An Uncommon Cause of Recurrent Rectal Bleeding in a Young Adult

Recurrent rectal bleeding in young adults is uncommon and may pose a diagnostic challenge. We present a case of a 21-year-old male with an 8-year history of intermittent rectal bleeding, initially misdiagnosed with ulcerative colitis based on mild proctosigmoiditis and nonspecific colitis on biopsy. Despite medical therapy, his anemia worsened, prompting computed tomography angiography, which revealed an inferior mesenteric arterial malformation. The patient underwent successful endovascular embolization, with complete resolution of symptoms and improved mucosal findings on follow-up colonoscopy. This case highlights the importance of considering vascular malformations in unexplained or refractory lower gastrointestinal bleeding in young adults.