When it comes to ovarian stimulation, doctors handle a wide range of stimulation protocols in order to offer patients the one that best suits their circumstances. However, the most commonly used protocol is GnRH antagonists. In this protocol, patients should begin ovarian stimulation on day 4 of their cycle. The administration of gonadotropins will promote the growth of follicles that would not grow naturally. Around day 9 of the cycle, the patient starts taking GnRH antagonists. This blocks the patient's own hormones, and in this way, the physician is assured that the hormones that are involved in the stimulation are only those from the gonadotropin medication. By blocking the patient's endogenous hormones, spontaneous ovulation or any other event that could spoil the assisted reproduction treatment is prevented. The patient should inject the last medication 36 hours before the ovarian puncture. This injection is of hCH and induces egg maturation and ovulation:
- The maturation of the eggs makes them suitable for fertilization. In addition, the tissue that connects the egg to the walls of the follicle becomes lax to facilitate the detachment of the egg at the time of ovulation.
- About 40 hours after ovulation induction, the egg is expelled from the follicle and released outside the ovary. This event is avoided at all costs in IVF-ICSI treatments since the released eggs cannot be hunted by the gynecologist and cannot be fertilized in the laboratory. This is why follicular punctures are planned 36 hours before the hCG injection, in order to achieve maturation of the egg and its detachment from the follicle wall, but it will be captured before its release from the ovary.
Failure to administer hCG may result in the intended effects of ovulation induction not occurring. That is why if the time elapsed between the hCG injection and the puncture is less than 36 hours, Empty Follicle Syndromemay occur. This syndrome is characterized by not having obtained any egg after an ovarian puncture. It is thought that this may be because the egg has not been released from the follicular wall because the injection has not yet had the desired effect. Empty Follicle Syndrome can also occur when the hCG-containing medication is expired. Therefore, the desired effect of this injection will not be the desired one.