Genetic testing may be performed during pregnancy to screen for the presence of certain genetic diseases and disorders. Genetic tests may determine the presence, or strong risk, of Down syndrome, Tay-Sachs disease, sickle-cell anemia, cystic fibrosis, and spina bifida. Any woman can choose to have genetic testing done, but most obstetricians only recommend them in the presence of certain risk factors. Because of this, insurance is unlikely to pay for testing unless it’s doctor recommended. For most of these tests, the chance of resulting complications is very small, but even so, the more invasive the test, the more higher the chance of complications. Here’s a look at understanding types of genetic testing and their possible complications.
Increased Risk for Genetic Disorders
Women over 35 years of age, who have previously given birth to a child with a genetic disorder, or families with a history of these genetic disorders are at a greater risk for giving birth to babies with genetic disorders and may especially want to consider genetic testing. Your obstetrician can help you decide if and what kind of genetic testing is appropriate for you.
Types of Genetic Testing
There are several different types of genetic tests. Some screen the fetus for potential genetic abnormalities, while others can actually provide a diagnosis. Amniocentesis, for example, is a diagnostic test often used on older mothers. This is an invasive test that has a small risk of miscarriage. Ultrasounds and blood tests are generally less invasive and only detect abnormalities. This detection can, however, alert your doctor to the need for more invasive options. Additionally, how far along the pregnancy has progressed may influence which testing is appropriate.
First Trimester Genetic Testing
In the first trimester, the fetus is tested for abnormalities that suggest the presence of Down Syndrome through blood testing and ultrasounds. Your doctor will measure the thickness of specific tissues, as well as the levels of certain hormones and proteins. Chorionic villus sampling can also be used as a diagnostic test. This involves the insertion of a tube into the cervix to gather placental and fetal chromosomes for further examination.
Second Trimester Genetic Testing
In the second trimester, quad testing may be performed. Quad testing is a combination of four different maternal blood tests to look for fetal abnormalities: the maternal serum alpha-fetoprotein (AFP) test, human chorionic gonadotropin test, unconjugated estriol test, and inhibin A test. These tests look at fetal liver function and the level of hormones and proteins produced by the placenta. Amniocentesis is a diagnostic test used to look for many serious issues. A long needle is used to collect a sample of amniotic fluid -- and particularly the fetal cells it contains -- to look for abnormalities. A comprehensive ultrasound may be used to look for more external defects, such as cleft palate.
Complications of Genetic Testing
Again, not all genetic tests are final -- many are simply used as screening tools to look for the potential presence of disorders. Remember that unfavorable abnormal results on some tests don’t mean a definitive genetic disorder in your baby. Conversely, a normal screening doesn’t guarantee the child won’t have a genetic disorder. For some families, the potential risks of genetic screening can outweigh the benefits. Potential complications may include uterine infection or internal bleeding, fetal injury and, in rare cases, miscarriage. Talk to your doctor about these risks, and make the best choice for you and your family.
