What is it?

A pleural effusion (say "PLER-uhl eh-FYOO-zhun") is the buildup of fluid in the pleural space. This is the space between the tissues lining the lungs and the chest wall. Because of the fluid buildup, the lungs may not be able to expand completely. This can make it hard to breathe.

Most pleural effusions don't become infected. But sometimes an infection causes pus to form in the pleural fluid. This is called pleural empyema (say "em-py-EE-muh").

What causes it?

A pleural effusion has many possible causes. They include pneumonia, cancer, inflammation of the tissues around the lungs, and heart failure.

What are the symptoms?

A minor pleural effusion may not cause any symptoms. When symptoms occur, they may include trouble breathing, chest pain, fever, or a cough.

How is it diagnosed?

Your doctor will ask questions about your symptoms and past health and do a physical exam. The doctor will do a chest X-ray to confirm the diagnosis. You may also have other tests to find out what's causing the fluid buildup.

How is it treated?

A minor pleural effusion often goes away on its own. If needed, a needle may be used to remove the fluid (thoracentesis). This may relieve symptoms and help the lungs to expand more fully. Some fluid may be sent to a lab to look for the cause of the buildup.

If you don't get better, a tube (catheter) may be placed in the chest to drain fluid from the lungs. Some people may then have medicine put into the chest to prevent future fluid buildup.

You may need treatment for the condition that caused the fluid buildup. For example, you may get medicines to treat pneumonia or heart failure. When the condition is treated, the effusion usually goes away.

If the fluid is infected (pleural empyema), the pus needs to be drained. A tube may be placed in the chest or you may have surgery. You also will get antibiotics.