Oocyte cryopreservation: a  technical and clinical update

The primary objective of this article is to review the most recent progress in oocyte cryopreservation using various slow-freezing and vitrification protocols. There is a significant improvement in the clinical outcomes with higher pregnancy rates following mature metaphase II oocyte cryopreservation. Moreover, some reassuring data were recently reported regarding the long-term safety of this technology. However, overall clinical pregnancy rates following oocyte cryopreservation remain less efficient than the more established practice of embryo cryopreservation. Oocyte cryopreservation is a viable alternative for fertility preservation for women at risk of premature ovarian failure due to diverse factors, such as gonadotoxic chemotherapy or radiotherapy. Currently, there are two distinct techniques for oocyte cryopreservation: slow freezing and vitrification. Oocyte vitrification is gaining popularity as the technique of choice; however, well-designed, randomized, controlled trials are still required to establish which method is the most efficient and safest for oocyte cryopreservation.