An intrauterine device (IUD) is a T-shaped plastic device that is inserted into the uterus to prevent pregnancy. Two IUDs are currently available:
1. Mirena – This IUD contains a progestin (progesterone-like hormone) called levonorgestrel, which is continuously released into the endometrial cavity. The Mirena IUD works by thickening the mucus plug in the cervix (the entrance to the uterus), thus blocking sperm entry and preventing conception. It is approved for contraception for up to 5 years.
Because Mirena releases a low continuous dose of a progestin into the uterus, it can decrease menstrual flow and improve some other conditions that typically cause excessive bleeding or uterine pain such as endometriosis, adenomyosis, fibroids, or endometrial hyperplasia. Mirena can serve as both a treatment for menstrual issues and an effective birth control option.
2. Paragard (Copper T 380A) – This IUD contains copper, which is released locally into the endometrial cavity. The Paragard IUD reduces sperm motility and function to prevent conception. It is approved for up to 10 years for contraception.
The main effect of the IUD is to prevent the union of sperm and egg to prohibit conception. While it is possible that an IUD could prevent the embedding of a fertilized egg into the uterine wall, this is not considered the mechanism of preventing pregnancy, as the egg is not fertilized with a functioning IUD in place.
IUDs have been used for many years to prevent pregnancy. In the past, there were problems with some IUDs due to design flaws and use in women at risk for sexually transmitted infections. Changes in IUD design and careful patient selection have made the IUD an extremely safe form of birth control. It is important to remember that IUDs are safest when used only by women in long-term, monogamous relationships.
The reported failure rate of Mirena is 0.1% to 0.7% (1-7 per 1000), for Paragard, 0.6% to 0.8% (6-8 per 1000). This is a slightly lower failure rate than surgical sterilization. For women who attempt pregnancy after an IUD is removed, fertility returns to baseline for the individual immediately after removal.
Risks associated with an IUD include: (1) inadvertent pregnancy; (2) tubal pregnancy - treatment of which may require surgery and may involve the removal of the fallopian tube; (3) pelvic infection – which may cause tubal scarring, infertility or result in need for surgery, possibly including hysterectomy; (4) perforation of the uterine wall - which may require surgery to remove the IUD; (5) if a pregnancy occurs with an IUD in place, it may result in miscarriage; and (6) expelling the IUD through the cervix.
Side effects associated with the IUD may include lower abdominal cramping and/or irregular bleeding. In some cases, though not commonly, Mirena may cause side effects due to the progestin being released in very small amounts into the general circulation. This could cause acne, mood changes, or bloating in some women. Generally, the amount of progestin that reaches general circulation is negligible and does not cause these systemic side effects. Mirena is considered a local uterine treatment.
The best candidates for IUD use for contraception are women with a normal uterus and low risk for a sexually transmitted disease (long-term, steady relationship with one partner with no history of infection). Any woman who has multiple partners or a partner with outside sexual relationships is at increased risk of acquiring sexually transmitted diseases and should not use an IUD. It is generally recommended to wait until after having at least one child before using an IUD because women who have not yet given birth generally have higher rates of expelling IUDs and may have more cramping during IUD use. However, not having given birth is not an absolute contra-indication to use of the IUD. Some young women with no children are good candidates. This should be discussed with your physician.
Women with the following conditions are advised not to use an IUD: (1) previous ectopic pregnancy; (2) history of pelvic inflammatory disease or PID; (3) congenital malformation of the uterus; (4) large fibroids, or fibroids of any size that distort the uterine cavity; (5) active liver disease or liver tumors (Mirena only); (6) allergy to levonorgestrel (Mirena), polyethylene or copper (Paragard); (7) known or suspected breast cancer (Mirena); (8) recent post-partum or post-abortion infection of the uterus; (9) Leukemia, AIDS or other conditions that predispose to infection.
The process of having an IUD inserted usually takes only about 5 to 10 minutes. Prior to insertion, you should avoid intercourse or douching for 24 hours before your appointment. Take a medication for cramping (800 mg ibuprofen or 2 Aleve tablets) about 30 minutes before you arrive for your appointment.
An IUD can be placed during your menstrual cycle or post-partum when the cervix is softer and slightly dilated; however, it can be placed at any time during your cycle. The IUD is placed using a special applicator that is introduced through the cervix into the uterus. During the procedure, most women feel cramping, which can be reduced by taking ibuprofen before the procedure. After insertion, a string at the end of the IUD will extend through the cervix but should not bother you or your partner. Patients who have an IUD insertion in our facility will undergo a pelvic ultrasound immediately afterward, thus assuring correct placement of the IUD within the uterine cavity. The IUD may take up to 2-4 weeks to become effective. Use a second method of contraception (condoms, birth control pills, Nuvaring, etc.) for one month after having the IUD placed.
In most cases, you should have a check-up about one to two months after having an IUD inserted to make sure the IUD is still in the correct location. A clinician should then check the location of the IUD once a year during your regular yearly exam. Some patients check the IUD string after each menstrual period as a regular check that it is still present.
During the first 3 to 6 months after Mirena insertion, irregular, light bleeding may occur as the body adjusts to the device. After 6 months of use, approximately 50% of women have only very light spotting, an average of about three days per month. Twenty percent of women stop having periods altogether after one year of use.
Paragard, the copper-containing IUD, may cause heavier bleeding or cramping with your menstrual period. This is likely to get better with time and can be relieved with ibuprofen.
If at any time you develop fever or chills with pelvic pain or tenderness, severe cramping, or unusual vaginal bleeding, contact your doctor to make sure no pelvic infection is present. If you are no longer in a monogamous relationship, you are more likely to be exposed to sexually transmitted diseases and condoms should be used to lower this risk. The IUD should only be removed by a doctor. Removal is usually a simple procedure.
