Blastocyst Transfer

A blastocyst transfer is an embryo transfer which involves transferring one or more embryos that are at a very advanced stage of development, the so-called blastocyst stage. This is usually done on the fifth day after follicular aspiration.
After the doctor has removed the eggs from an ovary (follicular aspiration), they are fertilized in the laboratory. This is done either by normal in vitro fertilization (IVF) or by means of intracytoplasmic sperm injection (ICSI).

Immediately after fertilization, an egg starts to divide and develop into an embryo. The stages of development are as follows:

The pronuclear stage on the first day (fertilized egg).
The two to the four-cell stage on the second day.
The eight-cell stage on the third day.
The morula stage on the fourth day.
The blastocyst stage on the fifth day. The doctor usually inserts one or more embryos in the woman’s uterus two to three days after egg retrieval. This process is referred to as embryo transfer. The embryos can also develop in an incubator up to the fifth day, i.e. the blastocyst stage, thanks to improved cell culture media (blastocyst culture). If the doctor transfers such developed embryos into the woman’s uterus, this is referred to as blastocyst transfer.

What are the advantages of Blastocyst Transfer?

It is possible to identify embryos with development potential :

Only 20 to 30 percent of the fertilized eggs develop into blastocysts at all. If an embryo reaches this stage, there is a higher chance of implantation.

The moment of Blastocyst Transfer is ideal:

Just like with a Blastocyst Transfer, in a natural pregnancy, it takes around five days after fertilization for the embryo to reach the uterine cavity, where it then implants. It is assumed that the lining of the uterus is particularly receptive on this day.