A Comparison Of High Definition White Light And High Definition Virtual Chromoendoscopy For The Detection Of Intraepithelial Neoplasia In Longstanding Colitis: A Randomised Controlled Trial

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.

Official international guidelines for surveillance in patients with ulcerative and Crohn's colitis advise to take 4 random samples of large bowel tissue (biopsies) every 10 centimeters and of any suspicious areas. Recent studies have shown that spraying dye such as indigo carmine (a type of food dye) helps highlight abnormal areas that could harbor pre-cancerous cells. This technique is time-consuming, and tedious. There are no set standards of what is considered a satisfactorily completed dye spray colonoscopy. The uptake of this technique in the UK has not been uniform. Therefore virtual chromoendoscopy has been studied as an alternative method to improve the detection of pre-cancerous tissue in patients with longstanding colitis.