preimplantation genetic diagnosis

Preimplantation genetic diagnosis tests embryos for a genetic disorder during in-vitro fertilization, before any embryo is placed in the womb. It shifts the genetic question to the very earliest stage, so that a pregnancy can begin with information already in hand.

After eggs are fertilized in the laboratory and grow for a few days, a few cells are gently removed from each embryo and analyzed for the specific condition the family is at risk of passing on. Embryos found to be unaffected can then be selected for transfer.

For couples who know they carry a serious inherited condition, this offers a way to start a pregnancy already tested for that disorder, avoiding decisions later in pregnancy. It requires IVF, is technically demanding and costly, and tests only for the conditions it is set up to detect.