Aorto-enteric fistulation is an uncommon catastrophic cause of gastrointestinal haemorrhage. Aortic fistulas can be primary (associated with an abdominal aortic aneurysm) or secondary (associated with graft repairs).
The annual incidence of primary aorto-enteric fistulas is thought to be around 0.007 per million while that of secondary aorto-enteric fistulas is about ~1% (range 0.6-2%) 1.
The incidence of secondary aorto-enteric fistulas is found to be more in patients with open aortic repair as compared to patients with endovascular stent placement.
Primary aorto-enteric fistulation occurs when there is a large abdominal aortic aneurysm which is closely abutting the bowel loops, usually the 3rd or 4th parts of the duodenum. Due to pressure, in the long run, the aneurysm slowly erodes into the wall of the bowel.
Secondary aorto-enteric fistulas are seen as complications of aortic reconstructive surgery with or without the placement of an aortic stent-graft. Secondary fistulas that result from perigraft infection may occur between 2 weeks and 10 years after surgery.
- initial presentation can be with a minor "herald" bleeding, which may be followed by catastrophic, life-threatening bleed
- primary aorto-enteric fistula: recurrent septicemia with enteric pathogens
Primary aorto-enteric fistula
Direct signs include:
- ectopic gas adjacent to or within the aorta
- the presence of vascular contrast within the gastrointestinal tract
Indirect signs include:
- bowel wall thickening overlying an aneurysm
- disruption of the aortic fat cover
- retroperitoneal hematoma or hematoma within bowel wall or lumen
Secondary aorto-enteric fistula
- increased perigraft soft tissue
- pseudoaneurysm formation
- disruption of aneurysmal wrap
- increased soft tissue between the graft and aneurysmal wrap
Treatment and prognosis
The only curative treatment is surgery. Without prompt surgical intervention, the mortality approaches 100%, even the operative mortality is as high as 50%.
- perigraft infection without fistulation
- retroperitoneal fibrosis
- infected (mycotic) aortic aneurysm
- infectious aortitis
- acute aortic syndrome
- thoracic aortic aneurysm
- abdominal aortic aneurysm
- endovascular aneurysm repair (EVAR)
- reporting tips for aortic aneurysms
- aortic coarctation
- aortic pseudocoarctation
- cervical aortic arch
- interrupted aortic arch
- transposition of the great arteries
- variant anatomy of the aortic arch
- traumatic aortic injuries
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