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Intrauterine Devices (IUDs)


Frances E. Casey

, MD, MPH, Virginia Commonwealth University Medical Center

Reviewed/Revised Aug 2023 | Modified Oct 2023
Topic Resources

Intrauterine devices (IUDs) are small, flexible, T-shaped plastic devices that are inserted into the uterus. In the United States, 12% of women who use contraception use IUDs. IUDs are popular because of their advantages as a contraceptive method, including being highly effective and having minimal side effects. Also, IUDs need to be changed only every 3, 5, 8, or 10 years, avoiding the need to use a daily, weekly, or monthly contraceptive method.

IUDs must be inserted and removed by a doctor or other health care professional. Insertion takes only a few minutes. Insertion may be painful, so an anesthetic may be injected into the cervix before the IUD is inserted. Removal usually causes minimal discomfort.

IUDs prevent pregnancy by

  • Killing or immobilizing sperm

  • Preventing sperm from fertilizing the egg

  • Creating an inflammatory reaction inside the uterus that is toxic to sperm

Understanding Intrauterine Devices

Intrauterine devices (IUDs) are inserted by a doctor into a woman’s uterus through the vagina. IUDs are made of molded plastic. Two types of IUDs release a progestin called levonorgestrel. The other type is T-shaped and has a copper wire wrapped around the base and on the arms of the T. A plastic string is attached to the IUD. The string enables a woman to make sure the device is still in place and a doctor to easily remove it.

Understanding Intrauterine Devices

In the United States, available IUDs include levonorgestrel-releasing IUDs and a copper IUD.

Different levonorgestrel-releasing IUDs last for different lengths of time: 3, 5, or 8 years. For all types, pregnancy occurs only in less than 1.5% of women.

The copper IUD is effective for at least 10 years. When it is left in place for 12 years, fewer than 2% of women become pregnant.

One year after removal of an IUD, 80 to 90% of women who try to conceive do so.

Most women, including those who have not had children, and adolescent girls, can use IUDs. However, IUDs should not be used when the following conditions are present:

Personal beliefs that prohibit abortion do not prohibit the use of IUDs because IUDs do not prevent conception by causing a fertilized egg to be aborted. However, when used for emergency contraception Emergency Contraception Emergency contraception may be used to prevent pregnancy for a short period of time after unprotected sex. Emergency contraception decreases the chance of pregnancy after one episode of unprotected... read more after unprotected sex, a copper IUD or a levonorgestrel-releasing IUD may prevent a fertilized egg from becoming implanted in the uterus.

An IUD may be inserted at any time during the menstrual cycle if women have not had unprotected sex since their last period. If they have had unprotected sex, a pregnancy test must be done before an IUD is inserted, and women are advised to use another method of contraception until the test is done. Pregnancy must be ruled out before the IUD is inserted unless women wish to use an IUD as emergency contraception after unprotected sex. In such cases, a copper IUD may be inserted to prevent unwanted pregnancy. If inserted within 5 days of one episode of unprotected sex, a copper IUD is nearly 100% effective as emergency contraception. Then, if the woman wishes, it may be left in place for long-term birth control. A levonorgestrel-releasing IUD is not used for emergency contraception, and pregnancy must be ruled out before it is inserted.

Before the IUD is inserted, doctors may recommend testing for sexually transmitted infections (STIs) based on a woman's risk factors. However, doctors do not need to wait for STI test results before inserting the IUD. If results are positive, the STI is treated, and the IUD is left in place. If doctors observe a discharge that contains pus just before the IUD is to be inserted, an IUD is not inserted. In such cases, STI testing is done, and antibiotics are started immediately, without waiting for test results. The IUD is then inserted after treatment of the infection is complete.

Before insertion, an anesthetic may be injected into the cervix to decrease pain during insertion.

An IUD may be inserted immediately after a miscarriage or an abortion that occurs during the 1st or 2nd trimester and immediately after the placenta is delivered after a cesarean delivery.

The uterus is briefly contaminated with bacteria at the time of insertion, but an infection rarely results. IUD strings do not provide access for bacteria. An IUD increases the risk of a pelvic infection only during the first month of use. If an infection develops, it is treated with antibiotics. The IUD can be left in place unless the infection persists after treatment.

A routine follow-up visit after IUD insertion is not necessary. However, women should see their doctor if they have problems such as pain, heavy bleeding, abnormal vaginal discharge, or fever, if the IUD is expelled, or if they are dissatisfied with the IUD.

Possible problems

Bleeding and pain are the main reasons that women have an IUD removed, accounting for more than half of all removals before the usual replacement time. The copper IUD increases the amount of menstrual bleeding and may cause cramps. NSAIDs can usually relieve the cramps. Levonorgestrel-releasing IUDs cause irregular bleeding during the first several months after insertion. But then after 1 year, menstrual bleeding stops completely in up to 20% of women.

Typically, IUDs are expelled in fewer than 5% of women during the first year after insertion, often during the first few weeks. Sometimes a woman does not notice the expulsion. Plastic strings are attached to the IUD so that if she wishes, a woman can check every so often to make sure that the IUD is still in place. However, a woman typically has bleeding or pain if an IUD is expelled or is in the wrong position. If another IUD is inserted after one has been expelled, it usually stays in place. If doctors suspect that the IUD has been expelled, women must use another form of birth control until the problem is resolved.

Rarely, the uterus is torn (perforated) during insertion. Usually, perforation does not cause symptoms. It is discovered when a woman cannot find the plastic strings and ultrasonography or an x-ray shows the IUD located outside the uterus. An IUD that perforates the uterus and passes into the abdominal cavity must be surgically removed, usually using laparoscopy Laparoscopy Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more Laparoscopy , to prevent it from injuring and scarring the intestine.

If women conceive with an IUD in place, they are more likely to have a mislocated (ectopic) pregnancy. Nonetheless, the overall risk of an ectopic pregnancy is much lower for women using IUDs than for those not using a contraceptive method because IUDs prevent pregnancy effectively.

Possible benefits

Drugs Mentioned In This Article

Generic Name Select Brand Names
AfterPill, EContra EZ, EContra One-Step, Fallback Solo, Kyleena , LILETTA, Mirena, My Choice, My Way, Next Choice, Next Choice One Dose, Norplant, Opcicon One-Step, Plan B, Plan B One-Step , Preventeza, React, Skyla, Take Action
No brand name available
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