Congratulations! You just found out you are pregnant and so many things start going through your mind. When you’re not dry heaving or completely exhausted you start planning for your exciting future but in the back of your mind you wonder… how do I know everything is okay with my baby?
We are entering an exciting time in the field of obstetrics that involves less invasive and more accurate options for genetic testing in pregnancy. ACOG, the American College of Obstetrics and Gynecology, recommends that all women, regardless of maternal age, be offered prenatal testing for chromosomal abnormalities.
For quite sometime our options for this testing have been somewhat stagnant. We have offered noninvasive risk profiling that involves a mixture of blood tests and ultrasounds at various times in the first and second trimesters to help evaluate the baby’s risk for Down syndrome or other lethal chromosomal abnormalities. Depending on how these tests are processed, the sensitivity ranges from 80-95% with about a 5% false positive rate. They are fairly accurate at identifying babies at higher risk, but can have false positive results (meaning an abnormal result followed by more invasive testing that shows normal results but of course this causes a lot of worry for the patient).
Obviously we want to be able to offer testing that has a high rate of detection and a low rate of false positives. More invasive testing is often offered also. This testing involves removing a sample of placental cells called chorionic villus sampling, or removing a sample of fetal cells from the amniotic fluid called amniocentesis. These cells are then analyzed for chromosomal abnormalities. Although these invasive tests are the most accurate, they do carry a small risk of miscarriage or fetal loss.
Fortunately, new testing has come out on the market called cell free fetal DNA testing. This is ....