title: The value of fast blastocoele re-expansion in the selection of a viable thawed blastocyst for transfer.
abstract: OBJECTIVE
  To investigate the role of fast blastocoele re-expansion in the selection of viable thawed blastocysts for transfer.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Academic assisted reproductive program.
  
  
  METHODS
  Transfer cycles were divided into two groups according to the presence or absence of fast re-expanded blastocysts. In group I (124 cycles), all transferred blastocysts had fast re-expanding blastocoele. In group II (113 cycles), no fast re-expanded blastocysts were included in the transfer.
  
  
  METHODS
  Blastocyst survival was defined as >50% of cells remaining intact after thaw and re-expansion after culture in vitro for 2-4 hours before transfer. Blastocysts with >or=50% re-expansion were designated as fast re-expanded blastocysts.
  
  
  METHODS
  Percentage of blastomere loss immediately after thaw, degree of blastocoele re-expansion, and clinical outcomes (pregnancy and implantation rates).
  
  
  RESULTS
  The rates of survival and fast blastocoele re-expansion of partially intact blastocysts were significantly reduced as compared with fully intact blastocysts. Significantly higher rates of clinical pregnancy (37.1% vs. 16.8%) and implantation (26.7% vs. 11.3%) were obtained when all transferred blastocysts had fast re-expanding blastocoele as compared with those transfers without fast re-expanded blastocysts included.
  
  
  CONCLUSIONS
  Our results showed that blastomere loss of thawed blastocyst was associated with a reduced ability to re-expand. As a discriminative morphologic marker of superior embryo viability, a fast re-expanded blastocyst would be given priority for transfer to better utilize the cryopreserved blastocysts.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University Medical Center, Stanford, California 94304, USA.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Shu
authors.forename: Jill
authors.initials: J
authors.lastname: Watt
authors.forename: Janice
authors.initials: J
authors.lastname: Gebhardt
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dasig
authors.forename: Julie
authors.initials: J
authors.lastname: Appling
authors.forename: Barry
authors.initials: B
authors.lastname: Behr
mesh_terms: D000328:Adult; D001755:Blastocyst; D049109:Cell Proliferation; D002470:Cell Survival; D015925:Cryopreservation; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome