PGS has been promoted as a means to improve the odds of a successful IVF cycle. However, a large-scale, randomized, controlled study performed in women older than age 37 failed to demonstrate an improvement in clinical outcome following its use. Although the use of PGS will likely decrease the rate of miscarriage resulting from aneuploidy, the overall delivery rate per IVF cycle initiated may not be increased with this technology.

One limitation of PGS is that many embryos at the 6- to 8-cell stage of development are mosaics, meaning that some of these cells carry a normal complement of chromosomes while other cells are abnormal. During further embryonic development, the abnormal cells presumably end up relegated to the placenta while the normal cells produce a healthy embryo. The high rate of mosaicism in cleavage-stage embryos raises a real concern about the accuracy of PGS. One respected geneticist has estimated a rate of misdiagnosis to be 20% with PGS. Approximately 17% of the time, a normal embryo is incorrectly labeled as abnormal and discarded. Even more concerning is the 3% chance that an abnormal embryo will be labeled normal and then transferred to the uterus.

In 2007, the ASRM and SART issued a joint statement concerning the use of PGS (and PGD) saying that there is insufficient evidence to support the widespread application of PGS given its failure to improve live birth rates (see below).

In the case of couples for whom the use of prenatal diagnosis and possible pregnancy termination are not an option, PGS may be appropriate. According to an October 2006 monograph produced by the European Society of Human Reproduction and Embryology (ESHRE), “Although widely used, PGS is still considered as an experimental procedure, and its clinical utility is not fully proven.”

In 2007, the ASRM and SART issued a joint statement concerning the use of PGS (and PGD) saying that there is insufficient evidence to support the widespread application of PGS given its failure to improve live birth rates.

(Reprinted with permission of Elsevier from Preimplantation genetic testing: a Practice Committee opinion. The Practice Committee of the Society for Assisted Reproductive Technology, Practice Committee of the American Society for Reproductive Medicine. Fertil Steril 90(5): S136-S143 (November 2008).)

Recommendations: PGD

  • Before PGD is performed, genetic counseling must be provided to ensure that patients fully understand the risk for having an affected child, the impact of the disease on an affected child, and the limitations of available options that may help to avoid the birth of an affected child.
  • PGD can reduce the risk for conceiving a child with a genetic abnormality carried by one or both parents if that abnormality can be identified with tests performed on a single cell.
  • Prenatal diagnostic testing to confirm the results of PGD is encouraged strongly because the methods used for PGD have technical limitations that include the possibility for a false negative result.

Recommendations: PGS

  • Before PGS is performed, thorough education and counseling must be provided to ensure that patients fully understand the limitations of the technique, the risk of error, and the lack of evidence that PGS improves live birth rates.
  • Available evidence does not support the use of PGS as currently performed to improve live birth rates in patients with advanced maternal age.
  • Available evidence does not support the use of PGS as currently performed to improve live birth rates in patients with previous implantation failure.
  • Because the prevalence of aneuploidy is high in the embryos of patients with recurrent implantation failure, decisions concerning future treatment should not be based on the results of PGS in one or more cycles.
  • Available evidence does not support the use of PGS as currently performed to improve live birth rates in patients with recurrent pregnancy loss.
  • Available evidence does not support the use of PGS as currently performed to reduce miscarriage rates in patients with recurrent pregnancy loss related to aneuploidy.