overview

A pleural effusion is an unusual amount of fluid around the lung. Many medical conditions can lead to it, so even though your pleural effusion may have to be drained, your doctor likely will target the treatment at whatever caused it.

The pleura is a thin membrane that lines the surface of your lungs and the inside of your chest wall. When you have a pleural effusion, fluid builds up in the space between the layers of your pleura.

Normally, only teaspoons of watery fluid are in the pleural space, which allows your lungs to move smoothly in your chest cavity when you breathe.

Causes

A wide range of things can cause a pleural effusion. Some of the more common ones are:

Leaking from other organs. This usually happens if you have congestive heart failure, when your heart doesn’t pump blood to your body properly. But it can also come from liver or kidney disease, when fluid builds up in your body and leaks into the pleural space.

Cancer. Usually lung cancer is the problem, but other cancers that have spread to the lung or pleura can cause it, too.

Infections. Some illnesses that lead to pleural effusion are pneumonia or tuberculosis.

Autoimmune conditions. Lupus or rheumatoid arthritis are some diseases that can cause it.

Pulmonary embolism. This is a blockage in an artery in one of your lungs, and it can lead to pleural effusion.

Symptoms

You might not have any. You’re more likely to have symptoms when a pleural effusion is moderate or large-sized, or if there is also inflammation.

If you do have symptoms, they may include:

Shortness of breath
Chest pain, especially when breathing in deeply (This is called pleurisy or pleuritic pain.)
Fever
Cough

Types

You may hear your doctor use the terms “transudative” and “exudative” to describe the two main types of pleural effusions.

Transudative. This pleural effusion fluid is similar to the fluid you normally have in your pleural space. It forms from liquid leaking across normal pleura. This type rarely needs to be drained unless it’s very large. Congestive heart failure is the most common cause of this type.

Exudative. This forms from extra liquid, protein, blood, inflammatory cells or sometimes bacteria that leak across damaged blood vessels into the pleura. You may need to get it drained, depending on its size and how much inflammation there is. The causes of this type include pneumonia and lung cancer.

How is pleural effusion diagnosed?

The tests most commonly used to diagnose and evaluate pleural effusion include:

Chest x-ray
Computed tomography (CT) scan of the chest
Ultrasound of the chest
Thoracentesis (a needle is inserted between the ribs to remove a biopsy, or sample of fluid)
Pleural fluid analysis (an examination of the fluid removed from the pleura space)
When the pleural effusion has remained undiagnosed despite previous, less-invasive tests, thoracoscopy may be performed. Thoracoscopy is a minimally invasive technique, also known as video-assisted thoracoscopic surgery, or VATS, performed under general anesthesia that allows for a visual evaluation of the pleura). Often, treatment of the effusion is combined with diagnosis in these cases.

How is pleural effusion treated?

Treatment of pleural effusion is based on the underlying condition and whether the effusion is causing severe respiratory symptoms, such as shortness of breath or difficulty breathing.
Diuretics and other heart failure medications are used to treat pleural effusion caused by congestive heart failure or other medical causes. A malignant effusion may also require treatment with chemotherapy, radiation therapy or a medication infusion within the chest.
A pleural effusion that is causing respiratory symptoms may be drained using therapeutic thoracentesis or through a chest tube (called tube thoracostomy).
For patients with pleural effusions that are uncontrollable or recur due to a malignancy despite drainage, a sclerosing agent (a type of drug that deliberately induces scarring) occasionally may be instilled into the pleural cavity through a tube thoracostomy to create a fibrosis (excessive fibrous tissue) of the pleura (pleural sclerosis).
Pleural sclerosis performed with sclerosing agents (such as talc, doxycycline, and tetracycline) is 50 percent successful in preventing the recurrence of pleural effusions.

What are the risk factors for pleural effusion?

Pleural effusions are caused by the underlying medical problems listed previously, therefore the presence of any of these medical problems are risk factors for the development of pleural effusions. It is important to note, however, that not all individuals with these medical problems will develop pleural effusions. Congestive heart failure is the most common cause of transudative pleural effusions, while infection (pneumonia) and malignancy are the most common causes of exudative pleural effusions.