Anonymous oocyte donation performed exclusively with embryos cryopreservedat the pronuclear stage

Objective: To evaluate the clinical outcomes of patients who participated i n an anonymous oocyte donation program that used embryos cryopreserved at t he pronuclear stage. Design: Observational study. Setting: A tertiary care reproductive medicine unit. Patient(s): Anonymous oocyte donors and their respective recipients. Intervention(s): Oocyte donors underwent a standard controlled ovarian hype rstimulation protocol and transvaginal ultrasound-guided oocyte retrieval. Oocyte recipients underwent at least one programmed hormone replacement cyc le with transcervical ET. Main Outcome Measure(s): Thaw survival, implantation, clinical and ongoing pregnancy rates. Result(s): Thirty-six oocyte retrievals resulted in one ET to date. The mea n numbers of oocytes that were retrieved and normally fertilized were 18.2 and 11.6, respectively. Fifty-one embryo thaw-transfer cycles were performe d, with an embryo thaw survival rate of 93.5%. The clinical and ongoing pre gnancy rates per ET were 52.9% and 51%, respectively. The overall implantat ion rate was 28.7%. The percentage of oocyte retrievals that resulted in at least one ongoing pregnancy to date was 69.3%. Conclusion(s): Anonymous oocyte donation can be conducted efficiently with the exclusive use of embryos cryopreserved at the pronuclear stage. This ap proach facilitates synchronization of the donor-recipient pair, eliminates the risk that recipients will begin hormonal therapy without embryo availab ility, and produces an acceptable ongoing pregnancy rate per oocyte donatio n. (C) 1999 by American Society far Reproductive Medicine.