Objective: To compare blastocyst-stage embryo transfers (ETs) with day 2-3 ETs in patients who failed to conceive in three or more day 2-3 IVF/ET cycles.
Design: Prospective, randomized.
Setting: Fertility unit in a university medical center.
Patient(s): Fifty-four patients with an adequate ovarian response underwent oocyte retrievals. The patients were prospectively and randomly divided into blastocyst-stage and day 2-3 ET groups.
Intervention(s): Ovarian down-regulation was obtained using GnRH agonist, and controlled ovarian hyperstimulation was achieved using daily administration of gonadotropins.
Main outcome measure(s): The rate of blastocyst formation, ET cancellations, pregnancies, implantation, multiple gestation, and live births.
Result(s): The clinical pregnancy rates per oocyte retrieval were 21.7% and 12.9% per blastocyst and day 2-3 ETs, respectively. Although there was a significantly higher implantation rate for blastocyst embryos (21.2%) as compared with 48- to 72-hour embryos (6%), the multiple-pregnancy rate was not significantly different between both groups. An ET cancellation rate of 26% and 6.4% for blastocyst and day 2-3 ETs, respectively, was observed. The presence of two or more 8-cell embryos on day 3 in culture carried a high probability of obtaining blastocysts for transfer.
Conclusion(s): This prospective randomized study suggests that in patients with an adequate ovarian response who failed to conceive in at least three IVF/ET cycles [1]. transfer of blastocyst-stage embryos carries a significantly higher implantation rate; [2]. the pregnancy rate per oocyte retrieval and ET are higher in the blastocyst-stage group, even if it did not reach statistical significance; [3]. a higher ET cancellation rate was observed in the whole blastocyst-stage group; [4]. the ET cancellation rate was reduced significantly if the decision to proceed to blastocyst transfer was made on day 3 after oocyte retrieval, which is a post hoc conclusion.