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Imaging Sciences Interesting Cases

Case 344

Scott Mooney, MD

Clinical Presentation: Patient is a 75-year-old male, with history of a prior abdominal aortic aneurysm (AAA) repair, presenting with syncope, hypotension, abdominal pain, and GI bleed.

Imaging Findings: CT images demonstrate high density fluid within the small bowel and mild inflammatory changes anterior to the aorta at the level of the third portion of the duodenum.
Figure 1. Axial CT with intravenous contrast demonstrates periaortic inflammatory changes and calcifications or surgical clips.
Figure 2. High density material is noted within the small bowel.

Diagnosis: Aortoenteric fistula

Discussion: An aortoenteric fistula can present clinically as limited or massive GI bleeding. Upper endoscopy and colonoscopy are often unremarkable, and the history of an aortic graft repair is the one clue to diagnosis.

Primary aortoenteric fistulae are rare. More commonly they are secondary, occurring after aortic aneurysm repair. Less than 2% of repairs develop this complication. Other conditions leading to a secondary fistula formation include an aortic aneurysm, aortitis, radiation therapy, malignancy, and peptic ulcer disease. Because of its close proximity to the aorta, the third portion of the duodenum is often involved, although any section of the GI tract can potentially fistulize.

CT is the preferred radiologic examination. Water as an oral contrast agent can help aid for intestinal blood or extravasated contrast. A tagged red blood cell scan, aortography, upper GI, and ultrasound can also be used.

Urgent surgery is required, as the mortality rate is as high as 30-75%.

References:

  1. Low RN, Wall SD, Jeffrey RB Jr, Sollitto RA, Reilly LM, Tierney LM Jr. Aortoenteric fistula and perigraft infection: evaluation with CT. Radiology. 1990 Apr;175(1):157-62. PMID: 2315475 [PubMed]
  2. Pickhardt PJ, Bhalla S, Balfe DM. Acquired gastrointestinal fistulas: classification, etiologies, and imaging evaluation. Radiology. 2002 Jul;224(1):9-23. PMID: 12091657 [PubMed]