A client seeks emergency contraception after unprotected intercourse. For a levonorgestrel-only pill to be most effective, it should be taken within how many hours?

1. A

   24 hours

2. B

   48 hours

3. C

   72 hours

4. D

   120 hours

Appeared in: Daman & Diu Staff Nurse - 2018

Explanation

• Levonorgestrel-only emergency contraception (EC) is indicated for use within 72 hours (3 days) of unprotected intercourse.
• The primary mechanism of action is the delay or inhibition of ovulation, preventing fertilization.
• While it should be taken as soon as possible for maximum effect, 72 hours is the standard upper limit for its approved high-efficacy window.
• Its effectiveness decreases with each day that passes after unprotected intercourse.

Why Other Options Were Wrong

• Option A: While efficacy is highest within the first 24 hours, this is not the maximum time limit for the drug to be effective. The standard window extends beyond this.
• Option B: This is within the effective period, but it is not the full duration. The medication remains effective for another 24 hours.
• Option D: The 120-hour (5-day) window is for other types of emergency contraception, specifically Ulipristal acetate (brand name Ella) or a Copper IUD.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology of Emergency Contraception as background academic context rather than a clinical decision trigger.
• Nurses must provide accurate, non-judgmental counseling on emergency contraception, including the different types, their effectiveness, and correct timing.
• Patient education should emphasize that EC is not a regular form of birth control and does not protect against sexually transmitted infections (STIs).
• It is crucial to inform patients that the efficacy of hormonal EC, like levonorgestrel, may be reduced in individuals with a higher body mass index (BMI > 25-30).

How to Approach the Question

• First, identify the specific drug mentioned in the question: 'levonorgestrel-only pill'.
• Next, recall the clinical context, which is 'emergency contraception'.
• Access your knowledge of pharmacology to remember the specific time window associated with this drug for this purpose.
• Differentiate this time window from those of other emergency contraceptives like Ulipristal acetate (120 hours) or the Copper IUD (120 hours).
• Select the option that matches the standard effective time frame for levonorgestrel, which is 72 hours.

Concept Tested & Keywords

• Concept Tested: Pharmacology of Emergency Contraception
• Stem keywords: emergency contraception, unprotected intercourse, levonorgestrel-only pill, how many hours
• Lead-in keywords: most effective
• Clinical cues: The care setting changes urgency, monitoring level, and the expected nursing action.

Question ID

Qk510CAFJdvK97TAibQOAP

Copy ID

Reference Book

E6 Gynecology Williams p. 137-161

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1238-1240