During endoscopic submucosal dissection (ESD), a clear view is essential for precise dissection of the appropriate submucosal layer. Some advantages have been reported for underwater techniques of endoscopic resection in comparison with the gas insufflation method. We have developed a new ESD method with the creation of a local water pocket (WP) that provides a clear view in the dissection field. Therefore, we aimed to investigate the feasibility and safety of WP-ESD for superficial gastric neoplasms.

We prospectively recruited 50 patients with gastric neoplasms (early gastric cancer or gastric adenomas) between April 2017 and December 2017. Among them, 48 patients were treated with the WP-ESD technique. The patients undergoing WP-ESD were compared with 48 patients treated with standard ESD (S-ESD) who were selected by propensity score matching. The primary outcome was the ESD procedure time.

Total procedure time was significantly shorter in the WP-ESD group than in the S-ESD group (median [interquartile range], 27.5 [19-45] minutes vs 41 [29.8-69] minutes; P < .001). Similarly, the dissection speed was significantly greater in the WP-ESD group than in the S-ESD group (median [interquartile range], 22.5 [16.8-35.3] mm²/min vs 17.3 [12.7-22.1] mm²/min; P < .001). The rates of complete en bloc resection in the WP-ESD group and the S-ESD group were 97.9% and 95.8%, respectively (P > .99). There were no perforations in either group.

WP-ESD was associated with a shorter procedure time than S-ESD. WP-ESD may provide an alternative method for resection of superficial gastric neoplasms. (Clinical trial registration number: UMIN 000030266.)