What is the most effective emergency contraception for an otherwise healthy 18‑year‑old woman who had a condom rupture at peak ovulation and took a single dose of levonorgestrel (Plan B) one hour later?

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Emergency Contraception After Condom Failure at Peak Ovulation

Since this patient took levonorgestrel (Plan B) within one hour of the condom rupture, she has already received appropriate emergency contraception, though ulipristal acetate (ella) would have been the superior choice given the timing at peak ovulation. However, at this point, no additional intervention is recommended as taking both medications is not advised and the levonorgestrel was administered optimally (within 1 hour). 1

Understanding the Clinical Situation

The critical issue here is that levonorgestrel loses effectiveness when administered at or after the LH surge begins (which occurs at peak ovulation), as it primarily works by delaying or inhibiting ovulation rather than affecting post-ovulation events. 2, 3

Why Ulipristal Acetate Would Have Been Preferable

  • Ulipristal acetate (ella, 30 mg) has superior efficacy compared to levonorgestrel when taken near or at ovulation, as it can directly inhibit follicular rupture even when administered shortly before ovulation—a time when levonorgestrel is no longer effective. 1, 4

  • The CDC guidelines specifically note that ulipristal acetate is more effective than levonorgestrel 3-5 days after intercourse, and emerging data suggest it may have increased effectiveness at the end of the 5-day window. 1

  • Research demonstrates that levonorgestrel has little or no effect on post-ovulation events—among women who took levonorgestrel after ovulation occurred, the observed pregnancy rate matched the expected rate without any emergency contraception. 2

Current Management Recommendations

No additional emergency contraceptive pills should be taken at this point. 1

  • The patient took levonorgestrel appropriately within the recommended 5-day window (ideally as soon as possible). 1

  • Levonorgestrel is estimated to be up to 85% effective overall, though this effectiveness is significantly reduced when taken at or after ovulation. 1

  • A copper IUD could still be inserted within 5 days of unprotected intercourse and represents the most effective form of emergency contraception (>99% effective), which can be continued as ongoing contraception. 1

Important Caveats About Weight

  • Levonorgestrel loses effectiveness in women weighing more than 165 pounds and may be ineffective in women weighing more than 176 pounds. 1

  • If this patient has a BMI >30 kg/m², the observed pregnancy rate with levonorgestrel is 3.1%, which is not significantly reduced compared to the expected pregnancy rate without emergency contraception. 5

  • Ulipristal acetate also shows reduced effectiveness in obese women but remains more effective than levonorgestrel in this population. 1

Follow-Up Plan

  • Pregnancy testing should be performed if menses is delayed by more than one week from the expected date. 1

  • Counsel the patient that her next menstrual period may be earlier or later than expected, and bleeding patterns may be temporarily altered. 6

  • Discuss ongoing contraception options to prevent future need for emergency contraception, as emergency contraception should not be used as a regular contraceptive method. 1, 6

  • Consider advance provision of ulipristal acetate for future potential need, as it is more effective than levonorgestrel, particularly when taken closer to ovulation. 1

Key Clinical Pitfall

The major pitfall in this case is that the patient's self-report of being at "peak ovulation" should have prompted consideration of ulipristal acetate or copper IUD as first-line options rather than levonorgestrel, given the mechanism of action differences. However, since levonorgestrel was already taken within one hour (optimal timing), switching or adding medications is not recommended. 4, 2

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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