Survival of cryopreservation and thawing with all blastomeres intact identifies multicell embryos with superior frozen embryo transfer outcome

Objective: To assess the impact of survival of cryopreservation and thawing with all blastomeres intact on the outcome of multicell frozen ET. Design: Retrospective study. Setting: Academic assisted reproductive technology program. Patient(s): One hundred sixteen exclusively multicell frozen ETs in 78 patients. Intervention(s): Frozen ET. Main Outcome Measure(s): Relation of embryonic blastomere survival to the outcome of frozen ET (i.e., pregnancy). Result(s): When at least one embryo survived with all blastomeres intact, the total pregnancy rate (biochemical, clinical, or delivered) was 37.7%, the clinical pregnancy rate was 24.6%, and the delivered pregnancy rate was 18.8%. When no embryo survived with all blastomeres intact, the corresponding rates were 10.6%, 8.5%, and 6.4%. The differences in the total pregnancy rate and the clinical pregnancy rate were statistically significant. The delivered pregnancy rates approached statistical significance. Conclusion(s): Multicell embryonic survival of cryopreservation and thawing with all blastomeres intact identifies embryos with superior developmental potential. (Fertil Steril(R) 1999;72:527-32. (C) 1999 by American Society for Reproductive Medicine.).