Report of four donor-recipient oocyte cryopreservation cycles resulting in high pregnancy and implantation rates

Objective: To determine the clinical potential of donor-oocyte cryopreservation and thaw techniques for recipient patients. Design: Institutional review board-approved prospective study of donor oocyte cryopreservation. Setting: A large, private infertility center. Patient(s): Four anonymous oocyte donors underwent ovarian hyperstimulation for the purpose of oocyte retrieval and cryopreservation. The oocytes were subsequently thawed, fertilized, and transferred to 4 recipient patients. Intervention(s): Oocytes were obtained from young donor patients and were cryopreserved with a slow freeze/rapid thaw protocol in which 1,2-propanediol (PrOH) and sucrose were used as cryoprotectants. Oocytes that survived were inseminated using intracytoplasmic sperm injection (ICSI). Resulting embryos were replaced into the recipient patients on the third day post-insemination. Main Outcome Measure(s): Post-thaw survival rate, fertilization rate, cleavage rate, implantation and clinical pregnancy rates. Result(s): A total of 79 metaphase II oocytes were frozen, stored frozen overnight in liquid nitrogen, and then thawed. The post-thaw survival rate was 86.1%. Normal fertilization following ICSI occurred in 89.7% of the surviving oocytes. Cleavage was observed in 91.8% of normally fertilized oocytes. A total of 23 embryos were transferred to 4 recipient patients. A clinical pregnancy rate of 75% and an implantation rate of 26.1% were achieved. Conclusion(s): Human oocyte cryopreservation is an effective technique that can be applied in clinical situations with high oocyte survival and clinical pregnancy rates expected.