Is pulmonary embolism associated with pleural transudates, exudates, or both?

Abstract

Introduction and objectives: Whether pleural effusions (PEs) secondary to pulmonary embolism can be exudative or transudative is controversial. This study aims to determine which type of effusion (exudate or transudate) is typically associated with pulmonary embolism, using Light's criteria as the discriminative gold standard. Methods: A retrospective analysis of all consecutive patients with pulmonary embolism subjected to a diagnostic thoracentesis over a 25-year period in a University Hospital was performed. Pleural fluid data were described in detail. Results: Seventy-one patients with pulmonary embolism-associated PEs comprised the study population. Pleural fluids were bloody in more than half the cases. The pleural fluid differential white blood cell count was variable; the predominant cells (> 50% of the total leukocytes) were lymphocytes in nearly two-thirds of the patients and neutrophils in about 30%. A proportion of eosinophils > 10% was observed in 7% of the cases. All fluids were exudates, meeting either 3 (78.2%), 2 (12.7%), or just 1 (9.1%) of the Light's criteria. Conclusion: The pleural fluid that accompanies pulmonary embolism is invariably an exudate.