Factors relating to a successful cryopreserved blastocyst transfer program

Patients: Women of all ages undergoing 64 frozen blastocyst nondonor thaw cycles. Design: Retrospective study. Setting: University IVF program. Patients: Women of all ages undergoing 64 frozen blastocyst nondonor thaw cycles. Intervention(s): Thaw cycles with day 5 or day 6 frozen blastocysts replaced into luteal day 5 endometrium, in natural or programmed cycles; cryopreservation of blastocysts by Menezo two-step protocol and Testart slow cool program; thawing by two step thaw protocol. Main Outcome Measure(s): Implantation, clinical pregnancy, and delivery rates. Result(s): The implantation rate was 16% and was similar with day 5 frozen blastocysts and day 6 frozen blastocysts cycles. The clinical pregnancy rate was 36% and the delivery rate was 27%, with no significant difference between day 5 and 6 blastocysts. Conclusion(s): Blastocyst cryopreservation is a viable option for patients of all ages and complements fresh blastocyst culture and transfer. The presence of good quality blastocysts for freezing on day 5 and day 6 yields comparable results and is critical for the success of thaw cycles.