Massive intraperitoneal hemorrhage followed by delayed perforation after forced cold snare polypectomy for a colonic adenoma.

Cold snare polypectomy (CSP) is widely considered a safe treatment for colorectal polyps. We report a rare case of intraperitoneal hemorrhage followed by delayed perforation after CSP in a 78-year-old man undergoing hemodialysis. CSP was performed for an 8-mm slightly elevated lesion in the ascending colon, requiring forced CSP to complete resection. Four hours after the procedure, the patient developed abdominal pain, and contrast-enhanced computed tomography revealed an intramural hematoma with active bleeding. Transcatheter arterial embolization achieved hemostasis. Two days after colonoscopy, recurrent abdominal pain occurred during hemodialysis, and repeat imaging demonstrated free air. Emergent right hemicolectomy revealed bloody ascites and a perforation at the CSP site. The patient recovered uneventfully and was discharged on postoperative day 22. This case suggests that impaired hemostasis related to hemodialysis and concomitant antithrombotic therapy may predispose patients to intramural hematoma formation and delayed perforation. Mechanical compression from the expanding intramural hematoma may have caused structural failure at the forced CSP site, ultimately leading to perforation. In our exploratory in vivo porcine colon experiment, forced CSP generated traction that appeared to pull the muscularis propria and serosa into the endoscopic working channel, indicating the need for careful use of the technique and perioperative management. (200 words).