Pleural effusion, also called “water on the lungs,” is extra fluid buildup between thin membranes that line your lungs and chest wall. These membranes (pleura) normally contain a few teaspoons of watery fluid to help your lungs stay moist and move smoothly.
But certain medical conditions can cause fluid to build up or leak out into the pleural space. The excess fluid can press on your lungs, causing shortness of breath, chest pain, and cough.
But with treatment, your doctor can drain the fluid to ease your symptoms and find out what's causing your pleural effusion. Early diagnosis can help treat the cause early and speed your recovery. Explore the types of pleural effusion, how it's diagnosed, and treated.
What Are the Types of Pleural Effusion?
At first, your doctor may classify your pleural effusion as "transudative" or "exudative" to describe how the fluid buildup happened.
Transudative pleural effusion
The term transudative simply means transit, to pass through. Extra fluid leaks out of your blood vessels to collect around your lungs, if you have:
- Higher blood pressure
- Lower amounts of blood proteins
Medical conditions like heart, kidney, and liver diseases can cause transudative fluid buildup.
Exudative pleural effusion
The term exudative means to flow out or exude. Exudative fluid build can happen if you have:
- Inflammation
- Infection
- Cancer
More than half of people with exudative fluid have pneumonia, but only about 80,000 to 160,000 have cancer.
What Causes Pleural Effusion?
More than 50 different medical conditions can cause pleural effusion. But the most common causes are heart failure, cirrhosis (liver disease), and kidney problems.
Leaky fluid from blood vessels
Transudative fluid can pass out of your blood vessels because your heart pumps less blood.
Common causes for leaky blood vessels include:
- Congestive heart failure
- Liver disease
- Kidney disease
- Pulmonary embolism, a blood clot in your lungs
Fluid related to inflammation
Most inflammation that causes exudative pleural effusion is from pneumonia, but other reasons can include:
- Cancer: Usually lung cancer, but other types of cancer that spread to the lungs or pleura can also cause fluid buildup.
- Infection: Viruses, bacteria, or parasites can cause pneumonia, tuberculosis, COVID-19, and fluid buildup in your lungs. Usually exudative, COVID can also cause transudative lung fluid.
- Connective tissue conditions: Lupus, rheumatoid arthritis, mixed connective tissue disease, and Ehlers-Danlos syndrome can inflame the pleura.
Other causes
Different conditions can inflame the thin membranes around your lungs or cause fluid to leak into the pleural cavity.
Pleural effusion can happen as a result of:
- Drowning
- Electrical burns
- Pancreatitis
- Radiation therapy
- Exposure to certain medicines
- Asbestos exposure
- Chylothorax (a lymphatic system trauma with chyle in the fluid)
- Trauma to your chest
The fluid in your chest can also have blood (hemothorax), pus (purulent effusion), or cancer cells.
What Are the Symptoms of Pleural Effusion?
Everyone can have different symptoms for pleural effusion, depending on the cause. Some people don’t have symptoms, but larger fluid amounts can build up on your lungs. If the liquid grows to a moderate or large-sized volume, it can press on your lungs and lead to symptoms.
With pleural effusion symptoms, you may have:
How Is Pleural Effusion Diagnosed?
Your doctor reviews your symptoms, medical history, and gives you a physical exam.
They'll ask if you have:
Your doctor may also tap on your chest and listen with a stethoscope. To confirm you have pleural effusion, you'll likely get an imaging test.
Ultrasound
A probe is placed on your chest to create images of the inside of your body. This test helps your doctor locate the fluid, measure the fluid volume, and check for any tumors.
Thoracentesis
If it's still unclear why you have fluid in your lungs or if it needs to be drained to ease your symptoms, your doctor can do a procedure called thoracentesis. A needle and a tube called a catheter are inserted between your ribs, into the pleural space. Your doctor removes the lung fluid and tests it for infection or cancer cells.
Chest X-ray
A chest X-ray helps your doctor check for fluid around your lungs. If you have a pleural effusion, you may get more X-ray films while you lie on your side. These can show if the fluid flows freely within the pleural space.
CT scan
A CT scanner quickly takes many X-rays, and a computer makes images of your entire chest, inside and out. CT scans can show more detail than chest X-rays. The scan can help diagnose your pleural effusion and show your doctor if you have a lung mass.
