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Pleural effusion

  • Definition

    A pleural effusion is a buildup of fluid between the layers of tissue that line the lungs and chest cavity.


    Alternative Names

    Fluid in the chest; Fluid on the lung; Pleural fluid


    Causes, incidence, and risk factors

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

    Two different types of effusions can develop:

    • Transudative pleural effusions are caused by fluid leaking into the pleural space. This is caused by increased pressure in, or low protein content in, the blood vessels. Congestive heart failure is the most common cause.
    • Exudative effusions are caused by blocked blood vessels, inflammation, lung injury, and drug reactions.