Surgical repair of a concealed aortocaval fistula associated with an abdominal aortic aneurysm: report of two cases.

Two cases of a concealed aortocaval fistula (ACF) associated with an abdominal aortic aneurysm (AAA) are presented herein. ACF is a rare complication of AAA and only a few cases have so far shown the triad of symptoms, including congestive heart failure, a continuous abdominal bruit, and a pulsating abdominal mass. Sometimes a definite diagnosis is not made preoperatively and as a result, massive bleeding is encountered. We believe that the presence of a large aneurysm, compression, and involvement of the inferior vena by an aneurysm, and pelvic venous dilatation on abdominal computed tomography and hematuria may additionally suggest the presence of a concealed ACF. A correct preoperative diagnosis will help greatly in selecting the optimal surgical modality and should also reduce the degree of bleeding.