Pregnancy following transfer of ooplasm from cryopreserved-thawed donor oocytes into recipient oocytes.

Objective: To determine if frozen-thawed donor oocytes could be used to provide cytoplasm for transfer into patients' oocytes to improve subsequent embryonic development.

Design: Prospective evaluation of the procedure in consenting IVF patients.

Setting: Assisted reproductive technology program.

Patient(s): The study was open to consenting IVF patients (of any age) with a history of poor embryo quality or those couples in which the wife's age was > or = 40 years.

Intervention(s): Transfer of donor egg cytoplasm from frozen-thawed oocytes into the oocytes of infertile recipients.

Main Outcome Measure(s): Donor oocyte survival following cryopreservation, fertilization following cytoplasmic transfer into recipient oocytes, embryo quality, and pregnancy outcome.

Result(s): Oocytes collected from four donors were cryopreserved and 61% (28/46) survived the thaw procedure. Cytoplasmic transfer was performed on the eggs of four patients, with fertilization occurring in 70.3% (26/37). Twin pregnancy was established in one patient (35 years of age) with a history of poor embryo quality.

Conclusion(s): Cryopreserved donor oocytes may provide a source of cytoplasm for transfer into recipient oocytes, eliminating the need for cycle synchronization between donor and infertile patient.