Abstract:Objective To evaluate the effect of water exchange method versus conventional methods including air insufflation and carbon dioxide insufflation method for the quality of colonoscopy.Methods We searched related randomized controlled trials published up to October 2022 from PubMed, Web of Science, the Cochrane Library, SinoMed databases, CNKI, Wanfang data. Two reviewers independently searched the literatures based on standards to extract the data and evaluate the quality. Meta-analysis was conducted by RevMan 5.4.1.Results 23 studies involving 10 654 patients were included. Although cecal intubation time was prolonged in water exchange (MD = 1.81, 95%CI: 1.28 ~ 2.35, P = 0.000), but water exchange had higher adenoma detection rate (ADR) (OR^ = 1.40, 95%CI: 1.26 ~ 1.55, P = 0.000), cecal intubation rate (OR^ = 1.62, 95%CI:1.24 ~ 2.10, P = 0.000) and scores of bowel preparation quality (MD = 0.61, 95%CI: 0.42~0.79, P = 0.000) compared with conventional colonoscopy. In addition, WE had significantly lower pain sores (MD = -1.07, 95%CI:-1.39 ~ -0.76, P = 0.000), number of abdominal compression (OR^ = 0.42, 95%CI: 0.29 ~ 0.60, P = 0.000) and number of position change (OR^ = 0.59, 95%CI: 0.42 ~ 0.82, P = 0.002) than conventional colonoscopy.Conclusion Although water exchange colonoscopy prolongs cecal intubation time, but it can significantly increase ADR, cecal intubation rate and scores of bowel preparation quality. Beyond that, water exchange reduces patient pain, the proportion of abdominal compression and position change. Water exchange is a better choice for high-quality colonoscopy.