The Silent Danger: A Rare Case of Asymptomatic Aortocaval Fistula Discovered During Routine Imaging

Background: Aortocaval fistulas resulting from abdominal aortic aneurysms are rare, representing 3–6% of ruptured cases. These fistulas are often asymptomatic or present with non-specific symptoms related to venous hypertension or high-output cardiac failure. Fortuitous diagnoses in asymptomatic patients are exceedingly uncommon. Case Presentation: An 86-year-old woman underwent CT angiography to evaluate left leg circulatory issues. Imaging revealed an aortic aneurysm with a fistula into the inferior vena cava, an enlarged right atrium, and pelvic vein varices. The asymptomatic fistula was treated with endovascular aneurysm repair (EVAR). Postoperatively, the patient developed superior mesenteric artery occlusion and intestinal ischemia, leading to palliative care and death. Discussion: Aortocaval fistulas can result from a variety of causes including infection and trauma. Diagnosis is typically achieved through CT angiography. While open surgical repair remains the standard treatment, EVAR is a viable alternative in selected cases. However, the prognosis remains guarded, even with appropriate treatment. Conclusion: Aortocaval fistulas are rare and life-threatening conditions that require prompt diagnosis and management, though outcomes are often poor.