Unilateral Pleural Effusions with More Than One Apparent Etiology. A Prospective Observational Study

Rationale: Evaluation of a pleural effusion has historically focused on establishing a single etiology. Pleural fluid may accumulate through multiple pathophysiological processes. The prevalence of multiple causes for pleural effusions has not been established. The identification of contributing processes may improve clinical outcomes.Objectives: The objective of this prospectively collected case series was to establish the prevalence and nature of multiple etiologies for a unilateral pleural effusion.Methods: Consecutive patients presenting with an undiagnosed unilateral pleural effusion were recruited at a tertiary pleural center. Patients underwent a comprehensive structured diagnostic clinical evaluation and were followed up for a minimum of 12 months, after which one or more diagnoses were recorded independently by two experienced clinicians.Measurements and Main Results: One hundred thirty patients were recruited to the study over a 24-month period, and 126 patients completed follow up. Altogether, ...