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 development and high implantation rates are confirmed in an expanded multicenter trial. Design: Retrospective review. Setting: Two private assisted reproductive technology units. Patient(s): One hundred seventy-four patients who underwent blastocyst culture 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. The 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 treating patients who respond well to gonadotropins. High pregnancy rates can be accomplished with low numbers of embryos transferred. Patients who failed to achieve ET were rare. (Fertil Steril(R) 1939;72:603-9. (C) 1999 by American Society for Reproductive Medicine.).