Examination of frozen cycles with replacement of a single thawed blastocyst.

This investigation examined frozen cycle outcomes with the transfer of a single thawed blastocyst. It also aimed to determine if the suggested model could aid in achieving a better understanding of factors that influence success with frozen blastocyst transfer. A retrospective analysis was conducted of single frozen embryo transfer cycles carried out at the Cleveland Clinic Fertility Centre in Beachwood, OH. Between January 2001 and March 2004, 88 thaw procedures were initiated that resulted in 75 frozen cycles in which only a single thawed blastocyst was transferred. In 66 of these 88 thaw procedures, only a single embryo was available for thawing. The post-thaw survival rate of a single frozen blastocyst was 85% (56/66). These 56 frozen transfers with a single thawed blastocyst resulted in a clinical pregnancy rate per transfer of 27% (15/56) and a live birth rate of 18%. Blastocyst post-thaw morphology at transfer was found to be an important prognostic factor associated with success. The ability to re-expand within a few hours of the thaw appeared to be a strong indicator of blastocyst potential. Blastocyst age at cryopreservation did not impact outcomes. The single frozen embryo transfer model can yield valuable information and help gauge the effectiveness of a laboratory's cryopreservation protocol.