The mechanism of action of emergency contraception
The mechanism of action of emergency contraception is to suppress or delay ovulation, impairment of fertilization, transport of the egg and implantation of the blastocyst. As you know, implantation of the latter into the lining of the uterus begins approximately 5 days after fertilization and ends one week after it. The effect is possible when using emergency contraception during the first 24-72 hours after unprotected sexual intercourse.
Currently for emergency contraception use:
- IUDs (copper-bearing).
The Yuzpe method
The method of emergency contraception with COCs is the Yusepe method, which was developed in Yuzpe and Lansy in 1977. It consists of a double admission of 100 μg EE and 0.5 mg levonorgestrel.
The first dose should be taken within 72 hours after unprotected intercourse, the second after 12 hours. For the purpose of emergency contraception, practically all modern COCs can be used in appropriate doses: 8 low-dose COC tablets (containing 30-35 μg EE) taken in 2 divided doses with a 12-hour interval, or 4 tablets of a high-dose COC (containing 50 μg EE), also taken in 2 doses with a 12-hour interval.
Contraindications to use are pregnancy, as well as conditions in which estrogens are contraindicated (history of thromboembolism, severe liver disease, bleeding of unclear etiology, breast cancer and endometrium).
The main side effects: nausea (51%), vomiting (19%), mastalgia, bleeding.
Emergency contraception with progestogens
As a progestogen emergency contraceptive, a postinor drug containing 0.75 mg levonorgestrel is used, and an escapes containing 1.5 mg levonorgestrel in 1 tablet.
Two postinor tablets are used: the first tablet should be taken within 48 hours after unprotected intercourse, the second after 12 hours. The escapel is taken 1 tablet not later than 72 hours after unprotected sexual intercourse.
Emergency contraception with copper-bearing IUDs
For this purpose, the IUD is injected into the uterus for 5 days after unprotected intercourse. This method is not shown for nulliparous women, as well as for patients with a high risk of developing inflammatory diseases of the genitals, primarily with sexually transmitted infections, the increased risk of which occurs when there are a large number of sexual partners and casual sex. The effectiveness of this method is 1 pregnancy per 5000 cases of use.
Despite the high contraceptive activity of emergency contraception, this method can not be used constantly - it can only be used in emergency cases.