The pleura are two thin, moist membranes around the lungs. The inner layer is attached to the lungs. The outer layer is attached to the ribs. Pleural effusion is the buildup of excess fluid in the space between the pleura. The fluid can prevent the lungs from fully opening. This can make it difficult to catch your breath.

Pleural effusion may be watery (transudative) or thick (exudative) based on the cause. Treatment of pleural effusion depends on the condition causing the effusion.

Pleural Effusion
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Effusion is usually caused by disease or injury.

Transudative effusion may be caused by:

Exudative effusion may be caused by:

  • Tuberculosis
  • Pneumonia and other lung infections
  • Rheumatic disease, such as sarcoidosis
  • Anti-inflammatory diseases, such as Lupus
  • Cancer, especially of the lung, breast, or lymph system
  • Blood clot formation in the lung