Blastocyst culture and transfer: analysis of results and parameters affecting outcome in two in vitro fertilization programs

Objective: To determine whether previously described advanced blastocyst de velopment and high implantation rates are confirmed in an expanded multicen ter trial. Design: Retrospective review. Setting: Two private assisted reproductive technology units. Patient(s): One hundred seventy-four patients who underwent blastocyst cult ure and transfer. Intervention(s): Culture of all pronucleate embryos in sequential media to the blastocyst stage (day 5) followed by ET. Main Outcome Measure(s): The number and percentage of blastocysts developed , implantation rates, pregnancy rates, and parameters that affected outcome were analyzed. Result(s): Only 3 of 174 patients failed to achieve blastocyst-stage ET. Th e mean blastocyst development rate was 48%. The ongoing pregnancy rate was 66.3% per oocyte retrieval, with a mean (+/-SE) of 2.2 +/- 0.05 blastocysts transferred and an implantation rate of 48% per blastocyst transferred. Conclusion(s): Blastocyst culture and transfer is an effective means of tre ating patients who respond well to gonadotropins. High pregnancy rates can be accomplished with low numbers of embryos transferred. Patients who faile d to achieve ET were rare. (Fertil Steril(R) 1939;72:603-9. (C) 1999 by Ame rican Society for Reproductive Medicine.).