Ovulation induction protocols.

Abstract

Ovulation induction protocols for oocyte retrieval have evolved from clomiphene citrate/human menopausal gonadotropins (menotropins) to human menopausal gonadotropins alone and, finally, to a combination of human menopausal gonadotropins and an agonist of gonadotropin-releasing hormone (GnRH-a). The almost abandonment of clomiphene use is due to findings from studies that showed reduced implantation due to the antiestrogen effect of clomiphene. The use of GnRH-a was introduced to maintain low levels of luteinizing hormone late in follicular development to prevent premature ovulation or premature senescence of the oocyte. The GnRH-a increases oocyte yield in poor responders, decreases cycle cancellations, improves the rate of pregnancy, and allows some control over the timing of retrieval. Attempts to use the GnRH-a to stimulate follicle maturation in a "short protocol" have resulted in variable and sometimes poor results. Therefore, the long GnRH-a/human menopausal gonadotropin protocol is currently used for most patients to prepare for oocyte retrieval.