Post written by Kenichiro Imai, MD, FJGES, from Division of Endoscopy, Shizuoka Cancer Center, Shizuoka, and Yohei Yabuuchi, MD, from the Department of Gastroenterology, Kobe City Medical Center General Hospital, Kobe, Japan.

Given the limitations of conventional EMR and the high recurrence rate associated with incomplete resection, our study focused on the safety and efficacy of underwater EMR (UEMR). This study aimed to assess UEMR as an alternative approach for achieving higher en bloc and complete resection rates.

Colorectal serrated lesions contribute significantly to colorectal carcinogenesis, but the optimal endoscopic resection method remains unclear. Conventional EMR and hot snare polypectomy have shown high incomplete resection rates, and piecemeal cold snare polypectomy, although effective, requires close follow-up. UEMR eliminates the need for submucosal injection and may improve resection outcomes. This study was conducted to assess its feasibility and safety.

Our study demonstrated that UEMR achieved a complete resection rate of 60.0%, with en bloc and R0 resection rates of 87.7% and 61.5%, respectively. The recurrence rate at 12 months was 5.3%, and all recurrent lesions were successfully treated endoscopically. Compared with conventional EMR, UEMR appears to offer similar efficacy while simplifying the procedure. Future research should focus on a larger, multicenter randomized controlled trial comparing UEMR with other endoscopic resection techniques.

This study featured several strengths. Tattooing near the resection site improved surveillance accuracy, allowing for a reliable assessment of recurrence rates. In addition, the use of acetic acid spray enhanced lesion visualization. These findings suggest that UEMR may be a viable alternative for resecting serrated lesions but requires further validation in larger, multicenter trials.

Procedure of underwater EMR for a serrated lesion. Snaring the lesion and the surrounding mucosa.

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