A
swelling composed of
blood that has escaped from an injured, diseased, or abnormally fragile blood vessel into tissues--in other words, a
bruise. The vast majority of hematomas subside in their own time, usually about a
week, without need for treatment, changing
color from
purple to
brown to green-yellow.
Internal hematomas may follow severe
injury; the effects depend on the site of the hematoma. After head injuries hematomas may occur over the surface of the
brain or within its
substance. Injury-induced hematoma of the
lung or
kidney can occur also.