Contraceptive LNG-IUD (levonorgestrel intra-uterine device) has the cumulative pregnancy rate at 5 years of:
**Core Concept**
The **levonorgestrel intra-uterine device (LNG-IUD)** is a type of **hormonal intrauterine system (IUS)** that releases **levonorgestrel**, a synthetic **progestin**, to provide long-term contraception. It works by thickening cervical mucus, preventing ovulation, and altering the endometrium to prevent implantation.
**Why the Correct Answer is Right**
The LNG-IUD has a very low cumulative pregnancy rate due to its effective mechanism of action, which includes **thickening of cervical mucus** to prevent sperm penetration, **inhibition of ovulation** in some cases, and **alteration of the endometrial lining** to prevent implantation of a fertilized egg. The **progestin** released by the device also has a local effect on the uterus, further reducing the likelihood of pregnancy.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the cumulative pregnancy rate for LNG-IUD is lower than this value.
**Option B:** This option might seem plausible but is incorrect as it overestimates the pregnancy rate.
**Option D:** This option significantly overestimates the cumulative pregnancy rate associated with LNG-IUD use.
**Clinical Pearl / High-Yield Fact**
The LNG-IUD is a highly effective form of contraception, with a failure rate of less than 1%. It's also notable for its non-contraceptive benefits, including reduction in **menstrual blood loss** and **dysmenorrhea**.
**Correct Answer:** Correct Answer: C. 0.5%