The reliability of NIPT results is very high (> 99 %), but not 100 %, which is also the case for amniocentesis and chorionic villus sampling.
The sensitivity of NIPT to exclude trisomy 21, 18 and 13 is very high: if NIPT is normal, the residual risk for trisomy 21, trisomy 18 and trisomy 13 is < 1 on 1.000 (false-negatives).
The specificity of NIPT for the chromosomes tested is > 99%, which means that in less than 1 on 100 pregnancies an abnormal NIPT result is obtained although the fetus has normal chromosomes (false-positives).
