Mechanical Methods of Contraception

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.