Blastocyst transfer may not be suitable for all patients. Centre for Assisted Reproduction Pte Ltd (CAREPL) does not do blastocyst transfer unless it is considered to benefit the patient. CAREPL will offer blastocyst transfer to patients who are not at risk of multiple pregnancy or have had three failed implantations.
Blastocyst transfer will normally take place on day 5 or 6 after egg collection depending on blastocyst development. In the situation where no 8-cell embryos are available on day 3, three of the best existing embryos will be transferred on the same day.
Advantages of Blastocyst Transfer
A. Allows greater harmony between embryo development and the uterine environment.
In most IVF Centres, embryo transfer routinely takes place 2 or 3 days after egg collection and fertilization, which places the embryos into the uterus at an earlier stage than would occur naturally. In contrast, blastocyst transfer places the embryo into the uterus at a later stage (day 5 or 6) which is approximately the time an embryo would normally arrive in the uterus.
B. To select chromosomally normal embryos.
Research studies showed that 60% of normal appearance embryos can be chromosomally abnormal. Majority of these embryos fail to develop past the 8-cell stage. Therefore, extending culture to the blastocyst stage may mean that more of the surviving blastocysts available for transfer may have normal chromosomes. However, there is no guarantee that embryos that do develop to the blastocyst stage are genetically normal or will implant.
C. To reduce multiple pregnancies
Studies have shown that pregnancy rates are similar between day 3 and blastocyst transfers. Reducing the number of blastocysts during transfer will reduce the number of high-order (triplets etc) multiple pregnancies.
Disadvantages of Blastocyst Transfer
Research suggests that about 30 to 40% of patients may not have a blastocyst available for transfer. In these cases the embryos have failed to develop to the blastocyst stage.
A. No embryos for transfer
It has been shown that only 50% of embryos may develop to the blastocyst stage. Patients with few eggs, embryos or poor developing embryos may end up not having any blastocyst for transfer.
B. Disappointment and stress
Some studies show that day 3 transfers often result in a 30% pregnancy rate compared to 0% if culture is extended to the blastocyst stage. To avoid the disappointment of having no blastocysts for transfer on day 5 or 6, we advise that when no 8-cell embryos have developed by day 3, up to 3 of the best available embryos are transferred on this day rather than extending culture to the blastocyst stage.
C. Risk for monozygotic (identical) twins
The incidence of monzygotic (identical) Twins is increased following blastocyst culture.
D. Risk of no frozen embryos
The number of embryos suitable for freezing is reduced following blastocyst culture. As a consequence, the possibility of having frozen embryo transfer for another attempt at pregnancy is also reduced.
E. Extra cost
There is an extra fee for couples who wish to use blastocyst transfer above what is normally charged for IVF/ICSI.
