What is empyema?

Definition

Empyema is the collection of pus (a liquid that forms from leukocytes, cellular debris,
and protein) in a natural body cavity. Empyema should not be confused with an abscess, which develops its own cavity. Empyema is most
common in the pleural cavity, the space between the inside of the chest wall and
the lung. Empyema may also occur in other body cavities, such as the pelvis,
abdomen, subdural space, gallbladder, and the pericardial sac surrounding the heart.

Causes

Empyema is caused by an infection that leads to the development
of pus in a body cavity or space. The amount of pus in such an infection can be as
much as one pint (16 ounces), putting pressure on the adjacent body part or organ.
A variety of bacteria, such as
Staphylococcus aureus,
Streptococcus pneumoniae, and
Haemophilus influenzae, may cause empyema.

Risk Factors

Bacterial
infection is the primary risk factor for empyema. Lung
abscess, chest surgery, and injury or trauma to the chest are also risk factors
for pleural empyema. Cholecystitis with contaminated bile is
a risk factor for empyema of the gallbladder. People with chronic diseases may be
more likely to develop empyema. Cancer may also contribute to empyema
development.

Symptoms

Symptoms will vary based on the location of the empyema. Fever is almost always present. Sweating, especially at night, often occurs. Sharp or shooting pains, undesired weight loss, headache, and a general poor feeling may occur. For empyema in the pleural space or chest cavity, shortness of breath and difficulty breathing are usually evident. For empyema in the pelvic cavity, foul smelling pus is present. A rigid or very tight abdomen may be noted.

Screening and Diagnosis

Screening and diagnosis are based on symptoms and careful evaluation of the
physical condition of the infected person and his or her complaints. Decreased
breath sounds (heard through a stethoscope) are often noted if pleural empyema is
present. Taking a sample of pus from the pleural space by using a needle or
plastic catheter (thoracentesis) is sometimes done to look for the causative
bacteria. The doctor also will investigate any complaints of pain. Radiology
tests, including X rays and computed tomography (CT) scans, are often used.

Treatment and Therapy

The primary goals of therapy are to cure the infection and to drain the pus if
possible. Antibiotics are prescribed and may be given intravenously
(in a vein), which requires hospitalization. If pleural empyema is the diagnosis,
a chest tube inserted into the pleural cavity may be used to drain the pus from
the body. In rare cases, a procedure to peel away part of the lining of the lung
may be done so that the lung can inflate. In empyema of the gallbladder, surgery
to remove the gallbladder may be indicated. Other surgeries may be necessary,
depending on the site of the empyema.

Prevention and Outcomes

One can help prevent the development of empyema by treating infections promptly and using antibiotics appropriately.

Bibliography

Celli, B. R. “Diseases of the Diaphragm, Chest Wall, Pleura, and the Mediastinum.” In Cecil Medicine, edited by Lee Goldman and Dennis Arthur Ausiello. 23d ed. Philadelphia: Saunders/Elsevier, 2008.

Levitzky, Michael G. Pulmonary Physiology. 7th ed. New York: McGraw-Hill Medical, 2007.

Madigan, Michael T., and John M. Martinko. Brock Biology of Microorganisms. 12th ed. Upper Saddle River, N.J.: Pearson/Prentice Hall, 2010.

Reed, James C. Chest Radiology: Plain Film Patterns and Differential Diagnoses. 5th ed. Philadelphia: Mosby, 2003.

Weedon, David. Skin Pathology. 3d ed. New York: Churchill Livingstone/Elsevier, 2010.