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Does the number of embryos loaded on a single cryo-carrier affect post-vitrification survival rate?

Published online by Cambridge University Press:  13 October 2020

Adva Aizer*
Affiliation:
Infertility and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center, Tel Hashomer, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
Meirav Noach-Hirsh
Affiliation:
Infertility and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center, Tel Hashomer, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
Olga Dratviman-Storobinsky
Affiliation:
Infertility and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center, Tel Hashomer, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
Jigal Haas
Affiliation:
Infertility and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center, Tel Hashomer, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
Raoul Orvieto
Affiliation:
Infertility and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center, Tel Hashomer, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel The Tarnesby-Tarnowski Chair for Family Planning and Fertility Regulation, at the Sackler Faculty of Medicine, Tel Aviv University, Israel
*
Author for correspondence: Adva Aizer. Infertility and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center, Tel Hashomer, Tel Aviv University, Tel Aviv, Israel. E-mail: adva.aizer@sheba.health.gov.il

Abstract

Background:

We aimed to assess whether the survival rate of embryos is influenced by the number of embryos/oocytes loaded on a single cryo-carrier during vitrification.

Methods:

This was a retrospective study that included 974 patients who underwent thawing of 1896 embryo-warming cycles between September 2016 and January 2020. A distinct analysis was made for cleavage stage embryos (2–10-cell stage) and blastocysts. For vitrification, embryos were placed in a Cryotop™ open device using a SAGE vitrification kit following the manufacturer’s instructions. Warming was carried using a SAGE warming vitrification kit according the manufacturer’s instructions.

Results:

Total post-vitrification survival rates of embryos at the cleavage stage or blastocyst stage was 94.8%. At the cleavage stage, cryo-preserving three embryos per single cryo-carrier gave the highest full intact embryo survival rate (91.5%) compared with one or two embryo(s) per single cryo-carrier (85.7%, P < 0.0002 and 87.3%, P < 0.004). Conversely, post warmed full intact blastocyst survival rate for two blastocysts was significantly lower compared with one blastocyst (76.7% vs. 87.9%, P < 0.0193) per single cryo-carrier.

Conclusion:

Post-thawing survival rate following vitrification is affected by the number of embryos per single cryo-carrier undergoing the vitrification equilibration phase, with the optimum number of three cleaved embryos or one blastocyst per single cryo-carrier. Further studies are required to determine the optimum number of cleaved embryos or blastocysts that should be loaded onto a single cryo-carrier vitrification device.

Type
Short Communication
Copyright
© The Author(s), 2020. Published by Cambridge University Press

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