A pleural effusion is a buildup of fluid between the layers of tissue that line the lungs and chest cavity.

Fluid in the chest; Fluid on the lung; Pleural fluid

Your body produces pleural fluid in small amounts to lubricate the surfaces of the pleura, the thin tissue that lines the chest cavity and surrounds the lungs. A pleural effusion is an abnormal, excessive collection of this fluid.

Two different types of effusions can develop:

• Transudative pleural effusions are caused by fluid leaking into the pleural space. This is caused by increased pressure in, or low protein content in, the blood vessels. Congestive heart failure is the most common cause.
• Exudative effusions are caused by blocked blood vessels, inflammation, lung injury, and drug reactions.

• Chest pain, usually a sharp pain that is worse with cough or deep breaths
• Cough
• Fever
• Hiccups
• Rapid breathing
• Shortness of breath

Sometimes there are no symptoms.

During a physical examination, the doctor will listen to the sound of your breathing with a stethoscope and may tap on your chest to listen for dullness.

The following tests may help to confirm a diagnosis:

• Chest CT scan
• Chest x-ray
• Pleural fluid analysis (examining the fluid under a microscope to look for bacteria, amount of protein, and presence of cancer cells)
• Thoracentesis (a sample of fluid is removed with a needle inserted between the ribs)
• Thoracic CT
• Ultrasound of the chest

Treatment aims to:

• Remove the fluid
• Prevent fluid from building up again
• Treating the cause of the fluid buildup

Therapeutic thoracentesis may be done if the fluid collection is large and causing chest pressure, shortness of breath, or other breathing problems, such as low oxygen levels. Removing the fluid allows the lung to expand, making breathing easier. Treating the cause of the effusion then becomes the goal.

For example, pleural effusions caused by congestive heart failure are treated with diuretics (water pills) and other medications that treat heart failure. Pleural effusions caused by infection are treated with appropriate antibiotics. In people with cancer or infections, the effusion is often treated by using a chest tube for several days to drain the fluid.

Sometimes, small tubes can be left in the pleural cavity for a long time to drain the fluid. In some cases, the following may be done:

• Chemotherapy
• Putting medication into the chest that prevents fluid from building up again after it is drained
• Radiation therapy
• Surgery

The expected outcome depends upon the underlying disease.

• A lung that is surrounded by excess fluid for a long time may be damaged.
• Pleural fluid that becomes infected may turn into an abscess, called an empyema, which will need to be drained with a chest tube.
• Pneumothorax (air in the chest cavity) can be a complication of the thoracentesis procedure.

Call your health care provider if you have symptoms of pleural effusion.

Call your provider or go to the emergency room if shortness of breath or difficulty breathing occurs immediately after thoracentesis.

Broaddus C, Light RW. Pleural effusion. In: Mason RJ, Broaddus CV, Martin TR, et al, eds. Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier;2010:chap 73.