Pleural Fluid Analysis
Reviewed
Also called: Pleural fluid aspiration, Diagnostic thoracentesis, Pleural fluid tap, Pleural fluid culture, Pleural fluid cytology, Pleural effusion testing
A pleural fluid analysis is a group of tests that examine a sample of abnormal fluid that builds up in the space between your lungs and chest wall.
Specimen: Pleural fluid obtained by thoracentesis
Why this test may be ordered
- To find the cause of a pleural effusion seen on imaging
- To evaluate symptoms such as chest pain, dry cough, trouble breathing, or fatigue when pleural effusion is suspected
Preparation and collection
In general, a thoracentesis doesn't require special preparations. For example, you may need to stop taking certain medicines before your test. But never stop taking any prescription medicines without talking with your provider first.
Your provider will remove some pleural fluid using a hollow needle. This is done with a procedure called thoracentesis. You'll be given an injection (a shot) to numb the area so you won't feel any pain.
Thoracentesis is a generally safe procedure. Serious complications are uncommon.
Understanding results
In general, the results of your pleural fluid analysis will show which type of fluid is in your pleural space.
- Transudate: Transudate is a watery fluid that has low amounts of protein. It's caused by pressure in your blood vessels. Limitation: Your provider will consider all your test results, your symptoms, and your medical history to understand what your results mean. Next step: Ask your provider to explain what your test results say about your health.
- Exudate: Exudate is a cloudy fluid that has high amounts of protein. Limitation: Exudate contains different substances depending on the condition that caused it. Next step: To help find the specific cause of your pleural effusion, your provider will order other tests on your fluid sample to check for certain substances.
- A pleural fluid analysis alone may not find the specific condition causing the pleural effusion; it helps narrow down possibilities and guides further testing.
- Results must be interpreted by a healthcare professional in the context of your overall health and other test results.
What to do next
If you have questions about your test results, talk with your provider.
- What type of pleural fluid do I have (transudate or exudate)?
- What are the possible causes based on my fluid type?
- What additional tests do I need to find the exact cause?
- Do I need treatment to remove the fluid now?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.