In IVF programme, embryos are usually transferred on the second or third day following egg retrieval at the four-to-eight cell stage. The IVF embryos must continue to grow for two or three more days to reach the blastocyst transfer stage (50-150 cells) before they are ready for implantation into the uterine wall (endometrium). Recent advances in IVF laboratory treatments have allowed for the successful culture of embryos to the blastocyst stage.
Blastocyst is an advance embryo which is developed for about 5-6 days, after fertilization. Blastocysts have two different cell types and a central cavity. A healthy Blastocysts should begin to hatch from the outer shell called the zona pellucida by the end of the sixth day. Within 24 hrs of hatching, it will begin to implant in to the lining of mother womb.
Blastocysts may have a better potential to implant into the uterine wall than earlier stage embryos. Many embryos stop growing at the four-to- eight cell stage, probably because of some inherent problem. Therefore, fewer embryos will have the ability to grow to the blastocyst stage. Those that successfully reach the blastocyst stage are probably more developmentally competent than earlier stage embryos. As well, their stage of development when replaced into the uterus is very similar to what it would be in a natural conception cycle.
Advantages and disadvantages of Blastocysts
The advantage the extending the growth on embryo to the Blastocysts stage enable the embryologist to select the better embryo to be replaced in the womb. The embryo can be grown outside the mother’s womb until a more natural time that is at Blastocysts stage before it is transferred in to the mother’s womb. Blastocysts are just associated with higher chance of pregnancy 50-60 percent and as we transfer fewer embryos we can reduce the chance of multiple pregnancies.
The disadvantage of attempting to grow embryos to the blastocyst stage is that fewer embryos will “survive” or grow to this stage (probably about 30 – 50% of the embryos). There is a possibility (up to 10%) that none will reach the blastocyst transfer stage and therefore, no embryos will be available for transfer.
Who is eligible for Blastocyst Embryo Transfer ?
Couples who have had unsuccessful prior attempts with IVF or IVF/ICSI despite having many good quality eggs retrieved are being offered blastocyst culture as an alternative treatment. The ability to select the most viable embryos for transfer and implantation should improve their chance of achieving a pregnancy.
The embryos will be cultured in the IVF laboratory for 5 days after egg retrieval. At least 5 good quality embryos (6 to 8 cells) should be available on the third day after egg retrieval to maximize the chances of obtaining a blastocyst. Couple can have the discussion with doctor whether this option will benefit them or not.
Blastocyst Transfer at IFC
During the blastocyst transfer, our priority is to maximize the IVF success rate while minimizing the risks of multiple pregnancy. We offer complimentary blastocyst culture to all couples undergoing IVF or ICSI at IFC. The ability of the growth of embryos for five to six days to the blastocyst stage of development in the laboratory, allows IFC’s embryology team to determine, with greater confidence, which embryos are really the “best” in terms of their potential for implantation.
This technology allows couples a significantly higher chance for pregnancy without the risk for multiple births. We have used blastocyst transfer to successfully increase our pregnancy rate since years and we usually do transfers for all our patients on day 5 to maximize success.
Please feel free to contact us regarding any questions concerning blastocyst culture and transfer. You can start a complimentary fertility consultation by filling the form below.