Pleural effusions. 2. Definitive evaluation of the exudate.

Based on the current literature, the following steps seem reasonable in evaluating a pleural effusion: document the presence, location, and approximate volume of pleural fluid; decide clinically on the likelihood of an exudative effusion; if clinical evaluation suggests an exudative effusion, perform a thoracentesis and obtain fluid for diagnostic evaluation; perform the necessary tests to characterize the effusion as a transudate or an exudate; if a transudate exists, normally do not perform further tests on the effusion; if an exudate exists, perform selected tests to narrow the differential diagnosis; if this evaluation is undiagnostic, consider closed pleural biopsy; if the diagnosis remains unclear after two closed biopsies, consider pleuroscopy with biopsy or open pleural biopsy at the time of a thoracotomy.