An IUS is a small, T-shaped plastic device that is inserted into your womb (uterus) by a specially trained doctor or nurse.

The IUS releases a progestogen hormone into the womb. This thickens the mucus from your cervix, making it difficult for sperm to move through and reach an egg. It also thins the womb lining so that it's less likely to accept a fertilised egg. It may also stop ovulation (the release of an egg) in some women.

The IUS is a long-acting reversible contraceptive (LARC) method. It works for between three and five years, depending on the type, so you don't have to think about contraception every day or each time you have sex. Three brands of IUS are used in the UK – Mirena, Levosert and Jaydess.

You can use an IUS whether or not you've had children.

The IUS is similar to the IUD (intrauterine device), but works in a slightly different way. Rather than releasing copper like the IUD, the IUS releases a progestogen hormone, which is similar to the natural hormone progesterone that's produced in a woman's ovaries.

Progestogen thickens the mucus from the cervix (opening of the womb), making it harder for sperm to move through it and reach an egg. It also causes the womb lining to become thinner and less likely to accept a fertilised egg. In some women, the IUS also stops the ovaries from releasing an egg (ovulation), but most women will continue to ovulate.

If you're 45 or older when you have the IUS fitted, it can be left until you reach menopause or you no longer need contraception.

Although we do not fit coils in Crookston Medical Centre, an IUS can be removed by our practice nurses/GP's if required. 

Although an IUS is an effective method of contraception, there are several things to consider before having an IUS fitted.

Advantages of an IUS

• It works for up to five years.
• It's one of the most effective forms of contraception available.
• It doesn't interrupt sex.
• An IUS may be useful if you have heavy or painful periods because your periods usually become much lighter and shorter, and sometimes less painful – they may stop completely after the first year of use.
• It can be used safely if you're breastfeeding.
• It's not affected by other medicines.
• It may be a good option if you can't take the hormone oestrogen, which is used in the combined contraceptive pill.
• Your fertility will return to normal when the IUS is removed.

Disadvantages of an IUS

• Some women won't be happy with the way that their periods may change. For example, periods may become lighter and more irregular or, in some cases, stop completely. Your periods are more likely to stop completely with Mirena or Levosert than with Jaydess.
• Irregular bleeding and spotting are common in the first six months after having an IUS fitted. This is not harmful and usually decreases with time.
• Some women experience headaches, acne and breast tenderness after having the IUS fitted.
• An IUS doesn't protect you against STIs, so you may also have to use condoms when having sex. If you get an STI while you have an IUS fitted, it could lead to pelvic infection if it's not treated.
• Most women who stop using an IUS do so because of vaginal bleeding and pain, although this is uncommon. Hormonal problems can also occur, but these are even less common.

• It's more than 99% effective. Less than one in every 100 women who use Mirena will get pregnant in five years, and less than one in 100 who use Jaydess will get pregnant in three years.
• It can be taken out at any time by a specially trained doctor or nurse and your fertility quickly returns to normal.
• The IUS can make your periods lighter, shorter or stop altogether, so it may help women who have heavy periods or painful periods. Jaydess is less likely than Mirena or Levosert to make your periods stop altogether.
• It can be used by women who can't use combined contraception (such as the combined pill) – for example, those who have migraines.
• Once the IUS is in place, you don't have to think about contraception every day or each time you have sex.
• Some women may experience mood swings, skin problems or breast tenderness.
• There's a small risk of getting an infection after it's inserted.
• It can be uncomfortable when the IUS is put in, although painkillers can help with this.
• The IUS can be fitted at any time during your monthly menstrual cycle, as long as you're definitely not pregnant. Ideally, it should be fitted within seven days of the start of your period, because this will protect against pregnancy straight away. You should use condoms for seven days if the IUS is fitted at any other time.
• The IUS does not protect against sexually transmitted infections (STIs). Use condoms as well as the IUS, to protect yourself against STIs.