Bruising happens when small blood vessels under the skin are broken and blood collects under the skin. How far bruises spread and what shape they take is affected by the muscle tone, tenseness of the subcutaneous tissue, the “geography” of the area and clotting state of an individual. Individual with a bleeding condition or on anti-coagulant medications will have larger bruises and will heal them slower.

I am being asked to briefly describe how bruises caused by medium to light impact or injury appear and evolve over time. An example of light/ medium impact would be a hit on the arm from a friend’s punch or a teacher that forcefully grabbed a student’s arm to gain control of the student. An example of heavy impact would be one that is caused by a 100 mph baseball impacting a hitters arm or body or an impact to the body from a car wreck, with or without underlying organ injury.

The following discussion is hypothetical. First, it is very often possible to ascertain the degree of impact and force that caused a bruise. At times, a bruise can show an outline of an open hand, or several sites, corresponding to fingers and/or palm, or be of a shape that suggests grabbing or pulling.

Bruises vary greatly based on the gender and age of the impacted individual (women bruise more as they age because of the loss of subcutaneous tissue and muscle tone), conditions or medications that may have an effect on vessels or clotting, and they can appear differently over time.

While it may take significant force to cause a bruise in a young person, even minor bumps and scrapes may cause extensive bruising in an elderly person. Women after their 30’s can have spontaneous bruising, even in the areas where inadvertent and forgotten trauma is unlikely, such as the upper back. These spontaneous bruises can usually be identified by being limited and small, but in the older individual they can be large and irregular in shape.

While it requires experience to apply, certain patterns can help date the impact. They include the degree of and rate of disappearance of tenderness, color, and shape. When it first appears, a bruise will be reddish looking, reflecting the color of the blood in the skin. Within one to two days, the reddish iron from the blood undergoes a change and the bruise will appear blue or purple. By day six, the color changes to green and by day eight to nine, the bruise will appear yellowish-brown. In general, the bruised area will be repaired by the body in two to three weeks after which the skin will return to normal. Fluctuance. persistent tenderness and delayed change in coloration may indicate a collection of blood under the skin, a hematoma.