Reviewed by Dr. Richard Galgano
An intrauterine device, or IUD, is a form of birth control that is inserted into the uterus and prevents pregnancy by interfering with the fertilization of eggs and the implantation of the eggs in the wall of the uterus, two crucial components of a successful pregnancy.
There are a number of ways to prevent pregnancy. These include condoms and diaphragms, which prevent the sperm from reaching the egg and fertilizing it, spermicides, which kill the sperm before it can get to the egg, and hormonal methods like the birth control pill and patch, which interfere with women’s menstrual cycles in several ways. These include the prevention of ovulation so no egg is produced and changing the uterus so that it’s inhospitable for eggs to become fertilized, or implant and grow in the uterus wall, as they would in a normal pregnancy. There are also permanent forms of birth control, such as surgical tubal sterilization, which ties off a woman’s fallopian tubes (the tubes that allow eggs to travel to the uterus from the ovaries) and vasectomy, surgery that ties off tubes called the vas deferens in a man’s testicles, and prevents sperm from mixing with the seminal fluid that is released during ejaculation.
Another method that can be used to prevent pregnancy is the IUD, a small device that is inserted into the uterus and can be left there for a number of years before it must be removed and either replaced or exchanged for another form of birth control. IUDs are available by prescription, and there are a variety of IUDs available in various countries all over the world; in fact Planned Parenthood and the Feminist Women’s Health Center, two non-profit organizations dedicated to facilitating women’s reproductive health, note that IUDs are the most widely used form of reversible birth control in the world.
Because the uterus can prepare for a successful pregnancy only if there is a special balance of hormone and chemical levels in the body, as well as unobstructed release of eggs from the ovaries and a healthy uterine lining that allows successful implantation of the fertilized egg, the presence of an object that interferes with all or any of these processes can prevent pregnancy. There are two types of IUD available in the United States, and both of them interfere with at least two of these processes:The ParaGuard IUD is a small, plastic device with a copper wire wrapped around it. The copper in ParaGuard inhibits sperm motility and function. This prevents them from reaching and fertilizing the egg. The IUD also causes the lining of the uterus to become inflamed which results in sperm death.Mirena is a small plastic device that contains trace amounts of synthetic progesterone, and has several effects. Cervical mucous thickens which blocks entry of sperm into the uterus. Uterine fluid composition also changes, which impedes the movement of sperm. The endometrium may become slightly inflamed, which prevents a fertilized egg from implanting. Lastly, a small percentage of women will not ovulate (produce an egg) when using this IUD.
Both types of IUD are inserted in the uterus through the cervix, typically during menstruation. Most doctors require a record of a healthy gynecological exam and Pap smear within the previous six months as well, before they will prescribe an IUD. Insertion usually takes between five and fifteen minutes, and must be done by a gynecologist or other qualified women’s health care clinician.
In order for the IUD to be inserted, the vagina is held open with a device called a speculum, and cervix is held steady with an instrument called a tenaculum. Another device called a “sound” may be inserted through the cervix to determine the length of the cervical canal and of the uterus. Once the clinician has put any necessary instruments in place, the IUD is inserted through the cervix via a narrow tube, then pushed out of the tube and into the uterus using a plunger (a device which works similarly to a syringe).
During insertion, women will experience a cramping sensation. For some women, this cramping may be very painful, but generally dies down after a minute or two, possibly followed by less intense cramps that feel similar to menstrual cramps. In rare cases, women may faint or feel dizzy, so it may be best to bring a friend or partner along to make sure they have a supportive person nearby, as well as a ride home. Women with especially sensitive cervixes (for example, those who find pap smears painful, or those who had an especially painful insertion in the past) may find that a local anesthetic administered to the cervix can reduce the cramping to a tolerable level, and should not be afraid to ask their clinician about this option.
Once the IUD is in the uterus, little “arms” spring out from its sides, so that it looks like a small T. A small string that runs from the IUD outside of the cervix and into the top of the vagina will remain in place so that the device can be removed more easily when the time comes, and so that the woman can check for the strings each month to be sure the device is in place. The string can be trimmed by the clinician if it is too long, and cannot be felt during sex.
IUDs are between 98 and 99 percent effective in preventing pregnancy. In very rare cases, women have experienced uterine punctures and infection of the fallopian tubes, but again, these outcomes are extremely unusual and often connected to another condition or a faulty insertion. The most common drawbacks of IUDs, aside from a potentially painful insertion, are increased menstrual cramping and flow (especially common during the first few months). On the other hand, IUDs can add spontaneity to women’s sex lives, are one of the most reliable forms of birth control available, and after the body gets used to them menstrual flow may even be reduced, with as many as 30 percent of women no longer having periods after the first few months.
Women with a history of sexually transmitted diseases (STDs) including HIV/AIDS, uterine scarring, certain clotting disorders of the blood, or ovarian cancer should not use IUDs. Also, it is important to remember that ONLY latex barrier methods (such as condoms as dental dams) or abstinence can prevent infection with STDs. Until both partners have been tested and are committed to a monogamous relationship, additional forms of birth control should be used to prevent the spread of STDs.
Last updated: 06-Jun-07