OBJECTIVE: To report an ongoing twin pregnancy after transfer of embryos that were vitrified at the 2-pronuclei stage in a new vitrification solution. DESIGN: Case report. SETTING: A tertiary-care infertility clinic. PATIENT(S): A 26-year-old infertile woman in whom two previous IVF implantations failed. INTERVENTION(S): Vitrification of 2-pronuclei embryos, in vitro culture for 48 hours, and transfer into the uterus. MAIN OUTCOME MEASURE(S): Survival and cleavage after vitrification and achievement of clinical pregnancy. RESULT(S): Six zygotes were vitrified by using a three-step protocol (4% ethylene glycol for 3 minutes, 20% ethylene glycol for 1 minute, and 38% ethylene glycol and 1.2 M trehalose for 0.5 minute). After 2 months of storage in a double-straw system in liquid nitrogen, two zygotes were warmed and cryoprotectants were removed by using a four-step protocol (1 M, 0.5 M, 0.25 M, and 0.125 M of trehalose). Two embryos were transferred after 48 hours of in vitro culture, cleaving to 5 and 6 cells. The resulting twin pregnancy was confirmed by ultrasonography at the sixth week. CONCLUSION(S): Vitrification by using ethylene glycol and trehalose appears to be a safe, promising method for cryopreservation of human zygotes. Storage of vitrified zygotes in a double-straw system does not compromise their subsequent potential for survival and development.
OBJECTIVE: To report an ongoing twin pregnancy after transfer of embryos that were vitrified at the 2-pronuclei stage in a new vitrification solution. DESIGN: Case report. SETTING: A tertiary-care infertility clinic. PATIENT(S): A 26-year-old infertilewoman in whom two previous IVF implantations failed. INTERVENTION(S): Vitrification of 2-pronuclei embryos, in vitro culture for 48 hours, and transfer into the uterus. MAIN OUTCOME MEASURE(S): Survival and cleavage after vitrification and achievement of clinical pregnancy. RESULT(S): Six zygotes were vitrified by using a three-step protocol (4% ethylene glycol for 3 minutes, 20% ethylene glycol for 1 minute, and 38% ethylene glycol and 1.2 M trehalose for 0.5 minute). After 2 months of storage in a double-straw system in liquid nitrogen, two zygotes were warmed and cryoprotectants were removed by using a four-step protocol (1 M, 0.5 M, 0.25 M, and 0.125 M of trehalose). Two embryos were transferred after 48 hours of in vitro culture, cleaving to 5 and 6 cells. The resulting twin pregnancy was confirmed by ultrasonography at the sixth week. CONCLUSION(S): Vitrification by using ethylene glycol and trehalose appears to be a safe, promising method for cryopreservation of human zygotes. Storage of vitrified zygotes in a double-straw system does not compromise their subsequent potential for survival and development.
Authors: Laura Rienzi; Clarisa Gracia; Roberta Maggiulli; Andrew R LaBarbera; Daniel J Kaser; Filippo M Ubaldi; Sheryl Vanderpoel; Catherine Racowsky Journal: Hum Reprod Update Date: 2017-03-01 Impact factor: 15.610