What type of fluid accumulation characterizes empyema?

Empyema is characterized by the presence of pus within the pleural space, typically as a complication of pneumonia, lung abscess, or chest trauma. The accumulation of pus suggests that there is an ongoing infection, leading to the production of inflammatory exudates that consist of both cellular debris and high concentrations of white blood cells. This specific type of fluid has a thick and turbid appearance, differentiating it from other types of fluid such as clear serous fluid or blood, which do not contain the same infectious components.

Empyema reflects the body's response to infections, where the infection in the lungs leads to an accumulation of inflammatory materials in the pleural cavity. Treatment often involves addressing the underlying infection and may require drainage of the pus to alleviate symptoms and prevent complications. Understanding that empyema specifically indicates an infected pleural effusion helps clarify the distinction from other types of pleural effusions that may contain clear fluid, blood, or serous exudate, which are not indicative of infection in the same way empyema is.