Does the Addition of a Cap Improve the Adenoma Detection Rate During Water Exchange Colonoscopy (ASGE)

  • participants needed
  • sponsor
    VA Greater Los Angeles Healthcare System
Updated on 7 February 2023
blood test
fecal immunochemical test
Accepts healthy volunteers


This is a study to compare two different, but normally, used methods of colonoscopy in patients that require a routine or repeat colonoscopy. There will be three arms in this study: WE water control, water plus Cap-1, and water plus Cap-2. The patient will prepare himself/herself for the colonoscopy as per normal instructions and he/she will be given the information for the study at that time so that he/she can make a decision to participate in the study. The control method will use water instead of air inserted into the colon. The study method will use a new accessory, a cap that will fit onto the end of the colonoscope plus water during the procedure. This study will also confirm if using the cap method with water is a better way of detecting polyps in the colon and possibly cancer.


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.

Condition Colonoscopy, Polyp of Colon
Treatment Water, CAP-straight, CAP-daisy
Clinical Study IdentifierNCT03566615
SponsorVA Greater Los Angeles Healthcare System
Last Modified on7 February 2023

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