What Is an Empyema?

Symptoms, Diagnosis 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

If you've been told you have an empyema, what does it mean? What are the causes of this condition and who is at risk? What treatment options are available and what is your prognosis?

Definition: Empyema

An empyema is a collection of pus between the 2 layers of tissue (pleura) that line the lungs. An empyema most commonly occurs as a complication of pneumonia, a lung abscess, or 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 a pint or more of infected pleural fluid. (When there is extra fluid in the pleural space it is referred to as a pleural effusion.)

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.

When a sample of pleural fluid is drained, the cloudy and thick appearance of an empyema is usually quite obvious in how it contrasts with normal pleural fluid which is thin and translucent.

Signs and Symptoms of an Empyema

Symptoms related to an empyema can be caused both by the presence of the infection and by pressure on the lungs and chest from the increase of fluid in the pleural space.

Common signs and symptoms include:

  • Fever and chills
  • Night sweats: These can be very significant with drenching sweats at night requiring a changing of night clothes
  • Chest pain, often sharp and which worsens with inspiration
  • Shortness of breath: Difficulty breathing can come on slowly or rapidly depending on the size of the effusion and the severity of the underlying process
  • A dry cough: A cough may also be productive due to associated pneumonia
  • Hiccups: Irritation of the diaphragm and nerves in this region due the build-up of fluid can result in hiccups 
  • Weight loss (unintentional weight loss)
  • Fatigue
  • A general sense of not being well

Causes of an Empyema

There are a number of different conditions which may result in an empyema. Some of these include:

  • Pneumonia (This 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: A bronchopleural fistula is a fistula or canal that 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 for an Empyema

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 take a careful history and perform a 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, an evaluation of the contents of the fluid.

Blood tests may also be done to look for evidence of infection.

Treatment Options for Empyema

The treatment of an empyema can be broken down into two steps; the first step is to remove the fluid, after which the infection must be treated. 

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 then be placed in order to continue draining the fluid.

When an empyema has been present for some time, it may become loculated. This occurs when scar tissue forms and separates the fluid into separate cavities.This makes draining the fluid much more difficult, and sometimes several attempts at thoracentesis are needed to remove the fluid.

Treating the infection: Doctors will start antibiotics as soon as a sample is taken. Some people wonder why not right away, but the start of antibiotics is often delayed to give the lab the best chance of determining exactly which bacteria are causing the infection. (If antibiotics are started before the thoracentesis, it can be difficult to identify which bacteria are responsible for 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.


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 portions of the pleura in order to resolve the infection. This can be done either through a thoracotomy (open lung surgery) or thoracoscopic surgery (minimally invasive lung surgery,) with video-assisted thoracoscopic decortication being an effective and less invasive option for many people. In addition, recent studies have found that non-surgical methods are often as effective as surgical methods for the treatment of empyema. Other complications may include sepsis—an overwhelming infection throughout the body, and scarring and thickening of the pleural membranes.


The prognosis of an empyema depends largely on the underlying cause. 

Bottom Line on Having an Empyema

An empyema is a term used to describe the presence of infected pleural fluid surrounding the lungs. The most common cause is pneumonia, but other conditions, as well as surgery and trauma, may be responsible. Treatment consists of taking a sample of the fluid to send to the lab and removing excess fluid which may result in shortness of breath and other symptoms. Antibiotics are then given to treat the infection.

Pronunciation: em-pie-ee-ma

Also called: pylothorax, pleural infection, 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

Redden, M., Chin, T., and M. van Driel. Surgical Versus Non-Surgical Management for Pleural Empyema. Cochrane Database of Systematic Reviews. 2017. 3:CD010651.

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