Thoracentesis is a procedure to remove fluid from the space between the lining of the outside of the lungs (pleura) and the wall of the chest.
Pleural fluid aspiration; Pleural tap
How the Test is Performed
The test is done in the following way:
- You sit on a bed or on the edge of a chair or bed. Your head and arms rest on a table.
- The skin around the procedure site is cleaned. A local numbing medicine (anesthetic) is injected into the skin.
- A needle is placed through the skin and muscles of the chest wall into the space around the lungs, called the pleural space. The health care provider may use
ultrasoundto find the best spot to insert the needle.
- You may be asked to hold your breath or breathe out during the procedure.
- You should not cough, breathe deeply, or move during the test to avoid injury to the lung.
- Fluid is drawn out with the needle.
- The needle is removed and the area is bandaged.
- The fluid may be sent to a laboratory for testing (
pleural fluid analysis).
How to Prepare for the Test
No special preparation is needed before the test. A
How the Test will Feel
You will feel a stinging sensation when the local anesthetic is injected. You may feel pain or pressure when the needle is inserted into the pleural space.
Tell your provider if you feel
Why the Test is Performed
Normally, very little fluid is in the pleural space. A buildup of too much fluid between the layers of the pleura is called a
The test is performed to determine the cause of the extra fluid, or to relieve symptoms from the fluid buildup.
Normally the pleural cavity contains only a very small amount of fluid.
What Abnormal Results Mean
Testing the fluid will help your provider determine the cause of pleural effusion. Possible causes include:
- Liver failure
- Low protein levels
- Kidney disease
- Trauma or post-surgery
- Asbestos-related pleural effusion
- Collagen vascular disease (class of diseases in which the body's immune system attacks its own tissues)
- Drug reactions
- Collection of blood in the pleural space (hemothorax)
- Swelling and inflammation of the pancreas (
- Blockage of an artery in the lungs (pulmonary embolism)
underactive thyroid gland
If your provider suspects that you have an infection, a culture of the fluid may be done to test for bacteria.
Risks may include any of the following:
- Collapsed lung (
- Respiratory distress
A chest x-ray is commonly done after the procedure to detect possible complications.
Blok BK. Thoracentesis. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 9.
Chernecky CC, Berger BJ. Thoracentesis - diagnostic. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:1068-1070.
Review Date: 07/20/2018
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright ©2019 A.D.A.M., Inc., as modified by University of California San Francisco. Any duplication or distribution of the information contained herein is strictly prohibited.
Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Health. Please discuss with your doctor any questions or concerns you may have.