Abstract / Summary
Abstract Background and aims : EMR is standard for colorectal polyps. Adding epinephrine to submucosal injectate reduces bleeding but may increase postprocedural pain. The optimal concentration is uncertain. We compared low (1:500,000) versus high (1:200,000) epinephrine for postprocedural pain after EMR of 10–20 mm non-pedunculated polyps. Methods : Single-center, randomized, double-blind trial. Patients received submucosal injectate with 1:500,000 or 1:200,000 epinephrine. Primary outcome: pain scores (100-mm VAS) at 30 and 60 minutes post-procedure. Multivariable logistic regression identified independent predictors of clinically significant pain scores. Results 163 patients (81 low, 82 high) were analyzed. Median pain scores at 30 min were significantly lower in the low-concentration group (3.00 vs. 3.00; Hodges-Lehmann estimate − 1.0; 95% CI, -1.0 to -1.0; P < 0.001), as were scores at 60 min (1.00 vs. 2.00; difference − 1.0; 95% CI, -1.0 to 0.00; P < 0.001). Intraprocedural bleeding (7.4% vs. 6.1%; P = 0.98) and postprocedural bleeding (1.2% vs. 1.2%; P > 0.99) did not differ significantly. Multivariable analysis confirmed high concentration epinephrine (OR 3.82; 95% CI, 1.74–8.93; P < 0.001) and larger injection volume (OR 1.44; 95% CI, 1.06–2.03; P = 0.018) as independent predictors of clinically significant pain scores. Conclusions : For EMR of 10–20 mm non-pedunculated colorectal polyps, submucosal injection with 1:500,000 epinephrine significantly reduced postprocedural pain compared with 1:200,000, while maintaining equivalent hemostatic efficacy and safety. Trial Registration ChiCTR2500110027||http://www.chictr.org.cn/) with the Chinese Clinical Trial Registry. Date: 29–09-2025.