How Risky is Genetic Testing?
Blood tests done during preconception testing and first- and second-trimester pregnancy screenings are basically risk-free other than the slight pinch of the needle and some bruising. The risks of most genetic testing are more emotional than physical, says Ellen Simpson, Ph.D., a genetics counselor in the prenatal diagnostic center at the University of California, San Francisco Medical Center. It can be disappointing and incredibly stressful if you find out during preconception testing that your and/or your partner carry gene mutations that could be passed along to future children, and waiting for the results of prenatal screenings can be anxiety-inducing.
If your pregnancy is determined to be higher risk you may be offered two other genetic diagnostic tests -- amniocentesis and chorionic villus sampling -- both of which do have possible side effects. In an amnio, a doctor removes a small amount of amniotic fluid (which contains some fetal cells) by inserting a needle through your abdomen into the uterus to diagnose many genetic conditions including Down syndrome and spina bifida, sickle cell anemia, cystic fibrosis, and Tay-Sachs. One to 2 percent of women have spotting, cramping, or leaking of amniotic fluid after the test, and there is about a very small 1 in 200 risk of miscarriage. Chorionic villus sampling (CVS) is done by inserting a needle through the cervix or abdomen to take a sample of the placental tissue. CVS can diagnose Tay-Sachs, sickle cell, CF. and other genetic conditions, but not spina bifida or certain others. Risk of miscarriage after CVS is about 1 in 100. There is also a very small risk of uterine infection.