EBSCO Health

Print PageSend to a Friend
Health Library Home>Procedure & Surgery Fact Sheets>Article


(Pleural Fluid Aspiration; Pleural Tap)

Pronounced: Thor-a-sen-TEE-sis


Thoracentesis is the removal of excess fluid from the space between the lungs and the chest wall (pleural space).

Reasons for Procedure

This procedure is done to ease or test for the cause of pleural effusion. This is a buildup of fluid in the pleural space that can make it hard to breathe.

The fluid may be tested to look for signs of health problems, such as:

  • Heart failure
  • Lung infections
  • Kidney disease
  • Pulmonary embolism —a clot that travels to the lung
  • Cancer
  • Collagen vascular disease like sarcoidosis or lupus
  • Liver disease
  • Pancreatitis
  • Asbestos exposure

Possible Complications

Problems are rare, but all procedures have some risk. The doctor will go over some problems that could happen, such as:

  • Infection
  • Bleeding
  • Fluid building up again
  • Collapsed lung
  • Damage to the lung, liver, or spleen

Things that may raise the risk of problems are:

What to Expect

Prior to Procedure

The surgical team may meet with you to talk about:

  • Anesthesia options
  • Any allergies you may have
  • Current medicines, herbs, and supplements that you take and whether you need to stop taking them before the procedure
  • Fasting before the procedure
  • Whether you need a ride to and from the procedure
  • Taking images to find the location of the fluid using:


A local anesthetic will be used. It will numb the area where the needle will be inserted.

Description of the Procedure

You will sit upright on the edge of a bed or chair. Your arms will be resting on a nearby table. A needle or thin plastic catheter will be inserted between the ribs. An ultrasound or CT scan may be used to guide the needle and monitor the fluid. The needle or catheter is then passed into the pleural space. Some or most of the fluid will be drawn into the syringe. The needle or catheter will be removed. A bandage will be placed over the site.

How Long Will It Take?

About 15 minutes

Will It Hurt?

You may feel slight pain or a stinging when the needle is inserted. You may feel a sense of pulling when the fluid is removed.

Post-procedure Care

At the Care Center

The fluid may be sent to a lab for testing. Another image may be taken to make sure your lungs are working well.

At Home

Physical activity may be limited for a few days.

Call Your Doctor

Call your doctor if you are not getting better or you have:

  • Signs of infection, such as fever and chills
  • Redness, swelling, excessive bleeding, or any discharge from the site
  • Pain that is not eased by medicine
  • Pain when taking a deep breath
  • Cough, shortness of breath, or chest pain
  • Coughing up blood

If you think you have an emergency, call for medical help right away.


American Lung Association

American Thoracic Society


The Canadian Institutes of Health Information

The Lung Association


How to Do Thoracentesis. The Merck Manual Professional Edition website. Available at: http://www.merckmanuals.com/professional/pulmonary-disorders/diagnostic-and-therapeutic-pulmonary-procedures/how-to-do-thoracentesis. Updated June 2019. Accessed May 5, 2020.

Thoracentesis. American Thoracic Society. Available at: https://www.thoracic.org/patients/patient-resources/resources/thoracentesis.pdf. Updated February 2016. Accessed May 5, 2020.

Thoracentesis. EBSCO DynaMed website. Available at:https://www.dynamed.com/procedure/thoracentesis. Updated March 25, 2020. Accessed May 5, 2020.

Thoracentesis. Johns Hopkins Medicine website. Available at: http://www.hopkinsmedicine.org/healthlibrary/test_procedures/pulmonary/thoracentesis_92,P07761. Accessed May 5, 2020.

Thoracentesis. National Heart Lung and Blood Institute website. Available at: https://www.nhlbi.nih.gov/health/health-topics/topics/thor. Accessed May 5, 2020.

Last reviewed February 2020 by EBSCO Medical Review Board Daniel A. Ostrovsky, MD