Gynaecological endocrinology: LH surge: practice question

A OBG 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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OBG · Gynaecological endocrinology: LH surge

Sample item

In a regular 28-day cycle the luteinising hormone surge begins on day 12. When is ovulation expected?

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

The answer and the reasoning

C. About 34 to 36 hours after the onset of the LH surge

Rising oestradiol from the dominant follicle triggers a positive feedback LH surge, and ovulation occurs about 34 to 36 hours after the onset of the surge and 10 to 12 hours after the LH peak. This timing underlies ovulation predictor kits and timing of hCG trigger and insemination. The surge also initiates luteinisation of the follicle.

Option by option

  • A. On the day of menstruation

    Ovulation occurs mid-cycle and not at menstruation.

  • B. About 7 days after the surge

    A 7-day delay would place ovulation far too late.

  • C. About 34 to 36 hours after the onset of the LH surge (correct)

    Correct. Ovulation follows the surge onset by 34 to 36 hours.

  • D. Immediately at the start of the surge

    Ovulation requires time after the surge for follicle rupture, not immediately.

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 OBG question

What is the answer to this OBG question?

The best answer is C, About 34 to 36 hours after the onset of the LH surge. Rising oestradiol from the dominant follicle triggers a positive feedback LH surge, and ovulation occurs about 34 to 36 hours after the onset of the surge and 10 to 12 hours after the LH peak.

Why is "On the day of menstruation" not the answer?

Ovulation occurs mid-cycle and not at menstruation.

Why is "About 7 days after the surge" not the answer?

A 7-day delay would place ovulation far too late.

Why is "Immediately at the start of the surge" not the answer?

Ovulation requires time after the surge for follicle rupture, not immediately.

What concept does this question test?

It tests Gynaecological endocrinology: LH surge in OBG. This timing underlies ovulation predictor kits and timing of hCG trigger and insemination. The surge also initiates luteinisation of the follicle.

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 Gynaecological endocrinology: LH surge?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG 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.