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Understanding Post-Mortem Changes After Death

Apr 2, 2025

Notes on Early Post-Mortem Changes

Introduction

  • Overview of early post-mortem changes after death.
  • Important changes: Algor mortis, Rigor mortis, and Liver mortis.

Algor Mortis (Post-Mortem Cooling)

  • Definition: Cooling of the body after death.
  • Initial phase: Body temperature does not fall due to endogenous heat production from still-living tissues.
  • Complete death of tissues leads to decreased metabolism and temperature drop.
  • Phases of Temperature Decline:
    1. Plateau Phase (First Hour): No temperature decrease due to ongoing metabolism.
    2. Linear Decrease Phase (12-16 hours): Temperature falls at a rate of 0.4 to 0.6 °C per hour.
    3. Terminal Phase (After 16 hours): Temperature stabilizes above baseline due to bacterial activity.
  • Core Temperature Measurement Sites:
    • Rectum
    • Subhepatic space
  • Conditions causing delayed temperature decline:
    • Heat stroke
    • Tetanus
    • Sticking poisoning
    • Septicemia

Liver Mortis (Post-Mortem Staining or Lividity)

  • Definition: Bluish-purple discoloration in dependent areas of the body due to blood pooling.
  • Contact Pallor: Areas compressed against a surface do not undergo staining.
  • Stages of Liver Mortis:
    1. Initial Staining (First 30 minutes): Starts in dependent areas.
    2. Confluent Staining (4 hours): Large areas of staining observed.
    3. Fixation (6-8 hours): Once fixed, staining pattern cannot change with body repositioning.
  • Secondary Lividity: Occurs if the body is repositioned before fixation, leading to staining in new dependent areas.
  • Absence of Lividity:
    • Cases of drowning (continuous movement)
    • Severe blood loss
  • Color Variations in Post-Mortem Staining:
    • Carbon monoxide poisoning: Cherry red
    • Cyanide poisoning: Brick red
    • Nitrites poisoning: Reddish brown
    • Potassium chlorate poisoning: Chocolate brown
    • Hydrogen sulfide poisoning: Bluish-gray or green

Rigor Mortis (Cadaveric Rigidity)

  • Definition: Stiffening of muscles after death.
  • Difference from Cadaveric Spasm:
    • Cadaveric spasm occurs immediately after death; rigor mortis takes time to develop.
  • Stages of Rigor Mortis:
    1. Primary Flaccidity: Muscles are relaxed immediately after death.
    2. Rigor Mortis Onset: Begins around 1-2 hours post-death, peaks at 6 hours.
    3. Secondary Flaccidity: Muscles become relaxed again after rigor mortis subsides.
  • Mechanism behind Rigor Mortis:
    • Calcium leaks into muscles post-death, causing contraction without ATP for relaxation.
    • ATP levels drop from 85% to 15%, coinciding with rigor onset and peak.
  • Nishtan Rule: Sequence of rigor mortis onset:
    • Starts in involuntary muscles (heart), then moves to eyelids, neck, lower jaw, face, chest, upper limbs, abdomen, lower limbs, fingers, and toes.
  • Duration of Rigor Mortis:
    • Longer in cooler climates (24-48 hours in winter), shorter in warmer climates (18-36 hours in summer).

Conclusion

  • Summary of Algor mortis, Liver mortis, and Rigor mortis.
  • Importance: These changes help in estimating time of death and understanding the circumstances surrounding it.

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