Comparison of noninvasive prenatal testing of cell‐free DNA in maternal blood and amniocentesis for evaluation of aneuploidy

Background: The aim of this study was to compare noninvasive prenatal testing (NIPT) of cell‐free DNA in maternal blood and amniocentesis in the diagnosis of aneuploidy. This study was designed to evaluate sensitivity, specificity, accuracy, positive predictive value and negative predictive value of NIPT for detection of aneuploidies compared gold standard test of amniocentesis. Materials and methods: This cross sectional study performed on Iranian pregnant women (GA≥12 weeks) and candidate for NIPT, referred to the Nilou laboratory in Tehran and 16 provinces of Iran between Aug 2016 and Aug 2018. Analysis study was performed by SPSS version 21. Results: 11960 pregnant women which candidate for NIPT enrolled in this study and 139 persons detected as high risk for NIPT.  The mean (±standard deviation) age of participants was 33.7 ± 6.4 years and 34.4 ± 5.2 years for amniocentesis and NIPT groups, respectively. Specificity of NIPT in the diagnosis of trisomies of T21, T18 and T13 was 99.94%, 99.95% and 99.97% respectively. Failure rate was calculated as 0.27. Conclusion: Non-invasive prenatal testing has very high sensitivity and specificity for aneuploidies but should not be used as a final diagnosis test.