**Question:** All of the following agents may be used for post coital contraception except:

A. Oral contraceptive pills (OCPs)
B. Intrauterine device (IUD)
C. Progesterone-only pills (PPPs)
D. Emergency contraceptive pills (ECPs)

**Core Concept:** Post coital contraception refers to the use of methods to prevent pregnancy immediately after unprotected intercourse. This is different from regular contraception which is used consistently and correctly.

**Why the Correct Answer is Right:** D. Emergency contraceptive pills (ECPs) are designed to be taken within 120 hours (5 days) after unprotected sexual intercourse to reduce the risk of pregnancy. While they are effective, they are not effective as a regular contraceptive method and should not be considered as such.

**Why Each Wrong Option is Incorrect:**

A. Oral contraceptive pills (OCPs) are regular contraceptives, not suitable for post coital contraception. They require consistent and correct usage for optimal effectiveness.

B. Intrauterine device (IUD) is a regular contraceptive method, not suitable for post coital contraception. It needs to be inserted before intercourse and is not effective immediately.

C. Progesterone-only pills (PPPs) are regular contraceptives, not suitable for post coital contraception. They require consistent and correct usage for optimal effectiveness.

**Clinical Pearl:**

- Emergency contraception is essential for unprotected sexual intercourse, but regular contraceptives and methods like OCPs, PPPs, and IUDs are not suitable for post coital contraception.
- Regular contraceptives like OCPs and PPPs require consistent and correct usage for optimal effectiveness, making them unsuitable for post coital contraception.
- IUDs need to be inserted before intercourse and cannot be used as a post coital contraceptive method.
- Emergency contraception like ECPs is a valuable option when used within the correct time frame (up to 120 hours after unprotected intercourse) for post coital contraception.