Those of you who follow me know I have several posts about how you can’t date bruises by color, but there is emerging literature to show that bruises can be dated on tissue analysis:
How can a bruise’s age be determined if not by color?
Once the bruise is formed, the body reacts by activating the inflammatory response. There are 2 types of inflammatory cells that migrate to the site of the bruise. Neutrophils are a type of white blood cell that arrive first. Then the macrophage cells, which are larger white blood cells, arrive later. Their arrivals to the injury occur at certain time intervals. Therefore, when the inflammatory response is activated, injured tissue can be analyzed for the presence of these cells to interpret the age of the bruise.
How cells respond to trauma helps determine the age of the bruise.
In one study, tissue analysis compared 1-day old bruises to 5-day old bruises. Neutrophils are not present in normal skin. Findings of the study demonstrated that when an injury occurred and the inflammatory response was activated, neutrophils migrated to the injured tissue at approximately 4 hours after the initial bleeding: This indicated fresh bleeding.
Macrophage cells began to migrate as early as 3 hours and up to 9 hours after initiation of a bruise with continued presence and migration at 1-2 days. With bruises aged 3-7 days old, the macrophage cells had infiltrated the injured tissue with the most intense infiltration occurring in the 5-day old bruises.
Therefore, according to the study, by analyzing in detail, the tissue changes in bruises every day from appearance until their healing and in conjunction with tissue analysis will support the precise determination of the age of the injuries themselves.
How does this apply in criminal cases?
Attorneys who are litigating homicide cases can utilize this information to assess which of the injuries sustained occurred just prior to death or several days prior. While this is still not common practice during autopsies, it is likely that we will see more and more histological samples of bruised areas included in the reports.
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