Polyps are common but abnormal growths from the lining of the colon which vary in size from a tiny dot to several centimetres. The majority of polyps are benign (not malignant or cancerous), but it can be difficult to discern whether a polyp is benign or cancerous by its outer appearance alone. Therefore, polyps are generally removed a soon as they are detected during the colonoscopy and analysed microscopically. Removal of colonic polyps is an important means of preventing colon cancer as the majority of cancers develop from polyps.
Tiny polyps may be completely destroyed by biopsy. Larger polyps are removed by a technique called snare polypectomy, in which a wire loop is passed through the colonoscope and the polyps are cut from the intestinal wall by means of a small electrical current.