Pleural aspiration (thoracocentesis)

What is a pleural aspiration? 

A pleural aspiration (also known as a thoracocentesis, pronounced “tho-rac-oh-sen-tee-sis”) is a simple procedure which involves passing a small needle through your chest wall, to remove fluid or air from the space between your lung and the rib cage (the pleural space).

Why do I need a pleural aspiration? 

We have recommended you have a pleural aspiration because fluid or air has collected in your pleural space. This is called a pleural effusion (collection of fluid) or pneumothorax (collection of air). These can both cause problems with breathing. 

Laboratory analysis of any fluid taken from your pleural space can help us to find out the cause for the fluid build up and help us decide how best to treat it. 

Removal of fluid or air from the pleural space can also help to relieve breathlessness.

Is there an alternative test that I can have instead of the pleural aspiration?

Your doctor can do ultrasound, X-rays and CT scans of your lungs, which will give additional information about the cause of the pleural effusion or pneumothorax. However, there may not be an alternative way of getting the specific information we obtain from pleural fluid samples.

Breathlessness caused by the fluid or air in the pleural space can be managed with other supportive measures, but often removing the air or fluid is the most effective way of managing these symptoms.

How should I prepare for my pleural aspiration?

If you are having the procedure done as an outpatient, please ensure we have the correct contact details for you and that you know when and where you need to come. 

Please bring a list of all your current medication, allergies and other medical conditions with you to the appointment.

It is important that you let us know in advance if you take blood thinning medications and why you are taking them as we will need to temporarily stop these before your procedure (the usual advice is given in the table below, although this may vary depending on why you need these medications, so please ensure you discuss it directly with the doctor or nurse). You should continue with all other medications as usual.

Blood thinning medicationInstructions
WarfarinUsually stopped 5 full days before the procedure. You will need an INR blood test 1-2 days before your procedure to ensure your INR is less than 1.5.
AspirinIf you take 75mg once daily, this can be continued as normal. If you are on a higher dose, the dose may need to be reduced a full 7 days before the procedure - please discuss this with the doctor.
Clopidogrel (Plavix) 
Dipyrimadole (Persantin)
Ticagrelor (Brilique)
Usually stopped 7 full days before the procedure.
Apixaban (Eliquis) 
Dabigatran (Pradexa) Rivaroxaban (Xarelto) 
Usually stopped 2 full days before the procedure.
Dalteparin (Fragmin) Enoxaparin (Clexane)Usually stopped 1 full day before the procedure.

What happens before and during the pleural aspiration procedure?

Before the procedure is performed, a member of the team will take your blood pressure, heart rate and oxygen saturation. They will also ask you questions about your medical history, medications and allergies

  • You will have an opportunity to ask questions and you will be asked to confirm you are happy for the procedure to be performed. You may be asked to sign a consent form.
  • You will either sit with your head and arms resting on a pillow on a table or lie on your bed in a comfortable position.
  • An ultrasound scan may be performed to choose the best place to insert the tube. Ultrasound is painless and involves a cool gel being to be applied to the skin.
  • You may be offered painkillers to take before the procedure starts.
  • Your skin will be cleaned with an alcohol-based liquid to kill any bacteria. If a large volume of fluid is to be removed, local anaesthetic is injected into the skin to numb the area, which can ‘sting’ temporarily but the pain will disappear quickly. Local anaesthetic may not be used if only a small sample is needed for diagnostic purposes.
  • A small tube will be passed through your numb skin into the pleural space to allow the fluid or air to be removed. This should not be painful, but you may feel some pressure
  • The length of time it takes to do the procedure depends on the volume of fluid or air that is removed. It usually takes between 10 and 30 minutes.

Are there any risks with pleural aspiration?

Pleural aspiration is generally a very safe procedure. However, as with all medical procedures, there are certain risks, although serious complications are very rare.

  • Pain: The local anaesthetic will sting briefly, but the aspiration procedure itself should not cause pain.
  • Infection: Very rarely (less than 1 in 100 patients) an infection in the skin or the pleural space may develop. If this occurs it can usually be treated with antibiotics, but in some cases a further drainage of fluid might be required. In the days following your procedure, if you feel feverish or notice any increase in pain or redness, inform your nurse or doctor.
  • Bleeding: A bruise at the site of insertion occurs commonly. Rarely (less than 1 in 250 patients) the pleural aspiration may accidentally damage a blood vessel and cause bleeding into the pleural cavity. Often it stops by itself but occasionally this might require an operation, blood transfusion, or other intervention to stop the bleeding
  • Discomfort during the procedure: As the lung stretches to fill the gap where the fluid or air was, it may cause cough, chest tightness or worsening breathlessness (1 in 10 patients). If the lung re-expands quickly, there is a small risk of fluid collecting in the lung itself (re-expansion pulmonary oedema) (less than 1 in 200 patients). If you experience these symptoms during the procedure, please let the nursing or medical team know as soon as possible so they can stop aspirating further air or fluid.
  • Organ damage: A very rare complication of a pleural aspiration (less than 1 in 200) is puncture of another organ. This could include other structures in the chest (e.g. the lung, heart, diaphragm or major blood vessel) or abdominal organs (e.g. stomach, liver or spleen). Usually this requires no specific treatment, but could mean you need to be admitted to hospital and very rarely would require an operation or other intervention. If the drain punctures the underlying lung, it may require a small tube to be inserted into the pleural cavity.

What happens after the aspiration?

  • After the procedure you will have your blood pressure, pulse and oxygen saturations checked. Some patients may require a chest X-ray.
  • You will have a dressing or sticking plaster over the area, which can be removed the following day.
  • The full results of the pleural aspiration will not be available immediately and usually take 7-14 days.
  • If you are an outpatient, an appointment will be made to discuss the results with you. Sometimes the pleural aspiration does not establish a firm diagnosis and other tests will be needed. We will discuss this with you if necessary.

© North Bristol NHS Trust. This edition published October 2022. Review due October 2025. NBT003501.


Pleural aspiration (thoracocentesis)