Written by Verneda Lights | Published on July 25, 2012
Medically Reviewed by Brenda B. Spriggs, MD, MPH, FACP on July 25, 2012


Empyema is a collection of pus (dead cells and infected fluid) inside a body cavity. Usually, this term refers to pus inside your pleural cavity, or “pleural space.” The pleural cavity is the thin space between the surface of your lungs and the inner lining of your chest wall.

A cavity is a hollow space. Your lungs sit inside your chest cavity, just as your brain rests inside your skull cavity. Any fluid inside the chest cavity decreases the amount of space that your lungs have to expand. In order to fill with air when you breathe in, your lungs must be able to fully expand. When you breathe, your lungs should expand smoothly and painlessly within the pleural cavity inside your chest. When your lungs can’t expand properly, you have trouble getting the oxygen you need. This causes you to become short of breath and it may even hurt for you to breathe.

Because empyema is pus, and pus is caused by an infection, empyema can lead to life-threatening problems such as sepsis (bacteria in the blood) and shock. According to the American College of Chest Physicians, empyema is a potentially life-threatening medical emergency.

What Causes Empyema?

Empyema doesn’t occur on its own; it is a complication of other medical conditions. In order for empyema to occur, bacteria, fungi, or chemicals must get into your pleural space and cause inflammation, leading to the production of pus.

Lung infections, such as pneumonia, and lung abscess are two of the most common ways that bacteria get into your pleural space. Bacteria can also get into your pleural space from medical instruments that are used to do tests or to operate on your chest.

Types: Simple & Complex Empyema

According to the medical journal Chest, there are two classes of empyema: simple and complex.

Simple Empyema

Simple empyema is seen early in the course of the illness. In simple empyema, pus is present, but it is free flowing. Treatment at the simple stage is best, because the pleural cavity can easily be drained.

Complex Empyema

In complex empyema, the inflammation is more severe. The longer you have empyema that is left untreated, the greater the chance that you will develop complex empyema.

In cases of severe inflammation, your body forms lots of scar tissue in the pleural space. Formation of scar tissue causes the cavity to become divided into multiple, smaller cavities. This is called loculation. Loculation creates complications, because infected areas that have been walled off can be difficult to drain. Complete drainage of pus from the pleural cavity is essential for treatment.

Who Is at Risk for Empyema?

According to the British Medical Journal, the greatest risk factors for empyema are: pneumonia, risk factors for pneumonia, and medical procedures that involve the lung and its surrounding structures.

Chest trauma and pre-existing lung diseases, such as COPD and lung cancer, also create an increased risk for empyema. According to Chest, people who have pre-existing lung diseases who develop empyema are more likely to die than those who don’t.

Pneumonia & the Presence of Risk Factors for Pneumonia

Seventy percent of empyema cases occur as a result of pneumonia. People who have difficulty swallowing, those who are immunocompromised, and those who use drugs or abuse alcohol have an increased risk for pneumonia. If you have been treated for pneumonia but didn’t get better, you might have empyema.

Risk From Medical Procedures

Twenty percent of empyema cases are related to medical procedures such as chest surgery and thoracentesis. Thoracentesis is a procedure that involves using needles and tubes to drain fluid from the pleural space. Medical instruments can transfer bacteria into your pleural cavity.

Symptoms of Empyema

The most common symptoms of empyema are fever, cough, shortness of breath, and pleurisy. Pleurisy is chest pain that occurs when you breathe and is caused by inflammation. The shortness of breath experienced by patients with empyema occurs when the lungs cannot fully expand. Pneumonia can also cause shortness of breath.

If you have empyema, you may also have other symptoms, such as fatigue, loss of appetite, and weight loss. The most severe signs of empyema are associated with sepsis (the presence of bacteria in the blood). Signs of sepsis include high fever, chills, rapid breathing, a fast heart rate, and low blood pressure (less than 90/60). Sepsis is life-threatening and requires emergency treatment.

How Is Empyema Diagnosed?

Diagnosis of empyema begins with a complete medical history and physical examination. Tests that are useful for diagnosing empyema include:

  • Blood tests, such as:
  • Blood cultures (to identify what bacterium or organism is causing the infection)
  • C-reactive protein (CRP) (elevated levels are seen in inflammatory conditions)
  • White blood cell count (WBC) (elevated levels in inflammatory and infectious conditions) )
  • X-ray (to diagnose pneumonia, lung abscess document fluid accumulation)
  • thoracentesis (aspiration of pleural fluid for microscopic examination and testing)
  • thoracic ultrasound (use of sound waves to tell if loculations are present)
  • CAT scan of the chest (use of computerized X-ray analysis to evaluate the lungs and pleural space)

Treatment Options for Empyema

Empyema is treated with intravenous antibiotics, such as cephalosporins (cefuroxime sodium), flagyl (metronidazole), and penicillins with beta-lactamase (ampicillin/sulbactam). Clindamycin can be used for patients who are allergic to penicillin.

A chest tube is used to drain pus from the pleural space and allow the lungs to expand normally. Fluids lost, due to lack of appetite and fever, are replaced, and medications such as acetaminophen (Tylenol) can be used to bring down the fever and relieve discomfort.

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