Stimulated intra-uterine insemination is not a natural choice for the treatment of unexplained subfertility. Current best evidence for the advanced treatment of unexplained subfertility.

When conventional treatment of unexplained infertility has not been successful, the next choice lies between either gonadotrophin treatment with intrauterine insemination (FSH/IUI) and IVF. Cohort studies indicate that FSH/IUI is less effective while the cost per birth is higher with IVF. The relevant evidence should come from randomized controlled trials, but the results need to be recalculated for the outcome of greatest interest, a singleton live birth. Judged by this standard, FSH/IUI is statistically superior to no treatment, but the effect is small in couples with unexplained infertility. By the same standard, IVF is superior to FSH/IUI treatment, but this benefit is achieved only at considerable cost. The evidence is not robust, comprising only a few trials which involve a minute fraction of the existing patients with unexplained infertility. Current best evidence is consistent with a progression from low-tech to high-tech treatment, but it is not convincing enough to support a rigid management protocol. A large multicentre factorial trial is needed to evaluate the relative value of existing empiric treatments for unexplained infertility.