Ureteroarterial Fistula Secondary to External Iliac Artery Pseudoaneurysm in a Patient With Metastatic Colon Cancer

Ureteroarterial fistula is an uncommon yet potentially fatal source of hematuria, typically arising in patients with a history of pelvic surgery, radiation exposure, or malignancy. An 80-year-old woman with a history of metastatic colon cancer status post chemoradiation and partial colectomy with Hartmann pouch formation, with bladder involvement, presented with abdominal pain and hematuria. During hospitalization, she developed hypotension with an acute drop in hemoglobin to 7 g/dL. Triphasic CT angiography (CTA) revealed active arterial contrast extravasation from the left external iliac artery into the distal ureter, consistent with a ureteroarterial fistula. Digital subtraction angiography (DSA) confirmed a left external iliac artery pseudoaneurysm, and the patient underwent successful endovascular management with a covered stent placement and exclusion of the left hypogastric artery. Hematuria resolved following intervention, with stabilization of hemodynamics and hemoglobin levels. The patient was maintained on continuous bladder irrigation. Although her long-term prognosis remained poor due to advanced malignancy, she was ultimately stabilized and discharged home. This case emphasizes the need for early recognition of ureteroarterial fistula in high-risk patients and underscores the value of multiphasic imaging and endovascular management.