Paraprosthetic Extravasation of Enteric Contrast: A Rare and Direct Sign of Secondary Aortoenteric Fistula

Abstract

Peirce RM, Jenkins RH, MacEneaney P(AQ1) n aortoenteric fistula is a communication between the aorta and the gastrointestinal tract. This condition is a rare cause of massive, lifethreatening gastrointestinal hemorrhage. Primary aortoenteric fistulas are typically caused by arteriosclerosis and occur in the elderly. Secondary aortoenteric fistulas (SAEFs) are uncommon complications of vascular surgical procedures. Presentations of SAEF can be straightforward but are notorious for elusive and temporally remote presentations. The symptoms of SAEF are variable and depend on the site of the graft infection. Infected femoral components in a patient may present with a fever, local tenderness, and, occasionally, purulent drainage through a sinus tract in the thigh. Intraabdominal infections tend to be more nebulous; malaise, back pain, elevated white blood cell count (WBC), and abdominal complaints are the usual presentation. These features mimic more common disease entities, making diagnosis difficult. Proving the existence of an SAEF radiographically can be difficult. In this article, paraprosthetic extravasation of enteric contrast, a rare and direct sign of SAEF, verified aorto-to-enteric communication on CT. Case Report A 72-year-old woman arrived at our emergency department with a fever, elevated WBC count, abdominal pain, and purulent groin drainage (Fig. 1). The patient had aortobifemoral prosthesis placement at an outside institution 6 weeks earlier. Because of abnormal renal function, a CT scan of the abdomen and pelvis was performed with enteric contrast only (meglumine diatrizoate [Gastrografin], Mallinckrodt). CT revealed a ring of high-contrast material and air in the paraprosthetic space of the left iliac limb of the graft. The contrast and air tracked superiorly, to the level of the aortic portion of the graft and inferiorly into the groin. This represented leakage of enteric contrast from the bowel. CT findings indicated an aortoenteric fistula and were confirmed at surgical exploration. Laparotomy revealed an infected aortobifemoral graft with a large intraabdominal collection of purulent fluid just behind the duodenum, anterior to the graft. The infected fluid collection extended into the left limb of the graft, with associated erosion into the adjacent sigmoid colon. The infected graft was removed and an aorto-to-popliteal bypass graft was inserted. Culture of the wound drainage revealed mixed bowel flora. The patient was treated with IV antibiotics and experienced a complicated postoperative course. However, the patient fully recovered and returned home weeks later.