Definition - What does Agonist Protocol mean?
The agonist protocol, also known as the "long protocol" or "down-regulation protocol" is used during in vitro fertilization (IVF) in order to prevent ovulation from occurring too soon. By using a gonadotropin-releasing hormone (GnRH) agonist such as Lupron, Synarel, or Buserelin it down-regulates the body's release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH are responsible for preparing the body for fertilization.
By "turning off" the body's natural hormone production there is no interference with the drugs given during IVF. The drugs can take over stimulating egg maturation, egg release, and preparing the uterus for embryo implantation.
FertilitySmarts explains Agonist Protocol
Agonist protocols are the most commonly use IVF protocols in the United States. The protocol starts seven days before the period is due, known as mid-luteal timing. The GnRH agonist is continued in combination with a follicle-stimulation hormone (FSH) drug which is started 2-7 days after the period starts. FSH stimulates egg maturation and release. Once the eggs are mature enough ovulation is triggered by an injection of a trigger shot of human chorionic gonadotropin (hCG). Within a day or two of hCG, eggs are retrieved and fertilized. At this time progesterone is sometimes given in order to support the uterine lining. This provides a healthy environment for embryo implantation. In the few days following egg retrieval, the embryo is returned to the uterus. Progesterone is continued until the pregnancy test.