A 26-year-old woman presents to the emergency department 48 hours after condom rupture during intercourse. She has a regular 28-day menstrual cycle and is on day 12 of her cycle. Which emergency contraceptive method is MOST effective at this time point?

Explanation

## Emergency Contraception at 48 Hours **Timing & Efficacy:** At 48 hours post-intercourse, the patient is in the fertile window (day 12 of 28-day cycle; ovulation typically day 14). While levonorgestrel and Yuzpe regimen are time-sensitive (most effective within 72 hours), **copper IUD insertion remains the MOST effective emergency contraceptive method at any time within 5 days of unprotected intercourse**, with >99% efficacy. **Key Point:** Copper IUD is superior because: - Works by creating a spermicidal/inflammatory environment - Effective regardless of cycle day or timing within 5 days - Does not depend on cycle phase for efficacy - Provides ongoing contraception for 10+ years - Efficacy ~0.6% failure rate (vs. levonorgestrel 1.2–2% at 48 hours) **High-Yield:** Levonorgestrel efficacy decreases significantly after 72 hours and is least effective in the luteal phase or when ovulation is imminent. At day 12 of a 28-day cycle, ovulation is approaching, making hormonal methods less reliable. **Mnemonic:** **CID > Hormones** for EC — Copper IUD Device is superior to hormonal methods in efficacy and timing flexibility.