title: Blastocyst formation in in vitro fertilization versus intracytoplasmic sperm injection cycles: influence of the fertilization procedure.
abstract: OBJECTIVE
  To compare the quality of early cleaving embryos and blastocysts obtained by IVF or intracytoplasmic sperm injection (ICSI).
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Tertiary infertility center.
  
  
  METHODS
  Sibling oocytes of 104 patients in 104 IVF vs. ICSI cycles.
  
  
  METHODS
  Cumulus oocyte complexes (n = 1,358) were randomly subjected to ICSI or IVF.
  
  
  METHODS
  Embryo development and blastocyst formation rate. The blastocyst quality and cycle efficiency were also evaluated.
  
  
  RESULTS
  Early embryo cleavage was higher after ICSI (37.1%) compared to IVF (14.1%). The percentage of > or =4-cell embryos on day 2 and > or =8-cell embryos on day 3 was similar for both procedures. The overall blastocyst formation was not different between ICSI (50.2%) and IVF (54.8%), neither was the percentage of good-quality blastocysts (31.3% for ICSI and 36.0% for IVF). The total cycle efficiency (percentage of embryos transferred and frozen per two pronuclei [2PN]) was comparable for the two techniques (51.7% for ICSI and 57.4% for IVF).
  
  
  CONCLUSIONS
  No differences were found on sibling oocytes in the embryo development and blastocyst formation, irrespective of the fertilization procedure. Earlier suggestions that the ICSI technique may result in impaired blastocyst development were not confirmed in this study.
authors.affiliation: Center for Reproductive Medicine, University Hospital, Dutch-speaking Brussels Free University, Vrije Universiteit Brussel-VUB, Brussels, Belgium. lisbet.vanlanduyt@az.vub.ac.be
authors.forename: Lisbet
authors.initials: L
authors.lastname: Van Landuyt
authors.forename: Anick
authors.initials: A
authors.lastname: De Vos
authors.forename: Hubert
authors.initials: H
authors.lastname: Joris
authors.forename: Greta
authors.initials: G
authors.lastname: Verheyen
authors.forename: Paul
authors.initials: P
authors.lastname: Devroey
authors.forename: André
authors.initials: A
authors.lastname: Van Steirteghem
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D016001:Confidence Intervals; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods* / Q000706:statistics & numerical data; D018709:Statistics, Nonparametric