Missed Diagnosis of Aortic Intramural Hematoma Presenting With Hemorrhagic Pericardial Effusion: A Case Report.

Acute aortic syndrome (AAS), encompassing aortic dissection, aortic intramural hematoma (AIH), and penetrating aortic ulcer, is a life-threatening condition requiring prompt diagnosis and often immediate surgical intervention. A 65-year-old woman presented with transient loss of consciousness and hemorrhagic pericardial effusion. Initial imaging revealed no clear aortic pathology, leading to diagnostic uncertainty despite clinical suspicion of AAS. Following pericardiocentesis, her condition temporarily stabilized but later deteriorated, revealing a missed diagnosis of aortic dissection with tamponade. Retrospective analysis of initial imaging identified subtle aortic wall thickening, indicative of AIH, overlooked at two hospitals. This case highlights the diagnostic challenges in atypical presentations of AAS and emphasizes the need for comprehensive imaging protocols, careful interpretation of ancillary findings, and repeat evaluations to prevent misdiagnosis. Clinicians should maintain a high index of suspicion for acute aortic pathologies in patients with hemorrhagic pericardial effusion, ensuring timely and accurate diagnosis to improve outcomes.