1p deletion syndrome: A prenatal diagnosis characterized by an abnormal 1st trimester combined screening test, yet a normal NIPT result

Every prenatal genetic screening test and diagnostic procedure has its benefit and risk. NIPT offers better sensitivity and specificity for trisomies 13, 18, and 21. Even so, for primary population screening, NIPT provides lower detection rate than sequential screening if considering detection of all chromosomal abnormalities. Diagnostic testing should be offered rather than cell-free DNA screening to pregnant women if a fetal structural anomaly is identified on ultrasound examination.