In vitro fertilization (IVF) is the fertilization of eggs by sperm in a dish (outside the woman’s body). The embryos which result are transferred back into the woman’s body (Embryo Transfer; ET). Although it is technically possible to perform IVF without the use of fertility drugs, only one egg would be collected and the chance for pregnancy would be low. With the use of fertility drug, many eggs (ova) are retrieved, improving the chances of success.
Injectable gonadotropins are used for most IVF procedures. In order to arrive at an ideal starting point, a cycle of oral contraceptive pills is often prescribed prior to beginning gonadotropin injections. In addition, many patients are pretreated with a gonadotropin releasing hormone (GnRH) agonists, for example Lupron, drugs that turns off a patient’s own luteinizing hormone (LH).
The GnRH agonist down-regulation allows injectable gonadotropins to synchronize the development of multiple follicles. GnRH agonists also prevent a woman from releasing LH and triggering her ovulation prematurely (before the eggs can be collected). Alternatively, a GnRH-antagonist medication may be utilized beginning a few days before oocyte collection in order to prevent premature LH surge and egg release.
In a typical IVF cycle the woman begins a package of oral contraceptive pills on or before the fifth days of her period. On the 18th day of that cycle injections of Lupron begin. A period is expected around day 26. An ultrasound and blood tests are then performed to verify that the woman is ready to receive the injectable gonadotropin drugs.
The dose of gonadotropins ( taken daily or twice daily) is adjusted with hopes of obtaining 12 to 15 oocytes (eggs) for use during the IVF procedure. Progress towards ovulation is monitored every few days with ultrasound and blood tests. If she has not been treated with Lupron, the woman will begin the medication Ganerelix after ultrasound has determined that her leading follicle is 12-14mm. in size. When the patient’s follicles are of sufficient size, ovulation is triggered with an injection of human chorionic gonadotropin (hCG).
Thirty-six to 37 hours after the hCG injection, eggs are retrieved by passing a needle through the vaginal wall into the ovaries to remove the eggs from the ovarian follicles. Intravenous sedation assures that the patient feels no pain. As the patient’s follicles are aspirated by the physician, an embryologist identifies eggs within the follicle fluid. The eggs are placed in a dish in an incubator, and they are later inseminated with sperm that the husband or partner produced around the time of the procedure.
On the day after the retrieval the embryologist evaluates the number and quality of newly fertilized embryoes. Sometimes, embryos are frozen the day after IVF for use in future cycles. The remaining embryos are cultured for transfer back into the woman’s uterus between three and six days in culture in the laboratory. In special situations the growing embryos are biopsied so that genetically abnormal embryos may be excluded by preimplantation genetic diagnosis (PGD).
The embryo transfer (ET) is a simple procedure which requires no anesthesia. The number of embryos transferred back into the patient is chosen in a way to balance the risk of multiple gestation against the risk of not conceiving. Injections of progesterone are taken daily to “support” the implantation process. About two weeks after the eggs were retrieved, blood tests are performed to determine whether or not pregnancy has successfully occurred. The early pregnancy will be followed with blood tests and ultrasounds in order to be sure it is progressing normally.