title: A prospective pilot study comparing fertilization and embryo development between fresh and vitrified sibling oocytes.
abstract: OBJECTIVE
  To evaluate the outcome of a newly established oocyte vitrification program in women undergoing in vitro fertilization (IVF) within a short timeframe by simultaneously evaluating embryos derived from vitrified and fresh oocytes from the same stimulated cycle.
  
  
  METHODS
  Cohort prospective controlled trial and case-control study.
  
  
  METHODS
  University-based tertiary fertility center.
  
  
  METHODS
  Fourteen women who fulfilled the inclusion criteria underwent controlled ovarian hyperstimulation and Intracytoplasmic sperm injection (ICSI) treatment.
  
  
  METHODS
  Oocyte vitrification.
  
  
  METHODS
  The primary outcome measures were oocyte survival, fertilization and cleavage rate, and subsequent embryo development, compared between vitrified and fresh oocytes. Secondary outcomes were implantation, clinical pregnancy, miscarriage and live birth rates using embryos derived from the vitrified oocytes for transfer. This was compared with age-matched controls who met similar inclusion criteria as the study patients and who underwent IVF during the same time period. Neonatal data on all newborns was also collected.
  
  
  RESULTS
  From October 2009 until November 2010, a total of 17 patients were enrolled in this study (mean age 31.9 +/- 2.9 years). Three subjects withdrew prior to retrieval and one subject did not have a transfer from vitrified oocytes. A total of 164 metaphase II (MII) oocytes were retrieved (mean 11.7 +/- 3.7), 83 were vitrified with 86.7% survival. Fertilization rate was similar between vitrified and fresh oocytes (69.4 vs 78.2%, P = 0.8). Cleavage on day two, however, was lowerin the vitrified oocytes (88% vs 100%, P = 0.004). Implantation rate (IR) was 25% (7/28) with a mean number of 2.0 +/- 0.5 embryos transferred. Live birth rate/embryo transfer (ET) was 46.1% (6/13) after transferring embryos derived only from vitrified oocytes, (six live births, seven babies,one set of twins). One additional ongoing pregnancy has been established after transfer of a cryopreserved blastocyst derived from a vitrified oocyte (combined pregnancy rate/ ET: 50%; 7/14).
  
  
  CONCLUSIONS
  This study provides a viable model to quickly assess the efficacy of a newly established egg vitrification program following American Society for Reproductive Medicine (ASRM) guidelines in an investigational protocol. Embryos resulting from oocyte vitrification resulted in optimal live birth and implantation rate. The lower cleavage rate noted in this study may indicate a possible detrimental effect of the vitrification process, which may be overcome with additional experience and refinement of the technique.
authors.affiliation: Center for Advanced Reproductive Services, Department of Ob/Gyn, University of Connecticut Health Center, Farmingon, CT, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Siano
authors.forename: Lawrence
authors.initials: L
authors.lastname: Engmann
authors.forename: John
authors.initials: J
authors.lastname: Nulsen
authors.forename: Claudio
authors.initials: C
authors.lastname: Benadiva
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002470:Cell Survival; D002970:Cleavage Stage, Ovum; D015331:Cohort Studies; D015925:Cryopreservation / Q000379:methods*; D004624:Embryo Transfer; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D007231:Infant, Newborn; D009865:Oocytes; D010865:Pilot Projects; D011247:Pregnancy; D018873:Pregnancy Rate