​Thoracentesis is a procedure used to remove excess fluid from the space between your lungs and chest, called the pleural space. This procedure is used when a patient has a pleural effusion.

What is a Pleural Effusion?

Normally, the pleural space in the chest is filled with about 4 teaspoons of fluid. However, conditions such as lung cancer, heart failure, tumors, infection or pneumonia may cause excess fluid to build up in the pleural space, making it difficult to breath.  This condition of excess fluid is called a pleural effusion.

If your pulmonologist suspects you have a pleural effusion, you will be scheduled for a chest x-ray, CT scan or ultrasound, which will reveal the effusion if it is present.

​Thoracentesis is then used either to find the cause of the pleural effusion, by withdrawing a small sample of the effusion for lab testing, or to remove excess fluid, in order to make breathing more comfortable for the patient.

pleural effusion

What Happens During ​Thoracentesis?


As shown in the image at left, your pulmonologist will ask you to sit on the edge of a chair or exam table, lean forward and rest your arms on a table in front of you.  Your pulmonologist may use an ultrasound to find the right place to insert the needle or tube that withdraws the pleural fluid.  Then medicine to numb the area above your pleural effusion will be injected, before your doctor draws out the excess fluid around your lungs.

The procedure will take approximately one hour, including set up and post-procedure.  You may also be sent for x-rays after the procedure, which could take up to one more hour.

In some instances, we may wish you to remain in the Department for observation, or in rare cases, be admitted to the hospital.

What Are Risks to Thoracentesis?

Thoracentesis is safe and relatively painless. You may have mild discomfort or minor bleeding during the procedure, or develop a bruise around the needle insertion point following the procedure.

However, please call your pulmonologist if following the procedure you have:

  • bleeding from the needle site
  • new, sudden difficulty breathing
  • pain when taking a deep breath
  • a cough that produces blood

*These side effects are rare

More Information on Thoracentesis

A patient information pamphlet released by the American Thoracic Society, explaining what a patient needs to know before the procedure.

A detailed overview of thoracentesis and what to expect, by the National Heart, Lung and Blood Institute.

We wish you good luck with your test! If you have any other questions, feel free to call our office at 203.759.3666