myUpchar प्लस+ के साथ पूरेे परिवार के हेल्थ खर्च पर भारी बचत

What is a Pleural Fluid Analysis test? 
Pleural fluid is a liquid present in the space between the chest wall and the outer lining of lungs (pleura). It helps lubricate the lungs for ease respiratory movements. Excess accumulation of pleural fluid or pleural effusion can occur due to an infection, disease or inflammation of the pleura, reducing the air space for the lungs to expand, leading to breathing problems. 

A pleural fluid analysis examines fluid accumulated in the pleural space to help diagnose pleural effusion.

  1. Why is a Pleural Fluid Analysis test performed?
  2. How do you prepare for a Pleural Fluid Analysis test?
  3. How is a Pleural Fluid Analysis test performed?
  4. What do Pleural Fluid Analysis results indicate?

Pleural fluid analysis is done to identify the reason for pleural effusion. The procedure also helps relieve shortness of breath that occurs due to fluid accumulation in the pleural cavity. Doctors recommend a pleural effusion test when they suspect a person of having a condition that causes pleural effusion. A few signs or symptoms of pleural effusion are

Results of this test can help distinguish between the types of pleural fluid (transudate or exudate) and identify the cause of fluid accumulation.

No special preparations are required for this test. A chest x-ray, ultrasound or computerised tomography (CT) scan is performed before and after the examination. Try not to move, breathe deeply or cough during the test to avoid any injury to your lungs. Inform your doctor if you are taking any blood-thinning medications.

A thoracentesis procedure is used to obtain a sample of the pleural fluid for this test. The obtained sample is examined for cancerous cells and inflammation; fungi, bacteria or viruses that might cause infections; along with the levels of protein, glucose or other substance in the pleural fluid.

For thoracentesis, the following steps are followed:

  • You will be asked to sit on the edge of a bed or a chair with arms and head resting on a table.
  • A lab technician will clean the area needle insertion site and inject anaesthesia (a numbing agent) into the skin 
  • A needle will then be inserted in the muscles of the chest wall through the skin into the pleural space, to drain the fluid into a collection container. 

You might cough during the fluid collection, as your lungs re-expand in an attempt to fill the space of the drained fluid. The sensation lasts for about a few hours after the test. Inform your healthcare provider if you experience shortness of breath or a sharp chest pain during the procedure.
Ultrasound is used in some cases to observe the fluid in the chest. Some risks associated with thoracentesis are as follows:

  • Pulmonary oedema
  • Pneumothorax (collapsed lung)
  • Re-accumulation of fluid
  • Infection
  • Cough that does not subside
  • Respiratory distress
  • Excessive blood loss

However, serious complications rarely occur.

Normal results:
A volume of less than 20 millilitres (mL) of yellowish, clear serous fluid is normal in the pleural space.

Abnormal results: 
Abnormal results might provide signs of diseases or conditions as mentioned below: 

  • Pleural fluid with a reddish colour is indicative of the presence of blood
  • Pleural fluid with a thick and cloudy appearance is indicative of the presence of white blood cells, infection or fluid leakage from lymph

Abnormal results might also indicate the possible causes of pleural effusion, such as

  • Trauma
  • Cancer
  • Infection
  • Cirrhosis (chronic liver damage due to a variety of reasons leading to liver failure)
  • Unexpected connections between the pleural space and other organs 
  • Heart failure
  • Severe malnutrition

If your doctor suspects an infection, he/she may recommend a culture test to detect microbes.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.  

और पढ़ें ...


  1. MedlinePlus Medical Encyclopedia. [Internet] US National Library of Medicine; Pleural fluid analysis
  2. MedlinePlus Medical Encyclopedia. [Internet] US National Library of Medicine; Pleural effusion
  3. Pennstate Hershey. [Internet] Milton S Hershey Medical Center, U.S. Thoracentesis
  4. Beaufort Memorial Hospital. [Internet] SC, U.S.Pleural fluid analysis
  5. Moon Jun Na. Diagnostic Tools of Pleural Effusion Tuberc Respir Dis (Seoul). 2014 May; 76(5): 199–210 PMID: 24920946
  6. Richard W. Light. Pleural diseases 5th Edition U.S: Lippincott Williams and Wilkins, 2007, Page no: 214