A New Diagnosis of Ulcerative Colitis on a Background of Diversion Colitis Following Hartmann's Procedure for Perforated Diverticula.

Ulcerative colitis (UC) is a chronic immune-mediated intestinal condition. This case report describes an 82-year-old woman who was newly diagnosed with UC. Two years prior, she had multiple admissions for abdominal pain and rectal bleeding, initially diagnosed as diverticulitis. Following Hartmann's procedure for a sealed perforation, she developed diversion colitis. Subsequent symptoms included abdominal pain, vomiting, and high stoma output, with CT imaging revealing upstream colitis and para-stomal cellulitis. Biopsies confirmed severe inflammation and ulceration consistent with UC. The patient was treated with intravenous hydrocortisone, but her symptoms rebounded upon steroid tapering. Vedolizumab was considered due to her venous thromboembolism (VTE) risk. Post-treatment, her stoma output and skin irritation improved. This case supports the theory that diversion colitis may predispose individuals to developing UC.