Intrauterine insemination (IUI) & unexplained infertility
When all the basic tests of a couple come back normal but pregnancy does not arrive, we call it unexplained infertility. It is one of the most common — and most frustrating — diagnoses.
The good news is that one does not always need to move straight to IVF. For many couples, intrauterine insemination (IUI) is the right first treatment.
What is unexplained infertility?
Infertility is called unexplained when, after a full basic work-up, no specific cause is found: ovulation is normal, the tubes are patent and the semen analysis is within limits.
It does not mean “there is no problem” — it means the problem cannot be identified with today’s tools. Often it is a combination of mild factors, with the woman’s age playing a central role.
What is intrauterine insemination (IUI)?
In IUI, the sperm is processed in the laboratory to concentrate the most motile sperm, and placed directly into the uterus on the day of ovulation, through a thin catheter. It is a simple, painless procedure that needs no anaesthesia.
It is usually combined with mild ovarian stimulation, so that one or two follicles develop and the chance of conception rises slightly.
When is IUI recommended instead of IVF?
This applies to couples with unexplained infertility and a relatively good prognosis. IUI is less invasive and clearly cheaper than IVF, and for many couples it works.
Does expectant management have a role?
Yes, in selected cases. When the woman is young, the duration of infertility short and the prognosis good, a period of focused watchful waiting can be reasonable — a fair number of pregnancies happen spontaneously.
The decision about when active treatment starts is based on the couple’s individualized prognosis, chiefly the woman’s age and the years of trying.
How many IUI cycles before IVF?
Most IUI pregnancies occur in the first three to four cycles. Generally up to 3–6 cycles are suggested; if pregnancy is not achieved, the next step is IVF.
In older women or those with a lower prognosis, the number of IUI cycles is limited, so as not to lose valuable time.
What are the risks?
The main risk of stimulated IUI is multiple pregnancy, if several follicles develop. That is why low doses of gonadotropins and close ultrasound monitoring are used; if too many follicles develop, the cycle may be cancelled for safety.
Otherwise the procedure is safe, with minimal discomfort.
Summary
For couples with unexplained infertility and a good prognosis, IUI with mild ovarian stimulation is the evidence-based first-line treatment, per ESHRE (2023) — before IVF. It is simple, safe and affordable. Up to 3–6 cycles are recommended, with attention to the woman’s age so that time is not lost. If it does not succeed, IVF is the next, effective step.
Sources: ESHRE, “Evidence-based guideline: unexplained infertility”, Hum Reprod 2023; NICE Fertility problems: assessment and treatment (CG156).
⚕ Medically reviewed by Prof. Stratis Kolibianakis · Thessaloniki Medical Association Reg. No. 16340
ARTICLE 6 · FEMALE CONDITIONS & FERTILITY
