Aortoenteric Fistula

Aortoenteric Fistulas are a rare but devestating occurrence that all GI Docs need to be aware of as identifying the proper diagnosis early usually means the difference between life and death. Dr. Trung Phan a rotating resident on the GI wards provides a need to know on the condition:

What is a Aortoenteric Fistula (AEF)?

-Communication between the aorta and GI tract. Two different types

· Primary AEF - a communication b/t the native aorta and GI tract 

· Secondary AEF - a communication between a reconstructed aorta (for either aneurysmal or occlusive disease) and the GI tract

Click on image to see the primary review that Dr. Phan used for this article!

Secondary AEF:

- Multiple possible causes including pressure from a non-compliant prosthesis, suture line disruption, bowel injury during a procedure

-More common then primary but also seen mostly in older males. Time of onset is usually 2-6 years after graft placement

-Most common sites are the distal duodenum and proximal jejunum. Wide variety of locations have been identified based on location of grafts

Primary AEF:

-Caused by degeneration of the aorta and enteric structures. Mostly by chronic pulsatile pressure over time

-Mostly seen in patients over the age of 60 and has a predominance in male patients

-Most common sites are 3rd and 4th portion of duodenum, Esophagus followed but he small and large bowel

Clinical Presentation:

Triad of GI bleeding(94%), abdominal pain (48%) and pulsatile abdominal mass(17-25%) is what is generally reported and taught. AEF’s can also have less dramatic presentations including leukocytosis, malaise, limb ischemia or abscess. A herald bleed is a self limiting bleed that occurs prior to a larger hemorrhage. It is important that AEF is on the differential for all patients with a GI bleed and previous vascular graft placement as the mortality rate following a “herald” bleed is high. Reported as 30% within 6 hours and 50% within 24 hours.

• Bacteremia is another presentation with most common organisms being Klebsiella, Staph epi, Group B strep and Candida. Salmonella bacteremia has a classic often tested association with primary AEF

Diagnosis:

Diagnosis modality is usually based on initial presentation, suspicion for a AEF and condition of the patient. If the patient is unstable exploratory laparotomy is preformed. If patient is stable then options include CT, EGD and angiography.

• CTA is the test of choice if highly suspicious for AEF. Not only does it have the highest detection rate it is also readily available, fast, easy to interpret and can rule out other etiologies

• EGD can also diagnose AEF’s but has limitations. It can only identify AEF’s to the level of the duodenum. In acute setting there may be a delay in diagnosis due to time needed to organize the logistics of the procedure. It also carries the risk of dislodging a thrombus which is preventing a catastrophic bleed.

• Angiography can be used but does not have the convenience and additional benefits that CTA has.

Treatment:

• Any non-operative treatment is fatal. Surgery should be notified as soon as AEF is identified to begin planning for a life saving procedure. Considerations which effect surgical management include type of AEF, location, active bleeding and sepsis.

Dr. Phan’s important take aways!

Timely recognition of AEF : Triad GI bleed, abdominal pain, pulsatile abd mass 

• UGIB in pt with aortic repair is AEF until proven otherwise 

Quick diagnosis 

• CT is preferred diagnostic modality 

Appropriate pre-operative management 

• Resuscitation 

• Broad spectrum antimicrobials