Does the Cap Increase the Finding of Polyps When Water Exchange Colonoscopy is Used

This will be a multi-site, multi-national, unblinded investigators, prospective Random Control Trial (RCT). Randomization (WE, WE Cap-1, WE Cap-2) will be based on computer generated random numbers placed inside opaque sealed envelopes. The envelope (in pre-arranged order) will be opened to reveal the code when the colonoscopist is ready to insert the endoscope to begin the examination. This will be a comparison of two different methods with three arms (WE, WE Cap-1, WE Cap-2) to see which one is better at detecting adenomas. Patients who are willing to participate will sign an informed consent before starting the colonoscopy procedure. Separate parallel randomization will be set up at each site, stratified by investigator and type of colonoscopy (screening or surveillance). Mode of sedation will include unsedated (China, US West Los Angeles VA), minimally sedated (Taiwan), on demand sedation (Italy, Czech Republic, US West Los Angeles VA), conscious sedation (US Sacramento VA and Palo Alto VA) or full sedation with propofol (Taiwan). Randomization (prepared by statistics consultant) will be carried out by the method of random permuted block design (based on computer generated random numbers) with variable block sizes of 3 and 6. Gender will be used as a stratification factor. Control Method: One arm of the study will include sedated/unsedated colonoscopy with water (WE) as the control method. Residual air in the colon will be removed and water will be infused to guide insertion through an airless lumen. Infused water will be removed by suction, along with residual fecal debris, predominantly during insertion. Study method: The other two arms entail the addition of a simple commercially available accessory to the colonoscopy device: Cap -1 (Disposable Distal Attachment) or Cap-2, fitted to the colonoscope per manufacturer instruction. The two arms include sedated/unsedated colonoscopy with either a Cap-1 plus water or Cap-2 plus water.