The Concept

Patients who undergo In Vitro Fertilization (IVF) may produce several eggs (oocytes) which, if fertilization takes place, will be developed into embryos. Very often and for very different reasons, one patient may need to freeze (cryopreserve) their oocytes or embryos. In the traditional cryopreservation methods (slow freezing), the formation of intracellular ice crystals can damage the structure of the cells decreasing their viability.


Vitrification is an advanced cryopreservation technique for oocytes and embryos that based on the nature of the cryo-protectants used and an extremely fast cooling rate is able to generate a glass-like state preventing the formation of ice crystals during the process. Once stored in liquid nitrogen (-196 degrees Celsius) the cellular activity is essentially brought to a halt, allowing the oocytes/embryos to remain viable indefinitely.

When patients decide to attempt pregnancy with their cryopreserved oocytes/embryos, a reverse process of thawing will be performed whereby the cryo-protectant will be replaced by water rehydrating again the cells.


Oocyte vitrification is recommended for:

– Patients who have a poor ovarian response in order to accumulate oocytes before undergoing the IVF cycle.
– Women who for one reason or another wish to postpone motherhood.
– Oncology patients and others who are going to be given gonadotoxic treatments.
– Women with an imminent ovarian surgery, for example in the case of endometriosis.

Embryo vitrification is recommended for:

– Patients where it is preferable to carry out the embryo transfer in a subsequent and different cycle from the one in which follicle stimulation takes place.

  • Inappropriate hormonal profile
  • Risk of Ovarian Hyper Stimulation Syndrome (OHSS)
  • Presence of polyps, hydrosalpinx or hydrometra
  • The absence of spermatozoa in the day of the oocyte retrieval.

– Patients having surplus good quality embryos besides the embryos selected for embryo transfer. Those embryos can be vitrified in order to have extra chances, if required, of having a baby in subsequent embryo transfers without the need to undergo a new stimulation cycle.