Editing Aortoenteric fistula

Communication between the aorta and GIT

* Primary AEF: native aorta
* Secondary AEF: reconstructed aorta

== Pathogenesis: ==

* Most common location for primary AEF is D3/D4 (presumably due to tethering from ligament of Treitz against the pulsation of the aorta). Also described in oesophagus, intestine and stomach
* Pathogenesis for primary AEF is uncertain
* Location more variable for secondary AEF

* Graft enteric fistulas tend to be more dramatic, whereas graft enteric erosion may manifest with infective symptoms first

== Aetiology: ==

* Primary AEF:
** Aneurysmal aorta (83%)
** Foreign bodies
** Tumours
** Radiotherapy
** Infection (Klebsiella and Salmonella nowadays; fungi frequently involved; previously TB and syphilis)
** PUD
** Perforating biliary stones
* Secondary AEF:
** Open abdominal aortic graft reconstruction (incidence 0.36% to 1.6%)
*** Generally occurs 2-6 years after graft placement
*** More common with synthetic grafts
*** More common with multiple vascular procedures, wound complications, infection, emergency operation and technical errors
*** Pathogenesis seems to be linked to infection
** EVAR/TEVAR
*** May occur due to persistent endoleak and infection at the time of implantation

== Clinical presentation ==

* Classic triad - GI bleeding (64-94%), abdominal pain (32-48%) and pulsatile mass (17-25%)
* Back pain
* Fever/sepsis
* Herald bleed - commonly followed by an exsanguinating bleed within hours to months

== Diagnosis: ==

* CT
** Don't give PO contrast
** Effacement of fat planes around aorta
** Perigraft fluid and soft tissue thickening
** Ectopic gas
** Tethering of adjacent thickened bowel loops toward the aortic graft
** Extravasation of contrast material from the aorta into the involved section of bowel
** Air within aortic sac, at least 3 months post-op
* Gastroscopy (down to D4)
** Graft
** Ulcer
** Erosion with adherent clot
** Extrinsic pulsatile mass
** Beware of dislodging a tamponading thrombus
* Angiography
** Fairly limited role
** Not very specific either, since there is rarely extravasation of contrast

== Management ==

* Conservative is uniformly fatal
* Relevant factors - active haemorrhage, primary vs secondary, presence of sepsis, and anatomic distribution of the patient's aneurysmal or occlusive disease
* Control of haemorrhage
** Endovascular is an option
** Otherwise midline incision, removal of synthetic graft, retroperitoneal debridement, extra-anatomic bypass
** Excise diseased section of bowel and re-join
* Surgical treatment in stable patients
** Perform extra-anatomic bypass first if possible
** Primary AEF - if no infection, in situ aortic replacement. If infected will need extra-anatomic bypass.
** Secondary AEF - either graft excision alone, in situ replacement, graft excision and reconstruction with autogenous vein, extra-anatomic revascularisation and graft excision, or endovascular repair with lifelong antibiotics



[[Category:Vascular]]