## Livor Mortis (Post-mortem Lividity) **Key Point:** Livor mortis is the purple-red discoloration of the skin in dependent areas caused by gravitational pooling of deoxygenated blood in capillaries and venules after circulation ceases. ### Timeline and Characteristics of Livor Mortis | Feature | Details | |---------|----------| | **Onset** | 30 minutes to 2 hours post-mortem | | **Maximum development** | 8–12 hours | | **Color** | Purple-red (due to deoxygenated hemoglobin) | | **Distribution** | Dependent areas (lower back, buttocks, legs if supine; face, neck if hanging) | | **Blanching** | Present in early stages (< 12 hours); disappears with pressure | | **Fixation** | Occurs at 8–12 hours; does not blanch after this point | **High-Yield:** Livor mortis is one of the EARLIEST and MOST RELIABLE post-mortem changes for time-since-death estimation in the first 12 hours. **Clinical Pearl:** The absence of livor mortis in dependent areas after 2 hours suggests either: - Severe anemia (insufficient hemoglobin) - Exsanguination (massive blood loss) - Carbon monoxide poisoning (cherry-red discoloration instead) - Hypothermia (pale appearance) **Mnemonic:** **LIVOR** = **L**ow gravity **I**nduced **V**ascular **O**xygen-depleted **R**ed discoloration. ### Early vs. Late Livor Mortis Features **Early (< 12 hours):** - Blanches with pressure (reversible) - Confined to dependent areas - Useful for estimating position at death **Late (> 12 hours):** - Does NOT blanch (fixed; hemoglobin has diffused into tissues) - Extends beyond dependent areas - Less useful for time estimation **Warning:** Do not confuse livor mortis with bruising or contusions — livor mortis respects gravity and does not cross the midline, whereas bruises are localized and do not follow gravitational patterns.
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