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Are PGD and PGS Safe?
Preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS) require extra steps in the in vitro fertilization process. The embryos are biopsied, and the cells retrieved from the embryos are sent to a laboratory for genetic testing. To date, studies have not shown that an embryo biopsy increases the risk of birth defects in the child.
There is a risk of damage to the embryo during the biopsy procedure, according to Serena H. Chen, M.D., a New Jersey reproductive endocrinologist with IRMS Reproductive Medicine at Saint Barnabas. "The good news is that embryos damaged by PGD appear to experience an "all or none" effect — they stop growing, rather than sustain long-term damage," she says. Embryos that continue to grow after the biopsy do not become abnormal as a result of the biopsy and are not at greater risk for miscarriage or birth defects.
However, “There is a general misconception that the whole embryo biopsy process is just another 'option' in the IVF/embryo transfer menu, like ICSI, assisted hatching, blastocyst transfer, cryopreservation and so forth. The most important thing to remember about PGD/PGS is that it is an invasive technology,” says Michael Tucker, Ph.D., Scientific Director and Chief Embryologist at Georgia Reproductive Specialists in Atlanta. “At least one cell or more must be removed from each embryo to enable the assessment to take place, and as such, it is not a procedure that should be undertaken lightly. For single gene defects and chromosomal structural anomalies that have a high probability of appearing in the next generation, then such an invasive procedure as embryo biopsy is justifiable, even though the embryo viability might be partially compromised.”
Dr. Tucker says the benefits become much less clear when the biopsy is used for aneuploidy screening to minimize the chance that a transferred embryo has a chromosome abnormality linked to advancing reproductive years. “In such a patient population, the number of potentially viable, good quality embryos might be limited in any event,” he explains. “Embryo biopsy to screen for chromosomal errors as a means to do anything other than reduce the already low risk of conceiving an abnormal child, or to minimize the risk of miscarriage, is much less easily justified."
When considering PGD or PGS, do your research and weigh the decision carefully. Direct specific questions about the biopsy and the procedure to the embryologist at your fertility clinic. "PGD/PGS technology is changing rapidly, and the experience of different centers varies widely," says Dr. Chen. "So the decision about whether or not you should proceed is a very individual one based upon the risks and benefits in your individual situation. Your doctor should be able to assess these risks and benefits for you from her or his center's experience, so that you can make an informed decision."