Objective: To assess the accuracy of day 3 morphologic criteria in identifying the best embryos.
Design: Prospective observational study.
Setting: University IVF program.
Patient(s): One hundred cycles in women desiring blastocyst transfer who had > or =3 eight-cell embryos on day 3.
Intervention(s): On day 3, the embryologist chose the two embryos that would have been transferred that day. On day 5, embryos were examined to determine the best and second-best blastocysts.
Main outcome measure(s): Accuracy of day 3 picks as measured in culture on day 5, outcome of nontransferred picks, and cryopreservation rate.
Result(s): All cycles reached the blastocyst stage and 73% had cryopreservation. The mean number of blastocysts was 4.8 (3.2 on day 5 and 1.6 on day 6). Neither pick was chosen in 39% of cycles; one pick was transferred in 38%; and both picks were transferred in 23%. Of 116 nontransferred picks, 51 were frozen and 65 arrested, with both picks arresting in 9 cycles. The single best blastocyst was chosen from the picks in 39% of cycles.
Conclusion(s): Morphologic criteria for cleavage-stage embryo selection may fall short when the transfer is limited to two embryos. Culture to blastocyst is warranted in this population to avoid high-order multiples and still be able to choose the two embryos with the highest implantation potential.