Health Encyclopedia - Test
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
A small area of skin on your back is cleaned. Numbing medicine (local anesthetic) is injected in this area.
A needle is placed through the skin and muscles of the chest wall into the space around the lungs, called the pleural space. Fluid is collected and 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 chest x-ray will be performed before and after the test.
Do not cough, breathe deeply, or move during the test to avoid injury to the lung.
How the test will feel
You will sit on a bed or on the edge of a chair or bed. Your head and arms will rest on a table.
The skin around the procedure site is cleaned and the area is draped. A local numbing medicine (anesthetic) is injected into the skin. The thoracentesis needle is inserted above the rib into the pleural space.
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.
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 pleural effusion.
The test is performed to determine the cause of the extra fluid, or to relieve symptoms from the fluid buildup.
The test may be also performed for the following conditions:
Normally the pleural cavity contains only a very small amount of fluid.
What abnormal results mean
Testing the fluid will help your health care provider determine the cause of pleural effusion. Possible causes include:
If your health care provider suspects that you have an infection, a culture of the fluid may be done to test for bacteria.
What the risks are
- Respiratory distress
A chest x-ray is done after the procedure to detect possible complications.
Broaddus C, Light RW. Pleural effusion. In: Mason RJ,Broaddus CV, Martin TR, et al, eds. Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 73.
Celli BR. Diseases of the diaphragm, chest wall, pleura, and mediastinum. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 99.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.