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.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
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.
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:
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:
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.
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.
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.
Last reviewed by a Cleveland Clinic medical professional on 12/18/2018.
Learn more about our editorial process.