Thanatology: post-mortem formation of ethanol: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Thanatology: post-mortem formation of ethanol

Sample item

A decomposed body is recovered from a ditch after five days and the blood ethanol is 80 mg/dL. There is no history of drinking. Which finding most strongly suggests that the ethanol was formed after death?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Little or no ethanol in vitreous humour and urine, with n-propanol in the blood

Bacteria and yeasts in a decomposing body can ferment sugars and produce ethanol in blood. Vitreous humour and urine are relatively protected, so an alcohol level in these that is much lower than blood, along with other fermentation products such as n-propanol, suggests post-mortem production. Sodium fluoride in the sample bottle limits further fermentation.

Option by option

  • A. Raised carboxyhaemoglobin in the blood

    Carboxyhaemoglobin indicates carbon monoxide exposure, which says nothing about ethanol formation.

  • B. Little or no ethanol in vitreous humour and urine, with n-propanol in the blood (correct)

    Correct. Low vitreous or urine ethanol with putrefactive volatiles points to post-mortem formation.

  • C. Smell of alcohol from a recent meal in the stomach

    A smell of alcohol in the stomach points to ingestion in life.

  • D. Ethanol concentration in urine higher than in blood

    Urine ethanol higher than blood suggests that drinking took place hours before death.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is B, Little or no ethanol in vitreous humour and urine, with n-propanol in the blood. Bacteria and yeasts in a decomposing body can ferment sugars and produce ethanol in blood.

Why is "Raised carboxyhaemoglobin in the blood" not the answer?

Carboxyhaemoglobin indicates carbon monoxide exposure, which says nothing about ethanol formation.

Why is "Smell of alcohol from a recent meal in the stomach" not the answer?

A smell of alcohol in the stomach points to ingestion in life.

Why is "Ethanol concentration in urine higher than in blood" not the answer?

Urine ethanol higher than blood suggests that drinking took place hours before death.

What concept does this question test?

It tests Thanatology: post-mortem formation of ethanol in Forensic Medicine. Vitreous humour and urine are relatively protected, so an alcohol level in these that is much lower than blood, along with other fermentation products such as n-propanol, suggests post-mortem production. Sodium fluoride in the sample bottle limits further fermentation.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Thanatology: post-mortem formation of ethanol?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.