A woman comes after 96 hours post coitus. Best contraceptive of choice is?
**Core Concept**
Emergency contraception is a method of preventing pregnancy after unprotected sex. It can be used up to 120 hours (5 days) after intercourse, but its effectiveness decreases with time. The most effective methods involve hormonal therapies like levonorgestrel or ulipristal acetate.
**Why the Correct Answer is Right**
The correct answer involves the use of levonorgestrel, which is a potent progesterone receptor modulator. It works by inhibiting ovulation and altering the endometrium, making it less receptive to implantation. The exact mechanism is not fully understood, but it's thought to involve the inhibition of progesterone receptors in the hypothalamus, leading to a delay in ovulation.
**Why Each Wrong Option is Incorrect**
**Option A:** Copper IUDs are an effective form of emergency contraception, but they are not the best choice for someone presenting 96 hours post coitus, as they are most effective when inserted within 120 hours.
**Option B:** Fertility awareness methods, such as the rhythm method, are ineffective as emergency contraceptives, as they rely on tracking ovulation and are not a reliable method for preventing pregnancy after unprotected sex.
**Option C:** The morning-after pill, which often contains levonorgestrel, is the correct answer. The other options do not accurately describe the best choice for emergency contraception in this scenario.
**Clinical Pearl / High-Yield Fact**
It's essential to note that emergency contraception is most effective when used within 24 hours of unprotected sex. The sooner it's administered, the better the chances of preventing pregnancy.
**Correct Answer:** C. Morning-after pill containing levonorgestrel.