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Outcomes of utilized cryopreserved autologous oocytes

      Objective

      Oocyte cryopreservation is a rapidly developing technology with reassuring outcomes from observational studies. However, there are limited studies on utilization of cryopreserved oocytes. Thus, our objective was to compare outcomes in women who returned to utilize their previously cryopreserved oocytes to IVF cycles that utilized frozen embryos.

      Design

      Retrospective cohort study from a large fertility center.

      Materials and Methods

      Women who underwent autologous oocyte cryopreservation for both medical and elective indications between 1/2010 and 12/2014 and returned to utilize their cryopreserved oocytes were selected. Oocyte cryopreservation was performed either by slow freeze or vitrification. Oocyte donation cycles were excluded. The control group consisted of women who underwent IVF-freeze all cycles followed by a frozen embryo transfer (FET) during the same time period. Clinical outcomes of interest included number of mature oocytes, fertilization rate, blastocyst progression (number of blastocysts per mature oocyte), and pregnancy rate. Statistical analysis was performed using a student t test for continuous variables and a fisher exact test for categorical variables.

      Results

      Of 523 patients who underwent autologous oocyte cryopreservation, 29 (5.5%) returned to utilize their cryopreserved oocytes. The mean age at oocyte cryopreservation was 37.3 ± 4.5 years (range of 24-44), which was comparable to the control group (P =0.24). The mean duration of cryopreservation was 478.9 days with a range of 76-880 days. The oocyte cryopreservation group had a similar number of mature oocytes (10.5 ± 7.2 vs 13.1 ±8.1 P= 0.08) and fertilization rate (69% ±24.3 vs 73.7% ± 20.14 P= 0.31) compared to the control group. In addition, the blastocyst progression was not significantly different between the oocyte cryopreservation and the control group (0.2 ± 0.19 vs 0.2 ± 0.28 P= 0.30). The pregnancy rate per embryo transfer was not significantly different from the IVF/FET group (45.5% vs 52.3% P = 0.65).

      Conclusions

      Utilization of cryopreserved autologous oocytes leads to similar outcomes, including pregnancy rates compared to women undergoing IVF with frozen embryo transfer. With greater utilization of cryopreserved oocytes, larger studies are needed to confirm these findings.