Thoracentesis is a procedure to remove excess fluid in the pleural space (the space between the lungs and the chest wall). During this procedure, your doctor will insert a thin needle or plastic tube into the pleural space and draw out the excess fluid. Usually, the doctor will remove only the amount of fluid needed to find the cause of the pleural effusion (the buildup of fluid between the lungs and chest wall). If, however, there is a lot of fluid, more may be removed. This helps the lungs expand and take in more air, which will allow you to breathe easier.
Your doctor will send the fluid removed during thoracentesis for testing. It will be looked at for signs of cancer, heart failure, infection, or other conditions that may be causing the pleural effusion. Once the cause of the pleural effusion is known, your doctor will plan a treatment. For example, if an infection is causing the excess fluid, you may be given antibiotic medication.
The entire procedure, including preparation, usually takes 10 to 15 minutes, but the needle or tube is inserted for only a few minutes during that time. If there is a lot of fluid, the procedure may take up to 45 minutes.