Aortofemoral graft limb–to–colon paraprosthetic fistula

A 58-year-old man presented with fever. During several hospitalizations in the preceding 3 months, bacteremia had been documented on seven occasions. Escherichia coli, Clostridium, and Candida spp were repeatedly recovered in blood cultures. The patient’s history was pertinent for tobacco abuse and severe claudication, which was initially treated with femorofemoral bypass graft. This failed, however, which prompted conversion to an aortobifemoral bypass (performed elsewhere), with resultant complete relief of claudication. The patient denied abdominal pain and had no evidence of overt or occult gastrointestinal (GI) bleeding. Fever and malaise persisted for 3 months. Abdominal computed tomography (CT) scans were performed on two occasions, and the results interpreted as negative. The Vascular Surgery Service was ultimately consulted and determined the patient’s clinical history and CT were highly suggestive of a secondary aortoenteric fistula (SAEF) involving the left aortobifemoral graft limb and the colon (A, arrow). The graft body, right limb, and both femoral regions appeared to be free of infection. An indium-111 white blood cell scan suggested isolated left midprosthetic limb involvement (B, arrow), and colonoscopy unequivocally established the diagnosis (Cover). Single-stage redo femorofemoral bypass and left aortofemoral graft limb excision was performed. At laparotomy, the left graft limb was densely incorporated to adjacent tissues, without gross contamination. The limb was transected and oversewn proximally. When followed distally, it was noted to traverse the sigmoid colon (C). Partial sigmoid resection with primary anastomosis was performed. The patient has since done well, without evidence of recurrent infection and with patent vascular reconstructions. SAEF is a direct communication between a vascular prosthesis and the GI tract. Most aortoenteric fistulas involve the graft-aortic suture line, with fistulization into the bowel lumen and resultant GI hemorrhage. A less common type of fistula, termed a paraprosthetic fistula, is defined as a communication between the surface of the graft body and the bowel lumen without suture line involvement or actual fistulization into the vascular lumen. The duodenum is the most frequently involved bowel segment for both types of SAEFs. Graft-colonic fistulae are much less common, comprising only 4.8% to 6.6% of cases in reported SAEF series. Because they do not involve the anastomosis, paraprosthetic fistulas do not result in GI hemorrhage, but rather sepsis, malaise, and other less specific symptoms. In patients who do not require emergency intervention, CT is the recommended initial diagnostic study of choice whenever SAEF is considered. A positive indium-111 white blood cell scan supports the diagnosis of SAEF. Endoscopy can be a definitive diagnostic tool, but may also serve to exclude other pathology in patients with GI bleeding. Traditional therapy for SAEF, especially for aortoduodenal fistula, is GI tract restoration, complete prosthetic graft excision, aortic stump closure, and extra-anatomic bypass. More conservative approaches such as partial graft preservation, excision of the involved limb, and extra-anatomic bypass, as used in this patient, are simpler, effective, and have potentially less morbidity in carefully selected, high-risk patients.