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Abstract Background Monopolar instruments are generally used in colorectal endoscopic mucosal resection (EMR). Bipolar instruments have previously been reported to be as safe as monopolar instruments. We sought to compare the safety of the monopolar and bipolar snare and hemostatic forceps in an animal model. Methods We created 5-mm, 10-mm, and 15-mm target lesions on an ex vivo porcine rectum. Two lesions of each size were resected via monopolar polypectomy (M-P), monopolar EMR (M-E), bipolar polypectomy (B-P), and bipolar EMR (B-E). We performed a pathological evaluation of the conditions of perforation and the effects of burning on the tissues. In addition, we burned the muscularis propria covered with submucosal layer using monopolar and bipolar hemostatic forceps and performed pathological evaluations. Results Polypectomy and EMR were performed in a total of 24 target lesions. A perforation was found on histology in one case of M-P and one case of M-E after removing target lesions of 15 mm in diameter. There were no perforations during endoscopic resection using the bipolar snare. The thermal denaturation in B-P did not reach the muscularis propria layer regardless of the size of the target lesion. Although thermal damage after using monopolar hemostatic forceps was extensive, thermal denaturation was only seen on the surface of the submucosal layer when bipolar hemostatic forceps were used. Conclusions Bipolar instruments cause less damage to the tissue than monopolar instruments. Our results also suggest that bipolar instruments may be safer than monopolar instruments in endoscopic procedures for colorectal lesions.

Background: Monopolar instruments are generally used in colorectal endoscopic mucosal resection (EMR). Bipolar instruments have previously been reported to be as safe as monopolar instruments. We sought to compare the safety of the monopolar and bipolar snare and hemostatic forceps in an animal model.Methods: We created 5-mm, 10-mm, and 15-mm target lesions on an ex vivo porcine rectum. Two lesions of each size were resected via monopolar polypectomy (M-P), monopolar EMR (M-E), bipolar polypectomy (B-P), and bipolar EMR (B-E). We performed a pathological evaluation of the conditions of perforation and the effects of burning on the tissues. In addition, we burned the muscularis propria covered with submucosal layer using monopolar and bipolar hemostatic forceps and performed pathological evaluations.Results: Polypectomy and EMR were performed in a total of 24 target lesions. A perforation was found on histology in one case of M-P and one case of M-E after removing target lesions of 15 mm in diameter. There were no perforations during endoscopic resection using the bipolar snare. The thermal denaturation in B-P did not reach the muscularis propria layer regardless of the size of the target lesion. Although thermal damage after using monopolar hemostatic forceps was extensive, thermal denaturation was only seen on the surface of the submucosal layer when bipolar hemostatic forceps were used.Conclusions: Bipolar instruments cause less damage to the tissue than monopolar instruments. Our results also suggest that bipolar instruments may be safer than monopolar instruments in endoscopic procedures for colorectal lesions. [ABSTRACT FROM AUTHOR]

Purpose: Almost any colorectal superficial neoplastic lesion can be treated by endoscopic resection (ER) but very little is known about outcomes of ER leaving circumferential or near-circumferential mucosal defects. We report the outcomes of ER leaving ≥ 75% circumferential mucosal defects performed in a western expert centre. Methods: Five hundred eighty-seven ERs of large colorectal lesions ≥ 20 mm were grouped according to the extent of the mucosal defect and comparisons made between those with < 75% and ≥ 75% defects. Independent predictors of stenosis were identified. Results: Forty-seven patients had ER leaving ≥ 75% circumference defect, most located at or distal to the rectosigmoid, with ≥ 90% defects in 5 and 100% in 11. There were no significant colonic muscle injuries in patients with ≥ 75% defect and no differences in post-procedure bleeding (OR 1.6, 95% CI 0.2–13.7, p = 0.64) between patients with ≥ 75% and < 75% defects. Stenosis developed in 9 patients. ≥ 90% circumference defect was the only independent risk factor for stenosis (OR 286, p < 0.001). Three of 4 patients with asymptomatic stenosis had successful expectant management. The remainder were treated with dilatation. Recurrence was more likely in those with ≥ 75% defect (OR 7.9, 95% CI 3.8–16.4, p < 0.001) but was managed with further ER in all but 2 cases. Conclusion: ER of colorectal lesions resulting in defects ≥ 75% of the luminal circumference is challenging but safe and effective when performed in an expert centre. The only independent predictor of stenosis is ≥ 90% circumference defect but some patients improve with expectant management; therefore, pre-emptive intervention may not be warranted. [ABSTRACT FROM AUTHOR]