Blastocyst transfer
Currently it’s possible to cultivate embryos in the laboratory till they achieve the phase of blastocysts (usually on the 5th day after the oocyte generation). Afterwards blastocysts can be transferred to the uterus. Some researchers note that the embryo transfer in the phase of blastocysts frequently results in pregnancy. It can have two explanations. Firstly, the transfer of blastocysts enables the embryologist to select “the best” embryos, as weak embryos or embryos with genetic anomalies stop developing before transformation into blastocysts.
The transfer of blastocysts reduces also the probability of dangerous multiple pregnancies. High frequency of the implantation of blastocysts allows to transfer few embryos to the uterus (as a rule one or two) thus decreasing the risk of multiple pregnancies and related complications.
Although the transfer of blastocysts is perspective for patients who have a big number of mature oocytes, its benefits for patients with complications (patients with the poor ovary response to the stimulation or small number of generated oocytes) is still a disputable question. This is conditioned with the fact that if the patient has very few oocytes, there is a high risk that no one will achieve the stage of blastocysts. They all can stop developing and there will be nothing to transfer. As the artificial conditions for cultivation are still far from natural ones, many embryologists think that the transfer of embryos to the uterus on earlier phases is more favorable, than their cultivation in artificial conditions. Artificially cultivated embryos that have achieved the phase of blastocysts can safely continue developing in the uterus.
Specialists of VitroMed clinic define the optimal phase of the embryo development for the transfer to the uters for each patient individually.