Preimplantation genetic diagnosis (PGD) is a screening test used to determine if genetic or chromosomal disorders are present in embryos produced through in vitro fertilization (IVF). Preimplantation genetic diagnosis screens embryos before they are transferred to the uterus so couples can make informed decisions about their next steps in the IVF process. Embryos unaffected by the genetic or chromosomal disorder can be selected for transfer to the uterus.
These genetic conditions can interfere with embryo implantation, result in pregnancy loss, or in the birth of a child with physical problems, developmental delay, or mental retardation. PGD improves the likelihood of a successful pregnancy and birth for two distinctly different groups of patients; couples with infertility related to recurrent miscarriage or unsuccessful IVF cycles and couples who are at risk for passing on an inherited genetic disease to their offspring. PGD can only be performed within the context of an IVF cycle where eggs and sperm, united in the laboratory, develop into embryos.
Today, PGD technology reduces the potential for adverse pregnancy outcomes for couples ‘at risk’ by testing the embryos for certain genetic abnormalities before they are chosen for transfer back to the woman. For example: 10 embryos resulted from an IVF cycle and through PGD testing, six were identified as genetically abnormal and four were normal. Armed with this knowledge, only the unaffected embryos would be selected for embryo transfer thereby reducing the possibility of miscarriage or birth defects.
For couples undergoing IVF, preimplantation genetic diagnosis may be recommended when:
- One or both partners has a history of heritable genetic disorders
- One or both partners is a carrier of a chromosomal abnormality
- The mother is of advanced maternal age
- The mother has a history of recurrent miscarriages
Learn more about how genetic disorders are inherited here on this video, sponsored by Progenity:
PGD for recurrent loss:
PGD is helpful for patients with unexplained infertility, recurrent miscarriages, unsuccessful IVF cycles, advanced maternal age, or male factor infertility. In those cases, the most likely cause is a chromosome abnormality.
The evaluation of these patients should first rule out genetic, anatomic, endocrine, and immunologic causes for recurrent miscarriage. Many doctors will also test for genetic blood clotting disorders, although this remains controversial. The medical evaluation recurrent miscarriage should be individualized, but typically includes a physical examination; pelvic ultrasonography, hysterosalpingography, or saline hysterosonography to evaluate the uterus; complete blood cell count; testing for thyrotropin, antithyroid antibodies, prolactin, lupus anticoagulant, anticardiolipin, and antiphosphatidylserine antibodies; karyotyping (chromosomal analysis) of both partners; and possibly an endometrial biopsy (biopsy of the lining of the uterus) and screening for genetic blood clotting disorders.
PGD/PGS will open doors for many couples wanting to have children who previously had no where to turn.