Water exchange versus air insufflation for colonoscopy: A meta-analysis

BACKGROUND/AIMS: To compare water exchange (WE) method with conventional air insufflation (AI) method for colonoscopy, evaluating the technical quality, screening efficacy, and patients' acceptance. MATERIALS AND METHODS: Electronic databases were systematically searched for randomized controlled trials comparing WE colonoscopy with AI colonoscopy. The pooled data of procedure-associated and patient-related outcomes were assessed, using the weighted mean difference (WMD) with 95% confidence interval (CI) for continuous variables and relative risk (RR) with 95% CI for dichotomous variables, respectively. RESULTS: A total of 13 studies involving 7056 patients were included. The cecum intubation rate was similar between WE and AI methods (RR = 1.01, 95% CI = 0.99–1.02, P = 0.37); however, a significantly longer cecum intubation time was shown in WE group (WMD = 1.56, 95% CI = 0.75–2.37, P = 0.002). Compared with AI, WE was associated with a higher risk of adenoma detection rate (ADR) (RR = 1.28, 95% CI = 1.18–1.38, P < 0.00001) and polyp detection rate (PDR) (RR = 1.30, 95% CI = 1.21–1.39, P < 0.00001). Patients in WE group experienced significantly less maximum pain score (WMD = −1.99, 95% CI = −2.68 to −1.30, P < 0.00001) and less requested on-demand sedation (RR = 0.58, 95% CI = 0.44–0.77, P = 0.0002). Likewise, they also experienced less abdominal compression (RR = 0.62, 95% CI = 0.51-0.74, P < 0.00001) and reposition (RR = 0.74, 95% CI = 0.63-0.86, P = 0.0001). Moreover, patients' willingness to repeat colonoscopy was significantly greater for WE (RR = 1.14, 95% CI = 1.07–1.21, P < 0.0001). CONCLUSION: This meta-analysis confirmed that WE method could significantly increase ADR/PDR and improve patients' acceptance of colonoscopy, while reducing the degree of pain and minimize the need for on-demand sedation and adjunct maneuvers, despite requiring more cecal intubation time.