The blastocyst culture and transfer technique is a new IVF method. It aims at maximizing pregnancy rates while minimizing the risk of multiple pregnancy. This method differs from traditional IVF, as far as to the day embryo transfer is performed.
Traditionally embryos are transferred to the uterus 2- 3 days after oocyte retrieval, when the embryos are at 2- 8 cell stage.
During the last few years, by using new sequential culture media, advanced embryo maturation (the blastocyst stage) has been made possible. Blastocyst is a 50-100 cell embryo, transferred to the uterus 5-6 days after oocyte collection.
Blastocyst transfer is indicated when many embryos are available for culture, since only a few of them (around 30%) have the potential to develop into blastocysts, whereas most of them will be destroyed.
By transfering embryos at the blastocyst stage, better coordination between the embryos and the endometrium is achieved, thus increasing the implantation per embryo rate. Also, because only up to two blastocysts are transferred, the risk for multiple pregnancy is avoided. We point out that the main goal for blastocyst transfer is to limit the chances of multiple pregnancy.