Primary aortocaval fistula in association with ruptured aneurysms

We report three cases in which ruptured aneurysm and aortocaval fistula went undetected until surgery was performed. Preoperative features suggestive of an arteriovenous fistula were not apparent in any of these patients; they all presented with cardiovascular collapse and all underwent emergency laparotomy after a ruptured abdominal aortic aneurysm was diagnosed. The fistula was discovered unexpectedly only after the aneurysmal sac was opened and the thrombus evacuated. In the first two patients the fistula was successfully sutured from within the aneurysmal sac. The first patient died 1 week postoperatively from rupture of a previously known associated thoracic aortic aneurysm and the second patient died during the operation from excessive blood loss. The third patient had a large fistula requiring an interposition synthetic graft to restore the continuity of the vena cava; the graft has remained patent 15 months postoperatively. Aortocaval fistula is an uncommon complication of aneurysmal aortic disease and may coexist with a rupture of the aneurysm into the retroperitoneum. In emergency cases such as ours it is usually discovered unexpectedly during the operation. The established method of treatment is to oversew the fistula from within the aneurysm; however, when the fistula is large reconstruction of the infrarenal inferior vena cava with an interposition synthetic graft is a good alternative to caval ligation.