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Thoracocentesis (pleural aspiration or pleural tap)

Patient information A-Z

Diagram of Thoracocentesis

What is a thoracocentesis?

Thoracocentesis is a procedure to remove fluid from the space between the lungs and the chest wall. This space is called the pleural space or cavity.

Typically, the pleural space is filled with a small amount of fluid (about four teaspoons) but some conditions, such as heart failure, lung infections and tumours, can cause more fluid to build up. When this happens it is called a pleural effusion. A lot of extra fluid can press on the lungs, making breathing difficult.

Why do I need a thoracocentesis?

Thoracocentesis is done to try to find the cause of a pleural effusion. It may also be done to help you to breathe easier.

How is it done?

No special preparations are needed before the test. It is performed in the clinic or during an inpatient stay. The entire procedure takes 10 to 15 minutes. Please tell your doctor or pleural nurse specialist about any previous bleeding problems or allergies to medicines or latex.

If you are able, you will be positioned in a comfortable sitting position leaning forward, resting your arms on a table. (We can find an alternative approach if this is difficult for you.) To avoid lung injury, it would be best to avoid coughing, breathing deeply or moving during the test.

Thoracic ultrasound (sound waves which create images of your lungs) will be used to find the correct location. Then, after cleaning the skin and anaesthetising the site, the doctor or pleural nurse specialist will insert a thin needle or plastic tube into the pleural space. Once the fluid is removed, the needle or tube is removed and a small dressing is placed where it was inserted.

Positioning for thoracocentesis
Positioning for thoracocentesis

What does thoracocentesis show?

The fluid removed will be sent to the laboratory to be tested to try to establish the cause of the pleural effusion. The appropriate treatment can then be discussed.

What to expect after the test

You will need a chest x-ray after the test to check for any lung problems. To make sure there are no complications, your blood pressure, breathing and oxygen levels will be checked for up to a couple of hours, after which you can go home. Once at home, call your own doctor/ GP immediately if you have any breathing problems.

What are the risks?

The risks are usually minor and are easily treated. Your doctor or specialist nurse will do a chest x-ray after the procedure to check for lung problems. The risks include:

  • Pneumothorax (where air collects into the pleural space). Sometimes, air enters through the needle, or the needle makes a hole in the lung. It will usually self heal; however, a large amount of air may cause the lung to collapse, and this would necessitate insertion of a chest drain to resolve the problem.
  • Pain, bleeding, bruising or infection where the needle was inserted (occurs in less than 5% of cases).
  • In rare cases, bleeding may occur in or around the lungs, in which event your doctor may need to insert a chest drain to drain the blood. In some cases, surgery may be required.

For further information

Call the pleural service team on 01223 349189.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151