ConditionLungs & breathing
Pleural Effusion (Fluid Around the Lungs)
A pleural effusion is a buildup of fluid in the pleural space, the thin gap between the lungs and the chest wall. People often call it "water on the lungs" or "fluid on the lungs". Small effusions may cause no symptoms; larger ones cause shortness of breath, chest pain on breathing and a dry cough. The most common cause is heart failure; others include pneumonia, cancer, pulmonary embolism, and liver or kidney disease. Treatment targets the cause, and fluid may be drained with a needle or chest tube.
Also called: Fluid on the lungs, water on the lungs, fluid around the lungs, pleural fluid
At a glance
- What it is
- Excess fluid in the space between the lung and the chest wall.
- Two main types
- Transudate (from pressure or protein imbalance, e.g. heart failure) and exudate (from inflammation, infection or cancer).
- Common causes
- Heart failure, pneumonia, cancer, pulmonary embolism, cirrhosis, kidney disease.
- Symptoms
- Breathlessness, sharp chest pain on breathing, dry cough; sometimes none.
- Treatment
- Treat the cause; thoracentesis (needle drainage), chest tube, pleurodesis or indwelling catheter for recurring fluid.
When to get help
Call 911 or go to the ER
- Severe shortness of breath at rest, blue or gray lips, or confusion
- Sudden breathlessness with sharp chest pain, coughing blood or a racing heart (possible pulmonary embolism)
- Breathlessness with chest pain spreading to the arm or jaw
See a doctor within a day or two
- Increasing breathlessness over days, especially when lying flat
- Fever, chills and chest pain on breathing, or a pneumonia that is not improving on antibiotics
- Breathlessness with swollen legs and rapid weight gain
Book a routine appointment
- A persistent dry cough or mild breathlessness with exertion that is gradually worsening
- Unexplained weight loss and breathlessness, especially in a current or former smoker or someone exposed to asbestos
What happens
Normally the pleural space contains a few teaspoons of lubricating fluid, letting the lungs glide smoothly against the chest wall as you breathe. Fluid is constantly produced and absorbed. A pleural effusion forms when more fluid enters than can be drained, which compresses the lung and makes breathing harder.
Types and causes
| Type | How it forms | Common causes |
|---|---|---|
| Transudate | Pressure or protein imbalance pushes fluid out of blood vessels | Heart failure (most common overall), cirrhosis, nephrotic syndrome, kidney failure, low albumin |
| Exudate | Inflammation or disease of the pleura makes vessels leaky | Pneumonia (parapneumonic effusion), cancer, pulmonary embolism, tuberculosis, rheumatoid arthritis, lupus, pancreatitis, after heart surgery |
Special types:
- empyema: pus in the pleural space, a serious infection
- malignant pleural effusion: cancer cells in the pleura, most often from lung cancer, breast cancer, lymphoma, ovarian cancer or mesothelioma
- hemothorax: blood, usually after chest trauma
- chylothorax: lymph fluid, after injury to the thoracic duct
Symptoms
- shortness of breath, worse with exertion and sometimes when lying flat
- sharp chest pain that worsens with deep breaths or coughing (pleuritic pain), often from pleurisy
- dry cough
- a feeling of heaviness in the chest
- symptoms of the cause: fever with pneumonia, swollen legs with heart failure, weight loss with cancer
Small effusions often cause no symptoms and are found on X-rays.
Diagnosis
- examination: reduced breath sounds and dullness when tapping the chest
- chest X-ray: shows fluid; larger effusions are clearly visible
- ultrasound: detects small effusions and guides safe drainage
- CT scan: shows the lungs, pleura and possible causes
- thoracentesis: a needle is inserted between the ribs, under local anesthetic and ultrasound guidance, to remove fluid for testing. The fluid is checked for protein, LDH (using Light's criteria to separate transudate from exudate), glucose, pH, cell counts, bacteria and cancer cells
- blood tests: BNP for heart failure, liver and kidney function, albumin
- pleural biopsy by thoracoscopy if cancer or tuberculosis is suspected and fluid tests are inconclusive
Treatment
Treat the underlying cause
- diuretics and heart failure medicines for heart failure effusions, which often clear without drainage
- antibiotics for pneumonia
- anticoagulants for pulmonary embolism
- cancer treatment for malignant effusions
- treatment of liver or kidney disease
Drainage
- therapeutic thoracentesis: removes fluid to relieve breathlessness. Usually up to about 1.5 liters is drained at one time to reduce the risk of the lung re-expanding too quickly
- chest tube: for empyema, infected effusions with low pH, or blood
- fibrinolytic medicines through the chest tube to break up pockets of infected fluid
- surgery (VATS): keyhole surgery to clear complex infected fluid
Recurrent or malignant effusions
- pleurodesis: talc is used to seal the pleural space so fluid cannot reaccumulate
- indwelling pleural catheter: a soft tube left in place so fluid can be drained at home as needed
Complications
- lung collapse (atelectasis) and trapped lung
- empyema
- pneumothorax after drainage (uncommon)
- pleural thickening and scarring
Outlook
Outlook depends on the cause. Effusions from heart failure or pneumonia often resolve with treatment. Malignant effusions indicate advanced cancer, but drainage procedures can greatly relieve breathlessness and improve quality of life.
Frequently asked questions
What causes fluid on the lungs?
The most common cause of pleural effusion is heart failure. Other causes include pneumonia, cancer, pulmonary embolism, cirrhosis, kidney disease, tuberculosis and autoimmune diseases. Tests on the fluid help find the cause.
What are the symptoms of a pleural effusion?
Common symptoms are shortness of breath, sharp chest pain when breathing deeply or coughing, and a dry cough. Small effusions may cause no symptoms. Symptoms of the underlying cause, such as fever or leg swelling, are often present.
How is fluid around the lungs removed?
Fluid is removed with thoracentesis, a needle inserted between the ribs under local anesthetic and ultrasound guidance. Larger or infected collections may need a chest tube. Recurring fluid may be treated with pleurodesis or a long-term catheter.
Is a pleural effusion serious?
It can be. Small effusions from treatable causes often resolve. Large, infected or cancer-related effusions can cause severe breathlessness and need prompt treatment. The seriousness depends mainly on the underlying cause.
Sources
This guide was written from current patient and clinical guidance, including:
- British Thoracic Society: Guideline for pleural disease (2023)
- American Thoracic Society: Management of malignant pleural effusions (clinical practice guideline)
- MedlinePlus: Pleural effusion
- National Heart, Lung, and Blood Institute: Pleural disorders
- Merck Manual Professional Version: Pleural effusion