Postmortem Changes and Injuries Flashcards

An investigator arrives at a scene where the decedent is found lying supine on the floor. The investigator notes distinct reddish-purple discoloration on the decedent's back and posterior legs, but the buttocks and shoulder blades appear pale. This phenomenon is known as:

Answer: Livor mortis with contact pallor

Livor mortis, or postmortem lividity, is the gravitational settling of blood in the dependent portions of the body after death, causing a purplish discoloration. Areas of the body in contact with a firm surface, such as the floor, will be compressed, preventing blood from settling in those capillaries. This results in pale areas known as contact pallor or contact blanching.

Which of the following factors would most likely accelerate the onset and progression of rigor mortis?

Answer: Death occurring after strenuous physical activity

Rigor mortis is a chemical process involving the depletion of adenosine triphosphate (ATP) in the muscles. Strenuous physical activity before death depletes ATP stores and builds up lactic acid, which accelerates the onset and progression of rigor mortis. Cold temperatures, advanced age, and obesity tend to slow down the process.

At a death scene, you observe small, pinpoint hemorrhages (petechiae) and larger purpuric hemorrhages clustered in the dependent areas of lividity on the decedent's lower legs. These findings are most consistent with:

Answer: Tardieu spots

Tardieu spots are petechiae and purpuric hemorrhages that develop in dependent areas (areas of livor mortis) secondary to the rupture of small, degenerating blood vessels under the influence of gravity and increased pressure. They are often seen in hangings but can occur in any position where there is significant dependency.

An investigator is attempting to estimate the postmortem interval using algor mortis. Which of the following environmental conditions would have the most significant impact on the rate of body cooling?

Answer: The body being submerged in cold, moving water

Algor mortis is the postmortem cooling of the body. The rate of cooling is significantly influenced by the surrounding environment. Water has a much higher thermal conductivity than air, and moving water will continuously remove heat from the body through convection, drastically accelerating the cooling rate compared to other factors.

A key difference between an antemortem (before death) wound and a postmortem (after death) artifact is the presence of a vital reaction. Which of the following is a characteristic of an antemortem injury?

Answer: Profuse bleeding with firm, adherent clots

Antemortem injuries occur while the person is alive and the circulatory system is functioning. This results in a vital reaction, which includes significant bleeding that infiltrates surrounding tissues, swelling, inflammation, and the formation of firm, adherent blood clots. Postmortem injuries lack this physiological response.

An investigator is called to a scene where a body has been discovered. The investigator notes that livor mortis is present and fully fixed, and rigor mortis is complete throughout the entire body. Based on these classic postmortem changes, the most likely postmortem interval is:

Answer: 12-24 hours

Livor mortis typically becomes fixed between 8 to 12 hours after death. Rigor mortis is generally complete throughout the body by about 12 hours and can remain for another 12 to 24 hours before beginning to dissipate. The combination of fixed lividity and complete rigor strongly suggests a postmortem interval in the 12 to 24-hour range.