An abbreviation for intrauterine contraceptive device. An IUD, which is also known as an IUCD or coil, is a mechanical device that is inserted into the uterus for purposes of contraception. Most IUDs are plastic devices with either copper or silver incorporated to improve their effectiveness. One type of IUD releases small amounts of the progestogen hormone levonorgestrel and is sometimes known as an intrauterine system (IUS). IUDs are believed to inhibit the implantation of a fertilized egg in the wall of the uterus (see implantation, egg). An IUD is inserted through the vagina and cervix into the uterine cavity. Once in position, an IUD provides immediate protection. Most IUDs have a plastic string attached to make removal easier and also to indicate its presence when in place. IUDs usually need to be replaced every 3–8 years. Women who have been pregnant are less likely to have complications than women who have never been pregnant. For example, they may experience less pain on insertion and have lighter menstrual flow and lower expulsion rates. IUDs are usually not recommended for women with fibroids or an irregular uterine cavity. If menstrual flow is heavy, or there is a history or increased risk of pelvic inflammatory disease (PID), a progestogen IUD may be recommended. Rarely, pregnancy can occur, although IUDs seldom cause problems and can be removed. Nonprogestogen IUDs increase the risk of PID, which can lead to permanent infertility. A rare complication of IUD use is perforation of the uterus, which most commonly occurs at the time of insertion.


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