Introduction

Endoscopic Submucosal Dissection (ESD) is the best endoscopic technique that enables en bloc resection of superficial colorectal neoplasms.Despite its effectiveness, ESD is not very widespread in Western countries due to technical complexity, long procedure times, and a steep learning curve. These barriers have created a significant gap in adoption and outcomes between Eastern and Western centers. Underwater ESD (U-ESD) has been introduced to simplify the procedure. This study aimed to evaluate the effectiveness of U-ESD versus conventional gas-based ESD (G-ESD) in a Western center, focusing on procedural efficiency and safety.

Aims & Methods

This is a single-center, prospective randomized controlled trial conducted at Fondazione Campus Bio-Medico in Rome between December 2024 and April 2025.Forty patients with non-pedunculated colorectal lesions were randomly assigned in a 1:1 ratio to undergo either Underwater ESD (U-ESD) or conventional ESD with insufflation of Carbon Dioxide (CO2) (G-ESD).The primary outcome was total procedure time. Secondary outcomes included dissection speed, en bloc and R0 resection rates, use of hemostatic forceps, and the incidence of adverse events such as delayed bleeding, perforation, and post-ESD coagulation syndrome (PECS).

Results

A total of 40 patients referred to our endoscopic unit for ESD between December 2024 and April 2025. The mean size of the colorectal lesions was 57.4 mm and 40.7 mm in the U-ESD and G-ESD groups. The location of the lesions was in the rectum in 15% and 55% of the U-ESD and C-ESD groups, respectively; in the right side of the colon in 35% and 20% of the U-ESD and G-ESD groups, respectively. The morphology of LST was classified as LST-nongranular in 20 % and 25% of the U-ESD and G-ESD groups, respectively; as LST granular in 60% and 35% of the U-ESD and G-ESD groups, respectively. Fibrosis (grade 1 and 2) was present in 45% and 30% of the U-ESD and G-ESD groups, respectively. The mean total procedure time was shorter in the U-ESD group compared with the G-ESD group (53.3 ±33 minutes vs 78.7 ± 25.6 minutes; mean difference,–25.4 minutes; P=0.009).Mean dissection speed was faster in the U-ESD group compared with the G-ESD group (42 ± 26.3 mm2/min vs 13.3 ± 8 mm2/min; mean difference, 28.7 mm2/min; P= 0.001). En bloc and R0 resection rates in both groups were 100%. The use of a hemostatic forceps was significantly lower in U-ESD compared G-ESD (40% vs 90%, P= 0.001). Delayed bleeding occurred in only one patient in G-ESD group and was managed successfully by endoscopic clipping. No perforations occurred in either group. PECS was noted in only one patient in the G-ESD group.

Conclusion

UESD has shown a significantly shorter procedure time and faster dissection speed compared with GESD. These both empower the possibility of considering U-ESD as the preferred colorectal ESD method for colorectal lesions.