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Cryopreservation Has No Detrimental Effect On Implantation And Pregnancy Rates In Egg Donation Cycles

This research presented at the Alpha Society Scientific Meeting, Antwerp, Belgium, 2003

CA Adams, LS Anderson , A. Scroop and SH Wood. Reproductive Sciences Center, La Jolla, CA, USA.

Introduction: Egg donation cycles typically yield excellent pregnancy rates. In some cases, however, a fresh embryo transfer is not advisable for medical (e.g., poor endometrial lining) or practical reasons. The aim of this study was to determine whether cryopreservation exerts a detrimental effect in egg donation cycles in which all embryos are electively frozen.

Materials/Methods: A retrospective analysis of all egg donation cases over a two-year period, 2001-2002. Fresh cycles (n = 71) were compared to elective cryopreservation cycles (n = 10) in which embryos were frozen at the pronuclear or cleavage stage using a modified propanediol/sucrose technique. All recipients underwent the same hormone replacement regimen for endometrial preparation with embryo transfers performed on day 2 or 3.

Results: There were no significant differences between the fresh and cryopreservation groups in age of donors, age of recipients, number of eggs retrieved or fertilization rates. The overall freeze-thaw embryo survival rate was 90% (46/51). Embryo transfers following elective cryopreservation cycles yielded implantation (69%) and pregnancy rates (90%) that compared favorably to fresh embryo transfer cycles (48% and 83% respectively)..

Conclusions: The elective cryopreservation of all embryos in egg donation cycles has no apparent detrimental effect on implantation or pregnancy rates suggesting that this is the optimal strategy for cycles in which fresh transfers are not indicated. Frozen cycles eliminate the need to synchronize donors and recipients thus allowing much greater flexibility in their scheduling. Using embryo cryopreservation to optimize donor and recipient cycles individually may result in enhanced implantation rates.