Aortoenteric fistula
An aortoenteric fistula is a connection between the aorta and the intestines, stomach, or esophageus. There can be significant blood loss into the intestines resulting in bloody stool and death. It is usually secondary to an abdominal aortic aneurysm repair. The third or fourth portion of the duodenum is the most common site for aortoenteric fistulas, followed by the jejunum and ileum. Diagnosis
Diagnosis is typically via a CT angiography, esophagogastroduodenoscopy, or arteriography. It is part of the differential diagnosis of gastrointestinal bleeding. References

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Diseases of the aorta