title: Clinical outcome of cryopreserved human pronuclear stage embryos resulting from intracytoplasmic sperm injection.
abstract: OBJECTIVE
  To compare the survival rate and pregnancy rate (PR) of embryos from intracytoplasmic sperm injection (ICSI) or conventional IVF, which were cryopreserved at the pronuclear stage in cycles where fresh transfer was deferred.
  
  
  METHODS
  Comparative observational study.
  
  
  METHODS
  University-associated IVF center.
  
  
  METHODS
  Ninety-nine patients who deferred ET and had all their embryos cryopreserved at the pronuclear stage after 153 oocyte retrievals. Thirty-nine patients had their oocytes inseminated by ICSI and 60 patients had conventional IVF insemination.
  
  
  METHODS
  All embryos were frozen-thawed at the two pronuclear stage and allowed to cleave for 2 days before transfer.
  
  
  METHODS
  Survival rate (morphologically intact after thaw), cleavage rate (cleaved by time of transfer), and the clinical PR after frozen ET.
  
  
  RESULTS
  In the ICSI group, 205 embryos were thawed for use in 57 frozen ETs; in the IVF group, there were 527 embryos thawed for use in 149 frozen ETs. There was no significant difference in any of the outcome measures by insemination method: survival rates (ICSI, 93.2%; IVF, 94.8%); cleavage rates (ICSI, 95.2%; IVF, 94.7%), and clinical PR (ICSI, 14.0%; IVF, 17.4%).
  
  
  CONCLUSIONS
  Pronuclear embryos resulting from ICSI can be cryopreserved successfully, thawed, and the survival rate and PR are comparable to conventional IVF.
authors.affiliation: University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School at Camden, USA.
authors.forename: L
authors.initials: L
authors.lastname: Hoover
authors.forename: A
authors.initials: A
authors.lastname: Baker
authors.forename: J H
authors.initials: JH
authors.lastname: Check
authors.forename: D
authors.initials: D
authors.lastname: Lurie
authors.forename: D
authors.initials: D
authors.lastname: Summers
mesh_terms: D000328:Adult; D002470:Cell Survival / Q000502:physiology; D015925:Cryopreservation; D003593:Cytoplasm; D005260:Female; D005307:Fertilization in Vitro; D005615:Freezing; D006801:Humans; D008297:Male; D008845:Microinjections / Q000379:methods*; D008875:Middle Aged; D011247:Pregnancy; D018873:Pregnancy Rate; D013094:Spermatozoa / Q000502:physiology*; D017388:Zygote Intrafallopian Transfer