What is the mode of action of hormone-releasing Intrauterine Devices (IUDs)?

MP CHO -2021 (Shift 1st)

Obstetrics & Gynecology

Easy

Appeared in: MP CHO -2021 (Shift 1st)

Explanation

Hormone-releasing IUDs, also known as levonorgestrel-releasing intrauterine systems (LNG-IUS), are a type of long-acting reversible contraception.
Their primary contraceptive action is mediated by the local release of the progestin, levonorgestrel.
This hormone causes the cervical mucus to become thick and viscous.
This thickened mucus forms a plug that physically blocks sperm from passing through the cervix into the uterus, thereby preventing fertilization.
Other secondary mechanisms include thinning of the endometrium (making it unsuitable for implantation) and inhibition of sperm motility.

Option A: This describes the mechanism of a copper IUD, not a hormone-releasing IUD. Copper IUDs induce a sterile inflammatory reaction (an enhanced cellular response) in the endometrium, which is spermicidal.
Option C: This is the opposite of the intended effect. Hormone-releasing IUDs impair or inhibit sperm motility and function, making it harder for sperm to reach and fertilize an egg.
Option D: This is the opposite of the intended effect. Hormone-releasing IUDs create an unfavorable environment for implantation by causing the endometrium to become thin and atrophic.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The primary mechanism of action for hormone-releasing intrauterine devices (IUDs) as background academic context rather than a clinical decision trigger.
Understanding the different mechanisms of IUDs is crucial for patient counseling. For example, the endometrial atrophy caused by LNG-IUS often leads to lighter periods or amenorrhea, which can be a therapeutic benefit for women with heavy menstrual bleeding.
In contrast, the inflammatory reaction from copper IUDs can lead to heavier bleeding and cramping, making it a less suitable choice for women with pre-existing menorrhagia.
What if a patient has severe dysmenorrhea and heavy menstrual bleeding and desires long-term contraception? A hormone-releasing IUD would be a superior choice over a copper IUD because its progestin effect thins the endometrium, which typically reduces both bleeding and menstrual pain.

How to Approach the Question

First, identify the key terms in the question: 'hormone-releasing IUDs' and 'mode of action'.
Recall the primary hormone involved in these devices, which is a progestin (levonorgestrel).
Think about the known effects of progestin on the female reproductive tract. Progestins are known to thicken cervical mucus and affect the endometrium.
Evaluate each option based on this knowledge.
Option A (increasing cellular response) is characteristic of copper IUDs.
Option B (increasing viscosity of cervical mucus) is a classic effect of progestin.

Concept Tested & Keywords

Concept Tested: The primary mechanism of action for hormone-releasing intrauterine devices (IUDs).
Stem keywords: hormone-releasing, Intrauterine Devices, IUDs, mode of action
Lead-in keywords: What is
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart C (pp 404-604 of 604) p. 190-192

E6 Gynecology Williams p. 116-144