Evidence-based clinical outcome of oocyte slow cooling

Abstract

In the last few years, there has been a significant improvement in oocyte cryopreservation techniques. To investigate the clinical significance of oocyte freezing, an assessment of the cumulative pregnancy rate per started cycle derived from the use of fresh and frozen-thawed oocytes was performed. Between 2004 and 2006, 749 cycles were carried out, in which no more than three fresh oocytes were inseminated either by standard IVF or microinjection. Supernumerary mature oocytes were cryopreserved by slow cooling. Cryopreservation of fresh embryos was performed in rare cases to prevent the risk of ovarian hyperstimulation syndrome using a standard embryo freezing protocol. Fresh embryo transfer cycles totalled 680, 257 of which resulted in pregnancy. The pregnancy rates per patient and per transfer were 34.3% and 37.8% respectively. When frozen-thawed oocytes were used, following 660 thawing cycles, 590 embryo transfers were performed in 510 patients. Eighty-eight pregnancies were achieved with embryos from frozen oocytes, with a success rate of 17.2% per cycle. When fresh and frozen-thawed cycles were combined, the number of pregnancies was 355, giving a cumulative pregnancy rate of 47.4%. Oocyte cryopreservation can contribute considerably to the overall clinical success, ensuring a cumulative rate approaching that achievable with embryo storage.

Qualitative and morphometric analysis of the ultrastructure of human oocytes cryopreserved by two alternative slow cooling protocols

“…Research endeavours may contribute to the expedient identification of optimal cryopreservation conditions that would assist the embryologist's choice of a more appropriate cryopreservation procedure. In this work, we describe the ultrastructure of human mature oocytes cryopreserved by two CRSC protocols that have been introduced in the clinical practice [3,25] but of which no information concerning possible cryodamage is available. In the two protocols, dehydration is achieved by one step or two step.…”

“…The two protocols have been tested and are still being used clinically [3,25], but nothing is known about their ability to preserve the cellular organization of the oocyte.…”

The current challenges to efficient immature oocyte cryopreservation

“…Slow-freezing protocols have been mainly studied by Italian researchers. Favourable success rates have been reported, with an increasing number of pregnancies recorded over the years [9][10][11][12][13][14][15][16][17].…”

Fertilitätserhalt bei Krebs

“…Die Ergebnisse lassen sich aus den Zahlen großer italienischer Zentren ablesen, die diese Technik aufgrund der strikten italienischen Gesetzgebung standardmäßig in der Kinderwunschbehandlung einsetzen. So berichteten Borini et al [22] von 680 Embryotransferzyklen mit frischen Embryonen, resultierend in 257 Schwangerschaften. Die überzähligen reifen Eizellen wurden in einem 7 Slow-freezing-Programm konserviert.…”