Abstract
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.
Keywords
NIPT - Aneuploidy - Prenatal testing - Prenatal screen - Cell-free fetal DNA
