Human oocyte cryopreservation: revised evidence for practice

This article reviews the evidence regarding human oocyte cryopreservation by slow freezing and vitrification and provides evidence-based clinical and laboratory guidelines on the effectiveness and safety of these technologies. The guidelines address the stage of oocyte maturity; cryopreservation and thawing/warming using slow cooling or vitrification; techniques used for insemination of thawed/warmed oocytes; information and support counselling. These are an update of previous guidelines. The following outcome measures were examined: cryosurvival, fertilisation rate, cleavage rate, implantation and clinical pregnancy rate, miscarriage rate, live birth rate, psychosocial wellbeing, health of resulting children. This update does not include recommendations specific to fertility preservation for defined patient groups and specific ovarian stimulation regimens as they are covered in detail in recent guidance from the European Society of Human Reproduction and Embryology (ESHRE).