No abstract

No abstract

Within the positive subgroup, 33% (299/894) were false positives (FP). Of 799 cases with normal NIPS results, 98% (779/799) had concordant PDT results, representing true negatives (TN), while 2% of cases (15/799) yielded abnormal PDT results (FN). The NIPS TP rate was highest for trisomy 21 (87%) and lowest for triploidy (22%). These TP rates include cases with additional findings identified by PDT and cases with partial concordance (PC); PC rates ranged from 0%-11%. Of the FP results, the most common, by specific abnormality, included triploidy (78%; 25/32), monosomy X (70%; 65/93), trisomy 13 (56%; 48/86), segmental deletions and duplications (55%; 36/66), trisomy 18 (26%; 40/151), other sex chromosome abnormalities (17%; 9/53). CONCLUSION: Our data demonstrating low false negative rates supports professional society recommendations for the use of NIPS as the primary screening test for detecting fetal aneuploidies. However, the considerably high false positive rates for abnormal NIPS results other than for trisomy 21, still strongly support the recommendation of follow-up PDT.