Objectives: The Cryotec method has been employed in all frozen-warmed cycles at Alpha Fertility Centre (AFC) since July 2013. With the Cryotec method, we have consistently achieved 100% post-warmed survival rates of embryos (Lee et al, 2016), and a near 100% post-warmed survival of vitrified oocytes (Lui et al, 2016). This robust cryopreservation method has enabled us to establish oocyte banking in AFC since 2014. In this study we compare the clinical outcome of vitrified-warmed oocyte and fresh oocytes in patients undergoing oocyte donation program.

Methods: Forty-one women underwent fresh blastocyst transfer using anonymously donated oocytes at Alpha Fertility Centre, Malaysia from March 2014 until December 2016. Nineteen of these patients were allocated with vitrified-warmed donated oocytes (Group A) while 22 patients received donated oocytes from fresh retrievals (Group B). Oocytes from Group A were vitrified and warmed using the Cryotec method (Cryotech, Japan). All oocytes had Intra-Cytoplasmic Sperm Injection (ICSI) and resultant embryos were cultured to day 5 or 6.  The mean age of oocyte donors in Group A and Group B was 23.2 and 24.4 respectively (p>0.05); and mean age of recipients was 41.0 and 39.8 respectively (p>0.05). All recipients underwent a medicated transfer cycle using down regulation with Intra-muscular Depot Leucrin 3.75 mg, and endometrial priming with oral oestrogen (Progynova) in graduated doses. Progesterone pessaries were administered daily 7 days prior to the transfer. Blastocysts were transferred using standard embryo transfer (ET) protocols.

Results: In Group A, a total of 284 oocytes were warmed. Two-hundred-and-seventy-two oocytes survived (Post-warmed Survival Rate: 95.8%).  One patient in Group A failed to reach ET due to poor blastocyst quality obtained; while all patients in Group B progressed to ET. The mean number of blastocysts transferred was 1.8 and 2.0 for Group A and Group B respectively (p>0.05). Clinical Pregnancy Rate (CPR) for Group A was 66.7% and for Group B was 63.6%. Implantation Rates (IR) were 46.9% and 51.2% for Group A and B respectively. There was no statistical significance (p>0.05) found in CPR and IR between both groups.

Conclusion: This study shows that vitrified-warmed donor oocytes using the Cryotec method yield clinical pregnancy and implantation rates comparable to fresh donor oocytes.