Classification of contraceptive vaginal rings

An intrauterine device, commonly known as an intrauterine contraceptive ring, is a contraceptive device placed inside the uterine cavity and can be made of metal, plastic or silicone rubber. In ancient Arabia and Türkiye, people put small stones in the camel's uterus to prevent the camel from getting pregnant while traveling in the desert. These little stones can be said to be the ancestors of intrauterine contraceptive devices. About 80 million women around the world use vaginal contraceptive rings or intrauterine devices. In my country, users of intrauterine devices account for about 40% of couples of childbearing age who take contraceptive measures.

Vaginal contraceptive rings can be divided into three categories according to the type of drug they contain, the amount released, and the retention time of the ring in the vagina:

(1) A vaginal contraceptive ring that releases large amounts of progestin and is used intermittently.

(2) A vaginal contraceptive ring that releases large amounts of estrogen and progesterone and is used intermittently.

(3) A vaginal contraceptive ring that releases a small amount of progestin and is used continuously.

The first two types are placed in the vagina for 21-28 days in each menstrual cycle, and the latter can be placed continuously for 3-12 months without being removed during menstruation. The vaginal contraceptive ring used in Shanghai belongs to the latter type. It is brown-red in color, with an outer diameter of 40 mm and a ring body of 4 mm. The ring contains 250 mg of the contraceptive drug megestrol, which releases an average of 130 micrograms per day. Each ring can be used continuously for one year.

After the vaginal contraceptive ring is inserted into the vagina, the contraceptive pills in the ring are continuously and slowly released, and then absorbed by the vaginal mucosa to exert a contraceptive effect. Its main function is to change the properties of cervical mucus, reduce the stringiness of cervical mucus during ovulation, and make the mucus thicker, which is not conducive to the passage of sperm, thus producing a contraceptive effect. The contraceptive effectiveness is about 97%.

The advantages of the vaginal contraceptive ring are that it is easy to use and can be placed by medical staff in the deepest part of the vagina (posterior fornix of the vagina). The daily dose of contraceptives released by the contraceptive ring is less than that of oral contraceptives, so the chance of side effects is also less. The contraceptives in the contraceptive ring are absorbed through the vaginal mucosa after release, and most of the absorbed contraceptives do not pass through the liver but directly enter the systemic circulation, thereby reducing the impact on the liver. Vaginal contraceptive rings are particularly suitable for women with poor health, heart, liver, and kidney diseases, and those who cannot tolerate other contraceptive measures.