Pleural Effusion

What is pleural effusion? An abnormal and excessive accumulation of fluid between the layers of tissue that line the lung and chest cavity.091



There are four general types of pleural fluid: (1) serous or hydrothorax (watery); (2) bloody or hemothorax; (3) chylous or chylothorax (lymph fluid); or (4) empyema (pus).

What are the causes? In the normal state, there is a thin layer of fluid, used to lubricate the pleural surfaces. Certain conditions can cause the amount of fluid to enlarge. Common causes of pleural effusion include congestive heart failure, cirrhosis (liver failure), pneumonia, tuberculosis, lung cancer, mesothelioma, breast cancer, lymphoma, drug reactions, trauma, chest surgery, asbestos, pulmonary infarction, and Rheumatoid Arthritis or Lupus.

What are the symptoms? The most common is sharp chest pain, worse upon deep inspiration or coughing (“pleurisy”). Other common symptoms include shortness of breath, cough, or chest tightness. There may be fever, depending upon the cause.

How do you diagnose it? During a physical examination, your doctor will listen to your chest using a stethoscope and tap on your chest with his fingers (percussion). He/she can then confirm the presence of pleural effusion by taking a chest x-ray (or sometimes a chest CT). X-rays taken while laying on your side (lateral decubitus x-rays) are helpful in looking for freely flowing fluid and is more able to detect small amounts of fluid than regular chest x-ray.


On occasion, ultrasound might be useful to your doctor in diagnosis.

How is it tested? Once detected, your doctor will usually wish to test the fluid to help determine the cause. The most common approach is by thoracentesis, wherein the doctor inserts a needle between the ribs and into the fluid cavity. Other methods include insertion of a chest tube or sometimes surgery.

Once your doctor has removed some or all of the fluid, it can be sent to the laboratory for testing. Common tests include a count of red blood cells, white blood cells, protein, glucose, pH, LDH, microscopic examination and culture for infection, and examination for cancer cells.

How is pleural effusion treated? Treatment may be directed at removing the fluid, treating the underlying cause, or preventing it from accumulating again.

For example, pleural effusions caused by congestive heart failure are treated with diuretics (“fluid pills”) and other medications that treat heart failure. Antibiotics are used to treat pleural effusions caused by infection. In cases where the fluid recurs, a chest tube may be inserted. Chemotherapy, radiation therapy, surgery, or instilling medication into the chest that prevents re-accumulation of fluid after drainage may be used in some cases. The expected outcome depends upon the underlying disease.

Complications of pleural effusion include:

  • Atelectasis, or collapsed lung, caused by the excess surrounding fluid over time.
  • Infected pleural cavity (empyema) from bacteria, often requiring prolonged drainage with a chest tube and intravenous antibiotics.
  • Pneumothorax (air within the chest cavity) or hemothorax (blood in the chest cavity), either of which can be a complication of the thoracentesis procedure.

What should you do? Call your health care provider if you have symptoms of pleural effusion. If you develop any sudden changes in your breathing after thoracentesis, see your doctor or go to the emergency room immediately.


Light RW (2001). Pleural Diseases (4th ed.). New York: Lippincott Williams & Wilkins.

Light RW (2005). “Chapter 245: Disorders of the pleura, mediastinum, diaphragm, and chest wall”. in Kasper DL, Braunwald E, Fauci A, Hauser S, Longo D, Jameson JL. Harrison’s Principles of Internal Medicine (16th ed.). New York, NY: McGraw-Hill Professional.