Pus is a fluid filled with immune cells, dead cells, and bacteria. Empyema is a condition in which pus accumulates in the area between the lungs and the inner surface of the chest wall. This area is known as the pleural space. Empyema, also called pyothorax or purulent pleuritis, usually develops after pneumonia, which is an infection of the lung tissue. Pus in the pleural space can’t be coughed out. Instead, it needs to be drained by a needle or surgery.
Empyema usually develops after you have pneumonia. Many different types of bacteria may cause pneumonia, but the two most common bacterial causes of empyema are Streptococcus pneumoniae and Staphylococcus aureus.
Clear fluid builds up in the pleural space. The fluid becomes infected with the bacteria that caused the pneumonia. The infected fluid thickens and can cause the lining of your lungs and chest cavity to stick together and form pockets. This is called an empyema. Your lungs may not be able to inflate completely. This can lead to breathing difficulties.
Occasionally, empyema may happen after you’ve had surgery on your chest. Medical instruments can transfer bacteria into your pleural cavity.
The biggest risk factor for empyema is having pneumonia. Empyema occurs most frequently in children and the elderly. However, it’s fairly uncommon, occurring in less than 1 percent of children with pneumonia, according to one study.
Having the following conditions can also increase your chances of having empyema following pneumonia:
- chronic obstructive pulmonary disease (COPD)
- rheumatoid arthritis
- gastroesophageal reflux disease (GERD)
- a weakened immune system
- surgery or recent trauma
- lung abscess
A doctor will usually suspect empyema when pneumonia doesn’t improve with treatment. Empyema can be simple or complex.
Simple empyema occurs in the early stages of the illness. A person has simple empyema if the pus is free-flowing. The symptoms of simple empyema include:
- shortness of breath
- dry cough
- pain in your chest when breathing that may be described as a stabbing pain
- loss of appetite
Complex empyema occurs in the later stage of the illness. In complex empyema, the inflammation is more severe. Scar tissue may form and cause the chest cavity to be divided into smaller cavities. This is called loculation and is more difficult to treat. If the infection continues to get worse, it can lead to the formation of a thick peel over the pleura called a pleural peel. This peel prevents the lung from expanding. Surgery is required to clear such a condition. Other symptoms in complex empyema include:
- difficulty breathing
- decreased breath sounds
- weight loss
- chest pain
In rare instances, a case of complex empyema can lead to more severe complications. These include sepsis and a collapsed lung, which is called a pneumothorax.
The symptoms of sepsis include:
- high fever
- rapid breathing
- fast heart rate
- low blood pressure
The signs of a collapsed lung, or pneumothorax, are sudden, sharp chest pain and shortness of breath that gets worse when coughing or breathing
These conditions can be fatal. If you have these symptoms, you should call 911 or go to an emergency room.
Empyema is suspected if you have pneumonia that isn’t responding to treatment. Your doctor will take a complete medical history and physical examination. They may use a stethoscope to listen for any abnormal sounds. Your doctor will usually perform the following tests or procedures to confirm a diagnosis:
- Chest X-rays and CT scans will show whether or not there’s fluid in the pleural space.
- An ultrasound of the chest is used to see the amount of fluid and its exact location.
- Blood tests are used to check for white blood cell count and C-reactive protein and to identify the particular bacteria causing the infection. White cell count is usually elevated when you have an infection.
- During a thoracentesis, a needle is inserted through the back of your ribcage into the pleural space to take a sample of fluid. The fluid is then analyzed under a microscope to look for bacteria, protein, and other cells.
Treatment is aimed at removing the pus, draining the fluid from the pleura, and treating the infection. Antibiotics are used to treat the underlying infection. The specific type of antibiotic depends on what type of bacteria is causing the infection.
The next step is to drain the pus. The specific method depends on the stage of the empyema.
In simple cases, a needle can be inserted into the pleural space to drain the fluid. This is called percutaneous thoracentesis.
In the later stages, a drainage tube must be used to drain the pus. This procedure is usually performed under anesthesia in an operating room:
- If you have a thoracostomy, your doctor will insert a plastic tube into your chest between two ribs, connect the tube to a suction device, and remove the fluid. They may also inject medication to help drain the fluid.
- If you have video-assisted thoracic surgery (VATS), your surgeon will remove the affected tissue around your lung, insert a drainage tube, or use medication to remove the fluid. Your surgeon will create three small incisions and use a tiny camera called a thoracoscope.
- If you have an open decortication, your surgeon will peel away the pleural peel and help prevent permanent disability.
People with empyema along with other conditions that cause a compromised immune system have a mortality rate as high as 40 percent. If it’s not treated, empyema can lead to potentially life-threatening complications such as sepsis.
The outlook for empyema is good with prompt treatment. Long-term damage to the lungs is rare. You should finish your prescribed antibiotics and go in for a follow-up chest X-ray to make sure your pleura has healed properly.