Mirenas and Coils

A Mirena (IUS) or coil (IUD) may be required for contraception purposes or for hormones purposes.

The Mirena is an intrauterine coil which delivers progestogen directly into the uterus, thus avoiding absorption into the circulation. It has all the benefits of protecting the uterus from abnormal changes, it suppresses bleeding usually by around 3-6 months post-fitting and it suppresses the cyclical swings of oestrogen hormones which can be debilitating to some women. It works by releasing progestogen, which is a synthetic version of the hormone progesterone and also acts as a contraceptive. It thickens the cervical mucus, which makes it more difficult for sperm to move through the cervix and thins the lining of the womb so an egg is less likely to be able to implant itself.

The copper coil works by releasing copper. The copper in the IUD stops sperm and eggs from surviving. It also changes your cervical mucus to stop sperm from reaching an egg. An IUD may also work by stopping a fertilised egg from implanting in the uterus.

For some people, both devices can also prevent the release of an egg each month (ovulation), but most people continue to ovulate.

It is fitted into the uterus through the vagina after inserting an instrument called a speculum (similar to that used for a cervical smear). Local anaesthetic can be used to ensure the procedure is as comfortable as possible. 

After having the coil fitted you may have:

• Some cramping similar to period pains
• Some light bleeding

These should settle quickly and you should be able to manage any pain by taking over-the-counter painkillers like ibuprofen and paracetamol.