Blastocyst Transfer

Blastocyst (Day 5) Transfer

As culture media and technology have evolved, ART programs have an opportunity to change the day that embryos are returned to the uterus. This change, to day 5 (blastocyst) embryo transfer, approximates the time embryos would normally enter the uterus from the oviducts. Previously, day 2-3 (2-8 cell) embryos were transferred. Although our program was very successful, especially with 8 cell embryos, we had to transfer more embryos to compensate for the lack of embryo selection and for placing oviductal stage embryos into the uterus.

Today, changes in culture conditions and culture media, when properly utilized, allow embryologist to extend in vitro embryo culture. It is now possible to culture embryos through the time of embryonic genome activation (~8 cell) to the blastocyst, a uterine stage embryo.

During the additional two days of in vitro culture (day 3 to 5), the embryologists have an opportunity to observe embryonic development and to select those embryos which appear to have the best potential for continued growth and implantation. The opportunity to improve embryo selection has enabled RRC to reduce the number of embryos transferred. This significantly reduces the chance of high order multiple pregnancy, without compromising the patient’s opportunity to become pregnant. For the last 3 years, RRC’s standard practice has been to transfer only 1-2 embryos. Over 1,400 babies have been born from blastocyst embryo transfer at RRC.