At ovulation, a mature follicle ruptures in response to a surge of?

DSSSB - 29 August 2019 (Shift-2)

Obstetrics & Gynaecology

Easy

Appeared in: DSSSB - 29 August 2019 (Shift-2)

Explanation

A mid-cycle surge of Luteinizing Hormone (LH) from the anterior pituitary gland is the direct and primary trigger for ovulation.
This surge is initiated by a positive feedback mechanism from high levels of estrogen produced by the maturing ovarian follicle.
The LH surge causes the release of proteolytic enzymes (like collagenase) that degrade the follicular wall, leading to its rupture and the release of the oocyte approximately 24-36 hours later.
Without this preovulatory LH surge, the final stages of follicular maturation and ovulation will not occur.

Option A: Prolactin's primary function is to stimulate milk production (lactation). High levels of prolactin (hyperprolactinemia) actually inhibit the hormones that cause ovulation.
Option B: Androgens are primarily male sex hormones. While they are precursors for estrogen synthesis in the female body, a surge of androgens does not trigger ovulation. In fact, excess androgens can disrupt ovulation.
Option D: Adrenaline is a stress hormone released by the adrenal glands. It is part of the 'fight or flight' response and does not trigger ovulation. Chronic or acute stress can disrupt the hypothalamic-pituitary-ovarian axis, potentially delaying or preventing ovulation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of ovulation as background academic context rather than a clinical decision trigger.
Understanding the role of the LH surge is fundamental for nurses providing patient education on fertility and family planning. Ovulation predictor kits (OPKs) work by detecting this LH surge in urine, helping to identify the most fertile window (the 24-36 hours following the surge).
In infertility treatments, a medication that mimics the LH surge (like hCG) is often administered to trigger ovulation at a precise time, allowing for timed intercourse or intrauterine insemination (IUI).
What if a patient reports using OPKs for several months but never gets a positive result? This could indicate an anovulatory cycle (a cycle without ovulation), a common cause of infertility. The nurse should advise the patient to consult a healthcare provider for further evaluation, which may include blood tests to check hormone levels.

How to Approach the Question

First, identify the key physiological process in the question: the rupture of a mature follicle, which is the definition of ovulation.
Next, note the keyword 'surge,' which indicates a rapid, peak release of a hormone that acts as a trigger.
Mentally review the primary roles of the main hormones in the female reproductive cycle: FSH (follicle growth), Estrogen (builds uterine lining, provides feedback), LH (triggers ovulation), and Progesterone (maintains uterine lining).
Based on this review, recall that the defining event that triggers ovulation is the 'LH surge.'
Eliminate the other options by considering their primary functions: Prolactin is for lactation, Androgen is a male hormone, and Adrenaline is a stress hormone. None of these are responsible for triggering ovulation.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 35-37

E6 Gynecology Williams p. 370-435