What is a pleural effusion (fluid on the lungs)?

Updated: Dec 28, 2018
  • Author: Kamran Boka, MD, MS; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
  • Print

A pleural effusion is collection of fluid abnormally present in the pleural space, usually resulting from excess fluid production and/or decreased lymphatic absorption. [1] It is the most common manifestation of pleural disease, and its etiologies range in spectrum from cardiopulmonary disorders and/or systemic inflammatory conditions to malignancy. Approximately 1.5 million pleural effusions are diagnosed in the United States each year (see images below).

Large right-sided pleural effusion. This effusion Large right-sided pleural effusion. This effusion was malignant.
Left-sided pleural effusion. Left-sided pleural effusion.

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!