Water Exchange Improves Detection of Advanced Colorectal Neoplasia: Pooled Analysis of Four Randomized Trials

To test whether water exchange improves advanced neoplasia detection rate (ANDR) by pooling data from four randomized controlled trials (RCTs) conducted in Taiwan with similar designs, patient populations, and endoscopists.

Water exchange colonoscopy has been shown to improve adenoma detection rate (ADR) compared to air insufflation. However, its effect on ANDR, a surrogate marker for colorectal cancer risk, remains unclear due to small sample sizes in individual studies.

Patient demographics, procedural outcomes, ADR, and ANDR from four RCTs comparing water exchange and air insufflation were pooled and analyzed.

A total of 1048 patients were included. Baseline characteristics were similar between groups. Water exchange significantly increased overall ADR (54.0% vs. 45.7%, p = 0.007) and overall ANDR (17.9% vs. 13.4%, p = 0.047) compared to air insufflation. The difference in ANDR was mainly observed in the proximal colon (8.7% vs. 4.6%, p = 0.007). Water exchange also resulted in a shorter mean withdrawal time (12.3 vs. 12.7 min, p = 0.023) and better bowel preparation scores. Adequate water exchange technique was confirmed by a cecal aspirated-to-infused water volume ratio of 106%.

Pooled analysis of four comparable RCTs showed that water exchange colonoscopy significantly improves overall and proximal colon ANDR compared to air insufflation. Further studies are needed to determine whether this translates into a reduced risk of interval colorectal cancer.