Empyema is a collection of pus in the cavity between the lung and the membrane that surrounds it (pleural space).

Empyema is caused by an infection that spreads from the lung and leads to an accumulation of pus in the pleural space. The infected fluid can build up to a quantity of a pint or more, which puts pressure on the lungs, causing shortness of breath and pain.

Risk factors include recent pulmonary (lung) conditions including bacterial pneumonia, lung abscess, thoracic surgery, trauma or injury to the chest, or rarely, a needle inserted through the chest wall to draw off fluid in the pleural space (thoracentesis).

• Dry cough
• Fever and chills
• Excessive sweating, especially night sweats
• General discomfort, uneasiness, or ill feeling (malaise)
• Unintentional weight loss
• Chest pain, which worsens on deep inhalation (inspiration)

The health care provider may note abnormal findings, such as decreased breath sounds or a friction rub, when listening to the chest with a stethoscope (auscultation).

Tests may include the following:

• Chest x-ray
• Thoracentesis
• Pleural fluid gram stain and culture
• CT scan of chest

The goal of treatment is to cure the infection and remove the collection of pus from the lung. Antibiotics are prescribed to control the infection. A doctor will place a chest tube to completely drain the pus. A surgeon may need to perform a procedure to peel away the lining of the lung (decortication) if the lung does not expand properly.

Usually, empyema does not result in permanent pulmonary damage.

A possible complication is pleural thickening.

Call your health care provider if you develop symptoms of empyema.

Prompt treatment of pulmonary (lung) infections may prevent some cases of empyema.

Mason RJ, Broaddus VC, Murray JF, Nadel JA. Murray and Nadel's Textbook of Respiratory Medicine. 4th ed. Philadelphia, Pa: Saunders; 2005.

Ahmed RA, Marrie TJ, Huang JQ. Thoracic empyema in patients with community-acquired pneumonia. Am J Med. October 2006;119:877-883.

Qureshi NR, Gleeson FV. Imaging of Pleural Disease. Clin Chest Med. June 2006;27:193-213.