Blog | Thursday, January 13, 2011

Contraceptive failures: a reality check


The media has been buzzing over recent reports of pregnancies occurring in women using Implanon, a single rod progestin-only contraceptive inserted under the skin of the upper arm and lasting for up to three years.

Parents by by aechempati via FlickrThe headlines make it sound horrifying: "Hundreds Become Pregnant Despite Contraceptive Implanon" and "British Pregnancy Scare in U.K. Implicates Implanon." I love how terminology can make something so common sound so frightening.

Actually, what happened was that 584 pregnancies occurred in Britain among about 1.3 million women using Implanon, for a failure rate of .04%. In other words, the method had an efficacy of over 99%. That's a pretty effective contraceptive if you ask me.

But it should have been better than that

As good as it may seem, this failure rate is significantly higher than most of us would have expected based upon data from clinical trials of Implanon.

I recall being told at an Implanon insertion training just prior to its introduction in the U.S. that in fact, not a single pregnancy had been reported at that point among users of the device in clinical trials. This would put the method up there with sterilization and IUD in terms of efficacy.

So what happened?

How did Implanon go from perfect efficacy to something less than perfect?

A study of Australian Implanon failures gives us a few clues. In that country, the majority of Implanon pregnancies occurred because the Implanon never left the needle at the time of insertion. In other words, there was an unrecognized failure to insert the device correctly.

For the rest, it appears that the women were actually pregnant at the time the device was inserted, were taking another medication that interfered with Implanon's efficacy, expelled the device or had it inserted in the wrong time of the cycle to be effective that first month of use.

Only 13 reported pregnancies were actual device failures during a period when over 200,000 devices were sold. 13/200,000, or .0065%--now that's more in line with what we expected of Implanon.

Did Merck do enough to assure Implanon's success?

While I have no idea what happened in Britain and Australia, I have to say that Implanon's manufacturer (Organon, then Schering-Plough, which is now Merck) made an extraordinary effort to be sure that those who inserted Implanon in the United States knew what they were doing. I was part of the first groups trained, and found the training and follow-through to be above and beyond anything I'd ever seen.

Was this because they had an inkling of the post-marketing experience in Britain and Australia?

Or because they learned from watching the Norplant debacle that bad surgical technique on the part of a few practitioners, combined with a few greedy lawyers, could take down one of the most effective contraceptives ever to hit the market?

Either way, I was impressed.

Nexplanon: The new, improved Implanon

I'm also impressed that the manufacturer, not satisfied with the insertion failures in real-world hands, have improved upon the design of the inserter. The device is also now visible under X-ray, allowing for a reliable way to assure its presence if it cannot be palpated under the skin.

But why is all this news?

You don't see any headlines about the millions of pregnancies conceived while using condoms or the pill, do you?

Pregnancy horror: "I was too lazy to get up and put in my diaphragm, and now I'm the mother of twins!"

Or better yet, pregnancy shocker: "I know I missed three pills this cycle, but I figured I'd get away with it."

While it probably should be, this is not news. That's because when we get pregnant on the pill, or while using condoms or a diaphragm, we blame ourselves.

But if it's someone else's fault, well, that's something to talk (and sue) about.

What also makes Implanon pregnancies special is that when they do occur, they can go undiagnosed for such a long time due to menstrual irregularity that women are told to anticipate as an effect of the method. Inability to detect an early pregnancy, combined with failed expectation of an almost perfect efficacy based on the manufacturer's literature, makes women feel betrayed.

And there's nothing the media likes more than a betrayed woman.

Unintended consequences and unintended pregnancies

While I don't wish to belittle or diminish the individual impact that an unexpected pregnancy has for any individual woman, especially when she has done all she can to prevent from becoming pregnant, I do have concerns about all this media attention to Implanon failures.

That's because, unfortunately, media attention such as this, rather than informing, tends to lead women to mistrust hormonal contraception. And when women distrust hormonal contraception, they tend to discontinue it and move towards less effective barrier methods, or worse yet, no contraception.

The end result? Unintended pregnancy. Thus, one consequence of all this media reporting about the contraceptive failures with Implanon could actually be even more unplanned pregnancies. Great.

Bottom line

Implanon remains an extremely effective contraceptive, when inserted properly and at the right time in the cycle in women not taking medications that interfere with its efficacy. New generation devices will hopefully have less insertion issues among practitioners, who must be properly trained in its insertion.

More info:
Implanon information from Planned Parenthood
Information on Implanon training for practitioners

This post by Peggy Polaneczky, MD, appeared at Get Better Health, a network of popular health bloggers brought together by Val Jones, MD. Better Health's mission is to support and promote health care professional bloggers, provide insightful and trustworthy health commentary, and help to inform health policy makers about the provider point of view on health care reform, science, research and patient care.