UNDERWATER EMR FOR COLORECTAL NEOPLASMS (WITH A VIDEO)

Abstract

Underwater endoscopic mucosal resection (UEMR) was proposed by Binmoeller et al. in 2012, and has gradually become popular in Japan as increasing evidence has been reported. In this article, we extracted 119 English articles on UEMR for colorectal tumors from PubMed, categorized them according to lesion characteristics, and examined their efficacy and safety. The results showed that UEMR was comparable to conventional EMR (CEMR) for colorectal tumors < 10 mm and occasionally superior to CEMR for tumors 10-20 mm in size, with the trend being more pronounced for tumors > 20 mm. While ESD was superior in the en bloc resection rate for colorectal tumors > 20 mm, the difference in the recurrence rate was smaller, and UEMR was superior in procedure time and safety, making it an alternative to ESD for tumors 20-30 mm in diameter under certain conditions. UEMR also shows better outcomes than CEMR for recurrent lesions after endoscopic treatment and is comparable to ESD. Although simpler and more promising results have been reported for rectal neuroendocrine tumors with UEMR than with ESD, the effectiveness of UEMR over endoscopic submucosal resection with a ligation device is unknown and further evidence is needed.

The current evidence suggests that UEMR is not a complete replacement for conventional procedures, but it can be considered one option according to the endoscopistsʼ preference. As UEMR becomes more widespread, its true value will be shown.