title: Blastocyst culture and transfer: analysis of results and parameters affecting outcome in two in vitro fertilization programs.
abstract: OBJECTIVE
  To determine whether previously described advanced blastocyst development and high implantation rates are confirmed in an expanded multicenter trial.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Two private assisted reproductive technology units.
  
  
  METHODS
  One hundred seventy-four patients who underwent blastocyst culture and transfer.
  
  
  METHODS
  Culture of all pronucleate embryos in sequential media to the blastocyst stage (day 5) followed by ET.
  
  
  METHODS
  The number and percentage of blastocysts developed, implantation rates, pregnancy rates, and parameters that affected outcome were analyzed.
  
  
  RESULTS
  Only 3 of 174 patients failed to achieve blastocyst-stage ET. The mean blastocyst development rate was 48%. The ongoing pregnancy rate was 66.3% per oocyte retrieval, with a mean (+/-SE) of 2.2 +/- 0.05 blastocysts transferred and an implantation rate of 48% per blastocyst transferred.
  
  
  CONCLUSIONS
  Blastocyst culture and transfer is an effective means of treating patients who respond well to gonadotropins. High pregnancy rates can be accomplished with low numbers of embryos transferred. Patients who failed to achieve ET were rare.
authors.affiliation: Colorado Center for Reproductive Medicine, Englewood 80110, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Schoolcraft
authors.forename: D K
authors.initials: DK
authors.lastname: Gardner
authors.forename: M
authors.initials: M
authors.lastname: Lane
authors.forename: T
authors.initials: T
authors.lastname: Schlenker
authors.forename: F
authors.initials: F
authors.lastname: Hamilton
authors.forename: D R
authors.initials: DR
authors.lastname: Meldrum
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology; D015925:Cryopreservation; D046508:Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D005314:Embryonic and Fetal Development; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D016896:Treatment Outcome