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

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.

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

Prospective, observational study.

Single, tertiary-care referral center.

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

Complete resection, bleeding, perforation, postpolypectomy syndrome, residual or recurrence adenoma.

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.

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

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

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.