Controlled ovarian hyperstimulation in in vitro fertilization

The purpose of Controlled Ovarian Hyperstimulation is to obtain a certain number of oocytes of high quality as well as not to change excessively the morphological and the endocrine patterns of the patient. The mechanism of COH mainly depends on the increasing of Gonadotropins and on the maturation of more than one follicle. It was suggested that the introduction of GnRH analogous (GnRH-a) into ovarian stimulation regimen might improve the follicular response, the fertilization and the implantation rates, leading to a net increase in pregnancy rate. The most important protocols of GnRH-a administration and Gonadotropin therapy (FSH purified or recombinant) are the "long" and "short" protocols. The first (down-regulation) involves initiation of GnRH-a either in the mid-luteal phase of the preceding menstrual cycle or in the early follicular phase of the treatment cycle. Only when suppression is confirmed, FSH therapy is commenced. The latter (flare-up) utilizes the initial stimulatory effect of the GnRH-a on the pituitary gonadotropin release. To achieve the flare effect, GnRH-a is administered with FSH at the beginning of the treatment cycle. ETRA results obtained in IVF utilizing the "long protocol", were very encouraging in terms of pregnancy and birth rates above all in young patients. In particular, in the ICSI programme, the PR/transfer in patients aged I 29 and greater than or equal to 38 was 29.4 % and 12.5 % respectively; in IVF-ET programme it was 42.3 % and 10 % respectively. Therefore, we emphasize the use of the GnRH-a and of the GN according to the "long protocol".