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Hormonal IUD
By Mayo Clinic staffThe hormonal IUD (Mirena) is a T-shaped plastic frame with thread attached. The device is inserted into the uterus and can remain in place for up to five years. It prevents pregnancy in a few different ways. The IUD frame contains a progestin called levonorgestrel, which inhibits sperm motility and makes the uterine lining thin and unsuitable for a pregnancy. The shape of the IUD impedes the sperm's journey to the fallopian tubes, inhibiting fertilization. If fertilization occurs, the device prevents the embryo from attaching to the uterine wall.
Effectiveness rate. The effectiveness rate for Mirena is 99.9 percent, so one woman out of 1,000 using the device for one year will get pregnant. Mirena must be replaced every five years.
Side effects and health risks. Unlike the copper IUD, the hormonal IUD decreases the amount of menstrual blood flow and menstrual cramping. The major side effect of hormonal IUD use is abnormal vaginal bleeding. Some women have unpredictable, light menstrual flow, while many may have no flow at all. Most women report discomfort and cramping during and after IUD insertion. Rarely, IUD users may experience a pelvic infection within the first three weeks of placement, as the insertion process can introduce bacteria into the uterus. Although most of the risk of infection with IUDs occurs at the time of insertion, many care providers continue to weigh risk of infection in their patients. Mutually monogamous relationships are the best defense against infection.
Hormonal IUDs don't protect against STDs. IUDs also carry a risk of spontaneous expulsion — which leaves you unprotected against pregnancy — or piercing (perforation) of the uterine wall during insertion. The risks of expulsion and perforation are extremely low.
How to use the hormonal IUD. If you decide on the hormonal IUD, your doctor will insert the device and give you information on its use. There's no maintenance required, but you should feel for the IUD string once a month to ensure the device hasn't been expelled. When the IUD needs to be removed, your doctor withdraws it by pulling on the IUD string. After removal, normal fertility returns promptly.
Cost and availability. The Mirena hormonal IUD costs between $300 and $400 every five years plus the cost of an office visit for insertion and a follow-up appointment.
IUD: Pros and cons Copper IUD
