A Step-Up Underwater Endoscopic Mucosal Resection Strategy with Rescue Underwater Injection Endoscopic Mucosal Resection for Non-Pedunculated Colorectal Lesions.
A step-up strategy using UEMR with conversion to UIEMR achieved 100% en bloc resection and negative margins in non-pedunculated colorectal lesions, with no adverse events reported.
Where it sits
this study against the rest of the cjc-1295 without dac (modified grf 1-29) corpusSummary and findings
This retrospective study evaluated a step-up strategy using underwater endoscopic mucosal resection (UEMR) with conversion to underwater injection EMR (UIEMR) for non-pedunculated colorectal lesions. The study included 56 lesions, achieving en bloc resection and histologically negative margins in all cases. No adverse events such as delayed bleeding or perforation were reported.
Abstract
<h4>Objectives</h4>Underwater endoscopic mucosal resection (UEMR) is an established treatment for non-pedunculated colorectal lesions, but securing an adequate resection margin can be difficult in selected cases due to poor visualization or snare instability. To address these limitations, we used a step-up strategy with UEMR first and selective conversion to underwater injection EMR (UIEMR) when necessary. This retrospective study evaluated the technical outcomes and safety of this step-up strategy for non-pedunculated lesions measuring 10-20 mm.<h4>Methods</h4>This single-center retrospective study included 56 consecutive 10-20 mm non-pedunculated colorectal lesions treated with UEMR as the first-line approach between September 2024 and September 2025. When predefined intra-procedural criteria for UEMR difficulty were met, the procedure was converted to UIEMR. The primary endpoints were technical success (en bloc and R0 resection rates) and procedure-related adverse events of the step-up strategy.<h4>Results</h4>Resection was completed using UEMR alone in 31 lesions, whereas 25 lesions required conversion to UIEMR. En bloc resection was achieved in all lesions, and histologically negative margins were reported in all cases. No delayed bleeding or perforation was observed.<h4>Conclusion</h4>For 10-20 mm non-pedunculated colorectal lesions, a step-up strategy with UEMR first and selective conversion to UIEMR was feasible and safe and may be a practical treatment option.Clinical trial registration: N/A.
Background
The study addresses the challenge of achieving adequate resection margins in non-pedunculated colorectal lesions using underwater endoscopic mucosal resection (UEMR). UEMR is an established technique, but visualization and snare stability can be problematic. This study explores a step-up strategy incorporating UEMR with conversion to underwater injection EMR (UIEMR) to improve outcomes.
Methods
This was a single-center retrospective study involving 56 consecutive non-pedunculated colorectal lesions measuring 10-20 mm. The lesions were initially treated with UEMR, with conversion to UIEMR based on predefined intra-procedural criteria. The primary endpoints were technical success, defined as en bloc and R0 resection rates, and procedure-related adverse events.
Results
The study achieved en bloc resection in all 56 lesions, with histologically negative margins in every case. UEMR alone was sufficient for 31 lesions, while 25 required conversion to UIEMR. No delayed bleeding or perforation was observed, indicating a high safety profile for the step-up strategy.
Interpretation
The findings suggest that the step-up strategy is both feasible and safe for treating 10-20 mm non-pedunculated colorectal lesions. While the en bloc resection rate was 100%, the retrospective design and single-center setting may limit the applicability of these results. The strategy may offer a practical alternative to traditional methods, but further studies are needed to confirm these findings.
Key findings
- 56 non-pedunculated colorectal lesions treated.
- 31 lesions completed with UEMR alone.
- 25 lesions required conversion to UIEMR.
- En bloc resection achieved in 100% of lesions.
- Histologically negative margins in 100% of cases.
- No delayed bleeding or perforation observed.
Limitations
- Single-center study
- Retrospective design
- No control group
- Limited to lesions 10-20 mm