Randomized controlled trial comparing conventional and underwater endoscopic submucosal dissection for superficial colorectal neoplasms

Aims Conventional endoscopic submucosal dissection (C-ESD) is performed under gas conditions. However, the newly developed underwater ESD (U-ESD) has advantages, including a clear visual field without halation, buoyancy, easy use of water pressure for opening the mucosal cutting edge, and heat-sink effects. The usefulness of U-ESD for superficial colorectal neoplasms (SCNs) has been reported, but few studies have compared it with C-ESD. This study aimed to investigate whether U-ESD improves the procedure-related outcomes compared with that of C-ESD in patients with SCNs.

Methods This was a single-center, randomized controlled trial conducted in our department. Patients with unresectable SCNs en bloc by endoscopic mucosal resection were eligible for this study. The participants were randomly assigned to undergo C-ESD or U-ESD performed by a single expert using a monopolar needle-type knife and a tapered hood. Saline was used to create underwater conditions for the U-ESD group. The primary outcome was the median dissection speed, defined as specimen area per ESD procedure time—from the first injection to the completion of submucosal dissection. The secondary outcomes included ESD procedure time, median dissection speed by lesion location categorized by the relationship between the lesion and gravity direction, tumor size, en bloc resection rate, perforation rate, and total amount of saline used during ESD.

Results Between November 2019 and October 2023, 140 patients underwent randomization. Of these, 69 patients who underwent C-ESD and 70 patients who underwent U-ESD were included in the analysis. The median dissection speed was 17.4 and 19.9 mm²/min in the C-ESD and U-ESD groups, respectively (P=0.19). The median ESD procedure time was 55.5 min in the C-ESD group and 48.3 min in the U-ESD group (P=0.38). For lesions located at the gravitational side, the median dissection speed was significantly higher in the U-ESD group than in the C-ESD group (20.8 vs. 13.4 mm²/min; P<0.001). The median tumor size for C-ESD and U-ESD groups were 26 and 25 mm, with no significant difference (P=0.27). En bloc resection was achieved without perforation in all patients. The total volume of saline used in the U-ESD group was significantly higher than that in the C-ESD group (900 mL vs. 100 mL; P<0.001). [1] [2] [3] [4]

Conclusions Our findings suggest that U-ESD does not facilitate dissection speed in colorectal ESD procedures in the overall patient population. However, U-ESD may be a better option for SCNs at the gravitational side where liquid easily collects.

Conflicts of interest

Authors do not have any conflict of interest to disclose.

• References

• 1 Nagata M.. Usefulness of underwater endoscopic submucosal dissection in saline solution with a monopolar knife for colorectal tumors (with videos). Gastrointestinal Endoscopy 2018; 87: 1345-1353
• 2 Nagata M.. Underwater endoscopic submucosal dissection in saline solution using a bent-type knife for duodenal tumor. VideoGIE 2018; 3: 375-377
• 3 Nagata M.. Tapered hood with wide holes in its sides for efficient air bubble removal during underwater endoscopic submucosal dissection. Digestive Endoscopy 2022; 34: 654
• 4 Nagata M.. Underwater endoscopic submucosal dissection using a tapered hood with air bubble outlets for a subcircumferential duodenal tumor. Digestive Endoscopy 2023 in press

Publication History

Article published online:
15 April 2024