Early Post-Mortem Changes

Overview

• Introduction to early post-mortem changes that occur after death.
• Important processes: Algor Mortis, Rigor Mortis, and Liver Mortis.

Algor Mortis (Post-Mortem Cooling)

• Definition: The cooling of the body after death.
• Initial Phase:
  • Body temperature remains stable due to endogenous heat production from living tissues.
  • Lasts for about 1 hour (plateau phase).
• Phase Two:
  • Decrease in body temperature begins after all tissues are dead.
  • Cooling rate: 0.4 to 0.6 °C per hour for about 12-16 hours.
• Terminal Phase:
  • Occurs after 16 hours; body temperature does not reach baseline due to bacterial activity.
• Measurement:
  • Core body temperature is measured from the rectum or subhepatic space.
• Conditions Affecting Cooling:
  • Heat stroke, tetanus, and certain poisoning conditions can delay cooling.

Liver Mortis (Post-Mortem Staining)

• Definition: Also known as lividity or hypostasis, it is the bluish-purple discoloration of the body.
• Mechanism: Blood pooling occurs in dependent areas of the body.
  • Example: If a person dies in a supine position, staining will occur on the back.
• Stages of Development:
  • Initial staining begins within 30 minutes.
  • By 4 hours, staining becomes confluent.
  • Fixation occurs by 6-8 hours; changes in body position will not affect staining.
• Secondary Lividity:
  • Occurs if body position is changed before fixation.
• Absence of Liver Mortis:
  • May occur in drowning cases or severe blood loss.
• Color Variations:
  • Staining color changes based on cause of death (e.g., carbon monoxide poisoning results in cherry red staining).

Rigor Mortis (Cadaveric Rigidity)

• Definition: Stiffening of muscles after death.
• Difference from Cadaveric Spasm:
  • Cadaveric spasm occurs immediately after death, while rigor mortis develops later.
• Phases:
  • Primary Flaccidity: All muscles are relaxed immediately after death.
  • Rigor Mortis Onset: Starts 1-2 hours after death, peaks at 6-12 hours.
  • Secondary Flaccidity: Muscles become flaccid again after rigor mortis subsides.
• Mechanism:
  • Caused by calcium leakage from the sarcoplasmic reticulum into muscle cells, leading to prolonged contraction due to lack of ATP.
• Nistan Rule:
  • Sequence of rigor mortis onset: involuntary muscles, eyelids, neck, lower jaw, face, chest, upper limbs, abdomen, lower limbs, fingers, and toes.
• Duration:
  • Influenced by temperature; lasts longer in cooler climates (24-48 hours in winter, 18-36 hours in summer).

Summary of Post-Mortem Changes

• Algor Mortis: Helps determine time since death.
• Liver Mortis: Indicates body position at time of death.
• Rigor Mortis: Aids in estimating time since death.

Conclusion

• Recap of the importance of understanding these processes in forensic science for determining time and circumstances of death.
• Encouragement to subscribe for more forensic content.