Polyps - Bowel Polyps

What are they?
Bowel polyps are small growths on the lining of the bowel wall. They may have the appearance of a small mushroom or a small cherry and can range in size from 1-2mm to 5cm or more. Their main significance is that they may cause bowel cancer but the large majority of polyps do not cause bowel cancer. Some polyps are quite flat on the lining of the bowel wall and others are attached to the bowel wall by a stalk, or pedicle.

Pathology
The two most common type of polyps are adenomatous and hyperplastic polyps. Adenomatous polyps may develop into cancer but hyperplastic polyps do not. Sometimes polyps can be "mixed" (both hyperplastic and adenomatous) and these are also potentially malignant. The larger an adenoma becomes, the more likely it is to undergo malignant (cancerous) changes.

Multiple hyperplastic polyps have been shown to lead to a slightly increased incidence of colorectal cancer.

There are also other types of less common polyps which have no relationship to cancer.

Symptoms
The majority of polyps do not cause any symptoms. The larger a polyp grows the more likely it is to cause bleeding. Bowel polyps that are benign very rarely lead to bowel obstruction.

Treatment
Most polyps can be removed with a colonoscope. A colonoscope is a long flexible instrument that can examine the entire length of the large bowel. If polyps are seen with the colonoscope they are almost always removed as it is not possible to tell which polyps have malignant potential or not. The larger a polyp is, the more important it is to be removed, as there is an increasing potential for malignancy as the polyp grows. Cancer is very unusual in a polyp less than 2cm in size.

Follow-up
If adenomas have been removed at colonoscopy it is usually advisable for further colonoscopies to be performed and the frequency of these examinations will depend on the number and size of the polyps previously removed.