The protocols used in assisted reproduction suppress the hormone secretion by the organism and then, with the administration of special medication, stimulate the ovaries to produce more than one follicle. The main goal is to collect more than one mature oocyte for fertilization and to avoid the possibility of premature ovulation. In assisted reproduction three protocols are mainly used, the long protocol, the short protocol and the antagonist protocol. The choice of the appropriate protocol and the suitable dosage for each woman is decided according to her age, the ovarian response as well as the number and outcome of previous treatments.
The down regulation begins on the 21st or the 2nd day of the menstrual cycle with the administration of GnRH analogues. It lasts for about two weeks, during this time ultrasound checks of the uterus and the ovaries are performed and the level of the hormone oestradiol in the blood is estimated. The doctor needs these tests to monitor the progress of the suppression. If the ovarian suppression is not satisfactory, the treatment is continued for one more week. At the end of the week the tests are repeated. When the suppression is sufficient, the ovarian stimulation starts with the administration of gonadotropin hormones. In the short and in the antagonist protocol the suppression and the ovarian stimulation take place simultaneously. The administration of the suppression agents starts at the 2nd day of the cycle and the administration of the stimulation agent starts at the next day (3rd day of the cycle).
Four to six days after the initiation of gonadotropin administration, ultrasound examination and estimation of oestradiol level is performed. The aim of this close monitoring is to adapt the hormone dosage according to every woman’s individual needs.
During the ovarian stimulation the follicles continue to develop with a steady rate. As their diameters increases, the oestradiol levels in the blood increase accordingly. When the follicles have reached the desirable size (17-18mm in diameter) and the level of oestradiol is sufficient, a hormone is administrated by injection, to allow the final maturation of the oocytes. The precise timing of the injection is very important, as oocytes collection is scheduled 35-36 hours later.