次發性主動脈腸道瘺管是在病患接受過主動脈瘤重建修復手術後相當罕見但死亡率高的嚴重併發症。我們在這裡報告一位68 歲男性病患，因為呼吸急促，慢性貧血，發燒寒意住院。過去病史包括糖尿病，冠狀動脈疾病，而且在十年前接受過主動脈瘤重建修復手術。病患在住院二周前曾經有過黑便。剛住院時的血液培養報告發現多菌叢菌血症(Streptococcussanguis，Lactobacillus paracasei, Candida lusitaniae)，後續追蹤血液培養又發現另一種細菌(Enterobacter Cloacae)。這些血液培養發現的菌叢跟消化道菌叢似乎有相關性。為了找出感染源， 正電子發射斷層掃描(FDG PET-CT) 發現在腹部主動脈移植物上端接近十二指腸位置，有異常代謝亢進訊號，懷疑似感染源。胃鏡檢查發現在十二指腸第三段位置，有一大型憩室樣異常結構，並有異物質地隆起，但並無出血現象，經仔細判讀確認是次發性主動脈十二指腸腸道瘺管。因此，病患接受手術移除已經損壞並感染的主動脈移植物，重新修復主動脈瘤重建手術，並修補十二指腸腸道瘺管，病患術後恢復順利出院。如果病患過去病史有接受過主動脈瘤重建修復手術，發生不明原因感染菌血症，無論是否臨床上有無明顯消化道出血現象，次發性主動脈腸道瘺管一定要列入鑑別診斷來考慮，保持高度警覺和懷疑，是臨床上迅速並正確診斷的基本的要件。

Secondary aortoenteric fistula is a rare yet fatal complication after reconstructive surgery of aortic aneurysm. A 68-year-old man with a significant past medical history of type 2 diabetes, coronary artery disease status post cardiac stent, and aortobifemoral bypass graft performed 10 years ago, presented with shortness of breath, chills, and progressive anemia for the past 14 months. Patient reported one episode of melena 2 weeks before admission. The initial blood cultures growth of a variety of microorganisms (Streptococcus sanguis, Lactobacillus paracasei, Candida lusitaniae) and the subsequent blood cultures growth of another microorganism (Enterobacter Cloacae) were considered to have a GI source. A contrast CT scan of abdomen and pelvis did not show acute intra-abdominal process. Then a FDG PET-CT scan result showed hypermetabolism signal associated with the proximal end of the aortoiliac graft, concerning for infection of the graft itself. An esophagogastroduodenoscopy revealed a large centrally bulging lesion, without bleeding, in the third part of the duodenum, which was consistent with a secondary aorto-enteric fistula formed by infected aortic graft eroding into duodenum. The patient subsequently underwent explantation of the infected aortobifemoral bypass graft, reconstruction with cryopreserved aortoiliac allograft, and resection of small intestine with anastomosis closure of duodenotomy. The patient was discharged from the hospital 10 days after the operation and later was doing well. Secondary AEF should be suspected in patients presenting with unclear source of bacteremia with or without GI bleeding and a history of aortic repair. Clinical suspicion is the most crucial factor contributing to the right diagnosis.