title: Cocultured blastocyst cryopreservation: experience of more than 500 transfer cycles.
abstract: OBJECTIVE
  To present our experience using cocultured cryopreserved and transferred blastocysts.
  
  
  METHODS
  Retrospective study of patients undergoing transfer of cryopreserved blastocysts.
  
  
  METHODS
  Three different IVF centers.
  
  
  METHODS
  Four hundred sixty-seven thawed cycles from January 1991 to June 1994.
  
  
  METHODS
  Pregnancy rate per cycle after transfer of pre-embryos developed from thawed blastocysts.
  
  
  RESULTS
  One thousand two hundred thirty-nine blastocysts were thawed. Of these, 1,033 (83%) survived thawing and were transferred. Five hundred sixty-three thawed cycles resulted in 516 (92%) receiving intrauterine transfer. One hundred twelve clinical pregnancies were established, resulting in a 21.7% pregnancy per transfer with a 19% ongoing rate. The implantation rate of 13.4% results from 138 implanted pre-embryos. There was a higher PR in the programmed cycle (79/302; 26.2%) compared with the natural cycle (6/47;13%).
  
  
  CONCLUSIONS
  Freezing at the blastocyst stage is a proven and reliable method in IVF technology. Although there may be fewer pre-embryos, their ability to implant appears to approach the potential of a fresh transfer.
authors.affiliation: Augusta Reproductive Biology Associates, Georgia 30904, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Kaufman
authors.forename: Y
authors.initials: Y
authors.lastname: Menezo
authors.forename: A
authors.initials: A
authors.lastname: Hazout
authors.forename: B
authors.initials: B
authors.lastname: Nicollet
authors.forename: M
authors.initials: M
authors.lastname: DuMont
authors.forename: E J
authors.initials: EJ
authors.lastname: Servy
mesh_terms: D001755:Blastocyst / Q000502:physiology*; D002478:Cells, Cultured; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D012189:Retrospective Studies