What’s more effective: IUI or FSP?

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“My husband and I have unexplained secondary infertility and are about to start our first IUI.

I was reading about the success rates of FSP (fallopian sperm perfusion) for unexplained infertility and how FSP may be more effective than IUI. It is suggested that couples with unexplained infertility may benefit from FSP over IUI, resulting in higher pregnancy rates.

I was just wondering what your thoughts were on FSP vs IUI and if you offer FSP treatments?”


We use a modified FSP technique much of the time.

FSP was developed in the 1990s, before ultrasound could be used widely. It addressed the concern: is it better to have the sperm highly concentrated and thus quite possibly left in the fundus of the uterus (“IUI”) or dilute the fluid 8x, put a balloon or other device to make sure nothing comes back, and thus ensure through higher pressure and volume that sperm must go up the tubes (“FSP”).

It took randomized controlled trials to see if there was a difference. The result: both techniques appear to deliver the same pregnancy rates. You can read more about this in The Cochrane review, here.

At our clinic we do a combination of IUI or a FSP variant with every insemination: we focus on ultrasound guidance and, when necessary, using a balloon catheter to keep the sperm up and inside. We’ve been doing this for about four years or so. When we started we saw a 50% boost in pregnancy rates from previous techniques. Now we find success rates are the same whether we use ultrasound or not (but M-F we use ultrasound).

In our opinion, pregnancy rates are maximized when your team is focusing on what you individually need. Its less about IUI FSP or ultrasound, more about your clinician taking care when completing the procedure.

Hope that helps!

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