Pleural effusion in acute pulmonary embolism in Bahrain: Radiological and pleural fluid characteristics.

Background and Objectives: Pleural effusion is seen in around half of the cases of pulmonary embolism (PE). There are no data on the incidence of pleural effusion in cases of PE in the Kingdom of Bahrain. This study was done to determine the frequency and radiological features of pleural effusion in cases of acute PE and also to characterize the pleural fluid biochemistry and cell type in patients subjected to diagnostic thoracentesis.

Methods: This was a retrospective, observational single-center study. All the data of patients subjected to computed tomography pulmonary angiography (CTPA) in suspected cases of acute PE over a 4-year period were analyzed.

Results: A total of 1756 patients were subjected to CTPA from January 2013 to December 2016. A diagnosis of acute PE was made in 200 patients (11.4%). Pleural effusion was identified in 70 cases (35%). Majority of the effusions were small to moderate in size, bilateral, and associated with peripheral emboli. Consolidation, atelectasis, and ground glass attenuation were common associated findings on CTPA in these patients. Consolidation was more common in patients of PE associated with pleural effusion as compared to those with PE alone (62.85% and 33.8%, respectively, odds rato: 3.279 and 95% confidence interval: 1.798-6.091, P < 0.001). Diagnostic thoracentesis was done in 6 (8.6%) of the cases. All the patients had an exudative effusion with normal glucose values and neutrophil predominance.

Conclusion: PE was associated with pleural effusion in around one-third of the patients in Bahrain. The effusions were mainly small and bilateral. The emboli in cases associated with pleural effusion were mostly peripheral. Consolidation was the parenchymal abnormality detected on CTPA which was significantly associated with the presence of pleural effusion. Most of the pleural effusions were not suitable for thoracentesis. In patients subjected to fluid analysis, the effusions were exudative, neutrophilic predominant, and associated with normal glucose levels.