ABC’s of infertility – assisted hatching and blastocyst transfer

What is assisted hatching?

Assisted hatching is a technique used in the in vitro fertilization (IVF). It is used for improving the embryo implantation in the uterus. It is done by making an opening with a microscopic cut so the embryonic cells are able to easily hatch out. There is no pregnancy without the hatching of the embryo. Just before the implantation occurs, the embryo has to hatch out from its outer shell. Some embryo shells are thicker than others which lowers their ability to hatch and that makes it a lot harder to properly implant. The reasons for the thicker shells of the embryos are unknown but it may have something to do with the woman’s age.
The shell lets only one sperm enter and fertilize the egg. When it is fertilized the cleaving of the embryo into a two-cell begins, then there’s the four-cell and so forth. At the moment the early cleavage stage occurs then the assisted hatching on the embryo can be conducted.

Oocyte age

Research shows that the oocyte shells produced by women older than 37 are harder and thicker than those produced by younger women. Reports show that even 75% of the embryos could never hatch. The time that the embryo spends in the laboratory can also add to this hardening of the shell because it is not exposed to the natural environment of the fallopian tubes where the natural enzymes are. There were also suggestions that the shells would harden if the embryos were frozen and thawed. In such cases the assisted hatching is very helpful.
Nowadays very often the laser assisted hatching is used as a very safe way to weaken the shell and let the embryo hatch. Laser assisted hatching is according to studies a better method than doing it manually or chemically. It is more precise and fast.

What is blastocyst transfer?

Blastocyst transfer is a process when the embryos are cultured to the blastocyst stage in the laboratory’s incubator before they are implemented into the womb. Embryos are cultured up to 6 days and then they become blastocysts and it is easier to choose the best quality embryos.
When the best embryos are chosen they are then implanted into the woman’s womb where they have to successfully attach so that the woman can become pregnant. So it is a process very similar to the standard embryo transfer but it is implanted after it is allowed to develop for 5 up to 6 days.

When is blastocyst transfer recommended?

The blastocyst transfer is often recommended for single embryo transfers because statistics show that in such case it improves the chance for pregnancy. It is a very effective technique for younger women which have good prognosis for an IVF pregnancy. Furthermore it is often recommended if a woman had an IVF treatment in the past and she produced quality eggs but they were not able to implant properly in the womb.

Like using embryo transfer also the blastocyst transfer has a risk of a multiple birth and you your clinic will probably suggest you do a single blastocyst transfer.


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