon. Sometimes a shorter instrument called a sigmoidoscope is used but this can only pass up through the lower colon. If the barium enema does reveal a polyp, a colonoscopy will then be needed to remove it.

The most common reason to carry out an examination of the bowel is that a patient has noticed symptoms, particularly rectal bleeding. Increasingly, patients are being asked to give a sample of their stool for a chemical test that can detect small quantities of blood that are not visible. This test is called “fecal occult blood” test and is likely to be much more widely used as an early screening tool. The idea is that unsuspected polyps might bleed a little, but enough for it to be picked up on a chemical test. Doctors recognize that many bowel cancers can be treated very early or can be prevented by screening.