A case of an aortocaval fistula documented by contrast-enhancement com
puted tomography is reported. in the presence of a large abdominal aor
tic aneurysm, the computed tomography (CT) triad findings of: (1) vena
caval effacement, (2) loss of the fat plane between the aorta and ven
a cava, and (3) rapid flow of contrast from the aorta into a dilated i
nferior vena cava is characteristic of an aortocaval fistula.