Toxicology: viper bite, 20-minute whole blood clotting test: 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 · Toxicology: viper bite, 20-minute whole blood clotting test

Sample item

A farmer bitten by a Russell's viper is given antivenom after a 20-minute whole blood clotting test shows unclotted blood. Six hours later the repeat test still shows unclotted blood. What is the next step?

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

The answer and the reasoning

B. Repeat the full initial dose of antivenom and retest after another 6 hours

The 20-minute whole blood clotting test detects venom-induced consumption coagulopathy. If blood remains unclotted 6 hours after antivenom, the dose is repeated and the test is repeated 6-hourly until blood clots. Plasma products do not neutralise circulating venom.

Option by option

  • A. Give fresh frozen plasma alone instead of more antivenom

    Plasma replaces factors but leaves venom active, so it is not a substitute for antivenom.

  • B. Repeat the full initial dose of antivenom and retest after another 6 hours (correct)

    Correct. Persistent incoagulability indicates continuing venom effect and needs another antivenom dose.

  • C. Stop antivenom because the venom has been neutralised

    Unclotted blood shows neutralisation is incomplete, so stopping is wrong.

  • D. Wait 24 hours before testing again

    Delay risks haemorrhage; retesting is done at 6-hour intervals.

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, Repeat the full initial dose of antivenom and retest after another 6 hours. The 20-minute whole blood clotting test detects venom-induced consumption coagulopathy.

Why is "Give fresh frozen plasma alone instead of more antivenom" not the answer?

Plasma replaces factors but leaves venom active, so it is not a substitute for antivenom.

Why is "Stop antivenom because the venom has been neutralised" not the answer?

Unclotted blood shows neutralisation is incomplete, so stopping is wrong.

Why is "Wait 24 hours before testing again" not the answer?

Delay risks haemorrhage; retesting is done at 6-hour intervals.

What concept does this question test?

It tests Toxicology: viper bite, 20-minute whole blood clotting test in Forensic Medicine. If blood remains unclotted 6 hours after antivenom, the dose is repeated and the test is repeated 6-hourly until blood clots. Plasma products do not neutralise circulating venom.

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 Toxicology: viper bite, 20-minute whole blood clotting test?

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.