Communicable diseases: HIV diagnostic window: practice question

A PSM 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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PSM · Communicable diseases: HIV diagnostic window

Sample item

A health worker has a needle stick injury from an HIV-positive patient. If the initial test is negative, follow-up testing is done to account for the window period, which is typically:

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

The answer and the reasoning

C. Up to about 3 months

The window period for antibody detection is usually up to 3 months, and fourth-generation assays shorten it. Post-exposure prophylaxis should start as soon as possible, ideally within 2 hours and not later than 72 hours.

Option by option

  • A. 7 days

    7 days is too short for antibody detection.

  • B. 24 hours

    24 hours is too short for seroconversion.

  • C. Up to about 3 months (correct)

    Correct. About 3 months is the conventional window period.

  • D. 2 years

    2 years is far too long.

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 PSM question

What is the answer to this PSM question?

The best answer is C, Up to about 3 months. The window period for antibody detection is usually up to 3 months, and fourth-generation assays shorten it.

Why is "7 days" not the answer?

7 days is too short for antibody detection.

Why is "24 hours" not the answer?

24 hours is too short for seroconversion.

Why is "2 years" not the answer?

2 years is far too long.

What concept does this question test?

It tests Communicable diseases: HIV diagnostic window in PSM. Post-exposure prophylaxis should start as soon as possible, ideally within 2 hours and not later than 72 hours.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Communicable diseases: HIV diagnostic window?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM 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.