A 73-year-old man complained of pain in the right lower abdomen with hypotension. The result of abdominal computed tomography (CT) suggested a rupture of an abdominal aortic aneurysm. Emergency Y graft replacement was performed. During surgery, a perforation of about 1cm in diameter was found in the posterior wall of the abdominal aorta just above the iliac bifurcation. The patient developed postoperative complication of retroperitonitis. The cultures of blood clots collected during surgery grew Bacteroides fragilis, as did postoperative drainage fluid from the retroperitoneum. On the 10th day of illness, axillo-bifemoral bypass was performed and the Y graft was removed. Although continuous lavage of the retroperitoneum was performed, he did not recover from retroperitonitis and died of sepsis 2 months after surgery. Infected abdominal aneurysm is rarely caused by Bacteroides. We discussed the infectious route and treatment of this rare condition with a review of the literature.

A 53-year-old man who had angina pectoris and juxtarenal aortic abdominal aneurysm was referred to our department. Because the coronary angiography showed severe triple vessel disease, coronary bypass grafting was performed prior to aneurysmectomy. Contrast enhanced computed tomography revealed a retroaortic left renal vein located behind the posterior wall of the aneurysm. The postoperative course was uneventful. Because of its complicated embryological development, the anatomy of the renal veins shows extensive variability. The incidence of retroaortic left renal vein was 2%. Large lumbar and retroperitoneal veins often joined it to form a complex retroaortic venous system. These veins are particularly vulnerable to injury during circumferential dissection of the proximal parts of the aorta. Unawareness of this anomaly and vigorous attempts at encircling the aorta with clamps can result in laceration of the vein. Subsequent catastrophic hemorrhage may lead to unfavorable results, nephrectomy or death. Therefore, preoperative evaluation by a contrast enhanced CT scan and adequate intraoperative management based on a understanding of the potential anatomical variations are imperative. We recommend crossclamp of the aorta proximally with a vertical clamp to avoid circumferential dissection with possible injury to a retroaortic left renal vein. Injury may necessitate division of the aorta to obtain exposure for venous repair. In addition, this anomaly may be related to aorto-left renal vein fistula syndrome and left renal vein entrapment syndrome.