The Blastocyst culture and transfer at Blastocyst Stage Procedure for In-Vitro Fertilization facilitates selection of the best quality embryos for transfer.Concept of embryo quality is very important concept to consider especially for couples who are experiencing fertility related issues and are unable to conceive. With Blastocyst embryo transfer, in KIC we transfer fewer embryos – which significantly improves the chances of implantation and thereby increases the chances of pregnancy. Another advantage of transfer at Blastocyst Stage is it reduces the risk of multiple pregnancies.
A Blastocyst is an embryo that has been developed for 5 to 7 days after fertilization unlike the normal transfer in 2 to 3 days (cleavage stage). At this point, the embryo has two different cell types and a central cavity. In this stage it has just starts to differentiate. The surface cells- called the Trophectoderm, will become the Placenta, and the inner cells-called the inner cell mass, will become the Fetus. A healthy Blastocyst should begin hatching from its outer shell- called the Zona Pellucid, by the end of the sixth day. Within about 24 hours after hatching, it should begin to implant into the lining of the mother’s uterus.
Blastocyst culturing is a technique to grow embryos beyond the 3rd day of culture. Typically incases of transfer in 3 days after the egg retrieval, , embryos generally develop between 6-8 cells. When the embryos culture is extended to blastocyststage on day 5 they become round 120 cells.
Natural process of embryo development begins with the fertilization of the egg in the outer aspect of the fallopian tube. As the newly formed embryo develops, it slowly movestowards the uterine cavity where it has to ultimately implant. This process takes approximately 6-7 days. Embryo in “Blastocyst” stage, are ready to implant.
Why one should consider Blastocyst transfer?
In certain patients, the advantage of Blastocyst culturing is to allow optimal selection of embryos for transfer, resulting in an increased implantation rate per embryo transferred. However, it is important to understand that this technology may not necessarily increase your chance of pregnancy as there are many other factors to be countered into to ascertain whether blastocyst culture will be beneficial for a particular case which includes age, number & quality of eggs developed. The main advantage is that fewer embryos may be transferred, still improvising chances of pregnancy, also eliminatingor limiting the possibility of multiple pregnancies.
Is Blastocyst Stage Transfer fit for everyone?
No. Generally speaking, this procedure should be limited to patients with excessive numbers of embryos (greater than 10) in which case further selection of embryos beyond the day 3 stage would be advantageous. As a general rule, patients under the age of 37 are candidates for this culturing technique. We do not recommend this procedure to older patients because the risk of having no Blastocyst embryos for transfer is too great.
What percentage of embryos will grow to the Blastocyst stage in culture?
For younger patients, up to 50% of all embryos will continue to grow to the Blastocyst stage. However, 10% of patients will not have an opportunity for embryo transfer due to the absence of Blastocyst development. Aging drastically impacts the numbers of embryos which are capable of developing to the Blastocyst stage.
What are the risks of Blastocyst culturing?
There are two main concerns with Blastocyst culture:
- In some cases there may be no development of embryos till Blastocyst Stage thereby, loss of chances of embryo transfer.
- Number of embryos left for freezing and the survival of embryos after thawing declines, potentially lowering the overall pregnancy potential of a single stimulation/egg retrieval treatment cycle.
How to determine if we should seriously consider this treatment?
Yes, if you have less than four, 8-cell quality embryos on the 3rd day of culture, we do not recommend proceeding with blastocyst culturing.In such cases, with blastocyst culturing, we will not be able to freeze many embryos because of poor embryo development till blastocyst stage.
Also, there appears to be an <1% risk of identical twinning with Blastocyst culturing (including the possibility of conjoint twinning where the babies may be connected and share some organs). Which is slightly higher than that in the natural process or by normal IVF Cycle