Intrauterine insemination (IUI) is generally used in cases when there is a mild sperm problem or when no abnormality has been detected by the usual investigations. It is nearly always combined with ovulation induction and even then most units would quote a pregnancy rate of somewhere in the region of only 1 in 10 treatments. The idea behind intrauterine insemination (IUI) is that many more sperm are brought close to the egg at exactly the right time. It is therefore used in cases of ‘unexplained’ subfertility.
It has been shown only to be of use if drugs are given to induce ovulation on a definite day. This is probably because the sperm are separated from the seminal plasma in which they are ejaculated and cannot therefore be stored in the cervix.
If you have tried this form of treatment for more than six attempts, it is highly unlikely to work and it would be time to consider IVF. Because IVF treats many more possible blocks to fertility, it has a pregnancy rate of about 1 in 3 per treatment cycle. Your luteal phase would be supported with progestogen therapy during an IVF cycle.