Treatment of abdominal aortic aneurysm by exclusion and bypass: an analysis of outcome. Abdominal aortic aneurysm is conventionally treated by aneurysmorrhaphy with inlying graft. Alternatively, division of the aorta, with suture closure of the distal aorta and outflow vessels (exclusion of the aneurysm), and end-to-end proximal to distal bypass may be performed. However, the long-term fate of this operation has not been determined. Specifically, concern exists that the excluded blood filled aneurysm may not thrombose or may be the source of late sepsis. During an 8-year period we have treated 280 abdominal aortic aneurysms (urgent and elective) by exclusion of the abdominal aortic aneurysm sac and bypass via the posterolateral retroperitoneal approach. Mean age was 70 years (range, 44 to 88), with 217 men and 63 women. Preoperative CT scanning and aortography were performed to assess arterial anatomy. Seventy tube grafts and 260 bifurcation grafts were used. Thirty-day mortality rate was 4%. Estimated blood loss was 731 +/- 52 ml; mean transfusion requirements were 456 +/- 82 ml. The minor complication rate was 6%, and it is of great interest that there were no cases of ischemic colitis requiring colectomy. Aneurysm sacs thrombosed except in two anticoagulated patients who required further treatment. No late infections occurred. Five-year bypass patency rate was 98%. These data demonstrate that this method of treatment effectively minimized operative dissection and blood loss and therefore is a viable alternative for the management of abdominal aortic aneurysms. 