Cell Free DNA Genetic Testing is Changing Chicago Obstetrics and Gynecology Practices
Each of us have 2 sets of 23 chromosomes for a total of 46 chromosomes. During a pregnancy your Chicago OBGYN may offer genetic testing that screens for aneuploidy. Aneuploidy is any deviation from the standard set of chromosomes. If aneuploidy is detected it could mean that there is a presence of more or less chromosomes.
Traditional tests for aneuploidy include CVS and amniocentesis. These tests can provide a lot of information but they also offer some risk of miscarriage. Recent improvements in technology have introduced cell free DNA testing which has no risk of miscarriage and can be done as early as 10 1/2 weeks gestation. Cell free DNA test accuracy is 99% for the three most common abnormalities and not for all chromosomes however, these non-invasive tests are not the first choice for all patients. It is the opinion of ACOG that cell free DNA screening is appropriate under the following conditions:
- Women over the age of 35
- Women with fetal ultrasonography findings that are concerning for aneuploidy
- Women who had aneuploidy in a prior pregnancy
- Women with abnormal first- or second-trimester genetic screening tests
- Parents with a balanced translocation and an increased risk of Trisomy 21 or 13.
Negative results are not diagnostic, and all positive results should be confirmed with invasive testing (chorionic villus sampling [CVS] or amniocentesis).
ACOG does not currently recommend the routine use of cell-free fetal DNA without a comprehensive history and adequate patient counseling, as well as a designation of “high risk.”
Many patients wonder why this test isn’t being performed on women who are not considered high risk when cell free DNA test accuracy is so convincing. There is a risk associated with false positives:
There is some preliminary data about the source of false-positive results; potential causes include an inadequate fetal fraction of cell-free DNA, maternal or placental mosaicism, and a vanishing twin.
It has been proposed by Mennuti and colleagues, that a registry of false-positive and false-negative results be established in an effort to gather further data. It is also anticipated that as low-risk patients and aneuploidies of lower and lower prevalence are incorporated into noninvasive testing, the false-positive rate will rise. Their findings have implications for patient counseling, patient distress, invasive testing, and reimbursement.
Your Chicago obstetrics and gynecology provider will work with you to determine what genetic testing is necessary during your pregnancy. Invasive testing is not done until a potential risk for aneuploidy has been determined. If you have any questions about cell free DNA test accuracy, it’s best to see your obstetrician in Chicago,. At Northwestern Women’s Health Associates we treat every patient and every pregnancy individually. You will be given the time and consideration needed to make the necessary decisions surrounding genetic testing during pregnancy.
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DISCLAIMER: All information on this website is provided for informational purposes only and is not intended to be construed as medical advice. Northwestern Women’s Health Associates shall not be liable for any errors or inaccuracies contained herein, or any actions taken in reliance thereon.