A 32-year-old woman attends the outpatient clinic 96 hours after unprotected intercourse during her mid-cycle (day 14 of a 28-day cycle). She reports nausea and mild lower abdominal discomfort. Urine pregnancy test is negative. She has no history of contraceptive use and wishes to prevent pregnancy. Which of the following is the most appropriate next step?

Explanation

## Emergency Contraception Beyond 72 Hours: Copper IUD as Salvage **Key Point:** At 96 hours post-intercourse, levonorgestrel efficacy has significantly declined. The copper IUD is the most effective emergency contraceptive option remaining, with >99% efficacy when inserted within 5 days of unprotected intercourse. ### Timeline and Efficacy Window **High-Yield:** The critical distinction is: - **Levonorgestrel:** Most effective 0–72 hours; declining efficacy 72–120 hours; rarely used beyond 72 hours - **Copper IUD:** Effective up to 5 days (120 hours) post-intercourse; efficacy does NOT decline with time ### Why Copper IUD Is Superior at 96 Hours 1. **Mechanism:** Copper ions create a spermicidal and embryotoxic environment; also induces local endometrial inflammation 2. **Efficacy:** >99% pregnancy prevention regardless of timing within 5-day window 3. **No ovulation requirement:** Works even if ovulation has already occurred (this patient is at mid-cycle—ovulation may be imminent or recent) 4. **Dual benefit:** Provides ongoing contraception for 10–12 years post-insertion ### Comparison: Emergency Contraceptive Methods by Timing | Method | Optimal Window | Efficacy at 96 hrs | Mechanism | |---|---|---|---| | Levonorgestrel | 0–72 hrs | ~20–30% | Ovulation inhibition | | Ulipristal acetate (SPRM) | 0–120 hrs | ~60–70% | Ovulation delay; not available in India | | Copper IUD | 0–120 hrs | >99% | Spermicidal; embryotoxic | | Mifepristone | Pre-implantation (not EC) | N/A | Abortifacient | **Clinical Pearl:** At mid-cycle (day 14), the patient is at peak fertility. Ovulation may have already occurred or be imminent. Levonorgestrel's mechanism (ovulation inhibition) is ineffective if ovulation has passed. The copper IUD's local endometrial effect remains effective regardless of ovulation timing. **Warning:** Do NOT confuse emergency contraception with medical abortion. Levonorgestrel and copper IUD prevent pregnancy; mifepristone terminates an established pregnancy (not indicated here as the urine pregnancy test is negative). **Mnemonic:** **CU-EC** = **C**opper **U**terine device is **E**ffective **C**hoice at 96 hours. ### Counseling Before IUD Insertion - Confirm negative pregnancy status (urine test is negative; consider serum β-hCG if high suspicion) - Screen for contraindications (active PID, STI, anatomical abnormalities) - Discuss insertion procedure, cramping, and bleeding patterns - Provide antibiotic prophylaxis if indicated [cite:Park 26e Ch 10; WHO Emergency Contraception Guidelines 2012]