Although false positive and false negative results can occur when performing NIPT testing, both are very rare and occur in approximately 1 in 300 pregnancies. False positives may be due to a vanishing twin syndrome if done very early in pregnancy, or because of the existence of confirmed placental mosaicism (CPM). False negatives usually occur because there is too little fetal DNA in the specimen to be analyzed. As previously mentioned, low fetal DNA fractions can occur due to sampling at an early gestational age or maternal size as well as a low sensitivity for the NIPT testing method.
Although the Panorama® NIPT assay indicates a use as early as nine weeks gestation and in multiple gestations, all cfDNA tests are typically intended for use in women 18 years or older with a singleton pregnancy, at a minimum of 10 weeks gestation, and who have been determined by their physician to be at risk for fetal trisomy. Such risks include advanced maternal age, positive results of prenatal screening tests (serum and/or NT ultrasound), the presence of ultrasound soft or hard markers, previous family history of genetic disorders, or a previously affected pregnancy for fetal aneuploidy.
It is important to remember that at present, invasive prenatal diagnostic tests (eg, CVS and amniocentesis), should be considered the most accurate and comprehensive way to assess fetal abnormalities.
