A modified embryo cryopreservation method increases post-thaw survival with a concomitant increase in implantation

To achieve maximum post-thaw survival of frozen embryos. Historical controlled study. Hospital-based fertility center. One hundred forty-five patients whose embryos were frozen and thawed according to the standard method, and 56 patients whose embryos were frozen and thawed according to a modified method. Modifications were made to the various steps of cryopreservation: freezing and thawing solutions, loading of embryos into the straws, and warming rates. Post-thaw survival, implantation, and pregnancy rates. With the modified method, 138 (93%) of the 149 embryos thawed for 56 patients survived freezing, and 79.8% had all their blastomeres intact, which is almost double the result obtained (41.8%) for patients whose embryos were thawed with the standard method. The implantation and pregnancy rates were also significantly higher with the modified method compared with the standard method. Greater post-thaw embryo survival was achieved, with a concomitant increase in implantation and pregnancy rates, by modifying the various steps in the standard cryopreservation methodology. This has important implications in IVF practice.