Intrauterine insemination (IUI)

⚕ Medically reviewed by Prof. Stratis Kolibianakis, MD, MSc, PhD · Thessaloniki Medical Chamber Reg. No. 16340 · Last reviewed 6 July 2026

Intrauterine insemination (IUI) is a simple, painless procedure performed at the IVF clinic. It is recommended as a first step in mild male-factor infertility, unexplained infertility, or when donor sperm is used. We process the sperm sample (from the partner or from the donor), select the most motile spermatozoa, and place them in the uterus with a thin catheter. Up to 3 IUI cycles are recommended before transitioning to IVF.

When IUI makes sense and when it does not. Insemination requires at least one open tube and an adequate number of motile sperm after processing. It is not indicated with bilaterally blocked tubes or severe male factor — in those cases IVF is the right choice from the outset. In women aged 38 or older, or with a long duration of infertility, moving earlier to IVF is often advised so that valuable time is not lost.

Natural or stimulated cycle. IUI can be performed in a natural cycle or combined with mild ovulation induction (letrozole or low-dose gonadotrophins). Mild stimulation modestly increases the chances but requires careful ultrasound monitoring to avoid growing several follicles and the risk of multiple pregnancy. The goal is 1–2 mature follicles, no more.

What to expect on the day. Insemination is timed around ovulation, detected by ultrasound or a trigger injection. Placing the catheter takes a few minutes, needs no anaesthesia and feels like a Pap smear. You can return to your activities immediately. A pregnancy test is done about 2 weeks later. Because the chance per IUI cycle is relatively low, the plan is reassessed after 3 unsuccessful cycles.

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