Renal arteriovenous fistulas and aneurysm: sonographic findings.

Two cases of congenital renal arteriovenous fistula and one case of intrarenal arterial aneurysm that were prospectively evaluated by real-time sonography are presented. The cirsoid type arteriovenous fistula had a characteristic sonographic appearance and was seen as a cluster of tubular anechoic structures within the kidney; it was supplied by an enlarged renal artery and drained by a dilated renal vein. Both the fistula (aneurysmal type) and the renal artery aneurysm were associated with a peripheral thrombus in the wall of the aneurysm and a central tubular anechoic lumen. The arterial aneurysm was also associated with visible pulsations on real-time sonograms. When present, the sonographic features as seen in these cases should facilitate a correct diagnosis, or at least suggest a renal lesion of vascular origin to be confirmed by renal angiography.