AB161. SOH22ABS171. Aortocaval fistula, a rare complication of abdominal aortic aneurysm: a case report

Background: Spontaneous aortocaval fistula (ACF) is a pathology that occurs in 3–6% of all ruptured abdominal aortic aneurysms. It is erosion into the inferior vena cava resulting in fistula formation. ACF presents with variable signs and symptoms such as abdominal pain, loin pain, congestive cardiac failure, renal and liver dysfunction and pulsating mass. It commonly arises from enlarging aortal aneurysms causing inflammation and peri aortic adhesions. This allows for subsequent pressure necrosis of the inferior vena cava wall creating a fistula. Its rarity provides a diagnostic dilemma when combined with its variable symptom range, increasing likelihood of delay and lethal outcomes.

Methods: A case report of a 64-year-old man who presented to the emergency department with sudden onset abdominal pain and palpable abdominal pulsating mass on examination. Abdominal aortic aneurysm was not previously diagnosed in this patient and this was his first presentation.

Results: Urgent computed tomography revealed an ACF. Transfer to tertiary centre ensued with emergency repair of the fistula and survival of the patient.

Conclusions: The prognosis of ACF is greatly depends on clinical suspicion and early diagnosis. Although survival up to two months without surgery has been reported, it is generally accepted that survival is improved with prompt surgery. Intervention before development of shock can increase the chance of survival from 25% to 50%. This case highlights the importance of clinical suspicion regardless of rarity of syndrome.

Keywords: Aortocaval fistula (ACF); aortic aneurysm; fistula; computed tomography; early diagnosis