EDITOR'S QUIZ: GI SNAPSHOT

Answer

From question on page 1275

Figure 1 shows a dacron graft reaching several centimetres into the third part of the duodenum far beyond the papilla, surrounded by a sanguineous and fibrinous ulcer of the bowel wall. The patient had a secondary aortoenteric fistula, a late onset complication following reconstructive aortic surgery with an incidence ranging from 1% to 2%.¹ The pathogenesis of secondary aortoenteric fistulas following aortic grafting often involves chronic low grade infection of the graft and perigraft connecting tissue due to suture line failure.² After a period of 10–15 years this may eventually lead to penetration into the bowel wall. Mechanical erosion of the bowel wall caused by constant pulsation of the solid aortic graft against the bowel wall is thought to be important. Two types of aortoenteric fistulas have been described. Type 1 is characterised by a direct connection of the aortic lumen at the suture site with the bowel lumen, causing intractable haemorrhage. In type 2 there is communication between the bowel lumen with the perigraft region. Here, bleeding results from erosion of the bowel wall. This was most likely the case in our patient. Localisation in the distal duodenum is also typical (80%) and explains why aortoenteric fistulas are often missed by standard oesophagogastroduodenoscopy. Immediate laparotomy of our patient revealed an infected aortic graft which had penetrated deeply into the duodenal lumen and was greenish as a result of discolouration by bile reflux. The duodenal wall was perforated twice adjacent to the graft.

Extensive reconstructive surgery was performed with thrombendarterectomy of the aorta, construction of a right sided aorto‐femoral bypass using the femoral vein, construction of an femoro‐femoral bypass using the saphenus vein, and removal of the occluded left sided femoropopliteal bypass. Post‐haemorrhages necessitated repeated laparotomies with partial resection and oversewing of the duodenum with reconstruction of the aortovenous anastomosis. Recurrent bleeding however led to multiorgan failure and the patient died.

Patients with melena are usually referred to the medical department for emergency care. In routine gastrointestinal endoscopy, aortoenteric fistulation is a rare differential diagnosis and may easily be missed, in particular if located in the distal part of the duodenum. With this case we emphasise the need to always consider aortoenteric fistulation as a cause of gastrointestinal haemorrhage in patients with abdominal prosthetic vascular surgery. Once the suspicion is raised an interdisciplinary approach will ensure immediate surgical treatment of the patient.