Vitrification is a relatively new technique for oocyte and embryo freezing. It has been increasingly used worldwide and modification in the technique has significantly improved pregnancy rates. PIVET Medical Centre introduced vitrification in 2008 principally to improve blastocyst freezing outcome. Unlike the slow freezing method that has been used since the early days of IVF, vitrification employs very rapid cooling rates to avoid the risk of ice crystal formation during freezing. Blastocyst freezing appears to be well suited to vitrification. Ongoing pregnancy results from 2008 for blastocyst vitrification were in the order of 35% per transfer of a single blastocyst with a very high level of recovery. As a result, embryos are increasingly cultured to blastocyst for cryostorage using vitrification with improved survival and implantation rates.
Vitrification is now the standard method for freezing for all embryos. PIVET has also recently introduced oocyte freezing, using vitrification for anonymous oocyte donation and for fertility preservation.