Intra-Uterine System (IUS)

If 100 sexually active women don’t use contraception, 80–90 will become pregnant in a year.

The IUS is over 99 per cent effective. Less than one woman in every 100 women who use the IUS will get pregnant over five years.

• It makes the lining of your uterus thinner so it is less likely to accept a fertilised egg

• It also thickens the mucus in your cervix. This makes it difficult for sperm to move through it and reach an egg

• In some women it stops the ovaries releasing an egg (ovulation), but most women who use an IUS continue to ovulate

• An IUS does not cause an abortion

• It works for five years.

• Your periods usually become much lighter and shorter, and sometimes less painful.

• Periods may stop completely after the first year of use.

• An IUS can be useful if you have heavy, painful periods.

• It can be used if you are breastfeeding.

• Most people can use this method including those with HIV.

• Your fertility will return to normal when the IUS is removed.

• It is useful if you cannot use estrogens, like those found in the combined contraceptive pill.

• The IUS is not affected by other medicines.

• Your periods may change in a way that is not acceptable to you

• A few women may get acne, headaches and breast tenderness, especially in the first few months and this usually improves over a few months.

• Some women develop small fluid-filled cysts on their ovaries. These are not dangerous and do not usually need to be treated. These cysts usually disappear without treatment.

• An IUS does not protect you against sexually transmitted infections (STIs), so you may need to use condoms as well.

Your periods will change; in the first six months it is common to have irregular bleeding or spotting.

Periods may become lighter than usual or may continue to be irregular and many women find that their periods stop altogether. If this happens to you, do not worry, this is not harmful.

Some of the conditions which may mean you should not use an IUS are:

• You think you might already be pregnant

You have now or had in the past:

• Breast cancer or breast cancer within the last five years

• Cirrhosis of the liver and liver tumours

• Unexplained bleeding from your vagina (for example between periods or after sex)

• Arterial disease or history of serious heart disease or stroke

• An untreated sexually transmitted infection or pelvic infection

• Problems with your uterus or cervix

The doctor or nurse will teach you how to feel the threads to make sure the IUS is still in place. It is very unlikely that an IUS will come out, but if you cannot feel the threads, or if you think you can feel the IUS itself, you may not be protected against pregnancy. See your doctor or nurse straight away and use an extra contraceptive method, such as condoms. If you had sex recently you might need to use emergency contraception

Rarely, a partner may say they can feel the threads during sex. If this is the case, get your doctor or nurse to check the threads.

Taking an IUS out is a simple, quick procedure. If you are not going to have another IUS put in, and you don’t want to become pregnant, use additional contraception, such as condoms, for seven days before the IUD is taken out