FAQ Frozen embryo Transfer

Embryo transfer during in vitro fertilisation (IVF) involves inserting one or more fertilised embryos into the uterus. There are two types of embryo transfer: fresh embryo transfer and frozen embryo transfer (FET).

Frozen embryo transfer takes place after the embryo has been frozen and then unfrozen. Fresh embryo transfer, on the other hand, takes place directly after embryo culture.

For a frozen embryo transfer, there is an endometrial preparation phase (in a substituted, stimulated or natural cycle) and then the gynaecologist decides on the best day to place the embryo.

For a Frozen Embryo Transfer (FET) protocol, the procedure consists of preparing the endometrium (thickening the tissue of the uterus that will receive the embryo and into which an embryo will be deposited) and then choosing the appropriate day for transferring the embryo(s).

For a transfer during a spontaneous cycle, the gynaecologist will monitor the cycle without treatment and use blood tests and ultrasound scans to determine the best time to place the embryo back in the uterus.

It depends on the treatment. The length of a treatment and its composition vary according to the patient.

This depends on the stage of the embryo. For example, embryo implantation occurs 5 days after the introduction of progesterone for an embryo frozen on day 5.

Embryo implantation can be carried out between 2 and 5 days after the puncture, depending on the decision taken by the clinical and biological team.

To prepare for an embryo transfer, the endometrium must be approximately 7 to 8 mm thick.

Whether fresh or frozen, embryo transfer is a painless procedure. It is usually carried out under ultrasound guidance. The gynaecologist places the embryo(s) in the uterus using a catheter.

This depends on the decision of your assisted reproduction centre. The embryo transfer can take place on D2, D3 or D5 after IVF (in vitro fertilisation).

There is a waiting period of between 2 and 5 days between the onset of ovulation and the replacement of the embryo(s).

Frozen embryo transfer must take place within the correct implantation window (the progesterone-modified endometrium must be in phase with the embryo). If the progesterone is added too early, the transfer may be compromised.

It is not possible to identify the signs of embryonic implantation because the treatments given, such as progesterone, can simulate the effects of pregnancy.

After an embryo transfer, it is important to continue taking the medication prescribed by your doctor. In addition, you can lead a normal life as there are no particular restrictions.

The sample is taken approximately 10 days after a blastocyst transfer.

It depends on your doctor's recommendations, but generally as soon as you feel ready.

After a transfer, sexual activity can be restarted within 24 hours. It has been shown that normal activity has no impact on the chances of success.

This depends on the team, from 24 hours (just before the puncture) to the time of transfer.

Nidation occurs between 2 and 7 days after the transfer of a D5 blastocyst.

It all depends on how many days old the embryo is at the time of transfer. For example, in the case of a blastocyst (5-day-old embryo), implantation occurs around 2 days later, on the 7th day.

After embryo implantation, you can go straight to the toilet and resume your normal life. It has been shown that normal activity has no impact on the chances of success.

Vitrification of oocytes and embryos is an ultra-rapid freezing technique that allows embryos to be preserved more effectively.

The embryos are unfrozen on the day of the frozen embryo transfer, just a few hours beforehand.

These are 2 different freezing techniques: vitrification is quick freezing.

Embryos can be frozen either after a fresh transfer (supernumerary embryo freezing) or with a view to a delayed transfer. This allows embryo transfers to be carried out without the need to stimulate and puncture oocytes again. 

Reheating vitrified oocytes involves thawing oocytes that have been vitrified (i.e. frozen using a rapid technique).