The outcomes of human blastocyst cryopreservation:vitrification using cryoloop versus slow-freezing method

Objective:To compare the outcomes of vitrification using cryoloop with slow-freezing meth-od for human blastocyst cryopreservation.Methods:In IVF-ET cycles,supernumerary embryos were cultured to Day 5 or Day 6,blas-tocysts were cryopreserved by vitrification using cryoloops or slow-freezing method,then blasto-cyst survival rate and pregnant rate were compared.Results:115 vitrified blastocysts from 39 cycles were warmed,104(90.4%)blastocysts sur-vived.After the transfer of 74 blastocysts in 38 cycles,28(73.7%)women got clinically preg-nant,2(7.1%)of them suffered from miscarriage,2 healthy babies were born in 2 deliveries,and the other 24 pregnancies are ongoing.As to slow-freezing method,87 blastocysts from 21 cy-cles were thawed,37(42.5%)of them survived,28 blastoeysts were transferred in 15 cycles,6(40%)women got clinically pregnant,1 of them miscarried,3 healthy babies were born in 2 de-liveries,and the other 3 pregnancies are ongoing.Conclusion:The survival rate and pregnant rate of vitrification using cryoloop are superior totraditional slow-freezing method,and the transfer cancel rate is lower than that of slow-freezingmethod.The miscarriage rate is similar in two methods.

Objective： To compare the outcomes of vitrification using cryoloop with slow-freezing method for human blastocyst cryopreservation. Methods： In IVF-ET cycles, supernumerary embryos were cultured to Day 5 or Day 6, blastocysts were cryopreserved by vitrification using cryoloops or slow-freezing method, then blastocyst survival rate and pregnant rate were compared. Results： 115 vitrified blastocysts from 39 cycles were warmed, 104（90.4%） blastocysts survived. After the transfer of 74 blastocysts in 38 cycles, 28（73.7%） women got clinically pregnant, 2（7.1%） of them suffered from miscarriage, 2 healthy babies were born in 2 deliveries, and the other 24 pregnancies are ongoing. As to slow-freezing method, 87 blastocysts from 21 cycles were thawed, 37（42.5%）of them survived, 28 blastocysts were transferred in 15 cycles, 6（40%） women got clinically pregnant, 1 of them miscarried, 3 healthy babies were born in 2 deliveries, and the other 3 pregnancies are ongoing. Conclusion： The survival rate and pregnant rate of vitrification using cryoloop are superior to traditional slow-freezing method, and the transfer cancel rate is lower than that of slow-freezing method. The miscarriage rate is similar in two methods.