A blastocyst transfer is an embryo transfer which involves transferring 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 or 5 days after starting Progesterone treatment, after estrogen treatment, in the frozen embryo transfer cycles

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 Blastocyst embryos into the woman’s uterus, this is referred to as blastocyst transfer.

What are the events or developmental stages after the egg ( oocyte ) is fertilized with sperm ?

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 four-cell stage on the second day
• The eight-cell stage on the third day
• The morula stage on the fourth day and
• The blastocyst stage on the fifth day.

What are the advantages of blastocyst transfer?

It is possible to identify embryos with development potential
Only about 70% 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 more similar to Natural Implantation
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.

What are the success rates of blastocyst transfer?

In selected infertile couples the ongoing pregnancy rates exceed 60% per transfer. In our egg donor program the success rate has increased alot.

Thus the chances of getting pregnant after blastocyst transfer are higher. Compared to embryo transfer at an early development stage (day 2 or 3). However, the benefit of Blastocyst transfer cannot be extended for all the patients. It depends on Clinical situation and our center will counsel you about your chances of doing Blastocyst transfer and its probability of success in your case.

Is blastocyst transfer preferable to a day-3 transfer?

There’s no hard-and-fast rule: every patient is different. But the consensus is that an embryo that survives for five days or more, particularly a top-grade one, is probably more viable for implantation. Many younger embryos don’t develop to five days and their future is harder to assess. So blastocyst transfers are, generally speaking, more likely to succeed than transfers using day 3 younger embryos.

Any other advantages in transferring blastocysts?

Transferring blastocysts can make things more straightforward for implantation. In non-IVF reproduction, a day-2 embryo (usually comprising four cells) will still be rolling down the fallopian tube towards the uterus. Putting a blastocyst directly into the womb on day five or six is an easier prospect for the now highly receptive uterus. Also, genetic testing such as PGD Is more accurately carried out on blastocysts.

Why don’t all IVF patients use blastocysts and ditch day-3 transfers?

You may not get there. Depending on factors like your medical history, age and the number and quality of embryos created in your IVF cycle, your consultant may feel it’s safer to transfer a younger embryo. Better to put in a tiddly one than none at all.

So are blastocysts a good thing or not?

The key point about blastocysts is that multiple births are less common than with younger transfers. The transfer of one good-quality blastocyst is often recommended.

Why does IVF fail?

If there is an embryo transfer involved, the IVF could have failed because of an embryo implantation failure. This could actually either be due to an issue with the embryos or with the uterus. However, it is believed by many fertility specialists that it is most often due to an arrest of the embryos

Why would an embryo fail to implant?

Many embryos are not able to implant after transfer to the uterus because they are flawed in some way. The embryo doesn't implant because it is not healthy enough to grow. When it comes to IVF, the age of the woman having IVF treatment is very importent. The exact reason of implantation failure is not yet discovered by medical science.