This is a question that reproductive endocrinologists have studied and debated since the technique of intrauterine insemination was first developed.
A study reported in the September 2010 issue of Fertility and Sterility again looks at the effect of timing of an IUI on the success rate.
They divided the patients into three groups: patients in group 1 underwent a single preovulatory intrauterine insemination (IUI) performed 24 hours after hCG administration. Patients in group 2 underwent two IUIs performed 12 and 36 hours after hCG administration. Patients in group 3 underwent a single periovulatory IUI performed 36 hours after hCG administration.
The total pregnancy rate per patient was 14.2 % ; group 1 had a rate of 11.3%, while groups 2 and 3 had 14.0% and 17.2% pregnancies, respectively. The difference between the three groups in regard to pregnancy rates was not statistically significant.
So there was no significant difference and maybe that's why it's been so difficult for reproductive endocrinologists to come up with a universal strategy. It simply doesn't matter. We employ a strategy which we think makes sense: if the follicle is still present at the first IUI, we do a second. If the follicle has disappeared there is no need for a second IUI. Any better ideas?
