Pleural Effusion (Water on the Lungs)

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Pleural effusion is the buildup of excess fluid in the space between the pleura. The pleura are two thin, moist membranes around the lungs. There are two layers of pleura:

  • Inner layerattached to the outside of the lungs
  • Outer layerlines the inside of the rib cage

There are two types of effusion: transudative and exudative , each having unique diagnostic properties. The two types have different causes, but in both cases, excess fluid prevents the lungs from fully expanding and causes shortness of breath.

Pleural Effusion

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Effusion is usually caused by disease or injury. The two types have different causes:

Causes of Transudative Effusion

  • Heart failure
  • Malnutrition
  • Liver disease
  • Kidney disease
  • A large shift in body fluids, such as during childbirth
  • Presence of a tumor

Causes of Exudative Effusion

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.


Some types of pleural effusion do not cause symptoms. Others cause a variety of symptoms, including:

Shortness of breathChest painStomach discomfortCoughCoughing up bloodShallow breathingRapid pulse or breathing rateWeight lossFever, chills, or sweatingHiccupping DiagnosisThe doctor will ask about your symptoms and medical history, and perform a physical exam. This may include listening to or tapping on your chest. Tests may include: Chest x-ray a test that uses radiation to take a picture of structures inside the chest Ultrasounda test that uses sound waves to examine structures inside the chestCT scan a type of x-ray that uses a computer to make pictures of structures in the chest Thoracentesis fluid sample extracted from the pleural space around the lungs with a needle Pulmonary function tests to check breathing ability Biopsy removal of a sample of pleural tissue for testing TreatmentTreatment is usually aimed at treating the underlying cause. If breathing is impaired, breathing treatments or supplemental oxygen may be given. The pleural effusion may be drained by inserting a needle into the area and withdrawing fluid (therapeutic thoracentesis) or by inserting a chest tube (tube thoracostomy) into the side of your chest and leaving it in place for several days, eventually attached to suction.
In some cases, the doctor may recommend chemical pleurodesis. During this procedure, a chemical is injected into the pleural space to permanently seal the two layers of the pleura together. This may help prevent further fluid build up. PreventionThe best way to prevent pleural effusion is to get prompt treatment for any condition that may lead to pleural effusion. RESOURCES: American Lung Association National Heart, Lung, and Blood Institute, National Institutes of Health (NIH) CANADIAN RESOURCES: BC Health Guide The Canadian Lung Association References: Celli, Bartolome R. Diseases of the diaphragm, chest wall, pleura, and mediastinum. Cecil Medicine . 23rd ed. Philadelphia, PA: Saunders; 2007. Pleural effusion. eMedicine Journal. August 20, 2001. Pleural effusion. The Pulmonology Channel website. Available at: . Last reviewed November 2007 by Rosalyn Carson-DeWitt, MDPlease be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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