Cryopreservation:

Additionally, it is becoming commonplace for PGD clinics to halt the development of embryos before implantation through a freezing procedure called cryopreservation (vitrification). In this process, pre-screened embryos, usually at the blastocyst stage are hyperchilled, to halt development, and thawed shortly before implantation. Not all embryos will survive this process. While PGD can be performed successfully without cryopreservation, there are several reasons why a clinic may recommend its use.

First, cryopreservation allows for extra time necessary for some form of genetic testing. Second, there is evidence to support that the embryos surviving the de-thawing process are more likely to result in pregnancy. Third, since the mutation is a dominant one, there is a higher probability of producing embryos that carry the mutation, so you may want to conduct multiple IVF cycles to obtain an adequate number of embryos for PGD testing and the embryos would need to be frozen until they are genetically screened and implanted.

The techniques involved in PGD are rapidly changing, and vary from clinic to clinic. Depending on the technology available at your clinic, and discussion with your counselor, you can understand and discuss your testing options.