Antemortem injuries are those injuries a body has received before death. They may be a contributing factor in the death or even its cause. On the other hand, they may have occurred many years ago. During an autopsy , the pathologist assesses the age of antemortem injuries, as well as distinguishing them from postmortem injuries—that is, injuries occurring after death. Postmortem injury can come from various sources such as deliberate mutilation of a body by a murderer following a homicide, predation by wild animals, or careless handling in the mortuary. Postmortem injuries can cause confusion over the manner and cause of death .
One major difference between an antemortem and a postmortem injury is the presence of signs of bleeding. While the person is still alive, the blood is circulating and any injuries such as cuts or stabs will bleed. After death, the body usually does not bleed. However, there are exceptions. For instance, when a person drowns, their body usually floats face down and this results in the head becoming congested with blood. If the cadaver receives a head injury by being buffeted around in the water and colliding with boats or propellers, then there could be some evidence of bleeding. Scalp wounds sustained after death may also leak some blood.
It can be especially difficult to distinguish between injuries inflicted in the very last few minutes of life and those caused postmortem. If the person collapses, there may be areas of laceration (cuts or scrapes) to the head and scalp which may be very hard to interpret.
After death, the blood stays liquid in the vessels and no longer clots. Careless handling of a cadaver may produce some post-mortem bruising which may need to be distinguished from antemortem bruising. Blood also tends to pool under gravity after death, causing a bruised appearance in the lower limbs, arms, hands, and feet known as lividity . Some of the smaller vessels may even hemorrhage under the pressure of this pooled blood. These bruises could be confused with ante-mortem bruising.
Recent research has focused on improved techniques for distinguishing between an antemortem and a postmortem injury by analyzing damaged tissue. Antemortem injuries show signs of inflammation, while postmortem injuries do not. Chinese scientists have found that tissue from antemortem injuries contains a chemical involved in inflammation leukotriene B4 (LTB4). Postmortem injuries were found to have no LTB4. This could help the pathologist classify injuries more accurately.
see also Blood; Body marks; Pathology; Wound assessment.