Sexually transmitted infections: diagnosis of genital herpes: practice question

A Dermatology 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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Dermatology · Sexually transmitted infections: diagnosis of genital herpes

Sample item

A woman has painful grouped vesicles and shallow ulcers on the vulva. The clinician unroofs a vesicle and swabs the base. Which test has the highest sensitivity to confirm herpes simplex infection?

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

The answer and the reasoning

C. HSV DNA detection by PCR

PCR for HSV DNA is the most sensitive test on lesion swabs and allows typing of HSV-1 versus HSV-2. Culture is less sensitive, especially on older or crusted lesions. A Tzanck smear is insensitive and cannot separate HSV from varicella zoster, and IgG serology cannot date the infection.

Option by option

  • A. HSV IgG serology

    IgG serology shows past exposure and cannot prove that the present ulcer is herpetic.

  • B. Tzanck smear

    Tzanck smear shows multinucleate giant cells but is insensitive and nonspecific.

  • C. HSV DNA detection by PCR (correct)

    Correct. PCR is the most sensitive method and can type the virus.

  • D. Viral culture

    Viral culture is less sensitive than PCR and falls in yield as the lesion ages.

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 Dermatology question

What is the answer to this Dermatology question?

The best answer is C, HSV DNA detection by PCR. PCR for HSV DNA is the most sensitive test on lesion swabs and allows typing of HSV-1 versus HSV-2.

Why is "HSV IgG serology" not the answer?

IgG serology shows past exposure and cannot prove that the present ulcer is herpetic.

Why is "Tzanck smear" not the answer?

Tzanck smear shows multinucleate giant cells but is insensitive and nonspecific.

Why is "Viral culture" not the answer?

Viral culture is less sensitive than PCR and falls in yield as the lesion ages.

What concept does this question test?

It tests Sexually transmitted infections: diagnosis of genital herpes in Dermatology. Culture is less sensitive, especially on older or crusted lesions. A Tzanck smear is insensitive and cannot separate HSV from varicella zoster, and IgG serology cannot date the infection.

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 Sexually transmitted infections: diagnosis of genital herpes?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.