In natural conception, fertilization of the egg occurs in a structure attached to the woman’s uterus called the fallopian tube. The initial cell divisions of the fertilized egg also take place there and result in an embryo of 4 to 8 cells three days later. As the newly-formed embryo continues to develop, it moves toward the uterine cavity where additional cell divisions result in formation of the “blastocyst”, an embryonic stage characterized by hundreds of cells and having the appearance of a hollow ball. This is the first time the embryo has differentiated into two distinct parts: the inner cell mass which becomes the fetus and the trophoblast which becomes the placenta. When the embryo reaches the “blastocyst” stage, it is ready to implant.
At Virginia Fertility & IVF we routinely culture embryos in vitro to the blastocyst stage, which takes place 5 to 6 days after fertilization. This allows us to identify the “best” embryos in a cohort and allows for the transfer of fewer embryos which reduces the risks involved in multiple pregnancies. Blastocyst-stage embryos are also suited for Preimplantation Genetic Testing (PGT) and have excellent survival and pregnancy rates following cryopreservation. It is important to know that not every fertilized embryo will continue to develop to the blastocyst stage.
To culture embryos to this stage requires optimal in vitro culture conditions, including well maintained embryo incubators and the use of commercially available culture media that has gone through rigorous quality control. Our state-of-the-art IVF laboratory and equipment is checked each day of use to ensure proper function. We have also invested in an independent air handling unit solely for the Virginia Fertility & IVF Laboratory that filters out not only small particulates with HEPA filtration, but also volatile organic compounds (VOCs) and inorganic compounds in order to provide the cleanest environment possible for growing embryos.