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Ultrarapid cryopreservation of human embryos: experience with 1,582 embryos
Y Y Hsieh1, H D Tsai, C C Chang
1Department of Obstetrics and Gynecology, China Medical College Hospital, Taichung, Taiwan, Republic of China.
Objectives:
To demonstrate the effectiveness of ultrarapid cryopreservation in human embryos.
Design:
Retrospective study.
Setting:
An IVF unit of a medical center.
Patient(S):
All cases received ultrarapid freezing (URF) of embryos and frozen embryo transfer.
Intervention(S):
Embryos were placed in phosphate-buffered saline (PB1) + 20% maternal serum (MS) for 5 minutes. Embryos were loaded to the straws containing PB1 + MS + 0.25 M sucrose (SUC) + 3.5 M dimethyl sulfoxide for 3 minutes, and then were stored in a liquid nitrogen tank. Embryos were thawed in a 37 degrees C water for 6 seconds and then cultured in PB1 + MS + SUC for 10 minutes. Embryos were transferred into PB1 + MS for 5 minutes and were transferred into patients.
Main Outcome Measure(S):
The embryo grades before and after URF, the survival and transferred embryo numbers, and the pregnancy and abortion rates were analyzed.
Result(S):
A total of 1,582 embryos were thawed, of which 1,273 (80.5%) embryos were transferred and 1,032 (65.2%) embryos survived with > or = 50% intact blastomere. The embryo numbers with grade I or II before and after freezing and thawing were 1,110 (70.2%) and 790 (50.0%). The mean embryo numbers per transfer was 5.0. Twenty-eight pregnancies (11.4% per transfer) were established, which included 5 miscarriages, 1 ectopic pregnancy, 4 preterm and 18 term deliveries.
Conclusion(S):
Ultrarapid freezing is worthy of reconsideration for embryo cryopreservation.