Question

A dead body with suspected poisoning is having hypostasis of red brown or deep blue colour. It is suggestive of poisoning due to:

• A. Nitrates.
• B. Carbon monoxide.
• C. Cyanides.
• D. Barbiturates.

Hint:

Match the lividity color to the poison: cherry red suggests carbon monoxide or cyanide, while brown that can turn bluish suggests a methemoglobin former like nitrates.

Answer 1

The Correct Option is A

Postmortem lividity normally settles as a plain purplish patch, but some poisons give it a specific color, and forensic pathologists read this color at autopsy as a clue to the poison involved.

1. Nitrates: nitrates and nitrites convert hemoglobin into methemoglobin, which is chocolate brown. As the methemoglobin fraction climbs, the discoloration can also shift toward a bluish, cyanotic shade, giving the mixed red brown to deep blue picture asked about here.
2. Carbon monoxide: carboxyhemoglobin produces a bright cherry red or pink lividity, a completely different shade from brown or blue.
3. Cyanides: cyanide stops the tissues from using the oxygen carried in the blood, so the blood stays bright red, again giving a pink or cherry red lividity rather than brown or blue.
4. Barbiturates: barbiturate deaths usually show a plain dusky purple lividity from simple respiratory depression and hypoxia, without the specific brown tint asked about here.

Only nitrate or nitrite poisoning explains both the brown shade from methemoglobin and the blue shade from the cyanosis that follows.

Let's summarize:

• Cherry red or pink lividity points to carbon monoxide or cyanide.
• Brown lividity that can turn bluish points to methemoglobin forming poisons like nitrates and nitrites.

So the poison responsible here is a nitrate.