Exudative pleural effusion implies the presence of exudative pleural fluid. This requires further investigation in order to understand the exact cause that led to the accumulation of fluid. Exudative pleural effusions can be triggered by different factors such as inflammation, tumors, pulmonary embolism, lymphoma, or viral infections. Some of the basic tests that help determine exudative effusions involve red blood cells counts, pH tests, as well as glucose level readings and amylase level readings.

Transudative pleural effusions imply the leakage of fluids in the pleural space. This type of pleural effusion usually coincides with conditions like congestive heart failure, peritoneal dialysis, cirrhosis, myxedema, advanced hypoalbuminemia, obstructive uropathy, or atelectasis.