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Lung Disease & Respiratory Health Center

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Pleural Effusion

Diagnosis of Pleural Effusions continued...

Computed tomography (CT scan): A CT scanner takes multiple X-rays rapidly, and a computer constructs images of the inside of the chest. Compared to chest X-rays, CT scans produce more detailed information about pleural effusions and other lung abnormalities.

Ultrasound: A probe placed against the skin reflects high-energy sound waves off structures in the chest, creating images on a video screen. Ultrasound can help guide drainage and identify whether pleural effusions are free-flowing.

Once a pleural effusion is identified on imaging, a fluid sample is usually taken to determine the pleural effusion's character and seriousness. In a procedure called thoracentesis, a doctor inserts a needle and a catheter between the ribs, into the pleural space. A small amount of fluid is withdrawn for testing; a large amount can be removed simultaneously to relieve symptoms.

Types of Pleural Effusions

There are two main categories of pleural effusions:

Uncomplicated pleural effusion: The pleural effusion contains fluid that is free of serious inflammation or infection. If large enough, an uncomplicated pleural effusion can cause symptoms. However, these pleural effusions rarely cause permanent lung problems.

Complicated pleural effusion: A complicated pleural effusion contains fluid that has significant inflammation or infection. If untreated, complicated pleural effusions may harden to form a constricting ring around the lung. This hardening process, called organization, can permanently impair breathing. To prevent organization, complicated pleural effusions require drainage, usually with a tube placed into the chest.

Doctors also use the terms transudative and exudative to describe pleural effusions:

Transudative: The pleural effusion fluid is similar in character to the fluid normally present in the pleural space. Transudative pleural effusions rarely require drainage, unless they are very large. Congestive heart failure is an example of a condition that can cause a transudative pleural effusion.

Exudative: The pleural effusion fluid has excess protein, blood, or evidence of inflammation or infection. An exudative pleural effusion may require drainage, depending on its size and the severity of inflammation. Causes of exudative pleural effusion include pneumonia and lung cancer.

The type of pleural effusion can only be identified by taking a sample of fluid from the pleural effusion.

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