empyema n : a collection of pus in a body cavity (especially in the lung cavity)

An empyema is a collection of pus within a naturally existing anatomical cavity. It must be differentiated from an abscess, which is a collection of pus in a newly formed cavity. In human medicine, empyema occurs most frequently in the pleural cavity (see below). Other common locations for empyemas are the uterus (pyometra) and the appendix (appendicitis).

Pleural space empyema

This condition is also known as a pyothorax or purulent pleuritis. Most pleural space empyemas arise from an infection within the lung (pneumonia), often associated with parapneumonic effusions. There are 3 stages: exudative, fibrinopurulent and organizing. In the exudative stage, the pus accumulates. This is followed by the fibrinopurulent stage in which there is loculation of the pleural fluid (the creation of grapelike pus pockets). In the final organizing stage, scarring of the pleural space may lead to lung entrapment.

Symptoms

Symptoms of empyema may vary in severity. Typical symptoms include: fever, chest pain or discomfort, cough, sweating and shortness of breath.

Clubbing of the fingernails may be present. There is a dull percussion note and reduced breath sounds on the affected side of the chest. Other diagnostic tools include chest x-ray, CT scan, and Ultrasonography.

Diagnosis

Diagnosis is confirmed by thoracentesis; frank pus may be aspirated from the pleural space. The pleural fluid typically has a low pH (<7.20), low glucose (<60 mg/dL), and contains infectious organisms.

Treatment

Definitive treatment for empyema entails drainage of the infected pleural fluid. A chest tube may be inserted, often using ultrasound guidance. Intravenous antibiotics are given. If this is insufficient, surgical debridement of the pleural space may be required.

External links

• Images of Empyema from MedPix