Iud - Intrauterine Device

The Basics

The letters "IUD" stand for "intrauterine device."

IUDs are small, "T-shaped" contraceptive devices made of flexible plastic. IUDs are available by prescription only. A woman and her clinician decide which is the right type for her, and the clinician inserts it in her uterus to prevent pregnancy. Two types are now available in the U.S.:

* ParaGard (Copper T 380A) -- contains copper and can be left in place for 12 years

* Mirena -- continuously releases a small amount of the hormone progestin, and is effective for five years

How IUDs Work

Both kinds of IUDs work by preventing sperm from joining with an egg by affecting the way they move. The hormone in Mirena increases effectiveness. It thickens cervical mucus, which provides a barrier that prevents sperm from entering the uterus. It also prevents some women's ovaries from releasing eggs (ovulation).

IUDs also alter the lining of the uterus. In theory, this may prevent pregnancy by preventing the implantation of a fertilized egg -- but this has not been scientifically proven.

IUDs have a string attached that hangs down through the cervix into the vagina. A woman can make sure the IUD is in place by feeling for the string in her vagina. A clinician uses the string to remove the IUD.

Effectiveness

The IUD is one of the most effective reversible methods of birth control. Of 100 women who use ParaGard or Mirena, one or fewer will become pregnant during the first year of typical* use. Fewer than one will become pregnant with perfect** use. Fewer pregnancies occur with continued use.

It is very important to remember that the IUD does not protect against sexually transmitted infections. Use a latex or female condom with the IUD to reduce the risk of infection.

*Typical use refers to failure rates for women whose use is not consistent or always correct.

**Perfect use refers to failure rates for those whose use is consistent and always correct.

Advantages

IUDs are the most popular form of reversible birth control in the world. More than 85 million women use them.

IUDs may improve a woman's sex life. There is nothing to put in place before intercourse to protect against pregnancy. Some women say they feel free to be more spontaneous because they do not have to worry about becoming pregnant.

ParaGard does not change a woman's hormone levels.

Mirena may reduce menstrual cramps and flow. Average flow is reduced by 90 percent. Flow stops altogether for about 20 percent of women within one year. Reduced flow may reduce iron deficiency anemia.

The ability to become pregnant returns quickly when IUD use is stopped.

The IUD is one of the most private methods of birth control. No one can tell you're using it. There is no packaging or other evidence of use that might embarrass some users.

The IUD as Emergency Contraception

The ParaGard IUD can reduce the risk of pregnancy by 99.9 percent if inserted within five days after unprotected vaginal intercourse.

Possible Side Effects

Possible side effects that usually clear up after the first several weeks to months include --

* changes to menstrual flow

o Spotting between periods is common with IUD use.

o ParaGard may cause a 50 to 75 percent increase in menstrual flow. In some cases this may lead to anemia.

* menstrual cramps or backaches

Possible Complications

Serious problems with the IUD are rare. Report problems to your clinician right away to avoid further complications.

Expulsion -- Occasionally, the IUD will partially or completely slip out of the uterus. It is more likely among younger women and women who have never had a baby. If it happens, a woman can become pregnant. If partially expelled, the IUD must be removed.

Perforation -- Very rarely, the IUD is pushed through the wall of the uterus during insertion. Although it sounds painful, it usually isn't. Perforation is usually discovered and corrected right away. If not, the IUD can move into other parts of the pelvic area, and could damage internal organs. Sometimes surgery is needed to remove the IUD.

Infection -- Pelvic infection associated with IUD use is rare. It is caused by bacteria getting into the uterus during insertion. Most infection develops within three weeks of insertion. Infection after three weeks is very rare. It usually happens through exposure to sexually transmitted infections such as chlamydia or gonorrhea. Pelvic infections left untreated can cause sterility.

Tell your clinician immediately if you ...

* find that the string length has become shorter or longer

* are not able to feel the string

* feel the hard plastic bottom of the "T" of the IUD against the cervix

* think you might be pregnant

* have periods that are much heavier or last much longer than usual

* have

o severe abdominal cramping, pain, or tenderness in the abdomen

o pain or bleeding during sex

o unexplained fever and/or chills

o flu-like symptoms - muscle aches, fatigue

o unusual vaginal discharge

o a missed, late, or unusually light period

o unexplained vaginal bleeding

Pregnancy -- Most pregnancies happen to IUD users when their IUDs slip out without their knowing it. The chance that a pregnancy will happen while an IUD is in place is very low. If it does happen, have the IUD removed, if at all possible, as soon as you know you're pregnant. Women who choose to complete a pregnancy with an IUD in place must have close medical supervision throughout their pregnancy.

If you are pregnant with an IUD in place,