ABSTRACT
I. Introduction The initial step in evaluating pleural effusions is performance of a thorough history and physical examination with a review of available imaging and laboratory studies. This evaluation may allow a presumptive diagnosis and therapeutic plan if the patient fits a well-established clinical profile, such as congestive heart failure with an associated rightsided pleural effusion. Conversely, if the etiology of the effusion remains uncertain after initial evaluation or if the effusion fails to respond to a therapeutic trial for a presumed diagnosis, a thoracocentesis is indicated for pleural fluid analysis. Routine pleural fluid tests may diagnose the specific etiology of the effusion as occurs with a positive-pleural fluid Gram stain in patients with an empyema or positive-pleural fluid cytology with a malignant pleural effusion.
