Abstract
Both arteriovenous malformation (AVM) and trisomy 21 are rare diseases. Studies have shown that individuals with trisomy 21 may have potential vascular malformations, with the main site of onset being the portal system. This case involved an adult patient with trisomy 21 who presented with pelvic iliac arteriovenous malformations. The patient underwent interventional treatment, and the prognosis was favorable. It is important to enhance the screening for vascular malformations in patients with trisomy 21 syndrome. At the same time, interventional treatment for AVMs is effective and increasingly important for managing AVMs.