Safety and Efficacy of Underwater EMR of Colorectal Polyps and Risk of Recurrence: A Single Center's Real World Experience

Aims Endoscopic resection of colorectal polyps reduces cancer related mortality, with incomplete resection has been identified as an important cause of interval cancer. Endoscopic mucosal resection (EMR) is the standard treatment for non-pedunculated colorectal polyps. Underwater EMR (UEMR) is a technical variant that does not involve injection of fluid into the submucosa and relies on submerging the polyp in water before hot snare resection. The aim of our study is to determine the safety and efficacy of UEMR and factors associated with polyp recurrence [1] [2] [3] [4].

Methods This is a single center retrospective study of all adult patients (> 18 years old) that underwent UWEMR of colonic polyps at the University of California Irvine from January 2018 to 2024. The primary outcome was polyp recurrence at first surveillance colonoscopy. Secondary outcomes include rates of technical success, en-bloc resection, margin ablation and adverse events. Descriptive characteristics were calculated for variables of interest and a multivariate regression analysis of factors associated with polyp recurrence was conducted including polyp size, en-bloc resection, HGD/malignant pathology, margin ablation and fellow participation.

Results In the study period, a total of 879 patients were identified with resection of 1088 polyps by UEMR technique. The mean age of patient was 65 years, with 48% male (N=420). Mean polyp size was 23.6 mm (range 12-80 mm, SD 16.4 mm). Polyp pathology included tubular adenoma in 32% (n=341), tubulovillous adenoma in 23% (N=251), sessile serrated adenoma in 20% (N=220), high grade dysplasia in 7.0% (N=76) and adenocarcinoma in 4% (N=46) of polyps. Technical success was achieved in 98% (N=1067). En-bloc resection was achieved in 42% (N=428). R0 resection was achieved in (57%, N=245). Margin ablation with STSC or APC was performed in 39% (N=421) of polyps resected. The adverse event rate was 6.5% (N=71) with major bleeding in 2.6% (N=29) and perforation requiring surgical intervention in 0.2% (N=2). A total of 476 polyps were followed-up. The median follow-up time to first surveillance colonoscopy was 123 days (IQR 77-268). Recurrence identified on first surveillance colonoscopy was 13.4% (N=64). On multivariate logistic regression of factors associated with polyp recurrence, only en-bloc resection was associated with lower odds of recurrence (0.36 adjusted odds ratio, P=0.013).

Conclusions In this very large, real-world, single center 6-year experience of patients who underwent UEMR for resection of non-pedunculated polyps, UEMR demonstrated a low recurrence rate, low adverse event rate and high technical success. These results are consistent with smaller prospective trials using this technique. Underwater EMR should be considered a safe and effective alternative to conventional EMR at this time.

Publication History

Article published online:
27 March 2025

• References

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