Underwater endoscopic submucosal dissection for large non-pedunculated colorectal polyps

Underwater endoscopic resections have emerged as promising alternatives to the conventional techniques for the treatment of large (≥2 cm) non-pedunculated colorectal polyps; this may also apply to colorectal endoscopic submucosal dissection (ESD) using saline. This retrospective study uses a propensity score-matched analysis of 82/208 such lesions treated during a 3-year period. Underwater ESD using saline improved R0 resection rates (97.6% vs 82.9%), enhanced dissection speed (31.8 mm2/min vs 22.9 mm2/min) and reduced the use of haemostatic forceps for intraprocedural bleeding (0% vs 14.6%). We recommend this technique to be adopted to facilitate ESD for large non-pedunculated colorectal lesions. ESD is a preferred technique for en bloc resection of large (≥2 cm) non-pedunculated colorectal polyps or adenomas, offering high R0 resection and low recurrence rates.1 2 However, its adoption in Western countries remains limited due to technical complexity, long procedure times and associated adverse events.3 Underwater ESD, which replaces CO2 insufflation with a saline-filled environment, has been proposed to enhance visualisation, traction and submucosal dissection, improving procedural outcomes.4–6 Additionally, saline impedance allows prophylactic underwater vessel coagulation when swift coagulation (effect: 4.0; electrosurgical generator: VIO3, Erbe Elektromedizin GmbH) is applied, improving submucosal vessel sealing to reduce intraprocedural bleeding.7–10 This retrospective study included all consecutive large non-pedunculated colorectal adenomas treated by ESD from January 2021 to December 2023. Underwater ESD using saline was gradually and systematically implemented after January 2023. Eligible participants were adults aged 18 years or older with large lesions (≥2 cm). Exclusion criteria were treatment by endoscopic mucosal resection, need for deeper resection (endoscopic intermuscular dissection or endoscopic full-thickness resection), or surgery, suspected sessile serrated lesions, inability to suspend anticoagulant therapy or to provide informed consent. Relevant clinical and endoscopic data were systematically collected in an electronic database. The procedures were conducted …