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Pleural Effusion

Definition: The human body naturally produces fluid to lubricate the thin tissues in your lungs and chest called the pleura. The pleura line the lungs and chest. A pleural effusion is a buildup of too much fluid between the layers of these tissues.

What Causes a Pleural Effusion?

There are two main types of pleural effusion:

  1. Exudative: The body will often make fluid when it is hurt. This also happens with some illnesses. An example of this is a blister on the skin. When there is an injury or infection in the lungs, the body will produce fluid in the lungs. This fluid can help to wash away the infection and other particles. This fluid also carries white blood cells to the affected site in an attempt to repair the damage. Sometimes a large amount of fluid may build up and leak into the lung tissues. When vessels are inflamed, blocked, damaged, or crushed the fluid cannot circulate properly.
  2. Transudative: This type of effusion is generally caused by an imbalance of pressure inside the blood vessels of the lungs. If the pressure is too high, the vessels can begin to leak. The most common cause of this type of effusion is congestive heart failure. Likewise, a decrease in pressure can also cause the fluid to leak. Protein in the blood helps to regulate this process. Any disease process that causes protein levels in the blood to drop can cause this type of effusion.

What are the symptoms?

If the amount of fluid becomes too large, it can begin to interfere with breathing. A patient may experience:

  • Chest pain
  • Cough
  • Pain that increases with a cough or a deep breath
  • Fever
  • Shortness of breath
  • Shallow and/or rapid breathing
  • Hiccups (the added pressure on the diaphragm causes it to spasm)

Risk Factors

  • Injury to the lungs
  • Broken ribs
  • Infection in the lungs
  • Procedures and surgeries performed on or near the lungs or chest area
  • Congestive heart failure
  • Illnesses that change the pressure levels in the vessels of the lungs
  • Illnesses that change the protein levels in the vessels of the lungs

How is it diagnosed?

During a doctor's appointment, the doctor will listen to your breath sounds with a stethoscope. The doctor may also tap on your chest to listen for dullness.

Tests used to look for an effusion:

  • Chest X-ray
  • Chest CT scan
  • Pleural fluid analysis (a sample of the fluid from around your lung is tested to look for germs, levels of protein, or for cancer cells)
  • Ultrasound of the chest


Remove the fluid: In some cases, the body will reabsorb the fluid on its own. When there is a large amount of fluid, a thoracentesis is done. A thoracentesis is the placing of a needle or plastic tube into the pleural space to draw off the fluid.

Chest tubes are also used to drain the fluid. Chest tubes may be left in place for several days.

Treating the cause will help stop more fluid from being made: Antibiotics are used to treat an infection. Diuretics are often called water pills. They can be given when too much fluid is being produced in cases such as congestive heart failure.

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Revised: 5/2015


This resource is provided as a courtesy of Craig Hospital. For more information, contact the Craig Hospital Nurse Advice Line at 1-800-247-0257.

Disclaimer: The content in this document is intended for general informational purposes only and is not a substitute for professional medical advice or treatment for specific medical conditions. No professional relationship is implied or otherwise established by reading this document. You should not use this information to diagnose or treat a health problem or disease without consulting with a qualified healthcare provider. Many of the resources references are not affiliated with Craig Hospital. Craig Hospital assumes no liability for any third party material or for any action or inaction taken as a result of any content or any suggestions made in this document and should not be relied upon without independent investigation. The information on this page is a public service provided by Craig Hospital and in no way represents a recommendation or endorsement by Craig Hospital.