What Is an Empyema?

Evaluation and Treatment of an Empyema

female doctor talking with patient and pointing at a chest x-ray
What is an empyema and how are they treated?. Istockphoto.com/Stock Photo©AlexRaths

Definition: Empyema

An empyema is a collection of pus between the 2 layers of tissue (pleura) that line the lungs. An empyema can occur as a complication of pneumonia, a lung abscess, or after chest trauma.


The pleural space or cavity is a region in the chest cavity that lies between the visceral pleura (the membrane on the outside of the lungs) and the parietal pleura (the membrane lining the inside of the chest wall.

 Ordinarily, this area contains just a few teaspoons of pleural fluid.  With an empyema, this area may instead contain up to a pint of infected pleural fluid.

Empyema Fluid

The fluid contained in an empyema is referred to as pus and contains a combination of bacteria, dead cells, and white blood cells.  The most common bacteria causing an empyema are Streptococcus pneumoniae (the "pneumonia" bacteria) and Staphylococcus aureus.

Symptoms of an Empyema

Symptoms are related to both the presence of the infection and pressure on the lungs and chest from the increase of fluid.  These may include:

  • Fever and chills
  • Night sweats - These can be very significant with drenching sweats at night
  • Chest pain, often sharp and which worsens with inspiration
  • Shortness of breath
  • Dry cough
  • Hiccups
  • Weight loss, fatigue, general feelings of not being well

Causes of an Empyema

An empyema may begin with:

  • Pneumonia is the most common cause of an empyema
  • Chest trauma
  • Chest surgery such as that for lung cancer
  • A thoracentesis - Sometimes an infection may be caused inadvertently when a thoracentesis (needle "tap" of the pleural space) is done to diagnose disease or when a chest tube is placed to drain air (as in a pneumothorax) or fluid (as in a pleural effusion.)
  • A bronchopleural fistula - Sometimes a fistula (a canal) may develop between the pleural space and ​bronchi during lung surgery allowing bacteria to pass from the bronchi to the pleural space.)
  • An extension of infection - An infection in the abdomen (peritonitis) or area between the lungs (mediastinitis) may spread into the pleural space.
  • A lung abscess may rupture into the pleural space.

Risk Factors

An empyema is more likely to occur in someone with:

  • Diabetes
  • A history of alcoholism
  • Autoimmune diseases such as rheumatoid arthritis
  • A suppressed immune system such as with chemotherapy
  • Lung diseases such as COPD and chronic bronchitis
  • Gastroesophageal reflux disease

Diagnosing an Empyema

To diagnose an empyema, doctors first do a careful history and physical exam.  A history can help determine if there are any risk factors, and a physical exam may reveal diminished breath sounds.  Following this, a chest x-ray or chest CT scan are done to further examine the lungs.  On occasion and ultrasound may also be done.

 In order to know whether bacteria are present, and to discover what antibiotics these bacteria are sensitive to, a thoracentesis is done to take a sample of the empyema (the fluid may be drained as well.)  The fluid is sent to the lab in order to do a pleural fluid analysis - evaluation of the contents of the fluid.  Blood tests may also be done to look for evidence of infection.


Treatment involves 2 steps: removing the fluid, and treating the infection.

Treating the infection - Doctors will start antibiotics as soon as a sample is taken.  Some people wonder why not right away, but this is often delayed to give the lab the best chance of determining exactly which bacteria are causing the infection.  After you are started on antibiotics the lab will do further tests to check on which antibiotics the bacteria are most sensitive to - and the antibiotics you are given may be changed after a few days.

Fluid removal - Fluid is removed via a thoracentesis.  Sometimes this is fairly simple, especially if the empyema has not been present for long.  A chest tube may be placed in order to continue draining the fluid.

When an empyema has been present for some time, it may become loculated - in other words, scar tissue may separate the fluid into separate cavities.  This makes draining the fluid much more difficult.


With an empyema, especially one that has been present for awhile, scar tissue may build up.  It may be necessary for a surgeon to remove some of the scar tissue and pleura in order to resolve the infection.  Other complications may include sepsis - an overwhelming infection throughout the body, and scaring and thickening of the pleural membranes.

Pronunciation: em-pie-ee-ma

Also called: pylothorax, purulent pleuritis, empyema thoracis

Examples: Jerry developed an empyema after his lung cancer surgery, and his doctor did a procedure to remove the infected fluid.


McCauley, L, and N. Dean. Pneumonia and empyema: causal, casual or unknown. Journal of Thoracic Disease. 2015. 7(6):992-8.

National Library of Medicine. MedlinePlus. Empyema. Updated 02/15/15. https://medlineplus.gov/ency/article/000123.htm

Zanotti, G., and J. Mitchell. Bronchopleural Fistula and Empyema After Anatomic Lung Resection. Thoracic Surgery Clinics. 2015. 25(4):421-7.

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