Pleural Effusion Causes, Signs & Treatment


What is pleural effusion?

Pleural effusion, sometimes referred to as “water on the lungs,” is the build-up of excess fluid between the layers of the pleura outside the lungs. The pleura are thin membranes that line the lungs and the inside of the chest cavity and act to lubricate and facilitate breathing. Normally, a small amount of fluid is present in the pleura.


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Is pleural effusion serious?

The seriousness of the condition depends on the primary cause of pleural effusion, whether breathing is affected, and whether it can be treated effectively. Causes of pleural effusion that can be effectively treated or controlled include an infection due to a virus, pneumonia or heart failure. Two factors that must be considered are treatment for associated mechanical problems as well as treatment of the underlying cause of the pleural effusion.

Symptoms and Causes

What are the symptoms of pleural effusion?

Some patients with pleural effusion have no symptoms, with the condition discovered on a chest x-ray that is performed for another reason. The patient may have unrelated symptoms due to the disease or condition that has caused the effusion.Symptoms of pleural effusion include:


What causes pleural effusion?

Pleural effusions are very common, with approximately 100,000 cases diagnosed in the United States each year, according to the National Cancer Institute.

Depending on the cause, the excess fluid may be either protein-poor (transudative) or protein-rich (exudative). These two categories help physicians determine the cause of the pleural effusion.

The most common causes of transudative (watery fluid) pleural effusions include:

Exudative (protein-rich fluid) pleural effusions are most commonly caused by:

Other less common causes of pleural effusion include:

  • Tuberculosis
  • Autoimmune disease
  • Bleeding (due to chest trauma)
  • Chylothorax (due to trauma)
  • Rare chest and abdominal infections
  • Asbestos pleural effusion (due to exposure to asbestos)
  • Meig’s syndrome (due to a benign ovarian tumor)
  • Ovarian hyperstimulation syndrome

Certain medications, abdominal surgery and radiation therapy may also cause pleural effusions. Pleural effusion may occur with several types of cancer including lung cancer, breast cancer and lymphoma. In some cases, the fluid itself may be malignant (cancerous), or may be a direct result of chemotherapy.

Diagnosis and Tests

How is pleural effusion diagnosed?

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

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.


Management and Treatment

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.


Pleural effusions that cannot be managed through drainage or pleural sclerosis may require surgical treatment.

The two types of surgery include:

Video-assisted thoracoscopic surgery (VATS)

A minimally-invasive approach that is completed through 1 to 3 small (approximately ½ -inch) incisions in the chest. Also known as thoracoscopic surgery, this procedure is effective in managing pleural effusions that are difficult to drain or recur due to malignancy. Sterile talc or an antibiotic may be inserted at the time of surgery to prevent the recurrence of fluid build-up.

Thoracotomy (Also referred to as traditional, “open” thoracic surgery)

A thoracotomy is performed through a 6- to 8-inch incision in the chest and is recommended for pleural effusions when infection is present. A thoracotomy is performed to remove all of the fibrous tissue and aids in evacuating the infection from the pleural space. Patients will require chest tubes for 2 days to 2 weeks after surgery to continue draining fluid.

Your surgeon will carefully evaluate you to determine the safest treatment option and will discuss the possible risks and benefits of each treatment option.

Care at Cleveland Clinic


If you need more information or would like to make an appointment with a specialist, contact us, chat online with a nurse or call the Miller Family Heart, Vascular & Thoracic Institute Resource & Information Nurse at 216.445.9288 or toll-free at 866.289.6911. We would be happy to help you.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 12/18/2018.

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