Introduction of blastocyst culture and transfer for all patients in an in vitro fertilization program

Objective: To evaluate the nonselective application of extended embryo cult ure on the outcome of IVF. Design: Retrospective analysis. Setting: Private practice assisted reproductive technology center. Patient( s): Seven hundred ninety nonselected patients undergoing IVF with controlle d ovarian stimulation. Intervention(s): For day 3 ET, multicell embryos were cultured in human tub al fluid medium and 12% synthetic serum substitute. For day 5 ET, embryos w ere cultured for 48 hours in S1 medium and then for 48 hours in S2 medium. Main Outcome Measure(s): Implantation rate (determined by total no. of visu alized gestational sacs), ongoing pregnancy rate, and number of embryos ava ilable for ET. Result(s): Respective day 3 and day 5 implantation rates for patients aged <35 years (29.5% and 38.9%), patients aged 35-39 years (20.7% and 28.2%), a nd all patients combined (23.3% and 32.4%) were statistically significantly different. Significantly more embryos were transferred on day 3 than on da y 5 for patients aged <35 years (2.9 vs 2.4), patients aged 35-39 years (3. 1 vs 2.6), and all patients combined (3.0 vs 2.5). The difference in ongoin g pregnancy rates per retrieval was statistically significant for day 3 com pared with day 5 transfers for all patients combined (35.9% vs 43.8%). Canc ellation rates for transfer after retrieval increased significantly for day 3 compared with day 5 transfer (2.9% vs 6.7%). Conclusion(s): These results demonstrate the feasibility of using extended embryo culture in a nonselective manner for couples undergoing IVF. Overall , extended embryo culture was associated with a significant increase in pre gnancy rates and implantation rates and a significant decrease in the numbe r of embryos transferred. The rate of multiple implantation among patients aged <35 years warrants consideration of single blastocyst transfers for th is group. ((C)1999 by American Society for Reproductive Medicine.).