Definitions

Normal Conception

In a normal conception cycle, an egg is released during ovulation. A sperm cell, deposited in the vagina during intercourse, travels through the uterus and fallopian tube to unite with the egg. Fertilization occurs when the sperm penetrates the egg. The fertilized egg, now called an embryo, develops for several days as it moves through the tube and into the uterus for implantation in the uterine wall.

In Vitro Fertilization - Embryo Transfer

In Vitro Fertilization - Embryo Transfer (IVF-ET) is an alternative for couples who have been unsuccessful with conventional infertility treatments.

During the IVF-ET procedure, the union of the egg and sperm, as well as the early growth of the embryo, occur in the laboratory. For a pregnancy to take place, all of the following steps must be successfully completed during the IVF-ET procedure (pregnancy will not occur if even one step fails):

• Retrieval of the Mature Egg
  To increase the success of the IVF-ET procedure, fertility drugs (hMG, FSH, GnRH agonists or antagonists and/or clomiphene citrate) are used to ripen more than one egg. Eggs are commonly recovered by using transvaginal ultrasound directed aspiration of follicles; the woman is usually under intravenous (IV) sedation. An alternative, and much less common, method for egg retrieval is laparoscopy, a more invasive procedure that requires general anesthesia. Because colleting the eggs on time is critical, daily ultrasound monitoring and hormone testing are performed prior to egg retrieval.





• Sperm Collection, Fertilization and Embryo Development
  A semen specimen is obtained and prepared on the day of egg retrieval. Meanwhile, the eggs are placed in culture medium to incubate and mature until insemination. After insemination and fertilization, the resulting zygote is called an embryo. (Note: Fertilization may not occur when egg and sperm meet, nor does development always continue once the egg is penetrated by sperm.)





• Transfer of the Developing Embryo(s) into the Uterus
  Embryo transfer usually takes place three or five days after egg retrieval. The embryos are transferred with a small tube through the cervix and into the uterus. This process is similar to a pelvic exam and requires no anesthesia. The patient then maintains five days of light physical activity.


    


• Implantation and Growth of the Embryo(s)
  The hormone progesterone governs further development and implantation of the embryo(s) in the uterine lining. Additional hormones are sometimes used to increase the chance for an early pregnancy. Blood tests are done to check hormone levels and detect an early pregnancy.

Gamete Intrafallopian Transfer (GIFT)

For patients with normal fallopian tubes, unexplained infertility or a minimal male factor dysfunction, Gamete Intrafallopian Transfer (GIFT) is an option.

GIFT provides placement of eggs (gametes) and adequate numbers of sperm (gametes) into the site where natural fertilization occurs. During this procedure the eggs and washed sperm are placed into normal fallopian tubes at the time of egg retrieval. To be eligible for GIFT, the patient must have at least one normal fallopian tube.

Zygote Intrafallopian Transfer (ZIFT)

During Zygote Intrafallopian Transfer (ZIFT), the eggs are retrieved from the ovarian follicles by transvaginal aspiration and then inseminated in the lab. The resulting embryo(s) are replaced in the fallopian tubes via laparoscopy. ZIFT, like GIFT, requires at least one normal fallopian tube.

Embryo Cryopreservation

Embryo cryopreservation, the freezing of embryos, preserves extra embryos not transferred in the original IVF-ET attempt. Since only two to three embryos are typically replaced into the uterus during a cycle, the “extra” embryos can be used in more natural cycles. Embryo cryopreservation increases the overall pregnancy success rate by approximately eight percent. Only about one-half of couples undergoing IVF have surplus embryos for freezing.

Approximately 65 percent of the cryopreserved embryos survive the freezing and thawing process, and about 20 percent of the transferred cryopreserved embryos will implant. Cryopreservation of embryos may only be performed with informed, written consent.

Micromanipulation: Assisted Hatching and Intracytoplasmic Sperm Injection

Since 1991, the use of the micromanipulation technique known as Assisted Hatching has been used in our embryology laboratory to enhance implantation. This technique involves the treatment of oocytes and embryos using microscopic equipment.

Intracytoplasmic Sperm Injection (ICSI) has been a standard practice since early 1995 at CRM for severe male factor-related infertility.

Preimplantation Genetic Diagnosis

Preimplantation Genetic Diagnosis (PGD) involves procedures which allow for the study of specific cells, taken from embryos formed outside of the uterus to be analyzed for genetic defects, prior to the time that such embryos would be transferred to the uterus for the possible establishment of pregnancy. Since both analyses require examination of embryos In Vitro (in a laboratory dish), PGD requires the use of In Vitro fertilization (IVF). During PGD, one or two cells are removed from the embryo prior to embryo transfer and are tested to determine the genetic status of the embryo. Embryos that do not possess disease-causing genes or chromosomal abnormalities, may be transferred into the uterus for implantation. The purpose of PGD, then is to attempt to detect chromosomal and other genetic abnormalities and potentially avoid the transfer of a genetically abnormal embryo (hopefully preventing a pregnancy with an abnormal fetus or the possible delivery of a child with genetic defects). By selecting embryos for transfer which appear to have the best chance for development, it is possible that the rate of implantation may be increased and the number of miscarriages may be reduced.

PGD is an alternative to more conventional prenatal testing with amniocentesis or chorionic villus sampling (CVS) in patients who are at risk for transmitting a genetic disease to their offspring. Currently there are a number of applications of PGD including advanced maternal age, repeated IVF failure, history of family genetic defects, and recurrent pregnancy loss.

Although PGD is an exciting technology that offers selected couples an alternative to pregnancy termination of an affected fetus, misdiagnosis may still occur, efficiency is less than 100% and the procedures are both labor intensive and costly. PGD, however, does offer the promise of becoming a clinically important tool for selecting transfer of a single embryo with the greatest developmental potential.