Water Exchange versus Air Insufflation for Colonoscopy: A Systematic Review and Meta-Analysis

Abstract

Introduction: Colonoscopy is a widely used modality for screening and diagnostic purposes and is the most important tool in the prevention and early detection of colorectal cancer. In settings where un-sedated colonoscopy is offered, minimal pain and discomfort are desired by the patients. Prominent efforts have been made in the last few years to improve the quality of the procedure and minimize patient discomfort, costs and side effects related to the procedure. The water exchange (WE) method that involves infusion and withdrawal of water during the insertion phase of colonoscopy has been shown to be superior to the more conventional air insufflation (AI) method in several aspects including reduction in pain scores, increased adenoma detection rate and improved quality of bowel preparation. We performed a systematic review and meta-analysis to compare the efficacy of WE method with the conventional AI method.Figure: Maximum Pain score during colonoscopy.Methods: We searched key bibliographic databases using keywords and MeSH terms related to ‘water exchange', ‘colonoscopy' and ‘air insuffl ation'. We included only randomized controlled trials (RCTs) that compared the WE method with the AI method. Our primary analysis included maximum pain score during insertion, adenoma detection rate and cecal intubation rate. Secondary outcomes included total time for colonoscopy, cecal intubation time, position changes, willingness to repeat colonoscopy and the quality of the bowel preparation. Relevant data were extracted and meta-analyses were performed using RevMan. Results: Thirteen RCTs with a total of 7543 participants were included in the meta-analysis after full text review that matched the inclusion and exclusion criteria. There was a significant reduction in maximum pain score with the WE method compared to the AI method (mean difference: -1.44; 95% CI: -1.85 to -1.03). There was an overall increase in the adenoma detection rate (odds ratio [OR]: 1.72; 95% CI: 1.35-2.20) and an increase in adenoma detection in the proximal colon (OR: 1.60; 95% CI: 1.35-1.90). There was no difference in cecal intubation rate between the WE and the AI methods. Although the time to reach cecum was increased with the WE method, there was no difference in the total time to complete colonoscopy. More people who underwent WE method were willing to repeat the colonoscopy and had better bowel preparation. These results are displayed in Table 1. Conclusion:: WE method appears to be a promising addition to colorectal cancer screening given the reduction in pain scores, increased adenoma detection rate and the willingness of the patients to repeat un-sedated colonoscopy. Further, there appears to be no difference in the time to perform colonoscopy which has been perceived to be a barrier to this method.Table: Table. Primary and Secondary Outcomes