Thoracentesis, also known as a pleural tap, is a procedure done when there’s too much fluid in the pleural space. This allows a pleural fluid analysis to be performed in the lab to figure out the cause of fluid accumulation around one or both of the lungs. The pleural space is the small space between the lungs and the chest wall. This space typically contains approximately 4 teaspoons of fluid. Some conditions can cause more fluid to enter this space. These conditions include:
This is called pleural effusion. If there’s excess fluid, it can compress the lungs and cause difficulty breathing.
The goal of a thoracentesis is to drain the fluid and make it easier for you to breathe again. In some cases, the procedure will also help your doctor discover the cause of the pleural effusion.
The amount of fluid drained varies depending on the reasons for performing the procedure. It typically takes 10 to 15 minutes, but it can take longer if there’s a lot of fluid in the pleural space.
Your doctor may also perform a pleural biopsy at the same time, to get a piece of tissue from the lining of your inner chest wall. Abnormal results on a pleural biopsy can indicate certain causes for the effusion, including: