IUI is a treatment whereby the woman is helped to conceive by specially prepared sperm being placed directly into the womb at the time when eggs are being released.
Production of eggs is helped by the use of fertility drugs. When you are about to ovulate, the most motile sperm will be used for insemination.
The success rate of IUI depends upon several factors. First of all the cause of the infertility problem is important. For example, men with normal sperm counts who are unable to have intercourse have a much higher chance of success than patients who are undergoing IUI for poor sperm counts. In addition, female factors play an important role. (Age, ovarian reserve, etc.)
If the couple is married for more than 5 years and still trying to have a baby; then IVF treatment is recommended rather than IUI treatment.