PGS is a procedure used to identify the embryos which have the greatest potential for an ongoing pregnancy. It is most often used in patients who have a history of recurrent miscarriage, repeated unsuccessful implantation, or specific genetic abnormalities.
The procedure is typically performed when an embryo is at the multicell or blastocyst stage. One or several cells are removed from the embryo and analyzed using a variety of screening techniques. Selected embryos are transferred back to the uterus as in a typical IVF cycle. PGS may also be used for sex selection.