A subdural empyema is characterized by the presence of what?

A subdural empyema is characterized by the presence of pus. This condition occurs when there is an accumulation of purulent material between the dura mater and the arachnoid layer of the meninges, often as a result of infection. The presence of pus differentiates a subdural empyema from other conditions such as hemorrhages, which involve blood accumulation, or cysts, which typically contain clear fluid, and emboli, which are clots that travel through the bloodstream. In clinical practice, timely identification of pus in cases of suspected subdural empyema is crucial for proper management, as it often necessitates surgical intervention to drain the infected material and relieve pressure on the brain.