Sitting in the bathroom, I am looking apprehensively towards the pregnancy test on the bench. My heart is pounding as I reach out to turn it over. Then I let out a huge sigh of relief: I’m not pregnant.

But, of course, I shouldn’t be. That’s because I’ve had the contraceptive implant Implanon in my arm for more than a year.

This matchstick-sized rod is designed to release hormones that prevent pregnancy. Licensed in 1999, it has become a ?popular form of ?contraception, with around 800,000 women using it, according to Department of Health estimates.

Implanon: The matchstick-sized rod is implanted in the arm to release hormones that simulate pregnancy (posed by models)

After a local anaesthetic, the implant is inserted into your upper arm through a tiny cut — you can just feel it under your skin.

It works by gradually releasing the ?synthetic ?hormone etonogestrel into the bloodstream, which fools the body into believing it’s pregnant. This stops eggs maturing in the ovaries and the womb becomes a hostile environment to sperm.

Implanon is designed for women who don’t want any more children, but don’t want to be sterilised, or who want long-lasting contraception (the device lasts for three years, when you then ?simply have it replaced).

And there are lots of plus points. Unlike the Pill, very few medicines affect Implanon (St John’s Wort is one that does). Nor do you have to worry about Implanon if you have a stomach bug (unlike with an oral contraceptive).

You also don’t have to ?remember to take it. No wonder so many women like the idea of it.

But last week it emerged that hundreds of women have been permanently scarred or become pregnant after their implant ?apparently failed — 584 have reported unwanted pregnancies and 1,607 ?complained about the implant going wrong.

As well as these side effects, the National ?Institute for Clinical Excellence (NICE) states that almost half of women will have infrequent, ?frequent or prolonged bleeding. Up to 43 per cent stop using it within three years — 33 per cent because of irregular ?bleeding.

That’s a lot of dissatisfied customers. I am one of them. for me, Implanon has been a nightmare from day one, starting with almost ?constant heavy bleeding for the first five months, which ?inexplicably stopped suddenly.

I then had all the ?symptoms of pregnancy — sore breasts, exhaustion, going off ?certain food. This was the reason I took the pregnancy test. it was to be the first of three such scares.

It really was terrifying because I nearly ?haemorrhaged to death after giving birth to my third child (I have a son aged two, and daughters who are four and six). I’m 38, and my husband and I have no ?intention of having any more children; we’re lucky to have three who still have a mother.

Health issues aside, we simply can’t afford another child. when I first went to my GP, just a couple of months after my son Ben’s birth, Implanon seemed like the only viable option (I can’t take the Pill because, with a history of migraines, it puts you at risk of stroke).

It sounded brilliant. Quite apart from the convenience, statistically, there is no question that Implanon performs extremely well.

‘though the Pill and Implanon are quoted as being over 99 per cent effective, that’s with ?correct usage,’ says Dr Alyson ?Elliman, vice-president of the ?Faculty of Sexual and Reproductive Healthcare of the Royal College of Obstetrics and Gynaecology.

‘The actual failure rate is more like 0.05 per cent in Implanon and 8 per cent with the Pill in real-life situations.’

Personal choice: Implanon is more convenient than taking a daily pill but can have adverse side effects (posed by model)

But there are those adverse effects. ‘Bleeding patterns may be affected,’ says Dr Elliman.

This is because the membranes ?lining the uterus can be affected. ‘but any method of ?contraception that targets egg release may cause erratic bleeding,’ she says.

Skin problems such as acne may also be ?exacerbated and you might ?experience breast tenderness.

A week after my first pregnancy scare, the bleeding started again. I was sufficiently concerned about it to return to the private gynaecologist who looked after me following the traumatic birth of my son.

He conducted various ?investigations — ultrasounds and even a biopsy — to ascertain whether something more sinister going on, but concluded that the Implanon was at fault.

He suggested that I find an ?alternative method of contraception — advice I foolishly ignored.

A few months later, I returned to my GP. The almost incessant ?bleeding was starting to affect our family life and holidays. but my GP was reluctant to remove the implant (another option, the Mirena coil, can also cause bleeding or spotting for the first six months).

My second pregnancy scare was highly traumatic and occurred a couple of months after the first. I was suffering all the symptoms, but despite taking test after test over a week, the results were all negative. but the symptoms were so strong I assumed I didn’t have sufficient ?levels of pregnancy hormones in my body to show up on the tests.

One evening I sat my ?husband down and, in floods of tears, asked him what we’d do. The thought of abortion is hideous at any time; if you have children, I think it an ?especially hard choice.

Throughout all this stress was the frustrating fact that I’d thought I was thoroughly protected.

I returned to my GP. it was time to consider other options.

‘just sit it out,’ he said, without looking up from my patient notes. ‘I’m sure it’ll all die down in time.’

‘I want to talk about sterilisation,’ I said firmly. He started and put his pen down.

‘That’s a very long and onerous process. You have to undergo all sorts of psychological assessments. You’re much better off as you are.’

I don’t believe I am. I know I don’t want any more children and I’m sure the stress of this is far worse than any of the assessments.

Of course, my experience with Implanon pales in comparison to those who actually got pregnant or badly scarred on their arms.

‘Statistically, it may be unlikely you suffer problems,’ says ?Jennifer ?Emerson of the law firm Irwin ?Mitchell, which represents a number of women affected by Implanon. ‘but if you’re one of the few who does have scarring or an unwanted ?pregnancy, it’s incredibly traumatic.’

One theory about those unwanted pregnancies is that the device wasn’t inserted properly; sometimes it is not released from the applicator.

Scarring may be caused if the device is inserted too deeply. Implanon can’t be detected by X-rays, so there is no way of ?finding it without an operation under general ?anaesthetic.

In one case handled by Irwin Mitchell, the device was inserted so deeply it couldn’t be found by the nurse.

‘The poor woman went through the ordeal of a nurse cutting deeper and deeper into the tissue before she realised that it had been wrongly inserted into the muscle in her arm,’ says Jennifer Emerson.

‘In these cases, the patient may need to have surgery under ?general anaesthetic to remove the implant, which carries risks and leaves scarring.’

Dr Elliman puts such problems down to a lack of training rather than the implant itself and is calling for a nationally recognised standard of training.

Yet not all medical professionals are convinced by Implanon. a ?leading gynaecologist, Dickinson Cowan from the Portland Hospital, says he has ‘reservations’.

‘I don’t use it myself, but have removed one from a patient who suffered incessant and heavy bleeding.’

He points out that if Implanon suits the patient then fine, but ?suggests there are superior ?alternatives.

‘I don’t understand why women wouldn’t simply opt for the Mirena coil — which releases progesterone locally in the lining of the womb — rather than having something which affects your whole body.’

Dr Elliman suggests that last week’s news reports about adverse effects of Implanon are unhelpful: ‘Women who were perfectly happy with their ?contraception will be ?worrying and those considering ?contraception might decide against it.’

Yet many women have been ?traumatised by its use. Who knows how many have suffered severe side-effects or pregnancies and not reported them?

As all the doctors concur, contraception is a ?personal choice. for me, Implanon was the wrong one.

Though I believe mine was ?correctly inserted, it has caused an awful lot of trouble and pain. and, 18 months later, I am going to have it removed. Sterilisation seems the easier option.