Primary aortoenteric fistula: a case report and literature review.

Introduction: Primary aortoenteric fistulas are rare, life-threatening conditions, usually secondary to abdominal aortic aneurysms. Primary aortoduodenal fistula (PADF) without aneurysmal disease is extremely rare, with very few cases reported in the literature. Delayed diagnosis is common and contributes to high mortality. Case presentation: We report the case of a 71-year-old woman with high-grade serous ovarian cancer who developed a PADF in the absence of an aortic aneurysm. The patient presented with hematemesis and abdominal pain. Initial investigations, including Computed Tomography (CT) scan and upper endoscopy (EGDS), were inconclusive. Although she was initially stabilized, she experienced recurrent gastrointestinal bleeding leading to hemodynamic deterioration. Emergency CT showed active arterial hemorrhage near the duodenum. An urgent exploratory laparotomy confirmed the presence of a PADF, which was surgically repaired using a bovine pericardial patch. Despite surgical intervention, the patient succumbed to postoperative multiorgan failure. Clinical discussion: PADFs most frequently involve the third or fourth portion of the duodenum and are strongly correlated with aneurysmal disease. However, rare etiologies such as radiation therapy, malignancy, or infection may precipitate fistula formation even in the absence of aneurysms. Our literature review identified only 16 similar cases reported since 2015. Diagnosis remains challenging due to non-specific symptoms and inconclusive early imaging. A high index of suspicion is essential. CT angiography is the most effective diagnostic modality. Definitive management requires urgent surgical or endovascular repair, although prognosis remains poor in hemodynamically unstable patients. Conclusion: This case underscores the need to consider PADF in the differential diagnosis of gastrointestinal bleeding, even in the absence of aneurysmal disease, particularly among oncologic patients with prior radiation exposure or retroperitoneal inflammation. Early diagnosis, prompt imaging, and a multidisciplinary approach are essential to improving patient outcomes.