Human oocyte cryopreservation in infertility and oncology

To evaluate the present state of research and clinical application of human oocyte cryopreservation in infertility and oncology.

Recent literature documents have an increasing interest in cryopreserving human eggs. A number of studies report on different freezing protocols and various types of clinical application. Increasing attention is paid to vitrification as an alternative to slow cooling for oocyte cryopreservation. Several studies cover the modification of meiotic spindle during cryopreservation in order to assess the less damaging cryopreservation system. The first births with cryopreserved oocytes in cancer patients are reported.

Egg freezing may circumvent the ethical and legal concerns regarding embryo cryopreservation, increase assisted reproduction flexibility and be a concrete option to save fertility in women with cancer. Recently, egg survival and pregnancy rates improved, with the birth of more than 500 children. The birth rate per thawed oocyte is around 5-6%. As regards safety, data on birth defects seems to be reassuring so far but must be monitored by an international registry. Comparative studies between slow freezing and vitrification in the same patient population are needed to elucidate pros and cons of each technique.