What is an intrauterine device (IUD)?

The intrauterine device (IUD), previously also called a coil or loop, is a birth control device placed into a woman's uterus by a medical professional. It can stay in the uterus for 1 to 10 years. It is usually made of plastic or metal with a string attached. Some IUDs contain copper or the female hormone progesterone.

The IUD prevents pregnancy by changing the physical environment of the reproductive tract. These changes prevent the egg from being fertilized or implanting and growing in the uterus.

There has been some controversy over the use of the IUD because of its association with pelvic infections. If you have ever had heavy menstrual bleeding, an infection in any of your reproductive organs (ovaries, uterus, fallopian tubes), or a pregnancy in your tube, talk to your health care provider about the risks of using an IUD.

How is it used?

A medical professional inserts the IUD into the uterus through the cervix (opening of the uterus). The IUD is usually inserted during a menstrual period, when the cervix is slightly open and you are least likely to be pregnant. It takes only a few minutes to insert an IUD. You may feel some cramping pain when the IUD is being inserted. You may be given a local anesthetic to help control discomfort during insertion.

During the first few months after insertion of an IUD, check often for the attached string to be sure that the IUD is still in the uterus. You should also check for the string after every menstrual period. You can do this by putting a finger inside the vagina and feeling for the string near the cervix. As long as you can feel the string, the IUD is in position and it is unlikely that you will become pregnant. If you feel the hard plastic of the IUD, it is no longer in the correct place and you will have to see your health care provider to change it.

The IUD could come out accidentally in the first few months, possibly without being noticed. Check the IUD before each time you have intercourse or consider using a backup method of birth control during the first few months, just to be safe.

You may be able to have an IUD from 1 to 10 years before it needs to be replaced. Usually progesterone IUDs are replaced after 1 year. Copper IUDs may be left in the uterus for up to 10 years.

What are the benefits?

The benefits of an IUD are:

• It is 97% effective as a method of preventing pregnancy.

• Love-making does not need to be interrupted by the insertion of a birth control device or spermicide.

• Replacement is required only every 1 to 10 years, depending on the type.

What are the risks?

A number of problems could occur while you are using an IUD, some of which can be severe. These problems are listed below (the first two are the most common):

• increased menstrual bleeding and cramps, mostly during the first few months of use

• spotting between menstrual periods

• irritation of your partner's penis

• increased risk of pelvic inflammatory disease, which can lead to infertility

• unnoticed accidental expulsion of the IUD, which may result in unexpected pregnancy

• embedding of the IUD in the uterine wall

• perforation of the uterus by the IUD, with possible damage to other organs as well as internal bleeding

• potential problems if pregnancy occurs with an IUD in place, including an increased risk of ectopic (tubal) pregnancy and miscarriage.

When should I call my health care provider?

Call if you:

• Cannot find the IUD string.

• Have vaginal discharge with a bad odor.

• Have severe, unexpected pain in your lower abdomen, especially if it happens when you have intercourse.

• Have a fever with no apparent cause.

• Think you might be pregnant with the IUD still inside the uterus.

• Want to have the IUD removed.