Short and long-term outcomes of underwater EMR compared to the traditional procedure in the real clinical practice.

BACKGROUND AND AIMS: underwater endoscopic mucosal resection (U-EMR) has been recently described as an alternative to endoscopic mucosal resection (EMR) for flat colorectal polyps. However, the real applications remain unclear due to the lack of comparative studies. METHODS: a multi-centric prospective study was performed from November 2016 to December 2017. All lesions larger than 15 mm that were resected with both techniques were included in the study. The samples were matched using the size, morphology, site and access (SMSA) score as a reference. The efficacy, efficiency and adverse events rates were compared. RESULTS: a total of 162 resections were collected (112 EMR and 50 U-EMR) with an average size of 25 mm. U-EMR achieved better results for the en bloc resection rate (49 vs 62%; p = 0.08) and there were no cases of an incomplete resection (10.7 vs 0%; p = 0.01). U-EMR was faster than EMR and there were no differences in the adverse events rate. Furthermore, U-EMR tended to achieve better results in terms of recurrence. Performing the resection in emersion appeared to prevent the cautery artefact, especially in sessile serrated adenomas. CONCLUSION: in the real clinical practice, U-EMR and EMR are equivalent in terms of efficacy and safety. Furthermore, U-EMR may be a feasible approach to prevent cautery artefact, allowing an accurate pathologic assessment.