There are two types of preimplantation genetic tests a fertility specialist may perform. These are preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD). Fertility specialists use these tests to determine if the embryo or embryos have any genetic abnormalities which may result in failed implantation or miscarriage. Embryos which have genetic abnormalities are not used in an IVF program. Here are five things to know about preimplantation genetic testing before seeing a fertility specialist.
No one is obliged to undergo preimplantation genetic testing. Both the tests are optional. However, these tests are often in the best interest of the couple. Testing can save time and avoid a failed embryo implantation or a miscarriage. Taking the tests increases the likelihood of becoming pregnant.
Preimplantation genetic testing has two other main advantages. Firstly, the tests significantly reduce the risk that a couple will pass on a genetic disorder to the child. Secondly, the tests increase the possibility of a healthy pregnancy through IVF. This is because, after testing, only embryos free of genetic defects are used.
PGS analyzes embryo cells to make sure the correct number of chromosomes are present. Aneuploidy is a condition where an embryo may have too few chromosomes, also called monosomy, or too many chromosomes, also called trisomy. PGD indicates the type of genetic disorders monosomy and trisomy can cause.
People who are about to undergo IVF should consider genetic testing if the woman or couple has had a previous pregnancy involving aneuploidy, have been diagnosed with unexplained infertility, or have undergone several unsuccessful IVF cycles. Women over the age of 35 should also consider preimplantation genetic testing.
Both PGD and PGS share the same two main steps. The first involves an embryo biopsy and the second involves the analysis of the biopsy in a lab. This is the stage when genetic testing is conducted. The tests are performed when the embryo is at the blastocyst stage, which is day 5 of embryo culture. The biopsy removes 3-10 cells from the pre-placenta, so the cells which will grow into the baby are not disturbed.
Find out more about preimplantation genetic testing by talking to a fertility specialist. A fertility specialist will also be able to explain a couple’s options. After taking the couple’s medical history, the doctor will be able to tell if either person is a candidate for preimplantation genetic testing.