Discuss cell-free DNA testing when offering fetal aneuploidy screening to pregnant women.1,2
Strength of recommendation
A: Based on multiple large, multicenter cohort studies.1,2
A 28-year-old woman (gravida 2, para 1001) at 10 weeks’ gestation presents to your clinic for a routine first-trimester prenatal visit. Her first child has no known chromosomal abnormalities, and she has no family history of aneuploidy. She asks you which tests are available to screen her fetus for chromosomal abnormalities.
Pregnant women have traditionally been offered some combination of serum biomarkers and nuchal translucency to assess the risk for fetal aneuploidy. Cell-free DNA testing (cfDNA) is a form of noninvasive prenatal testing that uses maternal serum samples to conduct massively parallel sequencing of cell-free fetal DNA fragments.
It has been offered to pregnant women as a screening test to detect fetal chromosomal abnormalities since 2011, after multiple clinical studies found high sensitivities, specificities, and negative predictive values (NPVs) for detecting aneuploidy.3-6However, until 2015, practice guidelines from the American Congress of Obstetricians and Gynecologists (ACOG) recommended that standard aneuploidy screening or diagnostic testing be offered to all pregnant women and cfDNA be reserved for women with pregnancies at high risk for aneuploidy (strength of recommendation: B).7
CARE (Comparison of Aneuploidy Risk Evaluation) and NEXT (Noninvasive Examination of Trisomy) are two large studies that compared cfDNA and standard aneuploidy screening methods in pregnant women at low risk for fetal aneuploidy. Based on new data from these and other studies, ACOG and the Society for Maternal-Fetal Medicine (SMFM) released a new consensus statement in June 2015 that addressed the use of cfDNA in the general obstetric population. The two groups still recommend conventional first- and second-trimester screening by serum chemical biomarkers and nuchal translucency as the firstline approach for low-risk women who want to pursue aneuploidy screening; however, they also recommend that the risks and benefits of cfDNA be discussed with all patients.8
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