"Underwater" EMR without submucosal injection for large sessile colorectal polyps (with video)

Background: Submucosal injection is widely performed before EMR of large sessile colorectal polyps to facilitate resection and decrease perforation risk. We developed a novel method of water immersion ("underwater") EMR (UEMR) that eliminates submucosal injection.

Objective: To evaluate the feasibility and outcomes of UEMR without submucosal injection for large sessile colorectal polyps.

Design: Prospective, observational study.

Setting: Single, tertiary-care referral center.

Intervention: The standardized EMR technique involves full water immersion for the entire procedure and piecemeal resection with a 15-mm "duck bill" snare.

Main outcome measurements: Complete resection, bleeding, perforation, postpolypectomy syndrome, residual or recurrence adenoma.

Results: Sixty patients with 62 large sessile colorectal polyps underwent UEMR. The mean/median polyp size was 34/30 mm, and the mean/median resection time was 21/18 minutes. Histology revealed the following: tubular adenoma (n = 22), tubulovillous adenoma (n = 19), villous adenoma (n = 4), serrated adenoma (n = 11), and high-grade dysplasia/carcinoma in situ (n = 6). The mean/median interval until a follow-up colonoscopy in 54 patients (90%) was 20.4/15.2 weeks. One of 54 patients (2%) had an adenoma smaller than 5 mm outside of the postresection scar, consistent with a residual lesion missed on index UEMR.

Complications: There was no perforation or postpolypectomy syndrome. Delayed bleeding occurred in 3 patients and was managed conservatively.

Limitations: Limited follow-up; single-center, single-endoscopist, uncontrolled study.

Conclusions: The underwater resection technique enables complete removal of large sessile colorectal polyps without submucosal injection. The technique was safe in a large patient cohort, and the early recurrence rate appears low. Use of a water interface for UEMR has potential advantages that deserve further study.