title: Successful freezing and thawing of blastocysts cultured in sequential media using a modified method.
abstract: OBJECTIVE
  To evaluate the clinical role of blastocyst freezing and thawing after prolonged culturing in sequential media.
  
  
  METHODS
  Retrospective analysis of 293 blastocyst freeze-thawing cycles.
  
  
  METHODS
  University hospital infertility unit.
  
  
  METHODS
  Nonselected couples undergoing IVF.
  
  
  METHODS
  Blastocysts were frozen and thawed by a modified method.
  
  
  METHODS
  Blastocyst recovery after freeze-thawing and pregnancy rates after the transfer. Evaluation of the effect of the number of transferred blastocysts, the method of IVF, and of the woman's age on the results achieved by frozen-thawed blastocysts.
  
  
  RESULTS
  Frozen-thawed blastocysts provided a 29.5% clinical pregnancy rate per transfer. After the transfer of three blastocysts the pregnancy rate was 42.0%, and after the transfer of one or two blastocysts it was approximately the same (25.0% and 28.0%, respectively). The method of IVF did not affect pregnancy rates, but the increasing age of the woman did. Pregnancies were characterized by a low abortion rate (8.0%) regardless of the age of the woman.
  
  
  CONCLUSIONS
  A modified method for blastocyst freeze-thawing provides good clinical results. It offers the possibility for a single-thawed blastocyst transfer and represents a good alternative for older women because of its lower risk of spontaneous abortion.
authors.affiliation: Reproductive Unit, Department of Obstetrics and Gynecology, University Medical Centre Ljubljana, Ljubljana, Slovenia. irma.virant@kclj.si
authors.forename: Irma
authors.initials: I
authors.lastname: Virant-Klun
authors.forename: Tomaz
authors.initials: T
authors.lastname: Tomazevic
authors.forename: Lili
authors.initials: L
authors.lastname: Bacer-Kermavner
authors.forename: Jozica
authors.initials: J
authors.lastname: Mivsek
authors.forename: Brigita
authors.initials: B
authors.lastname: Valentincic-Gruden
authors.forename: Helena
authors.initials: H
authors.lastname: Meden-Vrtovec
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D005615:Freezing; D006801:Humans; D008423:Maternal Age; D011247:Pregnancy; D012189:Retrospective Studies
chemical_list: D003470:Culture Media