What is a pleural effusion?

The lungs are covered by a lining (membrane) called the pleura. The pleura has 2 layers. The inner layer covers the lungs. The outer layer lines the ribcage and a sheet of muscle called the diaphragm. The diaphragm separates the chest from the tummy (abdomen).

Between the 2 layers of the pleura is a small amount of fluid that acts as a lubricant. It allows the lungs to move in and out smoothly and helps you to breathe easily. Sometimes, too much of this fluid builds up between the 2 layers of the pleura. This is called a pleural effusion.

Causes of a pleural effusion

A pleural effusion is common and is often caused by:

  • lung infections, such as pneumonia
  • heart failure, which is when the heart is not pumping blood around the body as well as it should.

A pleural effusion can also be a symptom of several types of cancer. An effusion can develop if cancer cells have spread into the pleura. They can lead to irritation and cause fluid to build up. The types of cancer that are more likely to cause a pleural effusion are:

Signs and symptoms of a pleural effusion

Common symptoms of a pleural effusion include:

  • breathlessness
  • a cough
  • chest pain.

The build-up of fluid presses on the lung, making it difficult for the lung to expand fully. In some situations, part, or all, of the lung will collapse. This can make you more and more breathless, even when you are resting. You may also get some chest pain and a cough.

If you are worried about any symptoms, speak to your healthcare team.

Diagnosing a pleural effusion

You may have a chest x-ray or an ultrasound scan, or both. Sometimes you need other tests to confirm the diagnosis, and the cause of the effusion.

Treating a pleural effusion

The first treatment of a pleural effusion involves draining it to help with the symptoms.

Draining a small pleural effusion

If there is only a small amount of pleural fluid in the chest, the doctor may insert a small needle or thin tube (cannula) into the chest. They will use a syringe to draw off the fluid. The tube is removed after the fluid has been drained off and the area is covered with a dressing.


A pleural effusion with drainage
Image: A pleural effusion with drainage

Draining a pleural effusion with a chest drain

A pleural effusion is usually drained by putting a tube into the chest. This is called a chest drain and is done by a doctor. They will ask you to sit on a chair, or on the edge of the bed. You will need to lean forward over a table with a pillow on it, so that your back is showing.

Your doctor usually puts the tube in the side of the chest. They clean the skin over the area with an antiseptic solution. They then give you an injection of a local anaesthetic to numb the area. You will not feel any pain during the procedure.

Your doctor makes a very small cut in the chest. They then insert the chest drain into the space where the fluid is collecting. Sometimes they use an ultrasound scan to help guide the tube into the correct position. When the tube is in position, they attach the chest drain to a bag or bottle for the fluid to drain into. The fluid that drains may have a small amount of blood in it.

Usually the fluid is drained off slowly, as a sudden release of pressure in the chest can cause your blood pressure to drop. A litre (about 2 pints) of fluid may be drained safely as soon as the drain has been put in. After this, drainage is done more slowly. Your blood pressure is checked during the procedure. You should tell your doctor or nurse if you feel dizzy, sick or light-headed.

In many hospitals, you usually have this done as a day patient by a specialist lung team. Sometimes, you need to stay in hospital for 2 days afterwards. 

You may have some pain when the local anaesthetic wears off. Tell your doctor or nurse if this happens so that they can prescribe painkillers. The drainage tube is held in place with a small stitch until all the fluid has drained. If your drainage tube is attached to a bottle or bag, you will be able to walk about with it. The chest drain may feel uncomfortable at times. Tell your doctors or nurses if it is very uncomfortable.

It is important to be careful with the bottle or bag. It should not be raised above the level of your chest, as the fluid could go back into your lungs.

When the drainage has slowed down, you will have a chest x-ray to see how well your lung has re-expanded. If it has expanded well, the drain will be removed.

Possible complications of chest drains

  • Blocked drain

    This is rare and can sometimes be cleared by you changing your position or sitting up straight. Sometimes, the drain may need to be replaced.

  • Infected drain 

    The staff will check your temperature for any sign that you are developing an infection.

