Successful Conservative Management of Inferior Mesenteric Artery Aneurysm with Arteriovenous Fistula: A Case Report.

Inferior mesenteric artery (IMA) aneurysm is a rare occurrence, accounting for 1% of all visceral artery aneurysms and is often found incidentally. Surgical resection and endovascular intervention have been first-line treatments because IMA aneurysms have a relatively high risk of life-threatening rupture. Herein, we report the case of a 57-year-old man having a large IMA aneurysm with an arteriovenous fistula that was treated conservatively. The IMA aneurysm was incidentally found using computed tomography (CT) and was connected to the splenic vein through the abnormally dilated tortuous vessels of an arteriovenous fistula. Surgical resection was planned initially; however, preoperative follow-up CT revealed that the aneurysm had shrunk with the growth of an intraluminal thrombus. Subsequently, the condition was conservatively managed with serial CT follow-up. Two years after the first visit, the aneurysm had shrunk and been completely replaced with a thrombus.