Blastocyst Culture and Transfer

Recent scientific advances in the understanding of the dynamic physiology of early human embryos have led to the development of in vitro culture systems capable of yielding viable blastocysts with greater consistency.

Growing embryos in vitro to the blastocyst stage (day 5–6) for assisted reproduction offers several theoretical advantages over the transfer of cleavage stage (day 2–3) embryos. These include a higher implantation rate, a decrease in the number of embryos transferred, the opportunity to select more viable embryos for transfer, better synchronization between embryo and endometrium at the time of embryo transfer, and a longer time in culture that provides the opportunity to perform pre-implantation genetic diagnosis (PGD) when such is indicated.

Although there are advantages, there may be potential risks and limitations of blastocyst transfer. Because there are no universally accepted criteria for predicting blastocyst development, the number of viable blastocysts may be lower than predicted. Under some circumstances, this may result in having no embryos for transfer despite observations of adequate embryo development in vitro on day 2–3. Moreover, in unselected patient populations and among couples who have experienced one or more previous failed cycles, pregnancy rates and live-birth rates after blastocyst transfer or cleavage stage embryo transfer are not significantly different.

Here at Laurel Fertility Care, we reduce the concerns for a blastocyst transfer by following stringent guidelines to ensure that we may have blastocysts for transfer. In the event that there are not a sufficient number of embryos on Day 3, we would recommend not pursuing the goal for blastocyst selection and transfer the embryos on Day 3. Our physicians work closely with Dr. Angle, our Embryology laboratory director, to determine the best stage and numbers of embryos to be transferred for our patients, for both cleavage state and blastocyst stage.