Acute Subdural Hematoma is the type of hematoma that occurs within the skull. Since head injuries are most likely to cause this condition, one must consult a doctor after suffering from any such injury.
A timely treatment can definitely prevent the development of fatal complications of subdural hematoma. You won't notice any visible sign of an injury.
In some cases there might be skin discoloration, skin would appear reddish or purplish. Also, this area would feel tender when touch.
It is prevalent more in women than men, mainly because the pelvis of women is broader than men, which leaves the coccyx more exposed to injury or trauma.