P-480 Oocyte survival and embryo viability rates are not affected by the transportation of vitrified donor oocytes: a sibling study with oocytes from the same cohort

Abstract Study question Are oocyte survival and embryo viability rates impaired by the shipment of vitrified donor oocytes in nitrogen vapors from one country to another Summary answer Oocyte survival and embryo viability rates are not affected by their transportation in nitrogen vapors showing similar parameters in the clinics of origin and abroad. What is known already The demand for donor eggs increases as egg donation cycles rise in ART clinics. Due to the legislation in some countries and the lack of donors, clinics choose to import vitrified oocytes from egg banks. Vitrification is a well established technique and the effectiveness of egg banks with vitrified oocytes has been proven. However, the comparison of sibling oocytes from the same donor's cohort in origin and after transportation remains to be study Study design, size, duration This is a retrospective, multicentric, observational study Participants/materials, setting, methods A total of 1030 vitrified oocytes from 55 donors were split between recipients in two different countries. Three clinics, one in Argentina (clinic of origin) and two in Brasil (clinics of destination) participated in this study. A total of 717 oocytes remained in the clinic of origin and were used to perform IVF cycles, while 313 oocytes were shipped abroad to the clinics of destination. Oocytes were transported at -196ºC in tanks with nitrogen vapors. Main results and the role of chance No significant differences were observed for any of the parameters analyzed except for the blastocyst rate. The lower blastocyst rate observed for the clinics of destination could be explained by the fact that one of the clinics performed embryo transfers and cryopreservations on day 3 leaving only surplus embryos (with lower potential) to blastocyst culture. When analyzing the embryo utilization rate, defined as the total of embryos on day 3 or day 5 destined to transfer or cryopreservation, results were not statistically different between the clinic of origin and both clinics of destination. P-480 Table 1 Clinic 1 (Origin) Clinic 2 (Destination) p-value Nº Donors 28 27 - Nº Oocytes 713 313 - Survival Rate (%) 92.7 96.6 NS Fertilization Rate (%) 78.5 78.3 NS Blastocyst Rate (%) 62.9 50.5