title: Vitrification of human hatched blastocysts: a report of 4 cases.
abstract: BACKGROUND
  Vitrification is a fairly well-established technique for cryopreservation of human zona-intact blastocysts. However, little is known about the efficacy of the vitrification technique for zona-free hatched blastocysts.
  
  
  METHODS
  A total of 4 hatched blastocysts from 4 healthy, infertile women undergoing in vitro fertilization were vitrified and warmed. All 4 hatched blastocysts expanded after warming and were transferred to 4 patients. Three of the women became clinically pregnant. Two healthy infants were born in 2 deliveries, and 1 pregnancy had progressed to 35 weeks at this writing.
  
  
  CONCLUSIONS
  Our results suggest that vitrification is a useful cryopreservation technique not only for zona-intact blastocysts but also for zona-free hatched blastocysts.
authors.affiliation: Kinutani Women's Clinic, 2-1-4-3F, Ohtemachi, Naka-ku, Hiroshima 730-0051, Japan. hiraoka@chive.ocn.ne.jp
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Hiraoka
authors.forename: Kaori
authors.initials: K
authors.lastname: Hiraoka
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kinutani
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kinutani
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D015925:Cryopreservation / Q000379:methods; D046149:Embryo Culture Techniques; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy