Aortoduodenal syndrome caused by infrarenal abdominal aortic aneurysm: Evolution of CT findings and early imaging clues

Aortoduodenal syndrome is a rare cause of proximal intestinal obstruction resulting from extrinsic compression of the third portion of the duodenum by an abdominal aortic aneurysm. We report the case of a 59-year-old man with longstanding early satiety and progressive weight loss in whom an infrarenal abdominal aortic aneurysm was initially detected incidentally. Despite multiple imaging studies, the characteristic computed tomography (CT) features of clinically significant duodenal obstruction did not become apparent until 2026, when contrast-enhanced CT demonstrated marked proximal duodenal dilatation with an abrupt transition at the third portion caused by aneurysmal compression. Retrospective review of earlier CT examinations demonstrated subtle imaging findings that were insufficient to establish the diagnosis at the time but preceded the development of overt imaging evidence of obstruction. This case highlights the importance of correlating serial CT findings with the clinical presentation and emphasizes that proximal duodenal dilatation together with an abrupt transition point are the key imaging features supporting the diagnosis of aortoduodenal syndrome. Recognition of these findings may facilitate earlier diagnosis and improve patient management.