Underwater versus conventional endoscopic mucosal resection for small size non-pedunculated colorectal polyps: a randomized controlled trial : (UEMR vs. CEMR for small size non-pedunculated colorectal polyps)

Abstract

Background: Underwater endoscopic mucosal resection (UEMR) is a recently developed technique and can be performed during water-aided or ordinary colonoscopy for the treatment of colorectal polyps. The objective of this clinical trial was to evaluate the efficacy and safety of UEMR in comparison with conventional endoscopic mucosal resection (CEMR) of small non-pedunculated colorectal polyps.

Methods: Patients with small size, non-pedunculated colorectal polyps (4-9 mm in size) who underwent colonoscopic polypectomy were enrolled in this multicenter randomized controlled clinical trial. The patients were randomly allocated to two groups, an UEMR group and a CEMR group. Efficacy and safety were compared between groups.

Results: In the intention-to-treat (ITT) analysis, the complete resection rate was 83.1% (59/71) in the UEMR group and 87.3% (62/71) in the CEMR group. The en-bloc resection rate was 94.4% (67/71) in the UEMR group and 91.5% (65/71) in the CEMR group (difference 2.9%; 90% CI - 4.2 to 9.9%), showed noninferiority (noninferiority margin - 5.7% < - 4.2%). No significant difference in procedure time (81 s vs. 72 s, P = 0.183) was observed. Early bleeding was observed in 1.4% of patients in the CEMR group (1/71) and 1.4% of patients in the UEMR group (1/71). None of the patients in the UEMR group complained of postprocedural bloody stool, whereas two patients in the CEMR group (2/64) reported this adverse event.

Conclusion: Our results indicate that UEMR is safer and just as effective as CEMR in En-bloc resection for the treatment of small colorectal polyps as such, UEMR is recommended as an alternative approach to excising small and non-pedunculated colorectal adenomatous polyps.

Trial registration: Clinical Trials.gov, NCT03833492 . Retrospectively registered on February 7, 2019.

Keywords: Colonic polyps; Colorectal cancer; Conventional endoscopic mucosal resection; Endoscopy; Underwater endoscopic mucosal resection.

Fig. 1

Underwater endoscopic mucosal resection (UEMR). a A flat elevated polyp was detected in the colon; b The colorectal lumen was completed deflated with sterile water; c The polypectomy snare was used for UEMR; d Biopsies were obtained from two marginal sites located symmetrically to the left and right of mucosal defects to confirm residual polyp tissue

Fig. 2

Schematic diagram of patient enrollment and study design. A total of 130 patients with 142 colorectal polyps were allocated randomly to the CEMR or UEMR group

Fig. 3

Non-inferiority graph for primary outcomes. Datapoints are the point estimate of the risk difference between the CEMR and UEMR, error bars are 90% CI