title: Vitrification of blastocysts derived from fair to poor quality cleavage stage embryos can produce high pregnancy rates after warming.
abstract: OBJECTIVE
  This study investigates whether certain embryos considered unsuitable for cryopreservation on day 3 might nevertheless have the potential to develop into worthwhile blastocysts that could be vitrified in the same cycle.
  
  
  METHODS
  Retrospective study: between 2010 and 2011, embryo transfers and cryopreservation took place mainly on day 3 in our centre. Supernumerary embryos of intermediate to poor quality were reassessed on days 5/6 and any good quality blastocysts were vitrified.
  
  
  RESULTS
  Out of 914 cleavage stage (day 3) embryos left in culture, 16 % were vitrified on days 5/6. Fifty blastocyst warming cycles resulted in a 76 % survival rate, 44 % clinical pregnancy rate and 39 % implantation rate. During the same time period, 213 warming cycles of good quality cleavage stage embryos rendered survival rates, clinical pregnancy and implantation rates of 97 %, 23 % and 16 % respectively.
  
  
  CONCLUSIONS
  Supernumerary average quality day 3 embryos should be given a second chance to be selected for cryopreservation. If blastocysts are obtained and survive vitrification, there is a good chance of implantation thus reducing embryo waste.
authors.affiliation: Department of Gynaecology, CHU St Pierre, (Université Libre de Bruxelles), rue Haute 322, Brussels, 1000, Belgium, Chloe_SHAW-JACKSON@stpierre-bru.be.
authors.forename: Chloë
authors.initials: C
authors.lastname: Shaw-Jackson
authors.forename: Evelyne
authors.initials: E
authors.lastname: Bertrand
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Becker
authors.forename: Jérôme
authors.initials: J
authors.lastname: Colin
authors.forename: Caroline
authors.initials: C
authors.lastname: Beaudoin-Chabot
authors.forename: Serge
authors.initials: S
authors.lastname: Rozenberg
authors.forename: Candice
authors.initials: C
authors.lastname: Autin
mesh_terms: D001755:Blastocyst / Q000166:cytology*; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D047108:Embryonic Development; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D058989:Vitrification