The technique of vitrification, or quick freezing, has dramatically improved results after thawing and transfer of supernumerary embryos from an IVF cycle. This is mainly due to several factors:
1. The vitrification process produces less cell damage than slow freezing.
2. The survival rate after thawing has increased from 75% (obtained with slow freezing) to 90% with vitrification.
3. All this results in a lower transfer cancellation rate, whether this is due to absence of survival or absence of evolved embryo after thawing. With slow freezing the cancellation rate was estimated to be approximately 30% and with vitrification it was 8%.
4. The lower level of cell damage in the embryo and the higher number of embryos available after thawing allow for better pregnancy rates.
In summary, vitrification allows us to optimize the survival and have better embryos after thawing. In this way we increase the pregnancy rate and the efficiency of IVF cycles.