Small transudative pleural effusions may require no treatment, while larger ones and most exudative pleural effusions require treatment. The initial treatment of choice is drainage of the pleural fluid. This is done by thoracentesis (this procedure may be both diagnostic and therapeutic), where a tube is inserted into the effusion, and the effusion is drained out. This procedure needs monitoring, and in some instances, the tube may need to remain in the pleural space for a longer period of time for continued drainage. The need for repeated thoracentesis varies from patient to patient depending on the underlying cause, the amount of effusion fluid, the type of effusion (thick, thin, malignant, or infectious, for example) and if there is recurrence of the pleural effusion.
Exudative effusions are caused by inflammation, infection, and cancer. Exudates have large amounts of protein cells, white blood cells, and immune cells that have migrated into the pleural fluid and deposited in tissues or on tissue surfaces. Exudates also are pale yellow in color but have a cloudy appearance. If pus is present because of infection (empyema), the fluid is yellow, cloudy, and has a foul odor. Pneumonia, tuberculosis, pulmonary embolism (blocked pulmonary artery), cancer, and trauma are common causes of exudative pleural effusion.