title: Human oocyte cryopreservation with slow freezing versus vitrification. Results from the National Italian Registry data, 2007-2011.
abstract: OBJECTIVE
  To compare mature human oocytes cryopreservation with slow freezing (SF) and vitrification (VT) in infertile couples.
  
  
  METHODS
  Retrospective study of national Italian data submitted during the period 2007-2011.
  
  
  METHODS
  National ART registry.
  
  
  METHODS
  Infertile patients with supernumerary oocytes.
  
  
  METHODS
  Thawing or warming of cryopreserved oocytes and ICSI.
  
  
  METHODS
  oocyte survival, fertilization, implantation and clinical pregnancy rate between SF and VT.
  
  
  RESULTS
  A total of 14,328 cycles with 11,599 transfers, 1,850 pregnancies, 1,168 deliveries and 1,342 babies born were analyzed from 146 reporting centers (range of cycles 1-1,255 per center). The SF oocytes' survival rate was lower than in VT (51.1% vs. 63.1%). Fertilization rate was significantly higher in SF than in VT (SF 71.6% vs. VT 70.1%). VT showed a significantly higher pregnancy rate, both per started cycle (14.4% vs. 12.0%) and per transfer (18.0% vs. 14.8%), and implantation rate (9.5% vs. 8.1%) than SF. However, the range and median pregnancy rate per started cycle were, respectively, 0%-50% and 7.7% in SF and 0%-100% and 6.7% in VT.
  
  
  CONCLUSIONS
  VT showed a statistically significant higher performance than SF. As with other ART procedures, the results are not homogeneous among clinics and protocols, but the confirm the clinical value of oocyte cryopreservation in infertile patients.
authors.affiliation: Humanitas Fertility Center, Division of Gynaecology and Reproductive Medicine, Department of Gynaecology, Humanitas Research Hospital, Rozzano (Milan), Italy. Electronic address: paolo.levi_setti@humanitas.it.
authors.forename: Paolo Emanuele
authors.initials: PE
authors.lastname: Levi Setti
authors.affiliation: Infertility and IVF Center, S. Orsola-Malpighi University Hospital, University of Bologna, Bologna, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Porcu
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, Yale University, New Haven, Connecticut.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Patrizio
authors.affiliation: ART Italian National Registry, National Center for Epidemiology, Surveillance, and Health Promotion, National Health Institute, Rome, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Vigiliano
authors.affiliation: ART Italian National Registry, National Center for Epidemiology, Surveillance, and Health Promotion, National Health Institute, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: de Luca
authors.affiliation: ART Italian National Registry, National Center for Epidemiology, Surveillance, and Health Promotion, National Health Institute, Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: d'Aloja
authors.affiliation: ART Italian National Registry, National Center for Epidemiology, Surveillance, and Health Promotion, National Health Institute, Rome, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Spoletini
authors.affiliation: ART Italian National Registry, National Center for Epidemiology, Surveillance, and Health Promotion, National Health Institute, Rome, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Scaravelli
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007246:Infertility / Q000503:physiopathology / Q000628:therapy*; D007558:Italy; D050498:Live Birth; D054315:Oocyte Retrieval; D009865:Oocytes; D011247:Pregnancy; D018873:Pregnancy Rate; D012042:Registries; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D058989:Vitrification
keywords: ART safety; Oocyte cryopreservation; methods; pregnancy outcome