A 28-year-old man is found dead in a closed garage with a running car. Autopsy reveals bright cherry-red discoloration of blood, skin, and viscera. Which postmortem finding BEST differentiates carbon monoxide poisoning from cyanide poisoning?

• A Cherry-red discoloration of blood and viscera
• B Pulmonary edema
• C Petechial hemorrhages in the brain
• D Bitter almond odor detectable at autopsy ✓

Explanation

Both CO and cyanide produce cherry-red blood discoloration because both cause failure of cellular oxygen utilization. The bitter almond odor, detectable by about 40-60% of the population, is specific to cyanide poisoning and is absent in CO cases. This is the most discriminating physical finding at autopsy. Petechiae and pulmonary edema are nonspecific and can occur in both conditions.

Reference: Spitz and Diaz's Spitz and Fisher's Medicolegal Investigation of Death, 5th ed.

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Written and medically reviewed by the StethoPrep medical team.