Postmortem Changes: Abiotic Phenomena and Cadaverous Cooling
Abiotic Phenomena and Cadaverous Changes
Abiotic phenomena, along with cadaveric changes, provide crucial insights into estimating the time of death. These phenomena are influenced by environmental factors and exhibit predictable patterns.
1. Abiotic Phenomena
Abiotic phenomena are cadaveric changes that have a generalized or localized expression. They are dependent on environmental circumstances and behave as inert. Key requirements include:
- Strong individual character
- Standardized data applicable to all cases
- Not influenced by biochemical or enzymatic processes
- Slow and regular progression
a. Dehydration
Generalized dehydration has limited practical value in determining the time of death. However, localized dehydration, particularly in the eye, can be informative.
Turbidity of the cornea depends on whether the eyes were open or closed after death. Open eyes exhibit turbidity within 2 hours, progressing to opacity within 4 hours. Closed eyes show turbidity after approximately 24 hours.
Ocular pressure decreases rapidly postmortem. Pupil distortion may occur. Measuring eye pressure with a tonometer is only feasible within 2-3 hours after death.
Transparency of the choroid through the sclera, due to thinning, can reveal a black spot around 10-12 hours postmortem if the eyes remained open. This observation is not always consistent.
b. Livideces (Livor Mortis)
Livideces can manifest as generalized or localized discoloration.
Generalized livideces are useful for estimating the time of death, progressing through phases of initiation, translation, and generalization. Initially, specks appear on the back of the neck within 0-1 hours.
Livideces should provide clues to the timing of death. The phenomena behave as inert and are dependent on environmental conditions. Key requirements include:
- Strong individual character
- Part of a data standard, valid for all
- Not influenced or dependent on enzymatic biochemical processes
- Slow and regular progression
2. Cadaverous Phenomena Caused by Putrefaction
These phenomena result from the action of germs within the body.
a. Green Discoloration
Green discoloration typically appears around 36 hours postmortem, resulting from hydrogen sulfide production during putrefaction interacting with hemoglobin. It usually starts in the lower right quadrant of the abdomen, where germ concentration is highest. While a reliable sign of death, its late onset (24-48 hours) limits its utility in early postmortem interval estimation.
3. Cadaveric Cooling (Algor Mortis)
Cadaveric cooling involves the gradual equalization of body temperature with the surrounding environment. The body behaves like a cooling object that no longer generates heat.
a. Period of Thermal Equilibrium
Cooling begins at the periphery and progresses inward. A noticeable “cooling wave” occurs approximately 2 hours postmortem, after an initial pause. Following this period, cooling becomes more consistent.
Hyperthermia Post-Mortem
Hyperthermia post-mortem can occur when muscles experience increased heat production, particularly in deaths involving seizures or excessive bacterial activity.
b. Evolution of the Cooling Process
Cooling initiates in the feet, hands, and face, becoming noticeable within 2 hours after death. It then extends to the extremities, chest, and back. The abdomen, armpits, and neck cool last. Deep abdominal organs retain heat for an extended period, even up to 24 hours. Palpable coolness is typically complete within 8 to 17 hours, most often between 10 and 12 hours postmortem.
Factors Influencing Cooling
Cause of death: Chronic diseases and hemorrhages can accelerate cooling.