Diagnostic Value, Sonographic Features, and Factors Associated with Misdiagnosis by Color Doppler Ultrasound for Abdominal Aortic Pseudoaneurysms in Patients With Abdominal Aortic Aneurysmal Dilatation

OBJECTIVES: To investigate the clinical, anatomical, and sonographic features of abdominal aortic pseudoaneurysms (AAP), evaluate the real-world diagnostic performance of color Doppler ultrasound for AAP in patients with abdominal aortic aneurysmal dilatation, and analyze factors associated with misdiagnosis. METHODS: This single-center retrospective diagnostic accuracy study followed STARD 2015. We included 520 consecutive patients with abdominal aortic aneurysmal dilatation detected by color Doppler ultrasound between January 2018 and January 2025. Using surgical findings, computed tomography angiography, or magnetic resonance angiography as the reference standard, we analyzed AAP features, evaluated ultrasound diagnostic performance, and reviewed misdiagnosed cases. RESULTS: A total of 393 patients were included, 25 (6.36%) were confirmed as AAP. Focal wall disruption most frequently occurred in the distal abdominal aorta (64.00%), predominantly on the left and posterior walls. Abdominal or back pain was the most common presenting symptom, with 76.00% of patients having elevated D-dimer levels. The characteristic sonographic findings of AAP were focal aortic wall disruption with a cystic lesion communicating with the aortic lumen. Ultrasound demonstrated 84.00% sensitivity (95% CI: 63.92-95.46), 100.00% specificity (95% CI: 99.00-100.00), and 98.98% overall accuracy (95% CI: 97.41-99.72). In all correctly diagnosed cases, the site of focal wall disruption was 100% concordant with the reference standard. Four cases (16.00%) were misdiagnosed as eccentric true abdominal aortic aneurysms. A retrospective imaging review revealed that these misdiagnoses may be associated with three imaging findings: broad focal wall disruption with absent neck, secondary loss of the typical pseudoaneurysmal to-and-fro flow signature, and coverage of the focal wall disruption by organized thrombus. CONCLUSIONS: Color Doppler ultrasound demonstrates favorable diagnostic performance for AAP in real-world clinical practice and can serve as a reliable first-line non-invasive modality for early screening and diagnosis. Recognition of characteristic features and avoidance of common diagnostic pitfalls can further improve diagnostic accuracy.