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.
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.