Efficacy of Gel Immersion Endoscopic Submucosal Dissection for Colorectal Lesions

Background and study aims: Endoscopic submucosal dissection (ESD) is curative for colorectal tumors but remains technically demanding, with perforation risk related to luminal distension and suboptimal visualization. Gel immersion ESD (GI-ESD) may offer mechanistic advantages over conventional CO₂-insufflation ESD (C-ESD), including reduced colonic distension, improved visibility/depth perception, buoyancy-assisted dissection stability, and heat-sink protection. We hypothesized that these features would improve short-term safety and procedural stability. Patients and methods: In this single-center retrospective study, consecutive colorectal ESD cases (2022–2024) were analyzed. C-ESD was performed from January 2022 to March 2024; GI-ESD using VISCOCLEAR (Otsuka Pharmaceutical Factory, Tokushima, Japan) from April to December 2024. After excluding non-epithelial lesions, 392 patients were included (293 C-ESD; 99 GI-ESD), including interrupted procedures. The primary outcome was adverse events (perforation, delayed bleeding). Secondary outcomes were en bloc and R0 resection rates, procedure time (including gel injection), and postoperative inflammatory response. Results: Of 392 patients, 293 underwent C-ESD and 99 underwent GI-ESD were analyzed. En-bloc and R0 resection rates were comparable between GI-ESD and C-ESD (97.0% vs. 99.9%, p=0.16, 90.6% vs. 91.4%, p=0.35). The perforation rate was significantly lower in GI-ESD (0% vs. 4.1%, p=0.04). Postoperative fever (≥37.6°C; 4.2% vs. 12.7%, p=0.02) and median CRP elevation (0.33 mg/dl vs. 0.42 mg/dl, p<0.01) were also significantly reduced in GI-ESD; however, the incidence of PECS, the clinically relevant composite inflammatory outcome, was not significantly different between groups. Conclusions: GI-ESD achieved curative outcomes comparable to C-ESD while reducing perforation risk; PECS remained comparable between groups.