What is empyema?

Empyema refers to the presence of pus in a body cavity, most commonly within the pleural space surrounding the lungs. This condition typically arises as a complication of pneumonia, thoracic surgery, or lung infections, where the body responds to infection by accumulating fluid that becomes infected, leading to pus formation. The pus-filled fluid creates an inflammatory response, which can result in symptoms such as fever, chest pain, and difficulty breathing.

Understanding empyema in this specific context highlights the importance of recognizing it as a serious medical condition that requires prompt evaluation and treatment, often involving drainage and antibiotics to resolve the infection. The other options describe different conditions: fluid accumulation in the lungs is known as pulmonary edema, air in the pleural space is called pneumothorax, and blood in the pleural cavity is referred to as hemothorax. Each of these conditions has distinct characteristics and implications for treatment, differentiating them from empyema.