Endoscopic submucosal dissection including the papilla (ESDIP) for superficial duodenal epithelial tumors (SDETs) is minimally invasive but technically challenging due to the complex local anatomy and exposure to bile and pancreatic juice. SDETs involving the papilla are not a general indication for laparoscopic endoscopic cooperative surgery because they are directly adjacent to the pancreas. To overcome these difficulties, we introduced gel immersion ESDIP (GI-ESDIP) in 2022. This study aimed to compare the clinical outcomes of GI-ESDIP with those of conventional ESDIP (C-ESDIP).

We retrospectively analyzed 29 consecutive ESDIP cases performed at our institution between January 2016 and October 2025. All procedures were performed using a scissor-type knife, with prophylactic biliary and pancreatic stent placement and attempted complete closure of the mucosal defect. Clinical characteristics, procedural outcomes, and adverse events were compared between the C-ESDIP group (n = 13, 2016–2022) and the GI-ESDIP group (n = 16, 2022–2025).

Baseline characteristics were comparable between groups. Median lesion size was not significantly different (37 vs. 31.5 mm, P = 0.357). Median procedure time was significantly shorter in the GI-ESDIP group (58 vs. 101 min, P = 0.020). En bloc resection was achieved in 100% of cases in both groups, and R0 resection rates were similar (76.2% vs. 87.5%, P = 0.632). The median number of intraoperative bleeding points was significantly lower in the GI-ESDIP group (4 vs. 8, P = 0.004). No intraoperative perforation occurred in either group. Muscularis propria exposure tended to be lower in the GI-ESDIP group (0% vs. 23.1%, P = 0.078). Delayed adverse events were comparable (7.7% vs. 12.5%), with one delayed perforation in each group, and one delayed bleeding and one cholangitis in the GI-ESDIP group. No pancreatitis occurred. One local recurrence was observed in the GI-ESDIP group and one metastatic recurrence in the C-ESDIP group.

GI-ESDIP appears to reduce intraoperative bleeding and shorten procedure time, likely due to its stable visual field, buoyancy-assisted tissue elevation, and maintenance of a low intraluminal pressure environment. These findings suggest that gel immersion may enhance the safety and efficiency of papilla-involving duodenal ESD.