LAUSR

BACKGROUND AND AIMS Incomplete resection of colorectal neoplasia decreases colonoscopy efficacy. Conventional resection (CR) of polyps, performed in a gas-distended colon, is the current standard, but incomplete resection rates of approximately 2% to 30% for nondiminutive (>5 mm), nonpedunculated lesions are reported. Underwater resection (UR) is a novel technique. The aim of this study was to determine the incomplete resection rates of colorectal lesions removed by UR versus CR. METHODS In a randomized controlled trial, patients with small (6-9 mm) and large (≥10 mm) nonpedunculated lesions were assigned to CR (gas-distended lumen) or UR (water-filled, gas-excluded lumen). Small lesions in both arms were removed with a dedicated cold snare. For CR, large lesions were removed with a hot snare after submucosal injection. For UR, large lesions were removed with a hot snare without submucosal injection. Four-quadrant biopsies around resection sites were used to evaluate for incomplete resection. RESULTS Four hundred sixty-two eligible polyps (248 UR vs 214 CR) from 255 patients were removed. Incomplete resection rates for UR and CR were low and did not differ (2% vs 1.9%, p=0.91). UR was performed significantly faster for lesions ≥10 mm in size (10-19 mm, 2.9 minutes vs 5.6 minutes, p<0.0001; ≥20 mm 7.3 minutes vs 9.5 minutes, p=0.015). CONCLUSIONS Low incomplete resection rates are achievable with UR and CR. UR is effective and safe with the advantage of faster resection and potential cost savings for removal of larger (≥10 mm) lesions through avoidance of submucosal injection. As an added approach, UR has potential to improve colonoscopy cost-effectiveness by increasing efficiency and reducing cost while maintaining quality.