Blastocyst Transfer



A blastocyst is a more developed embryo that has a higher chance of implantation. By transferring these more developed embryos, i.e. blastocysts, into the uterus, usually fewer numbers are needed, in order to minimise the possibility of multiple pregnancies which result from the implantation of several embryos during the In Vitro Fertilisation process.


The first week of fertilisation of an egg by a sperm and resulting formation of the embryo is an exciting time in the IVF process, and our embryologists are committed to ensuring the excitement continues as your embryo’s cells continue to divide and develop.


Why does it matter?


Why are the first few days so crucial? It is during that time when the transformation from egg to fertilised egg (zygote), then to embryo and further  to blastocyst, takes place. A blastocyst is simply an embryo that has had enough growth time—usually five or six days— and cellular division to display two separate types of cells: placenta-forming cells and fetal-forming cells.


The embryo is incubated in our laboratory and transferred to the uterus only after its viability is no longer in question. The blastocyst is hollow, with the outer layers becoming the placenta. The inner layer of cells will go on to form the fetus itself.


Blastocysts represent the most viable, fully functioning embryos and hold the greatest chance of full development once reintroduced back into the uterus. As only a blastocyst can attach itself to the uterine wall, having one already formed for the implantation dramatically increases the chance of a proper attachment.


By allowing these embryos to incubate for a few more days, our embryologists can also genetically determine exactly which embryos are most likely to result in a successful pregnancy.




It is during this time that Pre-Implantation Genetic Diagnosis/Screening (PGD/PGS) can be performed. PGD/PGS enables you to screen for genetic defects, enabling you to choose only the healthiest embryos for implantation. These more highly formed and healthy embryos are then reintroduced into the uterus.


During the Blastocyst Transfer, our doctor will pass a very thin tube called a catheter gently through the cervix into the uterus and deposit the embryos into the uterine cavity along with an extremely small amount of fluid. This procedure usually does not require anaesthesia, and the patient usually leaves the office after a brief recovery period.


Blastocyst Transfer not only raises the chances of a successful treatment, but also minimises the likelihood of multiple pregnancies when only one embryo is transferred. The remaining embryos can then be frozen and stored at cryopreservation bank for future frozen embryo transfer cycles.