IVF-ET is probably the most well known of the Assisted Reproductive Technologies. Otherwise known as “test tube baby,” (fertilization actually takes place in a dish and not a test tube) IVF-ET has helped many infertile couples conceive and bear children for more than a decade. Originally IVF-ET was developed to help couples overcome infertility due to a problem with a woman’s fallopian tubes. Now it has become a useful treatment option with other factors such as immunological problems or unexplained infertility.
IVF is basically a four-step process:
The first step involves superovulation, where you take injected medications to cause your ovaries to make multiple follicles/eggs. Monitoring of this process is down with serial blood draws, and ultrasounds to check on the growth of the follicles and development of the uterine lining. When it is determined that the follicles and the uterine lining are appropriately mature, a trigger shot of Human Chorionic Gonadotropin (hCG) is administered.
The second step begins approximately thirty-six hours after the trigger shot with the retrieval of eggs/oocytes. The night prior to the egg capture, the woman will do a vinegar douche to reduce the vaginal bacteria. She will arrive at the office the next morning, fasting, (NPO), and get prepared for conscious sedation with an IV placement and medications. Guided by ultrasound, the doctor aspirates the eggs from the follicles during a procedure performed in the office.
Shortly after the egg capture procedure, a sperm specimen ( 3 days abstinence) is collected from the partner or thawed from a donor and prepared for mixing with the eggs. The two are then placed together in a dish and incubated for 18 hours and fertilization is allowed to occur naturally. After 18-20 hours, the embryos are examined for normal fertilization. Normal fertilization is characterized by a pronucleus of the egg and sperm that can be visualized under a microscope.
This third stage is called the embryo culturing stage and can go out for five days. The day of egg capture is called day Zero, and day one we expect to see pronuclei or 2PNs, and by day three, 6-8 cell embryos, and by day five, blastocysts. The proembryos can then be transferred to the uterus or incubated for further development into multi-cell embryos and transferred two to five days later.
The fourth and final step is the transfer of the embryos into the uterine cavity using a small tube that is inserted through the cervix. The number of embryos transferred varies with the desires of the couple, their feelings about a selective reduction in the case of multiple pregnancies, the quality of the embryos and the days of growth, and the age of the woman. Using guidelines of age only, the following recommendations would be made: Routinely, day five embryos are recommended, but earlier day 3 embryos can be transferred with similar success.
Age 30 and under……..1-2 embryos if day 5, and 2 embryos if day 3
Ages 31-35……..2 embryos if day 5, and 3 embryos if day 3
Ages 36-40……..2 embryos if day 5, and 3-4 embryos if day 3.
Ages >40………2 embryos if day 5, and 4-6 embryos if day 3.
Any remaining embryos may be frozen and stored for future use (see Cryopreservation).
National delivery rates for women who undergo IVF-ET (with or without male factor) are as follows:
Under age 35 35% per embryo transfer
Ages 35-37 30.8% per embryo transfer
Ages 38-40 22% per embryo transfer
Over 40 11.6% per embryo transfer
(SART, 1998)