Blood and pleural fluid tests
If your doctor suspects that a certain medical condition causes your pleural effusion, they'll order blood tests. Sometimes, they can compare the amounts of a substance in your blood to the amount inside the pleural fluid.
Your doctor can test the pleural fluid for:
- White and red blood cells
- Total protein
- Glucose
- Cholesterol
- Certain enzymes, such as lactate dehydrogenase to check for tissue damage
Transudative fluid is often clear and watery, but exudative fluid can have different smells and colors. The fluid may turn a milky color from your feeding tube, lymphatic chyle, or cholesterol. But if your lung fluid is yellow or green, it may be mixed with pancreatic enzymes, bile, or infected.
Microbiology testing
Your doctor may also test your pleural fluid for bacteria and other germs if you have an infection. This can help identify what type of bacteria, virus, fungus, or parasite is causing the fluid to collect around your lungs. Tuberculosis, nocardia, and pneumonia commonly cause pleural effusion.
Cytology testing
If you use tobacco or have a higher risk for lung cancer, your doctor may do a cytology test. The test can check your pleural fluid for cancer cells and see any structures found in autoimmune conditions such as lupus and rheumatoid arthritis.
What Are Pleural Effusion Treatments?
Your doctor focuses on draining the fluid and finding the cause so they can treat your medical condition. This can ease your symptoms, relieve pressure from your lungs, and help you breathe better.
In some cases, you may get:
- Antibiotics to fight infection
- Steroid or NSAID medication to lower swelling and inflammation
- Bronchodilator medicine to widen your airways
- Diuretic medicine to rid of extra water from your body
Deep breathing
If you don't have symptoms, your doctor may monitor your condition, give you an incentive spirometer, and tell you to do deep breathing exercises. An incentive spirometer is a small, bottle-sized device that you blow air into to keep your lungs inflated. Deep breathing exercises can expand your lungs and prevent complications.
Thoracentesis
If your pleural effusion is larger, infected, or inflamed, thoracentesis can drain the fluid to help you feel better. But unless your medical condition is treated, the pleural effusion can come back. If your pleural effusion persists, your doctor will likely offer other treatments.
Tube thoracostomy (chest tube)
Your doctor makes a small cut in your chest wall and inserts the plastic tube into your pleural space. The tube may stay in place for several days.
Pleural drain
If your pleural effusions keep coming back, your doctor may put a long-term catheter through your skin into the pleural space. Your doctor will show you how to drain your pleural effusion at home.
Pleurodesis
If a chronic medical condition causes recurrent pleural effusion, a procedure can seal the pleura. Your doctor injects an irritant (such as talc or doxycycline) into the pleural space through your chest. The substance inflames the pleura and chest wall, causing your lung tissue layers to tightly heal together. And in most cases, this can prevent pleural effusion from coming back.
Pleurectomy and decortication
Your surgeon can remove any hardened, unhealthy, or inflamed tissue inside the pleura. If you have lung tumors or other lung problems, this procedure can help. They'll make small cuts (thoracoscopy), a large one (thoracotomy), or use video-assisted thoracoscopic surgery (VATS).
Takeaways
Pleural effusion traps fluid between the thin membranes called pleura that line the surface of your lungs and inside your chest wall. Transudative fluid leaks out from your blood vessels, but exudative fluid builds up due to lung inflammation. Many conditions can cause pleural effusion, but heart failure, cirrhosis, and kidney problems are the most common. If you're short of breath, have chest pain, or fever, or a cough, get medical help right away.
Pleural Effusion FAQs
What treatment options are available for pleural effusion?
Depending on the amount of fluid, presence of infection, and the cause, your doctor may suggest:
- Watchful waiting with an incentive spirometer and deep breathing exercises, if you don't have symptoms
- Medications to get rid of excess water, fight infection, and lower swelling and inflammation
- Thoracentesis to drain the fluid if you have symptoms or a larger lung fluid volume
- A chest tube, pleural drain, or pleurodesis to close up your pleural cavity if the fluid comes back
- Decortication procedure to remove any tumors or unhealthy tissue from around your lungs and help you breathe better
Can pleural effusion go away on its own?
If you don't have symptoms and there's a small amount of fluid around your lung, your pleural effusion may go away on its own. But your doctor will likely monitor you, watch for signs of infection, and give you an incentive spirometer with deep breathing exercises.
