In recent years, underwater endoscopic mucosal resection (UEMR) has gained widespread popularity. However, intestinal fluids, bubbles, or bleeding may impair visibility. Gel immersion endoscopic mucosal resection (GIEMR) has been reported in some Asian series. The use of an electrolyte-free gelling agent may offer advantages over UEMR due to its higher viscosity, and transparency, providing luminal stability, requiring smaller volumes, and ensuring a clearer visual field by displacing particles while limiting dilution with blood. Moreover, its greater weight favours bleeding control through a “slowing effect”.

The main objective of the study was to evaluate the use of a food thickener (xanthan gum), as a gel easily prepared in the endoscopy room,  for performing ft-GIEMR  of non-pedunculated duodenal and colorectal polyps.

A longitudinal, observational, single-centre pilot study was conducted. Consecutive cases prospectively collected in a dedicated database, from January 2024 to June 2025 were retrospectively analysed. Lesions treated with ft-GIEMR (food thickener) were included. The primary endpoint was feasibility and improvement of the visual field. Secondary endpoints included complete and en bloc resection, adverse events and procedure duration. Recurrence data are pending.  

Among 180 complex lesions resected by EMR, UEMR, EFTR, or ESD, 29 patients (58% male; median age:70.3 years [IQR: 60–81]) with 29 lesions were selected for GIEMR. Lesion locations included duodenum (n=2) and the colon and rectum (n=27), with a median size of 43.5 mm (IQR:32.5–55). Paris classification included Is, 0-IIa, or Is+0-IIa morphologies. Colorectal lesions were classified as LST-G homogenous (37%, n=10), LST-G nodular-mixed (37%, n=10), and LST-NG elevated (26%, n=7). Gel volumes ranged from 100 to 400 mL per procedure. Median overall procedure time was 87 minutes [IQR:45–120]. Complete resection was achieved in 93% (27/29), with piecemeal in 27 vs. en bloc resection in 2. One intraprocedural arterial bleed required conversion to CO₂ insufflation and prolonged procedure time. Post-procedure bleeding occurred in 3 cases. No intra or delayed perforations were observed.

The use of food thickener for GIEMR appears feasible, effective, and safe, with high complete resection rates (93%) and no perforations. Prospective comparative studies with UEMR are warranted to confirm these preliminary findings.