Extended culture – Blastocyst culture
Earlier, embryos were routinely transferred after a two-day culture, in the stage of four cells per embryo. However, the stage of four cells can be reached by numerous potentially defective embryos and it is virtually impossible to distinguish a quality embryo at this early stage.
Development of new cultivation media has allowed for prolonged cultivation of the embryos in a laboratory (in vitro). Such extended culture allows for better assessment of the embryos. It is possible to set apart embryos whose development slows down or stops and select the embryo or embryos with adequate development for transfer. Their culture can be extended to up to 5 days following the oocyte collection i.e. the blastocyst stage (a blastocyst is an embryo that consists of more than 100 cells).
It is at the blastocyst stage of development (5 days after fertilization) that an embryo would normally move out of the fallopian tube and into the uterus. Once in the uterus, the blastocyst starts to attach to the uterine lining in a process known as implantation. A higher implantation rate has been observed following transfer of blastocysts from the laboratory. Our experience shows that the success of transfer depends on whether the uterine lining is ready to receive the embryos rather than the stage at which the embryos are transferred.
Extended cultivation of embryos exceeding 48 hours offers the following positives:
- Endometrium preparedness is better in tune with embryo development.
- With extended cultivation it is possible to choose embryos showing more promising development.
- A transfer of two embryos at a later development stage has the same probability of pregnancy as a transfer of thee or four embryos transferred following a standard two-day culture.
This video details the process of fertilization post-intercourse. A step by step process is shown from the entrance of the sperm to the female reproductive system to the formation of the zygote.