• Magnitude of force
• Complexion of the skin
• Amount of extravasated blood
• Fragility of vessels (easy bruising syndrome)
• Conditions where clotting profile changes - Liver diseases, Bleeding disorders
• Natural diseases
• Site : Appear early when there is increased sub cutaneous fat, underlying bone (elbow)

             : Appear later when contusions are deep, in tough and hard tisues with dense fibrous tissue (scalp) and when the tone of muscle is good (e.g. boxers)