An aural hematoma literally means an accumulation of blood in the ear flap (pinna). How does this happen? Well, any sort of trauma to the ear can cause one of the vessels in the pinna to burst. The result is bleeding between 2 of the layers of the pinna- the cartilage and the skin. The blood gets trapped between these 2 layers and the pinna ends up filled with blood, resembling a water balloon!