The IUS, known as the Mirena, is a more effective contraceptive than the combined contraceptive pill. Having the IUS fitted is a long-term solution to preventing pregnancy. It can also stop your periods, which is a huge advantage to many women.
We asked family doctor Sarah Jarvis what she would want to know if she was thinking of having an IUS fitted.
What's the difference between an IUS and an IUD?
Both the intrauterine system (IUS) and intrauterine device (IUD) are T-shaped contraceptive devices, about one-and-a-half inches long, that are fitted inside the womb. An IUD (the coil) is made with copper and doesn't contain any hormones. The IUS releases a tiny amount of the hormone progestogen into your womb. This stops the womb from sustaining a pregnancy.
Which is better for me?
Most women can have either fitted.
- Women who haven't had children usually prefer an IUD because the IUS is slightly larger.
- If you like having regular periods because it reassures you, consider having an IUD fitted.
- If you like the idea of having no periods, consider an IUS. An IUS can cause fairly irregular periods up to the first three to six months. But after a year, periods are more than 90% lighter and at least a third of women won't have periods at all.
How effective is the IUS as a contraceptive?
About 99.9% (as effective as sterilisation) and completely reversible.
Where do I go to have an IUS fitted?
It's likely there will be a GP at your surgery who can fit one. Alternatively, phone your local family planning clinic and check whether they provide this service.
Does it hurt and can I feel it once it is inside?
Having an IUS fitted is slightly more uncomfortable than a smear test and takes a bit longer. Sometimes, the doctor will use local anaesthetic while fitting it. Once it is in, you will usually get some period-type cramps. These tend to settle down within two to three days. After that, most people don't even know it is inside.
Will my partner be able to feel it during sex?
It's highly unlikely. However, he may be able to feel the little wire threads that we leave outside the womb (so we can pull the IUS out). If that's the case, when you go back for your IUS check-up, ask your GP if they can trim those threads. We like to keep them slightly longer for the first few weeks in case the womb pulls the device further up inside.
Can it ever fall out or dislodge?
It's very unlikely that it will move, but it's worth getting into the habit of putting a finger inside and checking you can still feel the threads. It occasionally falls out within the first few months of it being inserted, but after that, it is highly unlikely.
Can it cause any health problems, such as infections?
If you already have a low-grade infection, fitting an IUS can increase the chance of the infection going up into your womb and into your tubes. This can cause quite nasty problems. Your doctor or nurse will usually do some swab tests before you have the IUS fitted and will only fit it if your results are negative. Just having an IUS fitted shouldn't cause infection.
Can I use tampons?
Absolutely, just as normal.
How long should I keep it in?
The IUS can be used for up to five years. If you have an IUS fitted after the age of 45 (or an IUD after the age of 40), you can keep it in until you have gone through the menopause, when you no longer need contraception.
Is it easily removed?
It is very easy to remove. It is much easier to remove than it is to put in, and it takes a few seconds. When we fit the IUS, we leave some little wire threads outside so we can just pull it out.
Will I be fertile as soon as it is removed?
Yes. As soon as it is taken out, your fertility returns immediately.
Can I have one fitted if I haven't had children yet?
Yes. Some women find it slightly more uncomfortable to have fitted if they haven't had children, and the IUS tends to be a little more uncomfortable than the IUD as it is slightly larger. But there's no reason why you shouldn't have one.
Will my periods be affected?
The IUS tends to cause irregular bleeding for the first three to six months, but after that your periods tail off. Some women don't have periods at all after a year.
