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

Area of Science:

• Reproductive Medicine
• Assisted Reproductive Technology

Background:

• Oocyte cryopreservation offers fertility preservation but its clinical efficacy requires evaluation.
• Slow-cooling protocols are commonly used, with sucrose as a cryoprotective agent.

Purpose of the Study:

• To assess the effectiveness of a specific slow-cooling oocyte cryopreservation protocol using sucrose.
• To compare clinical outcomes of frozen-thawed oocytes with fresh oocytes in in vitro fertilization (IVF) cycles.

Main Methods:

• An observational study comparing fresh and frozen-thawed oocyte cycles in infertile couples undergoing IVF.
• A standardized slow-cooling protocol with 0.2 mol/L sucrose was employed for cryopreservation.
• Maximum of three oocytes were used per cycle, with all thawed oocytes being microinjected.

Main Results:

• A total of 2,209 oocyte cryopreservations were performed, with a 55.8% survival rate for thawed oocytes.
• Frozen-thawed oocyte cycles showed significantly lower fertilization, implantation, and pregnancy rates compared to fresh cycles.
• Despite reduced rates, most clinics achieved a pregnancy rate per thawing cycle above 14%.

Conclusions:

• Oocyte slow-cooling cryopreservation with sucrose results in diminished clinical outcomes relative to fresh cycles.
• Oocyte cryopreservation is a recommended option for patients with surplus oocytes when embryo cryopreservation is not applicable.