## Livor Mortis (Post-mortem Hypostasis) **Key Point:** Livor mortis is the purple-red discoloration of dependent areas caused by gravitational settling of red blood cells and deoxyhaemoglobin formation. Initially blanching, it becomes fixed and non-blanching as haemolysis progresses. ### Timeline of Livor Mortis Fixation | Phase | Time After Death | Characteristics | |-------|------------------|------------------| | Appearance | 30 minutes – 2 hours | Faint purple-red in dependent areas | | Blanching stage | 2–8 hours | Pressure applied causes blanching (reversible) | | **Fixation begins** | **8–12 hours** | Becomes non-blanching; haemolysis releases Hb into tissue | | Complete fixation | 12–24 hours | Fully fixed; cannot be blanched | **High-Yield:** The transition from blanching to non-blanching (fixation) occurs at approximately **8–12 hours** post-mortem. This is a critical forensic timing marker. **Clinical Pearl:** Fixation is accelerated in: - Hot environments (heat increases haemolysis) - Severe anaemia (RBCs settle faster) - Carbon monoxide poisoning (cherry-red discoloration, fixed early) Fixation is delayed in: - Cold environments (slows haemolysis) - Exsanguination (few RBCs to settle) **Mnemonic:** **FIXED** — **F**ixation occurs **I**n the **X**-hour range (8–12) when **E**rythrocytes **D**isintegrate and release haemoglobin into tissue. ### Forensic Significance - **Before 8 hours:** Livor is still blanching → body may have been moved post-mortem (if livor pattern doesn't match current position). - **After 12 hours:** Livor is fixed → body position at death can be reliably inferred.
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