In Vitro Fertilization (IVF)
There are five basic steps in an IVF cycle: ovulation induction, egg retrieval, fertilization and embryo culture and finally implantation. The focus of this blog is ovulation induction.
Monthly, the ovary readies hundreds of eggs from which only the dominant egg is selected for ovulation. The remaining hundreds of eggs degrade. In ovulation induction, medications are used to rescue those eggs that competed to be the dominant follicle such that the strongest egg candidates may be used.
There are three basic protocols that are used. All of the protocols rely on the ability of the medications both to stimulate competent growth and to inhibit the body’s ability to trigger natural ovulation. Together with your physician, you will discuss your diagnosis and a protocol will be selected that is believed to be best suited for your needs.
These protocols may be used interchangeably and your stimulatory response may be used to gauge the type of protocol to be used in additional cycles if needed.
The agonist protocol, otherwise known as the long-cycle protocol, begins with a daily injection of a medication, leuprolide acetate (lupron) which temporarily desensitizes the brain receptors in their perception of when ovulation should occur; the signal for ovulation is initiated within the pituitary gland of the brain. Once this densensitization, or suppression is complete, the ovaries are ready to be stimulated to induce multiple follicular growth. The medication used for growth is a purified version of what the body already makes; it is Follicle stimulating hormone (FSH); In conjunction with the continued pituitary suppression, FSH is given daily.
Frequent ultrasounds and bloodwork allow us to monitor precisely the progress of follicular development. As the follicles begin to grow, a second stimulatory medication, Leutinizing hormone (LH) may be added to augment oocyte maturation. When the oocytes are deemed to be mature through measurements of estradiol blood levels and follicular size, ovulation will be triggered in preparation for the retrieval.
The second means of stimulating the ovarian pool of follicles involves utilizing leuprolide acetate, but capitilzing on its ability to induce an exaggerated response within the brain; it is know as a microflare protocol. In this scenario, at the beginning of the cycle, small doses of lupron are given twice daily. To the receptors within the brain, the sudden presence of lupron is deemed to be a drastic, although completely reversible, change of brain signaling. The pituitary gland in the brain responds immediately by releasing all of the natural stimulatory hormones that it had been saving for the upcoming cycle. The release of these hormones allows the ovary to be bathed in stimulatory hormones. The microdose of lupron is continued and FSH is added to augment the natural response.
The third major protocol is called the antagonist cycle (ganirelix acetate or cetrotide). With this protocol, the body begins with its own natural stimulation and FSH is used to augment the natural response. Just prior to your brain’s signaling of ovulation; a blocking signal, the antagonist, is added to the medical regimen. The antagonist blocks the brain from recognizing the ovarian stimulation signals and thus, the brain cannot stimulate ovulation.
Regardless of the protocol, when the follicles are deemed to be mature, the ovulatory trigger is given and egg retrieval is forthcoming.