Intrauterine Devices (IUD's) and Contraception

Image source: https://www.invitra.com/en/birth-control-methods/

Intrauterine devices (IUDs) are the most frequently used long acting reversible method of contraception. An IUD is a small plastic ‘T’ shaped device which is placed inside the uterus to prevent pregnancy. This T shaped device is inserted into uterine cavity through the cervix by folding the arms of the device with the help of an applicator tube. Once the device is placed properly, arms of T shaped IUD are released and applicator tube is removed. This non-surgical procedure is simple and generally takes 5 to 15 min. IUDs have a string at the bottom that hangs down into through the cervix into the vagina and is used to make sure the IUD is in place.

There are 2 types of IUDs namely: non-hormonal copper releasing IUDs and hormonal IUDs which release levonorgestrel, an androgenic progestin, for extended duration.

The copper IUD is a polyethylene device with copper wire wrapped around the stem and both arms of the frame. It slowly releases copper ions in uterine cavity which are spermicidal, and exerts sterile inflammatory response on endometrial tissue. In addition, copper-rich cervical mucus decreases sperm motility. After insertion in uterine cavity, a burst release of cupric ions is observed followed by stabilization of copper release over time.

Examples of copper IUDs are TCu380A, Multiload 375, Multiload 250, Copper T220, and Copper T200. The TCu380A with copper surface area of 380 mm2 is more effective than alternative devices and is labelled for 10 years of use but can be extended upto 12 years. In some women, the copper IUD can cause side effects such as increased uterine bleeding, cramps and pain, which may cause early removal.

Levonorgestrel releasing IUDs include Mirena (Bayer), Skyla (Bayer), Liletta (Allergan), and Kyleena (Bayer). All are T-shaped and include a polydimethylsiloxane sleeve with levonorgestrel encapsulated into the stem. Each IUD releases a different amount of levonorgestrel per day with gradual decline in release profile over the life of the device. Levonorgestrel releasing IUD cause decidualization and atrophy of endometrial glands, reduce sperm capacitation and survival. These IUDs also cause thickening of the cervical mucus, which inhibits the passage of sperm through the cervix. Liletta and Mirena contain 52 mg of levonorgestrel and release 20µg per day, effective for 5 years however, can be used for contraception upto 6 to 7 years.  Mirena treats heavy periods too, in women who choose intrauterine contraception (5).