In a lecture on sexual functioning, a nurse will include the fact that ovulation occurs when the?

JODHPUR AIIMS SNO-2018

Obstetrics & Gynaecology

Easy

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

The primary trigger for ovulation is a significant and rapid increase in the blood level of Luteinizing Hormone (LH), known as the LH surge.
This surge is initiated when high levels of estrogen from the maturing follicle switch from negative to positive feedback on the anterior pituitary gland.
The LH surge causes final follicular maturation and rupture, leading to the release of the ovum (egg) approximately 24-36 hours after the surge begins.
This hormonal event is a critical marker of the fertile window in the menstrual cycle.

Option A: The sloughing off of the endometrial wall is menstruation. This event marks the beginning of the menstrual cycle (Day 1) and occurs when pregnancy has not happened, leading to a drop in progesterone and estrogen. Ovulation happens mid-cycle, around day 14.
Option C: Oxytocin is a hormone primarily associated with uterine contractions during labor and the milk let-down reflex during breastfeeding. It does not play a direct role in triggering ovulation.
Option D: Progesterone levels are low before ovulation. They begin to rise at the time of the LH surge but reach their peak in the second half of the cycle (the luteal phase), after ovulation has already occurred. The primary role of high progesterone is to maintain the uterine lining for potential implantation.

Clinical Relevance

Nursing practice connection: Knowing Hormonal regulation of the female menstrual cycle, specifically the trigger for ovulation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding the LH surge is fundamental for nurses in fertility counseling. It allows them to educate patients on identifying their fertile window using ovulation predictor kits (OPKs).
This knowledge is also crucial for understanding the mechanism of action of certain hormonal contraceptives, which work by suppressing the LH surge to prevent ovulation.
A nurse can explain to a patient with polycystic ovary syndrome (PCOS) that irregular or absent LH surges are a common reason for anovulation and infertility in their condition.

How to Approach the Question

First, identify the key concept in the question, which is the specific trigger for 'ovulation'.
Recall the sequence of hormonal events in the menstrual cycle. Think about the roles of the key hormones: FSH, Estrogen, LH, and Progesterone.
Focus on the mid-cycle events. Remember that a surge of a specific hormone is required to cause the follicle to rupture.
Evaluate each option: A) Endometrial sloughing is menstruation (start of cycle). C) Oxytocin is for labor/lactation. D) Progesterone is high after ovulation. B) An LH surge precedes ovulation.
Based on this process of elimination and recall, conclude that the high level (surge) of LH is the correct trigger.

Concept Tested & Keywords

Concept Tested: Hormonal regulation of the female menstrual cycle, specifically the trigger for ovulation.
Stem keywords: sexual functioning, ovulation
Lead-in keywords: occurs when

QIGCA-vHZml-RsF-gmLt-2

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

E6 Gynecology Williams p. 372-437