LAUSR

Underwater endoscopic mucosal resection (UEMR) is a recently developed procedure characterized by resection of the colon polyps immersed in water. Thanks to the “floating effect” on the mucosa and submucosa, UEMR allows snaring the lesion much more easily compared to conventional EMR [1, 2]. However, it is technically challenging to use UEMR for large colon polyps, especially a large colonic laterally spreading tumor (LST), due to the risk of incomplete resection. In contrast, precutting EMR (PEMR) with a planned partial circumferential mucosal incision is reportedly useful for en bloc resection of a colonic LST [3]. We considered that UEMR would complement PEMR, exerting synergistic effects. Here we present a case of a large colonic LST successfully treated by UEMR in conjunction with underwater PEMR (▶Video 1). Colonoscopy revealed a flat elevated polyp 30mm in size extending along a semilunar fold in the descending colon. Magnifying endoscopy was indicative of adenoma (▶Fig. 1). Underwater PEMR using a multifunctional device equipped with both a snare and knob-shaped tip was applied to this lesion [4, 5] (▶Fig. 2). At the proximal side of the lesion in immersed water, a partial mucosal incision was made with the tip of the snare following local injection of hyaluronic acid solution (▶Fig. 3). By fixing the tip of the snare to the proximal mucosal incision, the lesion was easily introduced into the snare under a condition of immersed water. En bloc resection was achieved without any complications (▶Fig. 4). The total procedure time was only 11 minutes. Histopathology revealed an adenoma with negative margins (▶Fig. 5). The present case has shown that UEMR exerts synergic effects with PEMR for a large colonic LST. Another important advantage of underwater PEMR is that it can be completed with a single device. Underwater PEMR using a multifunctional device could be a good option for treatment of a large colonic LST.