The term “Dead On Arrival,” or DOA, indicates a person was already deceased when professional medical assistance reached them. “DOA blood” is not a unique biological substance; it refers to blood collected from a DOA individual for forensic analysis. This analysis is part of the broader investigation into the circumstances of the death.
What Happens to Blood Immediately After Death
At the moment of death, the heart ceases its pumping action, bringing the circulatory system to a halt. Blood no longer flows, meaning tissues and organs are deprived of the oxygen they need to function, and metabolic waste products are no longer carried away.
Without the heart’s pressure, blood succumbs to gravity. This initial period of circulatory arrest marks the beginning of predictable physical and chemical changes within the body, providing forensic investigators with their first set of clues.
Postmortem Blood Changes and Analysis
After death, blood undergoes several transformations useful for forensic analysis. One visible change is livor mortis, or lividity, where gravity causes blood to settle in the lowest parts of the body, creating a purplish-red skin discoloration. Livor mortis becomes noticeable within two hours and helps determine the body’s position and estimate the postmortem interval.
Another change is postmortem clotting, as blood coagulates within the vessels after circulation stops. Pathologists can distinguish these postmortem clots from antemortem clots (thrombosis), which may have formed while the person was alive and could be the cause of death. This distinction is based on the clot’s structure and adherence to vessel walls.
Toxicology screening is also a part of postmortem blood analysis. A blood sample is analyzed to detect the presence and concentration of substances that could explain the cause of death, including alcohol, prescription medications, illicit drugs, and other poisons. This toxicological profile provides a chemical snapshot of what was in the person’s system when they died.
Determining Cause and Manner of Death
Blood analysis does not determine if someone was DOA; that term describes the circumstances in which they were found. The findings from blood analysis help a forensic pathologist determine the cause of death, which is the specific injury or disease that resulted in the person’s demise. A toxicology report showing a lethal concentration of an opioid, for example, could establish the cause as a drug overdose.
This evidence also contributes to establishing the manner of death, which is categorized as natural, accidental, suicide, or homicide. The data from blood analysis is one piece of a larger puzzle.
Forensic experts integrate these findings with information from the physical autopsy, examination of the scene, and the individual’s medical history. For instance, the absence of lethal trauma combined with a high blood alcohol concentration might point toward an accidental death.