Blastocyst Culture and Transfer

Multiple recent studies confirm that blastocyst transfers (BT) on day 5 have essentially equivalent or better pregnancy rates when compared to embryo transfers on day 3. This occurs despite the fact that significantly fewer embryos are replaced on day 5 to maintain these pregnancy rates. Normally, 3-4 embryos will be replaced on a day 3 transfer compared to typically only 2 blastocyts replaced on a day 5 transfer. Blastocyst culture and transfer offers a way to eliminate high order multiple gestations (such as triplets or more), while maintaining high clinical pregnancy rates.

What is a blastocyst?

A blastocyst is an embryo that is approximately 5 days old following fertilization. A blastocyst contains around 100 cells that are formed into 2 distinct types, the inner cell mass (that goes on to make the baby), and the surface cells called the trophectoderm (that goes on to form the placenta). The trophectoderm surrounds a central cavity called the blastocele. A blastocyst hatches from the Zona Pellucida (the egg shell) around day 6, and begins the complex process of implantation over the next 24 hours or so. We grade each blastocyst based on its total number of cells, the size and shape of its inner cell mass, and the size and shape of the trophectoderm.

Are you a candidate?

Candidates for a blastocyst transfer (BT) typically are younger women who produce a large number of good eggs. Potential candidates include those women having at least 4 high quality embryos on day 3 (usually at least 4 8-cell embryos with grades A or AB. Other candidates include those patients in which a multiple pregnancy is medically contraindicated (such as those with a uterine malformation, or women with certain systemic diseases).