Colitis is inflammation of the large bowel and it is often caused by conditions known as ulcerative colitis and Crohn's disease. In these conditions, the body has an exaggerated inflammatory response against the bowel - the body attacks the bowel. Patients who have had colitis affecting most of the large bowel for more than 8 years are at increased risk of cancer of the large bowel. In view of this, many national gastroenterology organisations have recommended that such patients have regular colonoscopies to detect pre-cancerous areas and even early cancer in the large bowel. Early detection of such areas, will lead to early treatment thereby reducing the risk of developing significant large bowel cancer. These regular colonoscopies are known as surveillance colonoscopies.