A 63-year-old smoking woman presented with severe intermittent claudication for a couple of years. Her walking distance had gradually decreased to around 50–100 m. She had previously been healthy and very active. At investigation, she had no femoral pulses and a bilateral ankle brachial index of 0.6. Further evaluation with angiography showed an aortic occlusion at the level of the renal arteries, and she was reconstructed with an aorto-bi-iliac polyester graft (16 × 8 mm) after local proximal aortic endarterectomy. The proximal anastomosis was made end to end, and the iliac end to side. Polypropylene sutures were used. The operation was somewhat technically difficult, with the proximal anastomosis having to be redone; the duration of surgery was 3.5 h with a blood loss of around 800 ml. The immediate postoperative course was uneventful. After 3 years, the patient had distal septic microembolization in the left leg with an abscess around the left distal graft limb. This was extirpated, the wound was drained and a femoral–femoral cross-over graft was inserted. She was put on antibiotics for 6 months.

Five years after the aortic operation, she had melaena and a decrease in hemoglobin.

Question 1

What is the time interval between aortic surgery and the presentation of an aortoenteric fistula?

A.  It usually occurs in the first 48 h following aortic surgery.

B.  It typically presents within the first month following the operation.

C.  It may only occur in the first 5 years following the placement of the aortic synthetic graft. D.  It may present at any time during the lifetime of the patient after the placement of the

synthetic aortic graft.

The patient was investigated at her primary health care centre with gastroscopy and colon enema, with negative results. After 2 months, she again had melaena; after further melaena

D. Bergqvist

Department of Surgery, Uppsala University Hospital, Uppsala, Sweden

Question 4

Which part of the bowel is involved in an aortoenteric fistula?

A.  Duodenum

B.  Jejunum

C.  Ileum

D.  Appendix

E.  Any of the above could be involved

Followingadiagnosisofasecondaryaortoentericfistula,andwiththepatientbeingcirculatory stable, an axillo-bifemoral polyester graft was inserted. During the same period of anesthesia, the old aortic graft was extirpated. A duodenorraphy was made, and the aortic stump, which was about 2 cm below the renal arteries, was sutured and covered with omental tissue.

Question 5

Which treatment options are not to be recommended?

A.  Stent grafting the anastomosis

B.  Wait and see if the patient starts bleeding again

C.  Extirpation of the aortic graft and then an axillofemoral reconstruction D.  Axillofemoral reconstruction and then extirpation of the aortic graft E.  In situ reconstruction with a new graft

Thepatientrecoveredandshelefthospitalafter12days.After10months,shehadmelaena again and was admitted to hospital. Based on her previous history, a CT-scan was ordered, but suddenly she developed abdominal and back pain and a large gastrointestinal bleeding, bothhaematemesisandmelaena,andwentintochock.Shediedbeforeanytreatmentcould be given. Autopsy showed a blow out of the aortic stump with a fistula to the duodenum and also bleeding into the retroperitoneal space.

40.1  Commentary

Theterm“aortoentericfistula”meansacommunicationbetweenaortaandsomepartofthe gastrointestinal tract. It is rarely primary; most often, it is seen secondary to reconstructive vascular surgery, that is, secondary aortoenteric fistula. In the majority of cases it is seen after aortic graft insertion. It has also been reported after stent-grafting1 and also after

simple aortic suture.2 The majority of fistulas (about 75%) involve the duodenum, but any part of the gastrointestinal tract may be involved. [Q4: E] A few patients have more than one fistula. In exceptional cases it can occur after other abdominal operations or radiation treatment. It is an emergent situation and should always be suspected in patients with an aortic reconstruction presenting with a gastrointestinal bleeding. It can occur at any time postoperatively, which means that the patient with an aortic graft is at risk developing a fistula for their entire lifetime. Thus, the true incidence of this condition cannot be established until all patients in a risk population have died. The longest interval reported is more than 20 years. Often there is a delay of several years. [Q1: D] During a period of 21 years in Sweden, there are indications that the incidence has decreased to around 0.5% after abdominal aortic operations.3

Two factors have been considered of major etiological importance: mechanical stress from the pulsating graft, which is in continuous contact with the intestine, and the presence of a low-grade infection. In patients with an aortoenteric fistula, there is often a history of complicated and troublesome primary graft operation or infectious problems in the postoperative course. The three most common findings at surgery are suture line contact with the bowel, pseudoaneurysn rupturing into the intestine, and graft body erosion of the intestine. To avoid the complications, atraumatic surgical technique is important, avoiding bowel trauma and large hematomas. The surgeon should try to cover the graft to avoid direct contact between the graft and the bowel.

The main symptom is gastrointestinal hemorrhage, which can range from mild melaena with anemia to a profuse, immediately fatal haematemesis. Often, this large bleeding is preceded by small “herald” bleedings, which are an important warning symptom. [Q2: C] About half of the patients also have septic symptoms of varying severity. In some patients, septic symptoms dominate, and the bleeding may even be occult.

There is often a long delay between onset of symptoms and final diagnosis. In some patients with a large initial bleeding, the diagnosis is established at autopsy. The cardinal importance of a high degree of clinical suspicion for obtaining a correct diagnosis must be emphasized. Unfortunately, there is no specific diagnostic test. At gastroduodenoscopy, it is important to scrutinize the whole duodenum down to the ligament of Treitz. Observation of a bile-stained graft is obviously pathognomonic. Endoscopy is also important to reveal other sources of bleeding. CT, MR and angiography may be helpful in showing pseudoaneurysm or fluid outside the graft, sometimes with gas in it. Conventional radiological methods for gastrointestinal examination are rarely helpful. One great problem is that the absence of abnormalities does not exclude the diagnosis. Exploratory laparotomy is indicated in patients with massive bleeding or where diagnostic efforts have been negative and the patient is still bleeding. [Q3: E]

The management is difficult. Total removal of all old graft material and revascularization seems to give the best results.4 Just closing the fistula locally always leads to recurrence and the mortality is close to 100% and cannot be recommended.5 It seems optimal to start with an extra-anatomical revascularization of the extremities and thereafter removal of the graft. Some authors recommend a delay of a few days between the two procedures6; this is possible when the hemorrhage is under control. In emergency situations, an abdominal exploration with closure of the fistula and graft removal is vital, but this may lead to a delayed revascularization with profound limb ischemia. When the graft is removed, the