Post-mortem lividity (hypostasis) is used to estimate the time and position at death. Which statement about post-mortem lividity is CORRECT?

• A Lividity is fixed within 2–4 hours of death and cannot be shifted thereafter
• B Carbon monoxide deaths show blue-purple lividity identical to normal deaths
• C Lividity appears immediately upon death before rigor mortis
• D Lividity is initially unfixed (blanchable and shiftable) for about 6–8 hours, then becomes fixed by 8–12 hours ✓

Explanation

Post-mortem lividity begins within 30 minutes–2 hours as blood settles by gravity into dependent vessels. It is initially unfixed (lividity shifts if the body is moved, and blanches on pressure) during the first 6–8 hours. It becomes fixed (does not shift on repositioning, does not blanch on pressure) by 8–12 hours due to haemolysis and imbibition of haemoglobin into tissues. In CO poisoning, lividity is characteristically cherry-red, not blue-purple.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.