Contraceptive implants

Written by Dr David Delvin, GP and family planning specialist

When could I have it done?

Generally, Implanon is inserted during the first five days after the start of your period – mainly to ensure that you're not pregnant. The device can also be put in soon after childbirth, with the insertion generally being carried out when baby is three to four weeks old.

The device does not interfere with breastfeeding.

Is there anybody who shouldn't have an Implanon?

Yes. You shouldn't have one fitted if you're experiencing undiagnosed vaginal bleeding, or if you have severe liver disease, or are suffering from thrombosis. A history of certain types of cancer makes Implanon inadvisable.

There are a few other medical conditions (including a past history of 'pregnancy itch') which may make the doctor or nurse reluctant to put in an Implanon; more details from them.

Also, Implanon has been linked with cysts in the ovary. So if you've had an ovarian cyst, this is probably not the method for you.

Very importantly, larger women may find that Implanon isn't 'strong' enough to protect them against pregnancy. For example, if your Body Mass Index is over 35kg./sq.metre, the doctors may advise you that you shouldn't rely on it during the third year of use, when it could be producing less hormone. And if you are very big, you may not be able to use it at all.

Does Implanon react/interfere with any drugs?

Not to the same extent that the Pill does. For example, you can take antibiotics without lowering the efficiency of the implant.

However, its effectiveness can be reduced by certain pills, notably ones for tuberculosis such as rifampicin and rifabutin and some drugs for epilepsy such as phenytoin, carbamazepine, phenobarbital and primidone.

Most important: the popular herb St John's wort should not be used by women who have an implant.

What are the side-effects of Implanon?

There are quite a few, the main one being frequent or prolonged vaginal bleeding – which may affect a fifth of all users. But some women get no periods – and are very pleased about that!

Other possible side-effects include:

headache

spots

weight gain

breast tenderness

dizziness

depression

changes in level of sexual desire.

For a full list, read the product leaflet, or talk to the Family Planning nurse or doctor.

Is it true that an implant can 'wander' around a woman's body?

Occasionally, an Implanon can't be felt where it's supposed to be – ie under the skin of the upper arm.

In this event, you'd need an ultrasound scan to find the device. Frequently, the ultrasound reveals that the implant was simply pushed in too deeply during insertion.

In other cases, the problem turns out to be that the woman has just put on a bit of weight - so that the Implanon is now a little hidden by fat.

In January 2005, a leading medical journal published a report of two cases in which Implanons had managed to move a few inches upwards under the skin (possibly as a result of vigorous exercise). This is not a serious matter.

True 'migration' of the device within the body is very rare indeed, with only six instances having been recorded up to 2005.

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