Re-cryopreservation by vitrification of human blastocysts developed from frozen-cleaved embryos: A report of 15 cycles

Human blastocysts have been successfully cryopreserved and many live births occur each year using blastocysts that have been cryopreserved once. However, there is a paucity of information on recryopreservation of human blastocysts developed from frozen embryos. Therefore, we document the data for 27 blastocysts from 15 cycles (12 patients) of warming to review the efficacy of re-cryopreservation by vitrification of human blastocysts developed from frozen-cleaved embryos. A total of 27 surplus human blastocysts developed from frozen-cleaved embryos, obtained from 12 healthy infertile women undergoing IVF treatment between February 2004 and December 2006, were recryopreserved by vitrification. Of these, 26 (96%) reexpanded after warming and were transferred into 12 patients (15 cycles). Following transfer, the implantation rate was 35% (9/26) and the pregnancy rate was 47% (7/15). Two pregnancies ended in miscarriage, 5 healthy babies were born in 4 deliveries, and 1 pregnancy is ongoing. Our results suggest that recryopreservation by vitrification of human blastocysts developed from frozen-cleaved embryos can be performed without impairing their implantation ability after warming.