Early Post-Mortem Changes

Introduction

• Overview of key post-mortem changes: Algor mortis, Rigor mortis, and Liver mortis.
• Importance of understanding these changes for forensic purposes.

Algor Mortis (Post-Mortem Cooling)

• Definition: Body temperature starts to fall after death.
• Initial phase: Body temperature remains stable due to ongoing metabolism in surviving tissues.
  • Plateau Phase: Lasts for about the first hour with no temperature decrease.
• After tissues die: Metabolism decreases, leading to a drop in body temperature.
• Measurement locations:
  • Rectum is preferred.
  • Sub-hepatic space if rectum is not possible.
• Temperature drop rate: 0.4 to 0.6 °C per hour.
• Duration of cooling: Lasts for about 12 to 16 hours.
  • Terminal Phase: After 16 hours, body temperature does not reach baseline due to bacterial activity.

Conditions Affecting Temperature Decline

• Heat Stroke: Delayed decline due to high pre-death body temperature.
• Tetanus and Sticking Poisoning: Excessive muscle contraction leads to heat production, delaying temperature drop.
• Septicemia: High body temperature at death prolongs the cooling period.

Liver Mortis (Post-Mortem Staining)

• Definition: Bluish-purple discoloration of the body due to blood pooling in dependent parts.
• Contact Pallor: Areas compressed against surfaces do not undergo staining.
• Timeline of liver mortis:
  • 0-30 Minutes: Initiation in dependent parts.
  • 4 Hours: Confluent staining occurs.
  • 6-8 Hours: Fixation happens, making stains permanent regardless of body position changes.

Secondary Lividity

• Occurs if body position changes before fixation, causing staining in new dependent areas.
• Examples of Absent Liver Mortis:
  • Continuous movement in drowning cases.
  • Severe blood loss may prevent staining.
• Special Patterns:
  • "Glove and Stocking" pattern in hanging cases due to gravity affecting dependent areas.

Colors of Post-Mortem Staining by Poisoning

• Carbon Monoxide: Cherry red.
• Cyanide: Brick red.
• Nitrites: Reddish brown.
• Potassium Chlorate: Chocolate brown.
• Hydrogen Sulfide: Bluish-gray.
• Opium Poisoning: Gray.
• Hypothermia: Bright pink.

Rigor Mortis (Cadaveric Rigidity)

• Definition: Stiffening of muscles after death.
• Cadaveric Spasm: Immediate muscle contraction at the time of death, lasting longer than rigor mortis.
• Stages of Rigor Mortis:
  • Primary flaccidity: All muscles relaxed.
  • Onset of rigor mortis: Muscle stiffness occurs.
  • Secondary flaccidity: Muscles relax again after rigor mortis.

Mechanism of Rigor Mortis

• Skeletal muscle contraction involves calcium levels and ATP usage.
• After death: Calcium leaks into sarcomeres causing prolonged contraction.
• Rigor mortis appears when ATP levels drop to about 15% of normal.

Nistan Rule

• Sequence of rigor mortis onset:
  • Begins in involuntary muscles (heart).
  • Eyelids, neck, lower jaw, face, chest, upper limbs, abdomen, lower limbs, fingers, and toes follow.
• Timing: Starts 1-2 hours after death and well-established by 6 hours.
• Duration influenced by temperature:
  • Longer in cooler environments (24-48 hours in winter).
  • Shorter in warmer climates (18-36 hours in summer).

Conclusion

• Summary of the three initial post-mortem changes: Algor mortis, Liver mortis, and Rigor mortis.
• Algor mortis indicates time since death.
• Liver mortis helps determine the position of the body at the time of death.
• Rigor mortis is also useful for estimating time since death.