Aortocaval fistula: diagnosis with carbon dioxide angiography.

Aortocaval fistulas are an uncommon complication of atherosclerotic aneurysms that can present with a variety of clinical symptoms. Many of these patients present with oliguric renal failure, a contraindication for the use of iodinated contrast in radiological studies. We present a case of an aortocaval fistula diagnosed by using carbon dioxide gas without the use of traditional contrast media.