Depth, location, and skin complexion affect the time of appearance and the color of a bruise. Even which color should be assigned to a bruise is ill defined. Langlois and Gresham use any amount of a particular color to assign that discoloration to a bruise, whereas most references do not indicate whether the presence of a color or its predominance is used. How soon bruising first appears after an injury depends on the depth of the injury. A superficial bruise may discolor the skin immediately, whereas deep bruising may take days to appear.
When a particular color appears also varies in part according to injury depth. Smith and Feddes estimate that yellow generally appears in seven to ten days but may appear in three days if the bruise is superficial. Langlois and Gresham also note that yellow develops quicker in superficial bruises. This suggests that if a person has been bruised deeply and superficially at the same time in nearby locations, the bruises may be different colors and may seem to have occurred at different times. Another factor in determining the appearance of a bruise is its location.
Periorbital and genital bruises (where tissue is loose and blood vessels are poorly supported) will appear sooner than extremity bruises. Still another factor is skin color. Light-complexioned people may seem to bruise from relatively minor impacts, whereas bruises in dark-complexioned people may be masked by their skin color. The chronicity of bruising may affect the aging process. Mandy et al found that bruises in chronically injured animals healed on average 2 days sooner than bruises in acutely injured control animals. If also true of humans, this suggest that a chronically or repetitively injured person may heal more quickly than an acutely injured one. Although bruises of different ages have been described as a characteristic of the battered child syndrome, the wide variability in bruise development and healing urges caution in aging bruises. Yet, many current texts portray bruise aging as relatively straightforward.