  • Breathlessness and sharp pain in chest (pneumothorax)

    Sometimes when the fluid is drained from the chest, the lung cannot re-expand to fill the chest cavity. This leaves an air-filled space around the lung. This is called a pneumothorax. If it is a small pneumothorax, you may not need any treatment and it is likely to clear over a few days. You may need to have an x-ray to check that it is gone. If it is a larger pneumothorax, you may need to have another drainage tube put in to remove the air.

  • The fluid can collect again 

    If fluid builds up again, you may need to have the effusion drained more than once. To stop the fluid from building up again, your doctor may recommend other types of treatment. These may be chemotherapy or hormonal therapy, depending on the type of cancer. Your doctor may also advise you to have a pleurodesis or a thoracoscopy.

Draining a pleural effusion at home

If fluid keeps building up, it is possible to have repeated chest drains put in. However, this can be uncomfortable and may mean making a number of trips to the hospital.

It may be possible for you to have a special catheter put in, called a tunnelled indwelling pleural catheter (TIPC). This is so you can have your pleural effusion drained easily while you are at home. When you have a build up of fluid on the lung, the TIPC allows you to drain the fluid into a bottle. This can be done by you, a family member or a nurse.

The catheter is inserted in hospital on a day ward. As long as there are no complications, you can usually go home on the same day.

Your doctor or specialist nurse will explain more about this method and tell you if it’s suitable for you.

If a pleural effusion comes back

Talc pleurodesis for a pleural effusion

It may be possible to seal the 2 layers of the pleura together, to stop the fluid from building up again. This is called talc pleurodesis. If the lung re-inflates after the fluid has been drained, sterile talcum powder (talc) can be used to help stick the pleura together.

The doctor puts the talc through the tube attached to the drain and then leaves the drain clamped for about an hour. This allows time for the 2 linings of the lung to stick together. The doctor may attach the drain to a suction machine to apply a small amount of pressure. This can help the pleura to seal together. After a pleurodesis, you will usually have the drain in place for another 24 hours.

If there is a stitch that has been holding the drain in place, a doctor or nurse will pull this together when the drain is removed. This closes the hole. They will cover it with a dressing. The stitch is usually removed about a week later. Sometimes just a dressing is used to cover the area where the drain has been.

After a pleurodesis, you may get chest pain for a day or so and you may need to take painkillers. Your doctor or nurse can give you more information about pleurodesis.

Thoracoscopy for a pleural effusion

It may be possible to drain a pleural effusion and do a pleurodesis using a procedure called a thoracoscopy. The doctor puts a flexible tube (thorascope) into the chest. The tube has a light and camera at the end, so the doctors can see into your chest.

For this procedure, you lie on your side. You are given an injection of a sedative to make you feel drowsy. You also have a local anaesthetic to numb the area. The doctor makes 1 or 2 small cuts to put the thorascope in. The procedure takes about 40 to 60 minutes.

After the thoracoscopy, the doctors put a plastic tube (chest drain) through the cut. They use this to drain any remaining fluid. The drain is attached to a bottle or bag and secured in place with a stitch.

You will usually be able to go home 2 to 5 days after a thoracoscopy. Some people may be able to have it and go home on the same day. Your hospital team can give you more information about this procedure.

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About our information

  • References

    Below is a sample of the sources used in our mesothelioma information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Woolhouse I et al. British Thoracic Society Guideline for the investigation and management of malignant pleural mesothelioma. Thorax. 2018.

    Thomas A et al. Mesothelioma. BMJ Best Practice. 2019.

    Baas P et al. Malignant pleural mesothelioma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up.  Annals of Oncology. 26 (Supplement 5): v31–v39. 2015. Available from: www.pubmed.ncbi.nlm.nih.gov/26223247

    Kusamara S et al. Peritoneal mesothelioma: PSOGI/EURACAN clinical practice guidelines for diagnosis, treatment and follow-up. European Journal of Surgical Oncology. March 2020.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr David Gilligan, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 01 August 2021
Next review: 01 August 2024
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

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