Underwater EMR of adenomas of the appendiceal orifice (with video)

Background and Aims: EMR of adenomas involving the appendiceal orifice (AO) is controversial because of a high risk of perforation and incomplete resection. We evaluated the feasibility, safety, and outcomes of underwater EMR (UEMR) without submucosal injection for the treatment of adenomas involving the AO. Methods: This was a prospective, observational study of a standardized UEMR technique without submucosal injection for adenomas involving the AO in 27 consecutive patients meeting inclusion and exclusion criteria. Surveillance colonoscopy included biopsy sampling of the EMR site and base of the AO. Main outcome measurements include technical success, histology, resection time, adverse events, and follow-up data. Results: Over 42 months, UEMR of adenomas involving the AO (rim, 5 patients; inside, 22 patients) was attempted in 27 consecutive patients. Median adenoma size was 15 mm (range, 8 to 50). UEMR was successful in 24 patients (89%). Four patients were referred to surgery, 3 with UEMR failure because of an inability to exclude the adenoma extending into the appendix at the index procedure and 1 with invasive adenocarcinoma in the UEMR specimen. The median resection time was 3 minutes (range, 1 to 75). Adverse events consisted of postpolypectomy syndrome in 2 patients (7%). There was no perforation, bleeding requiring transfusion, or appendicitis. Final histology was tubular adenoma (7), tubulovillous adenoma (4), sessile serrated adenoma (15), and invasive adenocarcinoma (1). Twenty-one of 23 patients (91%), not referred to surgery, had follow-up colonoscopy with biopsy sampling of the resection site after a median of 29 weeks (range, 12 to 139) after resection. Residual adenoma was found in 2 of 21 patients (10%). Conclusion: On an intention-to-treat basis, UEMR without submucosal injection enabled safe and complete endoscopic resection of AO lesions. Close surveillance for residual or recurrence is warranted.