Prospective RCT Of Water Exchange (WE) vs. WE Plus Cap-Assisted Colonoscopy

Inclusion Criteria: * Informed/educated (about pros and cons of the unsedated option) Veterans undergoing: * diagnostic * surveillance (follow up of polyps) * screening (first-time) colonoscopy at participating sites * choosing scheduled unsedated colonoscopy for any reason (lack of escort, personal preference) Exclusion Criteria: * decline to be randomized * unable to give consent or respond to questionnaires * history of colon surgery * active inflammatory bowel disease * lower gastrointestinal bleeding (except for occult blood or FIT positive in the context of colon cancer screening) * therapeutic colonoscopy (e.g., hemostasis, removal of large polyp) * proctosigmoidoscopy * bidirectional endoscopy * inadequate consumption of bowel preparation * known history of severe diverticulosis or diverticulitis * history of abdominal surgery previously requiring sedation for colonoscopy * current narcotic/anxiolytic medication use * prior unsuccessful experience with unsedated colonoscopy * emergent colonoscopy * evidence of colonic obstruction based on pre-colonoscopy clinical evaluation * current participation in other studies * medical condition that could increase the risk associated with colonoscopy * active cardiac * or pulmonary disease * or other serious disease * medical condition that would preclude a benefit from colonoscopic screening * cancer * or any terminal illness * prosthetic heart valve * anticoagulant therapy * nonmedical problems * psy…