Normal left renal vein mimicking left renal artery aneurysm

On transverse ultrasound scans a small number of patients with a paucity of retroperitoneal fat show an initial false impression of a left renal artery aneurysm due to the confluence of two normal findings. The left renal vein is unusually prominent from the hilum of the left kidney to the area between the superior mesenteric artery and the aorta; and part of the normal aortic wall, adjacent to the left renal vein, is incompletely imaged. Explanations for the prominence in the left renal vein and the partial visualization of the aortic wall are discussed, and various maneuvers that allow for accurate identification of both are described. The use of this analysis should prevent the incorrect diagnosis of a left renal artery aneurysm, which might lead to more invasive diagnostic procedures.