A Coil is a small plastic T-shaped device which is placed inside your womb (uterus) to prevent you from getting pregnant. It has one or two thin threads on the end that hang through your cervix (the entrance to the uterus) into the top of your vagina. These threads cannot be felt and are not uncomfortable.
Once in place a coil can work for several years. It can also be easily removed should you wish to become pregnant or change your contraceptive method.
Your fertility will return to normal as soon as the coil is removed.
A coil works by stopping sperm meeting the egg, which prevents fertilisation. They may also work by preventing a fertilised egg from implanting into the womb. Coils are over 99% effective and over 5yrs, less than 5 in 1000 people using a coil will become pregnant. The coil is much more effective at preventing pregnancy than using pills or condoms.
There are 2 types of coil; the copper coil and the hormone containing coil.
The Copper coil – IUD (works for either 5 or 10yrs)
The copper coil is also known as the intrauterine device (IUD). This coil works by stopping the sperm from fertilising the egg and preventing implantation. It starts to work immediately after it is fitted and is effective for 5 or 10 years depending on which type of copper coil is inserted.
This coil does not contain any hormones and will not cause any hormonal side effects. It will generally not change the regularity of your periods. Some people may experience longer, heavier and more painful periods with this type of coil but this can settle over time.
The copper coil can also be used for emergency contraception.
The Hormone containing coil - IUS (5yrs)
This type of coil is also known as the intrauterine system (IUS). These coils contain a hormone called progestogen. This hormone makes the lining of the womb thin so that an egg cannot implant. It also makes the mucus at the neck of the womb thicker so sperm can’t get in. After insertion it takes 7 days before the coil is effective and its contraceptive effect lasts for 5 years.
Because of the effect of progestogen on the lining of the womb (uterus) these coils can lead to changes in bleeding pattern. Bleeding may become erratic and /or persistent in the beginning but this usually settles down over the first 3-6 months after insertion. Once the bleeding has settled many people may have lighter, infrequent bleeding or they may have no bleeding at all. Bleeding may also become less painful.
A few people experience hormonal side effects such as acne, breast tenderness, headaches and mood changes. These will also often settle with time.
These hormone containing coils can also be used to treat people with heavy painful periods and can also be used as part of Hormone Replacement Therapy.
The Sexual Health Service are unable to offer coil insertions to people who require a coil fit for non-contraceptive reasons. For example: if you need a coil fitting for heavy periods or HRT but do not require it for contraception, or you or your partner has had a sterilisation/vasectomy procedure in the past, WE WILL BE UNABLE to provide this. Please contact your GP to arrange the fitting elsewhere.