I am 15 weeks pregnant and had a nuchal translucency measurement of 1.2mm at 12 weeks and 5 days. I would like to ask the doctor if a nuchal translucency of 1.2mm after 12 weeks is concerning. I forgot to ask the doctor what the results for Trisomy 21 and Trisomy 18 mean.

NIPT is a non-evasive screening test that is increasingly used and has a very high value for prenatal screening. However, when undergoing and interpreting the test results, pregnant women need to understand certain information about the test's value. It is especially important to understand that any test has a certain rate of false-positive and false-negative results. For NIPT, the positive predictive value for common trisomies is around 90%. This can be simply understood as approximately 10% of women with abnormal test results actually have a normal fetus. So, what are the causes of false-positive and false-negative results in NIPT?