Clinical Applications of Noninvasive Prenatal Testing

Prenatal screening for aneuploidy provides individualized risk assessment that helps patients and clinicians decide who may choose invasive diagnostic testing. Noninvasive prenatal testing (NIPT) is a new technology that analyzes cell-free fetal DNA in maternal serum to screen for trisomy 21 and other common aneuploidies. Compared to existing prenatal screening tests, NIPT can be performed earlier in pregnancy, around 9–10 weeks of gestation, and has the best detection accuracy for screening. However, it does not replace invasive, diagnostic testing such as amniocentesis and chorionic villus sampling. Current guidelines recommend that women at an increased risk for aneuploidy can be screened using NIPT. There is insufficient data to recommend that low-risk patients or women with multiple gestations may benefit from NIPT. Various technologies achieve results with high sensitivity and specificity that significantly decrease the number of invasive diagnostic procedures performed. Limitations of NIPT include detection of only a few chromosomal abnormalities, test failure, and false positive and false negative results from various maternal, placental, and fetal conditions. A confirmatory diagnostic test is recommended following a positive NIPT result. The American College of Genetics and Genomics recommends use of the term noninvasive prenatal screening instead of NIPT to emphasize the screening nature of this test. It is essential that women are offered pre-test and post-test counseling to explain the performance and limitations of the test and the significance of a positive result.