Early Post-Mortem Changes

Introduction

• Importance of understanding post-mortem changes after death.
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Key Early Post-Mortem Changes

1. Algor Mortis
2. Livor Mortis
3. Rigor Mortis

Algor Mortis

• Also known as post-mortem cooling.
• Body temperature falls after death due to:
  • Endogenous heat production from dying tissues initially prevents temperature decrease.
  • Once tissues die, metabolism decreases, leading to temperature decline.
• Measurement Sites:
  • Rectum (preferred)
  • Sub-hepatic space (if rectal measurement is not possible)

Phases of Temperature Decline

1. Plateau Phase:
   • No initial decrease in temperature for about 1 hour due to ongoing metabolism.
2. Linear Decrease:
   • Temperature falls at a rate of 0.4 to 0.6 °C/hour for approximately 12-16 hours.
3. Terminal Phase:
   • After 16 hours, temperature stabilizes above baseline due to bacterial activity and putrefaction.

Delays in Temperature Decline

• Conditions when decline is delayed:
  • Heat Stroke: Initial higher temperature causes a delay.
  • Tetanus, Sticking poisoning: Excessive muscle contraction generates heat.
  • Septicemia: Elevated temperature due to fever at death.

Livor Mortis

• Also called post-mortem staining or hypostasis.
• Bluish-purple discoloration occurs in dependent regions of the body.
• Contact Pallor: White areas on body where bony prominences are compressed against the surface.

Phases of Livor Mortis

1. Initial Stage: Begins within 30 minutes in dependent areas.
2. Confluent Sites: By 4 hours, large areas show staining.
3. Fixation: Occurs by 6-8 hours; staining pattern remains fixed regardless of body position changes.

Secondary Lividity

• Occurs if body position is changed before fixation.
• Example: Changing from supine to prone can shift staining.
• Absent in:
  • Drowning: Continuous movement in water.
  • Severe Blood Loss: Insufficient blood for staining.

Patterns of Staining

• Glove and Stocking Pattern: Seen in hanging (dependent areas are hands and feet).
• Colors of Staining in Toxicity:
  • Carbon monoxide - cherry red
  • Cyanide - brick red
  • Nitrites - reddish brown
  • Others vary (e.g., opium, hypothermia, etc.).

Rigor Mortis

• Also known as cadaveric rigidity.
• Often confused with cadaveric spasm, which occurs immediately after death.

Cadaveric Spasm

• Immediate change post-death, often indicating cause of death (e.g., self-inflicted gunshot).
• Cannot be artificially changed.

Rigor Mortis Process

1. Primary Flaccidity:
   • Muscles relaxed; easy to move limbs.
2. Onset of Rigor Mortis:
   • Muscles begin to stiffen due to calcium influx into sarcomeres without ATP for relaxation.
3. Secondary Flaccidity:
   • Muscles eventually relax again.

Mechanism Behind Rigor Mortis

• Calcium leaks into sarcomeres; muscle contractions occur without ATP availability.
• Nishtan Rule: Sequence of rigor mortis onset:
  • Starts with involuntary muscles (heart), then eyelids, neck, jaw, face, chest, limbs, and finally fingers/toes.
• Timing:
  • Onset: 1-2 hours post-death.
  • Well established after 6 hours and varies by environmental conditions (e.g., longer in cold environments).

Summary of Changes

• Algor Mortis: Indicates time since death.
• Livor Mortis: Indicates position at death.
• Rigor Mortis: Helps ascertain time since death.

Conclusion

• Importance of understanding these changes in forensic investigations.
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