Fluid in the Chest (Pleural Effusion)

Written by April Kahn | Published on August 7, 2012
Medically Reviewed by George Krucik, MD

What is Pleural Effusion?

Pleural effusion, also called “water on the lung,” is an excessive buildup of fluids between your lungs and chest cavity. There is always a small amount of liquid on the outside of your lungs. This fluid works to coat the membranes that line the outside of your lungs and lubricates the chest cavity to facilitate breathing. Certain medical conditions can cause this fluid to build up between the chest cavity and your lungs; this buildup is called pleural effusion.

According to the Cleveland Clinic, pleural effusion is a common condition, with more than 100,000 cases diagnosed in the United States each year (Cleveland Clinic).

How Does Pleural Effusion Develop?

The membrane that lines the outside of the lungs is called the pleura. This membrane normally contains a small bit of liquid that acts to lubricate the lungs. When this membrane is irritated or infected it creates an excess of fluid with accumulates in the chest cavity outside of the lung, causing pleural effusion. Pleural effusions are often caused by certain types of cancer—such as lung, breast, and ovarian cancers—as well as lymphoma and mesothelioma. Fluid may also build up as a result of certain cancer treatments, such as radiation therapy or chemotherapy.

Other causes include:

  • heart failure
  • cirrhosis (poor liver function)
  • pulmonary embolism (blockage in one or more of the arteries in your lungs)
  • post open-heart surgery
  • pneumonia
  • kidney disease

Find out if you're at risk for pulmonary arterial hypertension »

Symptoms and Signs of Pleural Effusion

Common symptoms of pleural effusion are:

  • dry cough
  • trouble breathing when lying down
  • chest pain
  • shortness of breath

Some people have no symptoms of pleural effusion. These people usually find out that they have the condition through chest X-rays or physical examinations prescribed for another reason. If you have symptoms of pleural effusion, see your doctor immediately.

Diagnosing Pleural Effusion

In addition to a physical examination, which includes your doctor listening to your lungs with a stethoscope, a chest X-ray is often used to diagnose pleural effusion.

Your doctor may order you to have one of the following tests to evaluate your lungs further:

  • CT scan
  • chest ultrasound
  • pleural fluid analysis

A pleural fluid analysis is a test in which your doctor removes fluid from the pleural membrane area. He or she will usually insert a needle into the chest cavity and suction the fluid into a syringe. The fluid is then tested for the presence of protein or cancer cells. This test is also called thoracentesis.

If your doctor is unable to diagnose pleural effusion with these tests, and he or she suspects that you have the condition, you may be scheduled for a thoracoscopy. A thoracoscopy is a surgical procedure that enables the doctor to see inside the chest cavity using a fiber-optic camera. A few small incisions are made into the chest area while you are under general anesthesia. The camera is inserted through one incision, and the surgical tool is inserted through the other, for the purposes of extracting a small amount of fluid or tissue for analysis.

Treating Pleural Effusion

The treatment for pleural effusion will depend on the underlying cause of the condition and severity of the effusion.

Draining Fluid

Generally, treatment involves draining the fluid from the chest cavity, either with a needle or a small tube inserted into the chest. You will be given a local anesthetic before this procedure, which will make the treatment painless. However, you may feel some pain or discomfort at the incision site after the anesthetic wears off. Most doctors will prescribe medication to help relieve pain. Draining may need to be done more than once if fluid re-collects.

When pleural effusion is caused by cancer, other treatments may be necessary to manage fluid buildup.


Pleurodesis is performed after drawing the excess fluid out of the chest cavity. When the fluid is removed, a drug (typically talc) is injected into the area, which causes the pleura to close up and stop leaking.


In more serious cases, a shunt (small tube) is surgically inserted into the chest cavity to redirect the fluid from the chest to the abdomen, where it is removed easily. Pleurectomy, in which part of the pleural lining is surgically removed, is also an option in very severe cases.


Treatment for minor cases of pleural effusion is minimally invasive, and most people recover within a few days. Minor complications from treatment include slight pain and discomfort, which often go away with time. Some cases of pleural effusion can have more serious complications, depending on the severity of the condition and treatment used. Serious complications include:

  • pulmonary edema or fluid in the lungs, which can occur when too much fluid is drained through thoracentisis
  • partial collapsed lung
  • infection or bleeding
  • low blood pressure, which can result when fluid is drained too rapidly
  • shock

These complications, while serious, are very rare. Your doctor will help determine the most effective treatment option, and will discuss the benefits and risks of each procedure.

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