Improved Clinical Outcomes with Continuous Single CultureTM - A True Single Step Non-Interrupted Culture Medium Protocol That Does Not Require Medium Renewal During Six Days of Human Preimplantation Embryo Culture

Introduction: For over a decade, the culture of preimplantation mammalian embryos has been approached by one of two culture protocols separated by opposing philosophies. The sequential, two-step protocol is thought to mimic the physiological interaction between specific developmental stages of the embryo and its vicinity within the oviduct and uterus. This protocol is based on the ‘back to nature’ principle that consists of medium renewal approximately midway in the extended culture period; either day-3 or -4 of embryo culture. The opposing system is based on the ‘let the embryo choose’ principal that is analogous to a single step culture medium. By providing the embryo with the appropriate concentration of components as defined through biological standardizations, the embryo is ultimately allowed to determine when and which nutrients and compounds are needed for suitable development. Although the ‘back to nature’ dogma of a two-step protocol is thought to be optimal for zygote to blastocyst development, we now show that blastocyst development and implantation potential are strikingly similar, if not better, in an uninterrupted, non-renewed single step culture medium protocol.