ObjectivesTo investigate the clinical and imaging characteristics of pleural effusion in patients with acute pulmonary embolism (APE).MethodsComputed tomographic pulmonary angiography (CTPA) scans and clinical data of suspected APE patients from January 2014 to December 2018 were analyzed.ResultsA total of 1024 suspected APE patients underwent CTPA examination in the imaging department of our hospital. Two hundred patients (19.5%) were diagnosed with APE. Imaging findings of pleural effusion were revealed in 70 cases (35.0%). The majority of APE patients without pleural effusion were males (82.3% vs. 64.3%, P<0.01), and the majority of APE patients with pleural effusion were females (35.7% vs. 17.7%, P<0.01). Most of the effusions were bilateral, small to moderate, with peripheral embolism (62.9%, P<0.05). Pulmonary consolidation, atelectasis and ground-glass opacity were common manifestations of CTPA. Compared with patients with simple pulmonary embolism, pulmonary embolism with pleural effusion was more common (62.9% and 33.8%, respectively, OR=3.279 and 95%CI 1.798 - 6.091, P<0.001). Diagnostic thoracic puncture was performed in 6 cases (8.6%). Pleural effusion was exudate in these 6 patients, with normal blood sugar and neutrophils predominated.ConclusionsAbout one third of APE patients are associated with pleural effusion, which most presented with small and bilateral pleural effusions. The main embolism associated with pleural effusion is peripheral embolism. There is a significant correlation between pulmonary consolidation and pleural effusion. Pleural effusion is mostly exudate and neutrophils often predominate.