This 72 y/o male presented with acute onset of bilateral lower limb ischemia. Selected images from his abdominal CT scan shown above demonstrate an aorta-caval fistula complicating an abdominal aortic aneurysm. There is early, equal enhancement of the IVC and aorta and there is effacement of the IVC with loss of the normal aorta-caval fat plane. In this case, the actual site of fistula formation is visible. The lower limb ischemia was due to a "steal" phenomenon from the large A-V fistula. Renal function became abnormal, likely due to increasing venous pressure in the renal veins. Surgical correction of the fistula and aneurysm rapidly brought the associated abnormalities under control.