Implanon® - The Contraceptive Implant

What is the contraceptive implant?

A contraceptive implant is a small tube that is put under the skin. It contains a progestogen hormone. Implanon® is the only one prescribed in the UK at present. This is a tube 40 mm long and 2 mm wide (about the size of a hair grip).

How does the contraceptive implant work?

The progestogen hormone in the implant is released slowly into the bloodstream at a steady rate. The progestogen works mainly by stopping ovulation (the release of the egg from the ovary). It also thickens the mucus made by the cervix which forms a 'mucus plug' in the cervix. This stops sperm getting through to the uterus (womb) to fertilise an egg. It also makes the lining of the uterus thinner. This means that if an egg was to fertilise, it is not likely to be able to attach to the uterus.

How effective is the contraceptive implant?

It is more than 99% effective. This means that less than 1 woman in 100 who uses this method of contraception will become pregnant each year. (Compare this to when no contraception is used. More than 80 in 100 sexually active women who do not use contraception become pregnant within one year.)

What are the advantages of using a contraceptive implant?

• You do not have to remember to take a pill every day.
• You only have to think about contraception every three years.
• It does not interfere with sex.
• It can be used when breastfeeding.
• Period pain is usually less than usual.
• It can used by some women who cannot take pills that contain oestrogen.
• It may help protect against pelvic infection. (The mucus plug in the cervix may help to prevent bacteria from travelling into the uterus.)

What are the disadvantages of using a contraceptive implant?

The release of progestogen will usually cause changes to the pattern of periods. During the first year it is common to have irregular bleeding. Sometimes periods are heavier and longer than before. They usually settle back into a regular pattern after the first year, but may remain irregular. In some women the periods become infrequent and light, or even stop all together. One in five women with the implant have no bleeding. However, one in two have irregular bleeding which can be a nuisance.

If you do develop irregular bleeding after having the implant inserted then you should inform your doctor. Irregular bleeding can occasionally be due to another reason, for example an infection, which may need to be treated.

Who cannot have a contraceptive implant?

Your doctor or family planning nurse will discuss any current and past illnesses. Some illnesses may mean you cannot use progestogen based contraceptives such as Implanon®. However, the number of women this affects is small.

Are there any side-effects with the contraceptive implant?

As with all hormonal contraceptives, some women report side-effects such as breast discomfort, fluid retention and increase in acne. Some women actually find an improvement in their acne though. If side effects do occur they tend to develop in the first few months only. They often go after 3-6 months if the implant remains in. As with all small cuts to the skin there is a slight risk of a wound infection. The possible effects on periods are mentioned above.

There is no evidence that women with an implant in put on weight. It is also not associated with an altered sex drive or mood changes. It does not cause any thinning of your bones.

How is the contraceptive implant put under the skin?

• It is put in the inner side of the upper arm.
• It is usually first inserted within five days of a period starting. (This ensures that you are not pregnant.) It is effective from then on.
• An injection of local anaesthetic is used to numb the skin. A small cut is made and the implant placed under the skin. The wound is dressed and will soon heal just like any other small cut.
• The area around the implant may be bruised and sore for a few days, but this soon goes.

Do I need to be reviewed after the contraceptive implant is inserted?

You do not need to be routinely seen by your doctor or nurse after having your implant inserted. However, you can return at any time to discuss any problems. You should see your doctor or nurse if the following occur:

• You can not feel your implant.
• If you implant appears to have changed shape.
• If you notice any change in your skin or have any pain in the area around the implant.
• If you become pregnant.

When is the contraceptive implant taken out?

A replacement is needed every three years if you wish to continue with this form of contraception. It requires a small operation under local anaesthetic to remove it and put in a new one.

The implant can be taken out at any time if you request. It loses its effect immediately after being removed. So, if required, use other forms of contraception afterwards and for seven days before it is removed. This is because sperm can survive for up to seven days after sex.

There is no delay in your fertility returning after the implant is removed.

Do other medicines interfere with the contraceptive implant?

Some prescribed medicines may interfere with the progestogen (mainly some used for epilepsy and TB). Tell the doctor or pharmacist that you have a progestogen implant if you are prescribed another medicine. It is unlikely that a medicine bought without the need of a prescription will interfere. If in doubt, ask the pharmacist.

Further information

Your GP, practice nurse, and pharmacist are good sources of information if you have any queries.

The fpa (formerly the family planning association) also provide information and advice.
fpa's Helpline: 0845 310 1334 or visit their website www.fpa.org.uk