Is a pleural effusion serious?

Posted: 3rd Jan 20 8:00 AM

A pleural effusion is a build-up of excess fluid in the space between your lungs and chest wall. This build-up can limit the movement and capacity of your lungs.

Pleural effusions, also known as ‘fluid on the lungs’, are fairly common and can be caused by a range of respiratory conditions.

What is a pleural effusion?

Your lungs and chest wall are lined by two layers of thin membrane called the pleura. The area between the layers of pleura is known as the pleural cavity or pleural space and usually contains a small amount of fluid to lubricate and ease the movement of your lungs.

Sometimes, a larger amount of fluid can accumulate in the pleural space. When this happens, this is called a pleural effusion.

What can cause a pleural effusion?

A pleural effusion can be caused by a wide range of conditions, including lung infections (like pneumonia) and heart failure.

Pleural effusions can also be a symptom of various cancers, such as:

  • Lung cancer
  • Breast cancer
  • Ovarian cancer
  • Pleural mesothelioma (cancer caused predominantly by exposure to asbestos)

What are the symptoms of a pleural effusion?

Symptoms of pleural effusions include shortness of breath and a dry cough. In cases where the pleural effusion is more severe, symptoms can also include fever and chest pains, which are usually sharp or stabbing in nature.

Symptoms of a pleural effusion are caused by the excess fluid pressing against the lung, preventing it from expanding fully and reducing lung capacity.

Breathlessness and shortness of breath caused by a pleural effusion become a more noticeable problem when trying to exert yourself.

Diagnosing a pleural effusion

Diagnosing a pleural effusion

Your doctor will discuss any symptoms you are experiencing with you, and give you a physical examination.

To confirm a diagnosis of a pleural effusion, imaging tests are generally used. These can include:

  • Chest X-Ray

Pleural effusions appear on X-Rays as white areas, whereas regular air space appears black. If your first X-Ray shows signs of a pleural effusion, it is likely for you to have several more X-Rays while you lay on each side; these will show if the fluid flows freely within your pleural space.

  • CT scan

CT scans take many images in quick succession. These images are then constructed by a computer to show your entire chest. CT scans show more detail and are more accurate than chest X-Rays.

  • Ultrasound

A probe is placed onto your chest and will create images of the inside of your body. Ultrasounds are often used to locate fluid to take samples for analysis.

Types of pleural effusion

Your doctor may use one of two terms to describe your pleural effusion. These are “transudative” and “exudative” and are the two main types of pleural effusion.

  • Transudative pleural effusion

A transudative pleural effusion, or a non-inflammatory pleural effusion, is very similar to the fluid usually found in the pleural space and occurs when fluid leaks across the pleura, usually caused by heart failure.

Transudative pleural effusions don’t often need to be drained unless they become very large.

  • Exudative pleural effusion

Exudative pleural effusions, or inflammatory pleural effusions, form when an excess of fluid, blood, inflammatory cells and sometimes bacteria leak through damaged blood vessels into the pleura. The most common causes of exudative pleural effusions include pneumonia, lung cancer, and the asbestos-related cancer mesothelioma.

Exudative pleural effusions may need to be drained, depending on the size of the pleural effusion and how much inflammation has been caused.

If you have been exposed to asbestos and experience symptoms of an asbestos-related disease, including a pleural effusion, you should seek medical attention immediately.

Should you be diagnosed with an asbestos-related disease, such as mesothelioma, diffuse pleural thickening or asbestosis, get in touch with the National Asbestos Helpline today. Call us on 0800 043 6635 or send an email to

Further reading

5 Risk factors for developing mesothelioma

Why is asbestos dangerous?

What is the asbestos compensation claims process?

How long do mesothelioma claims take?

Is there a time limit on asbestos compensation claims?

Symptoms of a pleural effusion – Infographic