Pleural Effusion

Picture of Pleural Effusion

What is Pleural Effusion?

The pleural cavity is essential for respiration, it encapsulates each lung separately and between the space of the pleural membrane and the lung is a small amount of lubricating fluid. This helps the lungs to inflate and deflate during respiration. Pleural effusion, also called water on the lungs in Singapore, occurs when there is a build-up of excess fluid between the pleural membranes1. While having fluid between the pleural membranes is important as a form of lubrication, an excess of fluid can be detrimental to the whole respiratory process.

Illustration of Pleural Effusion

What are the causes of Pleural Effusion?

Pleural effusion can be caused by a number of serious or benign medical issues2. The excess fluid of the pleural effusion may either be rich in protein (exudative) or more watery (transudative). Knowing the contents of the pleural effusion will help to identify the cause of it. 

Exudative causes include2,3:

  • Pneumonia: approximately 40-60% of individuals with pneumonia go on to develop pleural effusion4.
  • Malignant diseases: such as cancer, especially of the lungs and breast
  • Infections: fungal, bacterial, or viral infections
  • Autoimmune diseases: such as, rheumatoid arthritis, lupus
  • Pulmonary embolism: 4th leading cause of pleural effusion5.
  • Kidney disease: when the kidneys are not working properly, fluid build-up occurs, and this can leak into other organs such as the lungs.

Transudative causes include2:

  • Congestive heart failure: the most common cause of pleural effusion6.
  • Liver cirrhosis: when the liver does not function properly, fluid build-up occurs, and this can leak into other organs such as the lungs.
  • Urinothorax: the presence of urine in the pleural cavity.
  • Hypothyroidism: characterised by fluid retention which also happens in the pleural cavity resulting in pleural effusion.
  • Cerebrospinal fluid leak: this leak can result in fluid build-up in the pleural cavity resulting in pleural effusion.

What are the common symptoms?

Some individuals do not experience any symptoms with pleural effusion, the condition may only be discovered during an x-ray for other associated conditions such as kidney disease, cancer, or congestive heart failure. 

Symptoms of pleural effusion are as follows3:

  • Breathlessness: also known as dyspnoea or short of breath, individuals may struggle to breathe and find it difficult to get the amount of air required for basic activities. As such, people might start to breathe faster and harder to compensate for this lack of oxygen.
  • Chest pain: also known as pleuritic pain, is one of the most common symptoms and is usually more pronounced when breathing.
  • Dry cough: due to inflammation or compression of the lungs.
  • Disturbed sleep: some individuals with pleural effusion struggle to get quality sleep.

Is Pleural Effusion painful?

Yes, chest pains are one of the most common symptoms experienced by individuals with pleural effusion. 

Who is at risk of Pleural Effusion in Singapore?

Some individuals may be at an increased risk of pleural effusion if they have any of the following risk factors:

  • Smokers: smoking substantially increases your risk of other diseases such as lung cancer which is one of the causes of pleural effusion.
  • Drinking alcohol: alcohol also increases your risk of other diseases such as cancer and liver cirrhosis which may cause pleural effusion.
  • Having an autoimmune disease: individuals with an autoimmune disease such as lupus or rheumatoid arthritis have an increased risk.
  • Heart disease: congestive heart failure is the main cause of pleural effusion.

How is Pleural Effusion diagnosed in Singapore?

If pleural effusion is suspected, the following diagnostic tests will be conducted:

  • Chest x-ray: pleural effusions will appear white while other unaffected areas will appear black.
  • Computed tomography scan (CT-scan): similar to an x-ray but with much more details and accuracy.
  • Chest ultrasound: a probe can be used to detect the pleural effusion.
  • Bronchoscopy: a long, thin tube with a camera and light attached on one end will be inserted and gently guided down your throat and into your lungs, to check for pleural effusion.
  • Pleuroscopy: insertion of an endoscope through the chest wall to check for pleural effusion.
  • Thoracentesis: removing fluid from the pleural effusion by inserting a needle into the chest and suctioning it out. The needle will be guided in using an ultrasound probe and the extracted fluid will be sent for a biopsy.
  • Pleural biopsy: tissue sample from the pleura will be taken and sent for a biopsy. 

What are the treatment options for Pleural Effusion in Singapore?

The treatment for pleural effusion depends on the underlying cause. Treatment options include:

  • Pleural drain: used for recurrent or chronic pleural effusions. A long-term catheter is inserted into the pleural space and excess fluid can be drained out.  
  • Pleurodesis: a procedure that sticks the lungs to the chest wall, which removes the space between the two and reduces or completely negates the possibility of future pleural effusions.
  • Chest tube: also known as a tube thoracostomy, it is the insertion of a chest tube into the pleural space for a few days.
  • Thoracentesis: drainage of excess fluid.
  • Pleural decortication: removal of inflamed or diseased parts of the pleura. 

Frequently asked questions

Is pleural effusion curable?

This depends on the underlying cause of your pleural effusion. While pleural effusions are serious and may be life-threatening, they can be treated.


  1. Aaron Saguil, K. W. (2014). Diagnostic approach to pleural effusion. American Family Physician, 99-104.
  2. Stéphane Beaudoin, A. V. (2018). Evaluation of the patient with pleural effusion. Canadian Medical Association Journal, 291-295.
  3. Berthold Jany, T. W. (2019). Pleural Effusion in Adults—Etiology, Diagnosis, and Treatment. Deutzsches Artzteblatt International, 377-386.
  4. Eman Shebl, M. P. (2022). Parapneumonic Pleural Effusions And Empyema Thoracis. Florida: StatPearls.
  5. Light, R. W. (2001). Pleural effusion due to pulmonary emboli. Current Opinion in Pulmonary Medicine, 198-201.
  6. Hildreth, C. J. (2009). Pleural Effusion. JAMA.
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