How well do Filshie clips protect against pregnancy?

Did you know that not all research is equally trustworthy? For example, the Filshie sterilization clips are touted to be 99,76% reliable (2-3 pregnancies in 1000). But actually.. the research that is supposed to back this up was a phone survey to ask gynecologists if they remembered Filshie failures… They didn’t check medical files.

The researcher claims (see picture) “surely a gynecologist would remember such a pregnancy”. So, a gynecologist, whose job it is to deal with pregnancies (avoiding or achieving them) on a daily basis, would remember that kind of detail? This is debatable in my opinion. Human memory is pretty awful if you ask me. Also, he says “it doesn’t occur often, so surely they would remember”, which shows that he is biased: He is convincing us it is rare, by telling us that it is so rare that gynecologists would surely remember. Circular reasoning.

Also, the researcher was sponsored by a Filshie clip distributor to present his findings. I think it’s a good thing that the competing interests are disclosed and I commend the researcher on his transparency.

On the left, the circular reasoning. On the right, Endovasive, a Filshie distributor, sponsored the researcher.

Here’s the PDF:

Let’s dig a bit deeper. Here’s some research from 2004

The research from 2004 compares the evidence on Filshie clips and concludes: “However, upon examining those studies that are well‐designed, prospective and recently published, the failure rate for Filshie clip has a wide range of between 1.1 and 19.3 per 1000 procedures.” They also state “an early study showed that the overall 10‐year failure rate for Filshie clip sterilisations was 0.56%, but fell significantly to 0.2% when cases caused by operator error were excluded.”

That’s anywhere between 0.11% and 1.93% unwanted pregnancies. Of course, if the manufacturer finds this, they’ll soon update their brochure to 99.89%, because that’s the most optimistic case they can find. But taking the best figure you can find and putting that in your brochure is not research, it’s marketing.

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