Pleural effusion

The pleura is a membrane that covers the lungs. It has two layers and produces fluid that helps the lungs move when we breathe. Sometimes cancer cells spread to the pleura. This can cause fluid to build up and press on the lungs, causing breathlessness.

You will normally have a chest x-ray or ultrasound scan to see if you have a pleural effusion. You may need to have other tests as well.

Treating a pleural effusion involves slowly draining the fluid. This is usually done by putting a tube into your chest through a small cut. You may spend a couple of days in hospital afterwards.

Fluid may build up again so you may need drainage more than once. You may have a drain left in place to collect fluid. Or you may have a procedure known as a pleurodesis, or a medical thoracoscopy. Your doctor will give you more information about these treatments if you need them.

To prevent the fluid from building up again, you may need chemotherapy or hormonal therapy to treat the cancer.

Pleural effusions

The lungs are covered by a membrane, or lining, called the pleura, which has an inner and outer layer. The inner layer covers the lungs. The outer layer lines the rib cage and diaphragm, which is a sheet of muscle that separates the chest from the abdomen.

The pleura produces a fluid that acts as a lubricant that helps you to breathe easily, allowing the lungs to move in and out smoothly. Sometimes too much of this fluid can build up between the two layers of the pleura; this is called a pleural effusion.

A pleural effusion
A pleural effusion

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Pleural effusions can be a symptom of cancer.

Causes of a pleural effusion

Pleural effusions are quite common and are often due to infections such as pneumonia or heart failure, which is when the heart is not pumping the blood efficiently around the body. A pleural effusion can also be a symptom of several types of cancer. The effusion can develop if cancer cells have spread into the pleura, where 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: 

  • lung cancer 
  • breast cancer 
  • ovarian cancer 
  • lymphomas 
  • mesothelioma (cancer of the pleura).

Signs and symptoms of a pleural effusion

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 increasingly breathless, not only when you’re active, but also when you’re resting. You may also get some chest pain and a cough.  

How a pleural effusion is diagnosed

A chest x-ray and/or an ultrasound scan may be used to diagnose a pleural effusion. Sometimes other tests may be needed to confirm the diagnosis and the cause of the effusion.

Drainage of a pleural effusion

The initial treatment of a pleural effusion involves draining it to relieve the symptoms.

Draining a pleural effusion with a chest drain

A pleural effusion is usually drained by putting a tube, known as a chest drain, into the chest. This procedure is carried out by a doctor. You will be asked to sit either on a chair or on the edge of the bed. Someone will then help you lean forward over a table with a pillow on it so that your back is exposed.

Your doctor will decide where to insert the drain - usually in the side of the chest. The skin over the area where the drain is to be inserted is cleaned with an antiseptic solution to prevent the area from becoming infected. You will then be given an injection of local anaesthetic to numb the area so you won’t feel any pain during the procedure.

Your doctor will then make a very small cut in the chest and insert the chest drain into the space where the fluid is collecting. Sometimes an ultrasound scan is used to help guide the tube into the correct position. Once in position, the chest drain is attached to a bag or bottle for the fluid to drain into. The fluid that drains may be bloodstained.

Usually the fluid will be drained off fairly slowly, as a sudden release of pressure in the chest can cause a drop in blood pressure. A litre of fluid may be drained safely as soon as the drain has been inserted. After this, drainage will be carried out more slowly. Your blood pressure will be checked during the procedure. You should let your doctor or nurse know if you feel dizzy, sick or light-headed.

You will usually need to stay in hospital for a couple of days after the procedure. You may have some pain when the local anaesthetic wears off. Let your doctor or nurse know if this happens so that they can prescribe painkillers. The drainage tube will be held in place with a small stitch until all the fluid has drained. If your drainage tube is attached to a bottle, you will be able to walk about with it. It's important to be careful with the bottle; it shouldn't be raised above the level of the chest as the fluid could go back into your lungs.

Once the drainage has slowed down and the doctors think that most of the fluid has drained, you will have a chest x-ray to see how well your lung has re-expanded. If it has, the drain will be removed.

It's possible for the fluid to collect again, so drainage may need to be carried out more than once. To prevent the fluid from building up again you may be prescribed chemotherapy or hormonal therapy to treat the cancer. Your doctor may also advise you to have a pleurodesis or a medical thoracoscopy.

Possible complications of chest drains

  • The chest drain can become blocked, but this is rare. It can sometimes be cleared by changing your position or sitting upright. Occasionally the drain may need to be replaced.
  • The drain can become infected. You will have your temperature checked for any sign that you may be developing an infection.
  • Sometimes the drain causes air to become trapped between the lung and the chest wall. This is called a pneumothorax. You may become more breathless and have a sharp pain in your chest. If it's a small pneumothorax, you may not need any treatment and it's likely to clear over a few days. You may need to have an x-ray to check that it's gone. If it's a larger pneumothorax, you may need another drainage tube to remove the air.

Draining a pleural effusion at home

Occasionally, it may be possible to have your pleural effusion drained while you’re at home using a catheter, which acts in a very similar way to a chest drain. The catheter will be put in while you’re in the hospital and then you will be able to go home. Your doctor or specialist nurse will explain more about this method of drainage if it’s suitable for you.

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 cannula into the chest rather than a chest drain. This is removed immediately after the fluid has been drained off and the area is covered with a dressing.


If the lung re-inflates after the fluid has been drained, it may be possible to seal the two layers of the pleura together to prevent the fluid from building up again. This is known as pleurodesis. It is usually done using a sterile talc that is injected through the drain.

The doctor injects the drug through the drain and then leaves the drain clamped for about an hour. You will be asked to lie in various positions in the bed (on your back, your front, and your left and right sides) to help the drug circulate around the lining of the lungs. The drain may then be attached to a suction machine to apply a small amount of pressure, which encourages the pleura to seal together. After a pleurodesis, the drain will usually remain in place for 24 hours.

If there is a stitch that has been holding the drain in, it can be pulled together when the drain is removed, sealing the hole that is then covered 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.

If you’re advised to have a pleurodesis, your doctor or nurse will give you more information about it.

Medical thoracoscopy

It may be possible to drain a pleural effusion and to do a pleurodesis using a procedure called medical thoracoscopy. A flexible tube (thorascope) is put into your chest through a small cut made in your chest wall. The tube has a light and a camera at the end so that the doctor can see the area clearly.

You will be asked to lie on your side and given an injection of a sedative to make you feel drowsy. A local anaesthetic will be given to numb the area where the doctor will make one or two small cuts. The thorascope is then put into the chest. Any fluid can be drained, and the doctor can spray sterile talc through the thoracoscopy tube to help the layers of the pleura stick together. The procedure takes about 40-60 minutes.

After the thoracoscopy, a plastic tube (chest drain) will be put through the cut to drain any remaining fluid. The drain will be attached to a bottle or bag and secured in place with a stitch. You will usually be able to go home 2-5 days after a thoracoscopy. Your hospital team will be able to give you more information about this procedure.

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