Aortoenteric fistulas: Spectrum of CT findings

Objective: This article reviews the causes of aortoenteric fistulas, diagnostic options, and important CT findings. Conclusion: Aortoenteric fistula, a rare but potentially fatal entity, presents a significant challenge to radiologists in diagnosis, largely because of its subtle and nonspecific imaging findings. These fistulas can be divided into primary and secondary forms, depending on the presence or absence of prior aortic reconstructive surgery, but the secondary form is more common. Typical CT findings, which can overlap with those seen in perigraft infection, aortitis, infected/mycotic aneurysms, perianeurysmal fibrosis, and the immediate post-operative period after placement of a graft, include: Effacement of the fat planes around the aorta, perigraft fluid/soft tissue thickening, ectopic gas, tethering of adjacent thickened bowel loops towards the aortic graft, and in rare cases, extravasation of contrast from the aorta into the involved segment of bowel.