Multicenter observational study on slow-cooling oocyte cryopreservation: Clinical outcome

Andrea Borini, Paolo Emanuele Levi Setti, Paola Anserini, Roberto De Luca, Lucia De Santis, Eleonora Porcu, Giovanni Battista La Sala, Annapia Ferraretti, Tiziana Bartolotti, Giovanni Coticchio, Giulia Scaravelli

Research output: Contribution to journalArticle


Objective: To evaluate the efficacy of oocyte cryopreservation by a single slow-cooling protocol involving sucrose (0.2 mol/L) in the freezing solution. Design: Observational comparison of the clinical outcome in fresh and frozen thawed cycles. Setting: Public and private IVF centers. Patient(s): Infertile couples undergoing IVF treatment. Intervention(s): Use of a maximum three oocytes in fresh cycles, as established by local law, and cryopreservation and later use of surplus oocytes. Likewise fresh cycles, maximum three thawed oocytes were used per cycle. All thawed oocytes were microinjected. Main Outcome Measure(s): Embryologic and clinical parameters of fresh and thawed cycles. Result(s): Two thousand forty-six patients underwent 2,209 oocyte retrievals involving oocyte cryopreservation. Overall, the survival rate of thawed oocytes was 55.8%. In 940 thaw cycles, the mean numbers of inseminated oocytes and fertilization rates were significantly decreased vs. fresh cycles outcomes (2.6 ± 0.7 vs. 2.9 ± 0.2 and 72.5% vs. 78.3%, respectively), as were the rates of implantation (10.1% vs. 15.4%), pregnancy rates per transfer (17.0% vs. 27.9%), and pregnancy rates per cycle (13.7% vs. 26.2%). Differences in clinical outcome were found among centers. A pregnancy rate per thawing cycle above 14% was achieved by most clinics. Fifty-seven retrievals involving oocyte cryopreservation achieved a pregnancy after fresh embryo replacement. Implantation and pregnancy rates per embryo transfer and per thawing cycles were 17.5%, 28.6%, and 24.6%, respectively. Conclusion(s): Under the conditions tested, the clinical outcome of oocyte slow-cooling cryopreservation is reduced compared with fresh cycles. Nevertheless, in cases of inapplicability of embryo cryopreservation, oocyte cryopreservation should be offered to patients with surplus oocytes.

Original languageEnglish
Pages (from-to)1662-1668
Number of pages7
JournalFertility and Sterility
Issue number5
Publication statusPublished - Oct 2010


  • ART
  • ICSI
  • oocyte cryopreservation
  • pregnancy
  • slow freezing

ASJC Scopus subject areas

  • Obstetrics and Gynaecology
  • Reproductive Medicine
  • Medicine(all)

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    Borini, A., Levi Setti, P. E., Anserini, P., De Luca, R., De Santis, L., Porcu, E., La Sala, G. B., Ferraretti, A., Bartolotti, T., Coticchio, G., & Scaravelli, G. (2010). Multicenter observational study on slow-cooling oocyte cryopreservation: Clinical outcome. Fertility and Sterility, 94(5), 1662-1668.