"Underwater" EMR of sporadic laterally spreading nonampullary duodenal adenomas

Background: EMR for the treatment of duodenal adenomas is challenging due to a thin wall and rich vascularity. Objective: To evaluate a novel technique of "underwater" EMR without prior submucosal injection for the removal of large (>= 2 cm) laterally spreading nonampullary duodenal adenomas. Design: Prospective, observational study. Setting: Tertiary academic referral center. Patients: Twelve patients (median age, 60 years) meeting the inclusion criteria. Interventions: Piecemeal EMR technique after sterile water submersion when using a double-channel endoscope. Main Outcome Measurements: Technical success, adverse events, completeness of resection on follow-up endoscopy. Results: Median adenoma size was 35 mm (25% greater than one-half circumference, 50% equal to one-third to one-half circumference, and 25% less than one-third circumference). Median procedure time was 65 minutes (range, 32-151). Final histology was tubular adenoma (7), tubulovillous adenoma (1), villous adenoma (3), and high-grade dysplasia (1). Eleven patients (92%) met the primary endpoint (technical success) and all patients met the secondary endpoint (completeness of resection). Median interval until follow-up endoscopy was 16 weeks (range, 11-56). Adverse events were as follows: delayed bleeding (3 patients, of whom 2 required transfusions), water intoxication syndrome manifested by altered mental status and hyponatremia (1), and stricture formation (1) that responded to balloon dilation. No perforation or postresection abdominal pain was found. Limitations: Single operator, single center, small sample size, limited follow-up. Conclusion: Underwater EMR for large sessile duodenal adenomas has high success rates for complete removal. The risk of delayed bleeding is significant, and precautions are needed when infusing a large volume of fluid into the GI tract.