Tip-in Underwater Endoscopic Mucosal Resection for Complex Colorectal Adenomas: A Case Series

Introduction Underwater endoscopic mucosal resection (UEMR) is now widely used in the colon but occasionally compromises visualization of the proximal margin. Tip-in EMR, where anchors the snare tip inserted into the non-neoplastic mucosa on the proximal side of the lesion, helps secure the proximal-side resection margin. The technique named "Tip-in UEMR", which combines UEMR and Tip-in EMR, merges the advantages of both procedures while omitting submucosal injection.
Methods Clinical outcomes of Tip-in UEMR for colorectal adenomas between November 2017 and March 2025 at a single institution were retrospectively evaluated.
Results Fourteen colorectal adenomas in 14 patients treated by Tip-in UEMR were identified. One case was located in the right colon, while 7 were in the left colon and 6 in the rectum. The macroscopic types included 0-IIa (1 case), 0-Is (3 cases), 0-Ip (8 cases), and residual/recurrent adenomas (2 cases). The median lesion size was 15.0 mm (range: 6-20). En bloc resection was achieved in all cases (100%). No perforation or delayed bleeding occurred.
Conclusion Tip-in UEMR may be effectively applied in selected cases. During this session, we will present advantages of Tip-in UEMR using video presentations of complex cases: a large pedunculated polyp, a flat elevated polyp extending to the appendiceal orifice, and a residual anorectal adenoma.