Egg freezing and vitrification are techniques used to preserve eggs for an indeterminate period of time. Until relatively recently, slow freezing was the most commonly used technique, but it has now been replaced by vitrification.
Vitrification and devitrification procedures are standardised processes that allow the risks of survival of both oocytes and embryos to be reduced to a minimum. Although it is true that, as with all assisted reproduction techniques, there are associated risks, reduced to around 3% both in terms of survival and in terms of a decrease in the potential success of the embryos. It is important to bear in mind that the survival of the embryos may be affected by poor handling or acceptance of the oocytes to the cryoprotectants, which may result in the oocytes not being able to survive the technique.
The decrease in survival will be associated with starting the microinjection process with fewer oocytes than those previously vitrified, but those that are able to evolve have gestational success rates similar to those of fresh oocytes.
Apart from the oocyte quality, the usefulness of vitrified oocytes, especially from donors, lies in the possibility of better coordination of the cycle and even the possibility of carrying out the transfer in fresh and natural cycle.
In any case, what is really important is the achievement of a full-term pregnancy, regardless of the fresh or frozen origin of the gametes or embryos.