Polyps in the Large Bowel

What is a “polyp”

A polyp looks a bit like a  wart. Typically it is a cherry-like swelling on a stalk or pedicle although it may be flatter. It may vary in size from a few millimetres to several centimetres. There are several types of polyps in the rectum and colon (the large or lower bowel). Hyperplastic or metaplastic polps are the commonest and are not generally felt to change into cancer. In contrast Adenomatous polyps (or ADENOMAS) do have the potential to develop into cancer of the large bowel particularly if they get to be large (greater than 2cm).

Pre-Cancer and Cancer

ADENOMAS are potentially precancerous although this can usually only be recognised by the pathologist when they examine the polyp under the microscope.

Most adenomas do not form cancer ever and if they do it can take up to 12 years for the polyp to undergo this change. If the adenoma is removed this sequence of events can be avoided altogether.


Although Polyps are very common they often produce no symptoms and may only be detected by colonoscopy. They can produce bleeding and mucus discharge when they get larger and particularly if they are in the rectum.

Are You at Risk?

Patients with symptoms, those with a family history of polyps or bowel cancer, those who have had a previous polyp and those patients with rare polyposis syndromes are at risk and need regular colonoscopy for surveillance.


The treatment of most polyps is for them to be removed at colonoscopy. If a clear view of the colon can be obtained then most polyps can be safely identified and removed this way without surgery.

It will probably be necessary to repeat colonoscopies in the future to pick up further polyps which may develop, but the need and frequency of these further examinations varies from one individual to another.