Click here to view next page of this article
Assisted reproductive technologies consist of procedures pertaining to the handling of oocytes and embryos outside of the body, with gametes or concepti replaced into the body to establish pregnancy. The most commonly used procedure is in vitro fertilization (IVF), which involves extraction of oocytes, fertilization in the laboratory, and transfer of embryos through the cervix.
In Vitro FertilizationEmbryo Transfer
Infertility due to abnormal fallopian tubes or endometriosis, idiopathic infertility, male infertility, and immunologic infertility all respond well to IVF. Women who have failed to conceive with donor insemination or ovulation induction are also excellent candidates. Rough guidelines as to when ART may be considered are after 2 years of unexplained infertility, 1 year after treatment of a particular defect, or after at least 1 year of donor insemination or ovulation induction.
Oocyte Retrieval
The follicle aspiration is scheduled for 34-36 hours after hCG injection. With administration of GnRH agonist and human menopausal gonadotropin, this can be extended to as late as 38 hours with minimal risk of ovulation. Prophylactic antibiotics are commonly given. Retrieval is almost always performed by ultrasound-guided transvaginal aspiration.
Insemination
Usually, 50,000-500,000 sperm are added to each oocyte, depending on sperm parameters, after a period of 2-8 hours of preincubation to allow further oocyte maturation. The oocytes are stripped of their surrounding cells and examined 12-20 hours after insemination.
Embryo Transfer
The fertilization rate is entirely normal with frozen donor sperm. The pregnancy rate with donated oocytes is generally 1.5- to 2-fold higher than with routine IVF because donors are generally young or fertile or both. Both known and anonymous oocyte donors are used. This has allowed women who have failed multiple IVF attempts, who have abnormal ovarian function (elevated FSH, poor response to stimulation), or who are advanced in age (even up to age 55) to have an excellent chance.
Gamete Intrafallopian Transfer
Gamete intrafallopian transfer is the placement of sperm and eggs into the fallopian tube. This transfer has generally been done by laparoscopy. The average delivery rate per retrieval for GIFT in 1994 was 28.4%, compared with 21.2% for IVF. Because IVF is less invasive, programs with IVF rates close to, or exceeding, the national average for GIFT are likely.
Zygote or Tubal Embryo Transfer
The placement of fertilized oocytes (ZIFT) or cleaving embryos (tubal embryo transfer or TET) into the fallopian tubes allows fertilization to be confirmed, while taking advantage of the tubal environment for part of the early development of the embryo. The success rates for these two procedures should, theoretically, be higher than that of IVF.
Ovarian Hyperstimulation With Intrauterine Insemination
The initial success achieved with IVF for treatment of tubal-factor infertility prompted broadening of the indication for this technique to include infertility in which there was no significant anatomic abnormality of the female reproductive tract.
Surrogacy
When a woman who desires children has no uterus or cannot carry a child for health reasons, the use of surrogates raises issues of possible exploitation and the