title: Late intracytoplasmic sperm injection in unexpected failed fertilization in vitro: diagnostic or therapeutic?
abstract: OBJECTIVE
  To evaluate fertilization potential of 24-hour-old unfertilized oocytes using intracytoplasmic sperm injection and the pregnancy potential of resultant embryos.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Private infertility clinic, London, United Kingdom.
  
  
  METHODS
  Fifteen patients with a history of infertility who underwent treatment with IVF and showed failure of fertilization on the day after oocyte retrieval.
  
  
  METHODS
  Assisted fertilization with intracytoplasmic sperm injection was carried out at 24 hours after oocyte retrieval.
  
  
  RESULTS
  A total of 121 metaphase II oocytes were subjected to intracytoplasmic sperm injection. Of these, 9 were damaged (7%), 2 were polyploidic (2%), and 58 showed normal fertilization (48%). Of the latter, 47 cleaved normally (81%). Forty embryos were transferred and three were cryopreserved. One patient conceived (7%) but in this case only one of three embryos transferred was from intracytoplasmic sperm injection.
  
  
  CONCLUSIONS
  Late (24 hours) intracytoplasmic sperm injection can give good fertilization and cleavage rates but the potential of the generated embryos to achieve pregnancy seems to be low.
authors.affiliation: London Gynaecology and Fertility Centre, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Tsirigotis
authors.forename: N
authors.initials: N
authors.lastname: Nicholson
authors.forename: M
authors.initials: M
authors.lastname: Taranissi
authors.forename: V
authors.initials: V
authors.lastname: Bennett
authors.forename: M
authors.initials: M
authors.lastname: Pelekanos
authors.forename: I
authors.initials: I
authors.lastname: Craft
mesh_terms: D000328:Adult; D002970:Cleavage Stage, Ovum; D003593:Cytoplasm; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D008845:Microinjections; D011247:Pregnancy; D011446:Prospective Studies; D013094:Spermatozoa; D013997:Time Factors; D017211:Treatment Failure