Water aided colonoscopy without air insufflation - a comparison of suction removal of infused water during withdrawal versus during insertion

Background: Water exchange (WE) and one form of water immersion (WI) use water infusion without air insufflation (AI). WI entails removal of infused water during withdrawal while WE, during insertion. In an observational study of WI and WE, together with a historical control group examined by AI, we assessed the impact of these approaches on loop formation during colonoscopy. Aim: We test the hypothesis that AI is the main cause of looping recorded by magnetic endoscope imaging (MEI). Method: Endoscopist was blinded to MEI data which were coded and reviewed by 2 blinded observers. The main outcome measure was sigmoid looping before/upon reaching cecum. Results: Loop formation occurred in 34.7% of WI and 39.4% of WE, vs. 62.5% in a historical control group of AI patients. Based on assigned method WI had significantly lower cecal intubation rate than WE (82% vs. 99%). Mean normalized units of sedation medication were WE 6.9 (4.7) and WI 9.1 (2.8), p=0.0001. The volume (ml) of water suctioned during insertion was significantly higher in the WE than WI group. Limitation: A performance improvement observational project, not a randomized controlled trial (RCT). Conclusion: Compared to AI, WE and WI both without air insufflation significantly and equally reduced loop formation, confirming air insufflation predisposes to looping. Based on enhanced cecal intubation and reduced sedation requirement, conversion from WI as described in this study or by others to WE, by adding suction removal of water predominantly during insertion, may gain the potential benefits of improving clinical outcome for screening colonoscopy.