Oocyte Cryopreservation: A 9-Year Single-Centre Experience.

OBJECTIVE: Oocyte cryopreservation (OC) has increased in recent years; however, there is a paucity of published data on the use of cryopreserved oocytes and associated outcomes. METHODS: A retrospective review of 748 OC cycles between 2013 and 2022 at a private fertility centre was performed. Outcome parameters for oocyte retrieval cycles were reviewed. For patients who returned for oocyte disposition, outcomes subsequent to oocyte re-warming, fertilization, and transfer were analyzed. RESULTS: There were 748 OC cycles (653 elective and 95 non-elective) in 646 patients (556 elective and 90 non-elective). Patients were older at the time of freezing in the elective oocyte group compared with the non-elective group (36.5 vs. 28.8 y; P < 0.001). Sixty-five patients returned to warm and fertilize their oocytes (50 in the elective group and 15 in the non-elective group). The survival rate for warmed oocytes was 76.1% (541/711), and 66.2% of surviving oocytes were successfully fertilized, and 39.1% reached blastulation. Twenty-three patients underwent embryo transfers (10 after preimplantation genetic testing for aneuploidy), with 15 patients having at least 1 delivery or ongoing pregnancy. CONCLUSIONS: To date, this is the largest published experience with OC in Canada. OC can lead to successful live births but does not guarantee a viable outcome for all patients. In this study, most patients with vitrified oocytes had not returned for disposition, so long-term follow-up is still required to verify the efficacy of OC.

The role for preimplantation genetic diagnosis in balanced translocation carriers.

OBJECTIVE: Preimplantation genetic diagnosis is an established technique that provides an alternative to prenatal diagnosis for patients who are at risk of transmitting a serious genetic disorder to their offspring. Preimplantation genetic diagnosis has been used for couples who have been at risk for having offspring with single gene or X-linked disorders and for screening for common age-related aneuploidy and in couples who themselves carry balanced chromosomal rearrangements. The aim of this study was to summarize our experience using preimplantation genetic diagnosis after the identification of a parental balanced translocation, specifically as it relates to the number of embryos that are suitable for transfer after preimplantation genetic diagnosis for a known translocation and aneuploidy screening. STUDY DESIGN: This is a retrospective review of data from a single center that involved 6 couples that initiated the process of preimplantation genetic diagnosis for translocation and aneuploidy screening by fluorescent in situ hybridization. RESULTS: A total of 65 embryos were obtained, of which 56 embryos (86%) were suitable for fluorescent in situ hybridization analysis. After fluorescent in situ hybridization, 1 embryo was diagnosed as normal or balanced (1.7%). Forty-three embryos (76.8%) were unbalanced for the translocation; 8 embryos (14.3%) were aneuploid, and 4 embryos (7.1%) were uninformative. There were no clinical pregnancies. CONCLUSION: In our experience, there are very few embryos that are available for transfer from these patients after translocation and aneuploidy screening because of multiple unbalanced segregation products and a high rate of aneuploidy. Factors that contributed to this may be related to which parent carries the translocation, methods that were used for in vitro fertilization, and advanced maternal age. Although preimplantation genetic diagnosis for translocation carriers theoretically can enhance the pregnancy rate for a couple, there are limitations. This information should be shared with couples who are contemplating preimplantation genetic diagnosis for translocation, and the options of sperm or egg donor should be considered.