Intrauterine Devices (IUDs)

The intrauterine device (IUD) is a method of birth control designed for a woman. The IUD is a small “T” made of molded polyethylene plastic coated with barium so that, if need be, it can be seen on X-ray.

When inserted into the uterus, the arms of the “T” are folded down, but they then open out to form the top of the “T”. The device rests inside the uterus with the base of the T just above the cervix and the arms of the T extending horizontally across the uterus.

A short plastic string attached to the IUD extends through the cervix into the vagina. This string makes it possible to be sure that the IUD is still in the uterus.

Intrauterine devices (IUDs) come in two different types:

 
• Intrauterine contraceptive device (IUCD): This device is made of copper and releases copper from a copper wire that is wrapped around the base. Examples of IUCDs include the ParaGard, Copper 7, and Mini-7.  
• Intrauterine system (IUS): This form of IUD releases the hormone progesterone from the vertical part of the T. Examples of IUSs include Progestasert and Mirena.

It is not known fully how IUDs work. They are thought to prevent conception by causing a brief localized inflammation that begins about 24 hours after insertion. This causes an inflammatory reaction inside the uterus that attracts white blood cells. The white blood cells produce substances that are toxic or poisonous to sperm. The progesterone-releasing IUDs cause a subtle change in the endometrial environment that impairs the implantation of the egg in the uterine wall. This type of IUD also alters the cervical mucus, which, in turn, inhibits sperm from passing through the cervix.

IUDs are only available by prescription and must be properly inserted by a health care professional. A pelvic exam is required to insert an IUD. The IUD is usually inserted into the uterus during a woman’s menstrual period although it can be done at any time during her monthly cycle as long as she is not pregnant.

The woman must check her IUD every month to be sure that the IUD is still in place. Sometimes, the uterus expels (pushes out) the IUD. The spontaneous expulsion rate is 10% during the first year of use, and it is even higher in younger women or in women who have never given birth. It is estimated that 20% of IUD expulsions are overlooked. In addition to the woman checking the IUD, the device must also be checked periodically by a health care professional.

Side effects of the IUD are limited primarily to the uterus. These include cramps, spotting, heavy menstrual flow, infection, pelvic inflammatory disease (PID) and infertility. It is also possible for the IUD to pass through (perforate) the uterine wall and enter the abdominal cavity, where it must be retrieved surgically. Perforation of the uterus by the IUD occurs in 1/1,000 insertions. Warning signs of possible complications from an IUD include abdominal pain, heavy bleeding, abnormal spotting or bleeding, and a smelly discharge. If a woman experiences any of these signs, she should contact her health care professional.

An IUD may not be appropriate for women who have heavy menstrual bleeding, had previous pelvic infections, have more than one sexual partner, or plan on getting pregnant. This is because IUD’s do not protect against sexually transmitted infection and should not be in place if a woman intends to become pregnant. If women become pregnant with their IUDs in place, 55% of the pregnancies end in miscarriage. Users of non-progesterone types of IUDs are 50% less likely to have an ectopic pregnancy compared to women using no contraception. When a woman using an IUD does become pregnant, the pregnancy is more likely to be ectopic, but still ectopic pregnancy in a user of an IUD is a rare occurrence. Serious complications due to infection associated with an IUD may prevent a woman from being able to become pregnant in the future. Also, with the progesterone-releasing IUD (levonorgestrel IUD), 70 percent of women notice a gradual lessening of menstrual bleeding after two years of use and 30 percent may notice a complete cessation of menses. This is because the progesterone hormone can cause thinning of the lining of the uterus. These menstrual changes are not dangerous in any way and do not mean that the contraceptive action of the IUD is diminished.

The IUD provides no protection against sexually transmitted infections.

The advantages of the IUD include the fact that it is highly effective in preventing conception and starts working almost immediately. A woman with an IUD does not need to use other birth control methods before she has sexual intercourse, and once the IUD is removed, there is a quick return to fertility. The Progestasert (progesterone) IUD has 98% effectiveness and needs to be replaced once a year. The Mirena (99% effectiveness) and is replaced every 3-5 years. The copper Paragard is 99% effective and only needs replacing every 10 to12 years.

Although 25 to 30% of European women use the copper IUD, less than 1% of American women use an IUD, in large part because of adverse publicity and litigation over an IUD called the Dalkon Shield. More than 10,000 lawsuits were filed by women who had used the Dalkon Shield. These women claimed primarily that the Dalkon Shield, which had a multifilament string that allowed bacteria to travel from the vagina up into the uterus, caused them to contract pelvic inflammatory disease. The IUDs in use today have a monofilament nylon string (much like fishing line) that reduces the risk of pelvic inflammatory disease. As a result of this and other improvements, both the World Health Organization (WHO) and the American Medical Association (AMA) consider IUDs to be one of the safest and most effective forms of reversible contraception that a woman can use.

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SOURCE: Archives of Pediatrics & Adolescent Medicine