An 85-year-old man falls in the bathtub and strikes the back of his head. Over the next 24 hours, he becomes increasingly somnolent. A head CT scan shows an accumulation of fluid beneath the dura, compressing the left cerebral hemisphere. Which of the following terms best describes this collection of fluid?

He has a subdural hematoma from this traumatic injury causing tearing of cerebral veins. A hematoma is a collection of blood in a potential space or within tissue. Congestion occurs when there is vascular dilation with pooling of venous blood within an organ. Ecchymoses are blotchy areas of hemorrhage beneath skin, serosal surfaces, or mucous membrane surfaces from a contusion (bruise), which he likely has on the back of his head. Petechiae are 1- to 2-mm pinpoint areas of hemorrhage. Purpura denotes blotchy hemorrhage on skin, serosal surfaces, or mucous membrane surfaces larger than 3 mm; areas from 1 to 2 cm in size are called ecchymoses.