Idiopathic renal arteriovenous fistulae

A 48-year-old woman was admitted owing to her complaint of right flank pain. Her previous medical history was unremarkable, except that she was receiving thyroid replacement after partial thyroidectomy and propanolol for migraine headaches. Physical examination was normal except for a mild resting tachycardia (85 b.p.m.) and a right flank bruit. The patient was normotensive (120/80 mm Hg). Routine laboratory tests were within normal limits. An initial renal ultrasound revealed a discrete area of heterogeneous echogeneity of the right upper renal pole. Color Doppler sonography showed increased blood flow in a giant right renal artery. Computed tomography angiography and renal angiograpy (Figure 1a, b) revealed a right arteriovenous fistula (AVF) with dilatation of the main renal artery and a segmental branch in the upper pole with multiple aneurysmal dilatations of the draining veins. Pathological neoplastic vessels were ruled out radiomorphologically. Endovascular occlusion of the AVF was attempted with an Amplatzer vascular plug. Postembolization angiographic images (Figure 1c) revealed complete occlusion of the feeding vessel, absence of opacification of the dilated veins, and a better opacification of the remaining segmental normal branches and no signs of malignancy (Figure 1d).