Blind loop mucocele of a side-to-end colorectal anastomosis as a rare cause of large bowel obstruction.

Large bowel obstruction (LBO) after colorectal surgery draws wide differentials. To our knowledge, LBO due to blind colonic limb mucocele of a side-to-end colorectal anastomosis has not yet been described. We report a man in his late 50s presenting with pain, abdominal distension and constipation. He had extensive surgical history; notably, a side-to-end colorectal anastomosis was fashioned following Hartmann-type colostomy reversal. CT and MRI suggested a mucus-filled short blind colonic segment compressing the anastomotic site and causing LBO. Flexible sigmoidoscopy under general anaesthesia showed external rectal compression and lumen narrowing. Transrectal needle aspiration of the blind segment yielded 145 mL of mucoid fluid. The patient's symptoms improved and he was discharged with outpatient Gastrografin enema and flexible sigmoidoscopy which confirmed successful blind segment emptying. This case highlights that blind colonic loop mucoceles in colorectal anastomosis can rarely cause obstruction, and endoscopic management is feasible when accurate diagnosis is confirmed on imaging.