Blastocyst culture and transfer is a technique developed for in vitro fertilization (IVF). This procedure intends to maximize pregnancy rates while minimizing the risk of multiple pregnancies. Blastocyst Embryos are typically cultured for 3 days (cleavage stage with 4-10 cells) before being transferred into the uterus. By extending the culture to 5 or 6 days (blastocyst culture), some embryos will develop to the blastocyst stage (up to hundreds of cells). This allows the embryologist to select more advanced embryos with better potential for implantation at the time of the transfer.A significant benefit of blastocyst culture and transfer is the reduction of multiple births that can result from IVF, since there are fewer embryos (1 or 2) to be transferred.
Blastocyst transfer may be appropriate for those patients who have:
a better chance of having blastocyst development (this will be determined by age and infertility conditions)
previous failed attempts at achieving a pregnancy
strong concerns about delivering high-order multiple pregnancy
Advantages of blastocyst transfer for IVF
One problem with this is that 2 to 3-day-old embryos are normally in the fallopian tubes, not in the uterus. The embryo gets to the uterus about 80 hours after ovulation. Embryo implantation process begins about 3 days later - after blastocyst formation and hatching out of the embryonic shell have occurred. Therefore, if in vitro culture conditions are maximized so healthy blastocysts form at a high rate, then day 5 blastocyst embryo transfer can be done. The uterine lining on day 5 should be receptive to the arriving embryo, this a more natural time for the embryos to be in the uterus. It is the same timing as with a natural pregnancy. The transfer is done shortly before the time for actual invasion and implantation.