Thoracentesis (Pleural Tap)

Thoracentesis (pleural tap) is a procedure to remove excess fluid from the space between the lungs and the chest wall. This space is called the pleural space. The procedure is done with a needle or a plastic catheter that is inserted through the chest wall. Thoracentesis may be done for diagnostic and/or therapeutic reasons.

Normally there is a small amount of fluid in the pleural space, but a buildup of excess fluid, known as pleural effusion, may occur due to infection, inflammation, heart failure, or cancer. A large amount of fluid in the pleural space can also make it difficult to breathe and cause pain. 


Thoracentesis may be done to figure out the cause of pleural effusion and/or relieve the symptoms caused by the buildup of fluid. This procedure may also be done to diagnose systemic lupus erythematosus (SLE), pancreatitis, pulmonary embolism, empyema, and tuberculosis.

A chest x-ray, ultrasound or computed tomography (CT) scan is usually done to confirm pleural effusion, which may be found during a physical examination. Please let your doctor know about all medication that you are taking as some may need to be stopped before the procedure. Also, let your doctor know if you are allergic to medication and/or medical equipment. You may need someone to drive you home if a sedative is used during the procedure.

You will be positioned in a sitting position and will lean forward over a table or a padded surface. The site for insertion of the needle, which will be between your ribs on your back, will be cleaned. A local anesthetic will then be injected. A long needle or catheter will then be inserted into the pleural space. Ultrasound may be used to guide the needle or catheter.

The procedure usually takes 10 to 15 minutes, but may take longer if a large amount of fluid must be removed. The needle or catheter may be attached to a container to hold the fluid if a lot of it has to be removed. After the needle or catheter is removed, a bandage will be placed on the site.

An x-ray may be taken immediately after the procedure to make sure that no complications has occurred and that the procedure was successful. Most patients are able to return to normal activities after the procedure.

  • Pneumothorax, when air is trapped in the pleural space, causing the lung to collapse.
  • Pulmonary edema, which is fluid in the lungs.
  • Bleeding.
  • Infection.

Your doctor will assess your condition before making any recommendations for travel. Recommendations may vary from patient to patient.

  • If there is a lot of fluid in the pleural space, after the procedure the patient’s breathing will slowly improve.
  • Normally, removing this fluid and examining it in the laboratory allows for diagnosis in 75% of patients.


What if this procedure is not performed?

Fluid build-up causes pain and difficulty breathing, and without collecting fluid to diagnose the cause of pleural effusion, the condition cannot be appropriately treated.

Please ask your doctor about any alternatives to diagnose and/or treat your condition. In some cases, there may be no other option.

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