Ruptured Intrahepatic Arterial Aneurysm due to Segmental Arterial Mediolysis Treated with Coil Embolization

A 67-year-old man presented with sudden-onset abdominal pain and hemorrhagic shock. Contrast-enhanced CT revealed a large hematoma in hepatic segments VI-VII with capsular rupture and hemoperitoneum. CT angiography demonstrated a saccular pseudoaneurysm in a posterior segmental branch of the right hepatic artery and a beaded appearance with irregular dilatation and segmental narrowing of the right hepatic artery branches, without inflammatory or atherosclerotic findings, supporting a diagnosis of segmental arterial mediolysis (SAM). Emergency angiography followed by coil embolization achieved hemostasis. Follow-up CT at 5 months showed complete exclusion of the aneurysmal lesions, with no evidence of recurrence or new vascular lesions. Coil embolization may be an effective, minimally invasive option for ruptured intrahepatic SAM lesions.