Definition of Pleural effusion:

A pleural effusion is an accumulation of fluid between the layers of the membrane that lines the lungs and chest cavity.

Causes, incidence, and risk factors:

Your body produces pleural fluid in small amounts to lubricate the surfaces of the pleura, the thin membrane that lines the chest cavity and surrounds the lungs. A pleural effusion is an abnormal collection of this fluid.

Two different types of effusions can develop:

• Transudative pleural effusions are often caused by abnormal lung pressure. Congestive heart failure is the most common cause.
• Exudative effusions form as a result of inflammation (irritation and swelling) of the pleura. This is often caused by lung disease. Examples include lung cancer, pneumonia, tuberculosis and other lung infections, drug reactions, asbestosis, and sarcoidosis.