A 32-year-old nulliparous woman requests a copper IUD for emergency contraception 4.5 days after unprotected intercourse. She is confirmed to be HIV-negative and has no history of STIs. Which statement BEST reflects current WHO Medical Eligibility Criteria (MEC) and effectiveness data?

• A Copper IUD can be inserted up to 5 days after unprotected sex and has a failure rate < 0.1%, the most effective EC method ✓
• B Copper IUD is ineffective after 72 hours and should not be offered
• C Copper IUD is WHO MEC category 3 for nulliparous women due to insertion difficulty
• D Ulipristal acetate 30 mg is superior to copper IUD for emergency contraception at 4.5 days

Explanation

The copper IUD is the most effective emergency contraception available, with a failure rate of < 0.1% when inserted within 5 days (120 hours) of unprotected intercourse. It works by preventing fertilization (copper is spermicidal) and if fertilization has occurred, prevents implantation. WHO MEC classifies nulliparous women as category 2 (advantages generally outweigh risks) for IUD insertion, not category 3. It also provides ongoing contraception for up to 10–12 years. Ulipristal acetate 30 mg maintains efficacy up to 120 hours but its failure rate (~1–2%) is higher than copper IUD. Copper IUD remains the gold standard EC method regardless of time from intercourse (within 5 days).

Reference: Shaw's Textbook of Gynaecology, 17th ed.

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Written and medically reviewed by the StethoPrep medical team.