Aortoenteric fistula and perigraft infection: evaluation with CT

A blinded retrospective study was performed to determine the sensitivity and specificity of computed tomography (CT) in detecting perigraft infection (PGI) and aortoenteric fistula (AEF), rare but devastating complications of aortic reconstructive surgery. Two observers independently reviewed CT scans in 55 cases including AEF (n = 23); PGI (n = 12); and normal, noninfected grafts (n = 20). Each scan was assessed for ectopic gas, focal bowel wall thickening, perigraft fluid, perigraft soft tissue, pseudoaneurysm formation, disruption of the aneurysmal wrap, and increased soft tissue between the graft and surrounding wrap. Comparison of CT findings with operative results revealed that each observer correctly identified as abnormal 33 of 35 cases of PGI either with or without AEF (sensitivity, 94%) and that results were falsely positive in three cases (specificity, 85%). CT findings ranged from large amounts of perigraft soft tissue and ectopic gas to subtle findings of minimal or no abnormalities; thus, strict criteria must be applied to the interpretation of CT scans after aortic surgery. Although CT is not 100% sensitive or specific, the authors conclude that it will continue to be valuable for diagnosing PGI and AEF.