title: Twin pregnancy after vitrification of 2-pronuclei human embryos.
abstract: OBJECTIVE
  To report an ongoing twin pregnancy after transfer of embryos that were vitrified at the 2-pronuclei stage in a new vitrification solution.
  
  
  METHODS
  Case report.
  
  
  METHODS
  A tertiary-care infertility clinic.
  
  
  METHODS
  A 26-year-old infertile woman in whom two previous IVF implantations failed.
  
  
  METHODS
  Vitrification of 2-pronuclei embryos, in vitro culture for 48 hours, and transfer into the uterus.
  
  
  METHODS
  Survival and cleavage after vitrification and achievement of clinical pregnancy.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.affiliation: Christian-Lauritzen-Institut, Frauenstrasse 51, 89073 Ulm, Germany. ljeli@seznam.cz
authors.forename: Ladislava
authors.initials: L
authors.lastname: Jelinkova
authors.forename: Helmy A
authors.initials: HA
authors.lastname: Selman
authors.forename: Amir
authors.initials: A
authors.lastname: Arav
authors.forename: Erwin
authors.initials: E
authors.lastname: Strehler
authors.forename: Natalie
authors.initials: N
authors.lastname: Reeka
authors.forename: Karl
authors.initials: K
authors.lastname: Sterzik
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000379:methods; D003451:Cryoprotective Agents; D004624:Embryo Transfer; D019855:Ethylene Glycol / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D011247:Pregnancy; D011272:Pregnancy, Multiple; D014199:Trehalose / Q000494:pharmacology; D014427:Twins
chemical_list: D003451:Cryoprotective Agents; D014199:Trehalose; D019855:Ethylene Glycol