It’s concerning when we experience frequent shortness of breath or when we struggle to breathe. There are many causes of breathing difficulties, and one is pleural effusion. While it may not be as common as allergies, pleural effusion still affects over 100,000 people a year in the US.

What is pleural effusion?

Also known as “water in the lungs” or pleurisy, pleural effusion occurs when fluid accumulates in the membrane layers surrounding the lungs. These membranes, called pleura, line the outside of the lungs as they sit inside the chest cavity. They provide lubrication for your lungs and can easily expand and contract. It is normal to have a small amount of fluid between the pleura, but excessive is problematic.


Pleural effusion has a broad range of symptoms that include:

  • Cough
  • Dry cough that does not produce sputum
  • Shortness of breath or difficulty breathing (also known as dyspnea)
  • Inability to breathe normally unless sitting or standing up straight (orthopnea)
  • Rapid or shallow breathing
  • Chest pain when inhaling deeply (pleuritic pain)
  • Fever

It’s important to note that some people have no symptoms, and diagnostic scans performed for other reasons stumble upon this excess of pleural fluid.


When diagnosing and treating pleural effusion, it is important to differentiate between the two types.

  • Transudative pleural effusion comes from other parts of the body. It occurs when fluid leaks into the spaces within the pleura because of a low protein count in the blood or because blood vessels are under increased pressure. Heart failure is the most common cause.
  • Exudative pleural effusion comes from within the pleura. IT occurs when fluid builds up because of blood, protein, bacteria, or inflammatory cells accumulating in the pleura. This is caused by infection, inflammation, injury, tumors, and blocked lymph vessels or blood vessels.

Being able to tell the difference is important when finding the cause and providing the proper treatment.


There are several tests available to form a diagnosis. This includes taking images of the chest through:

  • X-ray
  • Computed tomography (CT) scan
  • Ultrasound

Other procedures include thoracentesis or pleural fluid analysis. In a thoracentesis, doctors insert a needle between the ribs to remove a small tissue or fluid sample. They then analyze this pleural fluid or tissue to help form a diagnosis. 

If these tests cannot reveal pleural effusion, doctors may perform a thoracoscopy or video-assisted thoracoscopic surgery (VATS) to visually confirm effusion.


Pleural effusion

There are several causes of pleural effusion:

  • Cancer
  • Cirrhosis
  • Heart failure
  • Inflammatory disease
  • Kidney disease
  • Pneumonia
  • Post-open heart surgery
  • Pulmonary embolism
  • Pulmonary embolism

While less common, asbestos exposure can also cause pleural effusion.

Risk factors

The risk factors for pleural effusion can be broad. They include:

  • Smoking
  • Diseases such as heart failure or pericarditis, tuberculosis, and liver disease
  • Infections like pneumonia
  • Pulmonary embolisms
  • Health problems such as cancer and autoimmune diseases
  • Surgery on major organs like the heart or lungs
  • Organ transplant
  • Major injuries such as those to the chest


The treatment options available for pleural effusions vary in their level of intensity. When treating this disorder, your doctor could use the following treatments:

  • Thoracentesis – using a needle to drain fluid 
  • Tube thoracostomy – also known as a chest tube. This requires a small incision in your chest where a plastic tube is inserted for drainage of fluid.
  • Pleural drain – this is similar to the thoracostomy, but it is a long-term option where you can drain the fluid at home.
  • Pleurodesis – irritants are inserted into the pleural space to cause inflammation between the chest cavity and the pleura. This causes the two to heal tightly together and often prevents the disorder from returning.
  • Pleural decortication – In this procedure, a surgeon will open your chest cavity through either a large or small incision to remove damaged or unhealthy tissue.

For those interested in preventing pleural effusion, first talk to your doctor or another medical professional. They will address your concerns and provide more information. If you’re curious to find out more information on your own, you can learn more at the National Heart, Lung, and Blood Institute and the American Lung Association.