Once out of favour, IUDs – otherwise known as the coil – have made quite a comeback. Effective and ‘forgettable’, they’re one of the easiest ways of preventing pregnancy. But did you know there are two very different types of coil and that it can even be used as emergency contraception? From exactly how it works to who it’s best suited to, we sat down with Coyne Medical’s Dr Lucy Hooper for the lowdown…
How exactly does the coil work?
An intrauterine device, or IUD (sometimes called the coil) is a small T-shaped plastic and copper device that’s inserted into your womb by a specially trained doctor or nurse. There are two main types of coil that work in slightly different ways:
Copper coils release small copper ions into the womb, which act like a spermicide to kill sperm. In addition, the copper coil also prevents fertilised eggs from implanting in the womb.
Hormone coils work by releasing the hormone progesterone (similar to the mini pill) as it thickens the mucus at the entrance of the womb and thins the womb’s lining so a fertilised egg is unable to implant. The hormone coil (often referred to as an IUS and including the likes of Mirena) also prevents the ovaries from releasing mature eggs.
Who are they best suited to?
The coil is a fantastic choice for women who aren’t so good at remembering to take pills, as well as those who cannot take the pill because they have a history of blood clots or severe migraines.
Hormone-based coils are especially good at helping ease heavy periods and are most popular among women over the age of 45, especially those receiving oestrogen treatment for menopausal symptoms. The copper coil, on the other hand, is completely hormone-free, making it a great option for women who are keen to cut back on their exposure to hormones.
So how is the coil inserted?
To insert the coil, you’ll be asked to assume a similar position as for a smear test or gynaecology examination. Your doctor or nurse will usually perform an internal examination to ascertain the shape of your womb and may take swabs for STIs to remove the risk of infection. Next, a thin plastic tube is used to measure and insert the coil into the womb; this part can feel a little uncomfortable, and sometimes a local anaesthetic injection is given.
It’s common to get period-like cramps after the procedure and it’s a good idea to take some anti-inflammatory medication such as ibuprofen before and afterwards. There’s also evidence to suggest women who haven’t had children may find the insertion procedure a little more uncomfortable than those who’ve given birth.
What happens to your periods with the coil?
It’s common to have irregular and frequent bleeding in the first three months with both types of coil. Copper coils tend to make periods slightly more painful and heavier, while with the hormone coil periods often become lighter and less frequent over time. After 12 months, about 20% of women with a hormonal coil will have no periods, while 20% will continue to have irregular spotting.
Are there any side effects?
The most common reason women decide to have a coil removed early is erratic spotting and bleeding, which can be disruptive and annoying. If you have a tendency to get thrush or bacterial vaginosis infections, they can become more frequent too. Also, in the very unlikely event that a pregnancy occurs with a coil in place (this is very rare) then it's more likely to be an ectopic pregnancy, where a pregnancy develops outside the womb, usually in one of the fallopian tubes.
With hormonal coils, the progesterone can cause acne, breast tenderness and headaches in a small number of women.
What about weight gain?
Some studies have shown a very small weight gain with both types of coil, of approximately one to two kilos over five years. However, it’s been suggested that the weight gain seems to be related to getting a little older.
Will your partner be able to feel the coil during sex?
This is a very common worry for women, but unless there’s a problem with your coil, it’s rare that a man’s penis would be able to feel it during sex. The coil itself sits inside the womb, with two very fine threads hanging down through the cervix into the vagina – these threads tend to stick to the surface so it’s very unlikely a man would feel them.
Can the coil fall out?
There is around a one in 20 chance of a coil being expelled. This is most common in the first three months of having the coil fitted, so be sure to feel the threads of your coil at the cervix to check it’s in place.
How effective is the coil?
The coil is incredibly effective contraception; the chance of pregnancy is estimated at less than 1%. For reference, the failure rate for the combined contraceptive pill is estimated at 9%, with condoms even higher at 21%. The coil can even be used as an emergency contraceptive – it just needs to be inserted within five days of the episode of unprotected sex.
So in a nutshell…
The coil is a very effective form of contraception and works well for women who suffer from heavy periods or those who struggle to remember to take regular pills. However, whether you decide to opt for the hormone or copper version depends on your health and lifestyle – pop to your GP to discuss your options.