Underwater versus conventional endoscopic submucosal dissection for colorectal lesions: systematic review and meta-analysis.

Objective: Effect of underwater endoscopic submucosal dissection (UESD) on clinical outcomes as compared with conventional ESD (CESD) remains unclear. We conducted a meta-analysis of the available data.

Methods: Online databases were searched for studies comparing UESD with CESD for colorectal lesions. The outcomes of interest were en-bloc resection, R0 resection, procedure time (minutes), dissection speed (mm2/min), and adverse events. Pooled odds ratios (ORs) and standardized mean difference (SMD), along with 95% confidence intervals (CIs) were calculated.

Results: Seven studies with 1401 patients (UESD, 452; CESD, 949) were included. Mean patient age was 69 years, and 57% of patients were men. UESD had both a shorter procedure time (SMD, -1.33; 95% CI, -2.34 to -.32; P = .010) and greater dissection speed (SMD, 1.01; 95% CI, .35-1.68; P = .003) when compared with CESD. No significant differences were observed between the 2 groups with respect to en-bloc resection (OR, 1.13; 95% CI, .37-3.41), R0 resection (OR, 2.36; 95% CI, .79-7.05), delayed bleeding (OR, 1.34; 95% CI, .65-2.74), perforation (OR, 1.13; 95% CI, .64-2.00), and postresection electrocoagulation syndrome (OR, .38; 95% CI, .10-1.42).

Conclusions: UESD was faster in patients with colorectal lesions but had comparable rates of en-bloc resection, R0 resection, and adverse events when compared with CESD.