A woman using a copper IUD (Cu-T 380A) as emergency contraception presents 4 days after unprotected intercourse. The mechanism of action in this context is primarily:
- A Progesterone-like action thickening cervical mucus
- B Suppression of LH surge preventing ovulation
- C Copper ions are spermicidal and prevent fertilization; copper also inhibits implantation if fertilization has occurred ✓
- D Endometrial atrophy preventing implantation only
Correct answer: C. Copper ions are spermicidal and prevent fertilization; copper also inhibits implantation if fertilization has occurred
Explanation
Copper IUD as emergency contraception is >99% effective if inserted within 5 days. Copper ions have direct spermicidal activity, preventing fertilization. If the IUD is inserted before or shortly after fertilization, the copper also creates a hostile uterine environment inhibiting implantation. It does not suppress ovulation (unlike levonorgestrel EC) and does not rely on endometrial atrophy alone.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.