Embryo biopsy (trophectoderm biopsy)

Embryo biopsy is the laboratory step of removing a small number of cells from an embryo so they can be analysed by PGT. It is most commonly done at the blastocyst stage, taking a few cells from the trophectoderm (the outer layer that will go on to form the placenta) rather than the inner cell mass that develops into the fetus. The biopsy sample is sent for genetic analysis while the embryo is frozen, and the embryo is only transferred once results are available. Embryo biopsy requires specific embryology expertise; done well, it is not thought to meaningfully reduce an embryo's chance of implanting, but it adds a technical step, cost and time to treatment, and a very small number of embryos may not survive biopsy or freezing.

Also known as: trophectoderm biopsy, embryo cell sampling

Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.