Oocyte cryopreservation: Clinical outcome of slow-cooling protocols differing in sucrose concentration

Lucia De Santis, I. Cino, E. Rabellotti, E. Papaleo, F. Calzi, F. M. Fusi, C. Brigante, A. Ferrari

Research output: Contribution to journalArticlepeer-review


Oocyte cryopreservation represents an important option for management of female fertility, avoiding the ethical concerns associated with embryo storage. This retrospective study evaluated the clinical outcome of two alternative slow freezing protocols involving different sucrose concentrations. From January 2004 to March 2006, spare oocytes from selected couples undergoing lVF or intracytoplasmic sperm injection were frozen using a slow-cooling protocol and thawed at a later stage. Patients were divided into two groups: group A (n = 65), whose oocytes were frozen with propane-1,2-diol (PrOH) and 0.1 mol/l sucrose; and group B (n = 66) whose oocytes were frozen with 0.3 mol/l sucrose. A total of 543 oocytes were thawed in group A and 601 in group B, achieving a survival rate of 24.3 and 71.2% respectively. Whilst fertilization rate (53.5 and 80.4% respectively) was higher in group B, enhanced results for group A were achieved over all (implantation rate per transferred embryos 12.2 versus 5.7%; pregnancy rate per transfer 16.7 versus 9.5%). Normal births and ongoing pregnancies have occurred in both groups. Although in slow-cooling methods higher sucrose concentration in the freezing mixture allows higher post-thaw survival and fertilization rates, overall this did not coincide with an improved clinical outcome.

Original languageEnglish
Article number2465
Pages (from-to)57-63
Number of pages7
JournalReproductive BioMedicine Online
Issue number1
Publication statusPublished - Jan 2007


  • Cryopreservation
  • Oocytes
  • Pregnancy rate
  • Slow freezing

ASJC Scopus subject areas

  • Obstetrics and Gynaecology


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