Supplementary Material for: Dialysis, Antithrombotics, and Lesion Location: Who Benefits Most from Gel Immersion Endoscopy in Gastric Endoscopic Submucosal Dissection?

Introduction: Gel-immersion endoscopy (GIE) is a technique used to maintain a clear view during gastric endoscopic submucosal dissection (ESD). We aimed to identify cases most likely to benefit from GIE for ESD bleeding by reviewing our clinical experience and determining the associated factors. Methods: We retrospectively analyzed 470 lesions in 380 patients who underwent gastric ESD between October 2020 and March 2023. The patients were divided into conventional method (CM, n=433) and GIE groups (n=37). We compared the clinical and pathological characteristics between the groups. Univariate and multivariate logistic regression analyses were used to identify factors associated with GIE use. Among the GIE group, hemostasis times under gas, water, and gel conditions were compared using the Kruskal–Wallis test. Results: Multivariate analysis revealed that dialysis (odds ratio [OR]: 15.3), concurrent antiplatelet and anticoagulant use (OR: 9.5), and tumor location in the middle third (OR: 3.5), upper third (OR: 5.7), or remnant stomach (OR: 9.3) were independently associated with GIE use. No significant differences in overall hemostasis time were observed between gas, water, or gel. Of the nine bleeding events exceeding 300 s under gas immersion, seven achieved successful hemostasis by switching to GIE, with a median of 32 s to locate the source and 140 s to complete hemostasis. Conclusion: Dialysis, combined antithrombotic use, and certain tumor locations were key factors influencing GIE for ESD bleeding. Although the overall hemostasis times did not differ, GIE may be particularly beneficial in high-risk scenarios.