title: Analyzing factors affecting the success rate of frozen-thawed embryos.
abstract: OBJECTIVE
  In recent years the infertile population applying for IVF treatments was changed and so the indications for performing intracellular sperm injection (ICSI). The aim of this study was to analyze predicting factors of our thawing cycles.
  
  
  METHODS
  From December 1998 to July 2001, 440 consecutive thawing cycles were performed. Patient characteristics were examined. The number of cryopreserved embryos, number of transferred embryos, the timing of cryopreservation (48 h vs. 72 h), and embryo survival rate were analyzed as a possible predictor for pregnancies achievement.
  
  
  RESULTS
  Conventional IVF patient's characteristic was significantly different from ICSI population and analysis has been performed for every population separately. In the IVF population the women age, the number of transferred embryos, and timing of cryopreservation were factors significantly influencing the pregnancy rate. Interestingly, in the ICSI population only the number of transferred embryos was found to be a predictive factor.
  
  
  CONCLUSIONS
  ICSI and IVF cycles should be analyzed separately. Not all the factors influencing the success rate in the conventional IVF population are valid in the ICSI population.
authors.affiliation: Department of Obstetric and Gynecology, IVF unit, Carmel Medical Center, Haifa, Israel. lahav@adi.org.il
authors.forename: S
authors.initials: S
authors.lastname: Lahav-Baratz
authors.forename: M
authors.initials: M
authors.lastname: Koifman
authors.forename: H
authors.initials: H
authors.lastname: Shiloh
authors.forename: D
authors.initials: D
authors.lastname: Ishai
authors.forename: Z
authors.initials: Z
authors.lastname: Wiener-Megnazi
authors.forename: M
authors.initials: M
authors.lastname: Dirnfeld
mesh_terms: D000328:Adult; D017677:Age Distribution; D015925:Cryopreservation; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer; D004622:Embryo, Mammalian; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D015996:Survival Rate; D015053:Zygote / Q000737:chemistry / Q000254:growth & development*