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Intrauterine devices & systems (IUDs & IUSs)

Intrauterine means something that sits inside your womb. An intrauterine device (IUD) or intrauterine system (IUS) is inserted into your womb through an opening in your cervix. Strings attached to the devices hang down into your vagina so a doctor or nurse can check the position of the device, and it can be removed. You and your partner will not feel these strings during sex.

Usually, an IUD or IUS is inserted by a specially trained GP, and you don't need any anaesthetic.

An IUD is a plastic and copper device that stops sperm from reaching the egg, and may also stop a fertilised egg implanting in the uterus. It does not contain any hormones. It is effective for five years and you can get it taken out at any time.

An IUS (or hormone IUD) is a plastic device that releases a small amount of the hormone progestogen, which acts like the natural hormone progesterone, into your womb. This thins the lining of your womb and thickens your cervical mucus, so that an egg can't be fertilised or implant into your womb and grow. It prevents some women from ovulating (releasing eggs).

Because an IUS thins your womb lining, most women using one have much lighter periods or no bleeding at all. This means it can also be used to control heavy periods. An IUS is effective for between three to five years.

You may want to compare the benefits of an IUD or IUS with the other types of long-acting contraceptives.

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Written by HealthInfo clinical advisers. Last reviewed August 2016.

In this section

Inserting an IUD or IUS (Mirena)

Page reference: 54617

Review key: HICAS-53138