Maternal age at delivery was significantly lower for patients with abnormal discordant results, compared to patients with abnormal concordant results ( P = 0.034). This incomplete follow-up of normal NIPS results does not affect PPV calculations, but it did preclude calculations of sensitivity, specificity, and NPV. Of 578 patients with normal NIPS results, normal pregnancy outcome was confirmed for 156 (27 %) patients. The PPV for all conditions included in the screen was 77.4 % (95 % CI, 63.4 – 87.3). Forty-one of 55 abnormal NIPS results were concordant with abnormal fetal outcomes, 12 were discordant, and 2 were undetermined.
However, all four laboratories are represented in both the normal and abnormal results groups.
Of 632 patients undergoing NIPS, 92 % of tests were performed in one of the four major commercial laboratories offering testing.
