Feasibility of salvage colonoscopy by water exchange for failed air-insufflated patients: a prospective, randomized, controlled trial

Background A complete colonoscopy is crucial for screening colorectal diseases and colorectal cancer. However, a failure rate of up to 43% still exists. Several studies have indicated that the water exchange method can enhance the cecal intubation rate while reducing discomfort of the patient. Water exchange colonoscopy (WEC) might be a salvage treatment for the patients who failed from air insufflation colonoscopy (AIC). We aimed to assess the feasibility of WEC as a salvage measure following the failure of conventional AIC Methods Patients willing to undergo unsedated colonoscopy at a tertiary-care referral center in China were randomly assigned 1:1 to WEC or AIC group for salvage after the initial AIC attempt failed. Patients were blinded to group assignment. The primary outcome was cecal intubation rate, the secondary outcomes included time to the cecum, maximum pain scores, and technical difficulty level. Results Recruited 104 patients were randomized to the WEC (n = 52) or AIC (n = 52) group. WEC significantly increased the cecal intubation rate (92.3% vs 73.1%; p = .02). The maximum pain scores and technical difficulty level in the WEC group were significantly lower than the AIC group during salvage procedure (p < .001). Conclusions This randomized, controlled trial confirms that the WEC significantly enhanced cecal intubation rate in difficult colonoscopy in unsedated patients after the failure of standard AIC. The increased cecal intubation rate, lower pain scores and technical difficulty level suggest WEC is a good alternative for incomplete unsedated colonoscopy.