title: Discordant non-invasive prenatal testing (NIPT) - a systematic review.
abstract: With a high sensitivity and specificity, non-invasive prenatal testing (NIPT) is an incomparable screening test for fetal aneuploidy. However, the method is rather newly introduced, and experiences with discordant results are few. We did a systematic review of literature reporting details of false positive and false negative NIPT results. Discordant sex chromosome results were not included. We identified 22 studies reporting case details. In total, 206 discordant cases were included, of which 88% were false positive and 12% false negative. Details on maternal age, gestational age, platform/company, Z-score, fetal fraction, results and explanation were specified. The main reasons for discordant results were confined placental mosaicism, maternal copy number variation, vanished twin, maternal cancer and true fetal mosaicism. A very high percentage of cases (67%) were reported with no obvious biological or technical explanation for the discordant result. The included cases represent only a minor part of the true number of false positive or false negative NIPT cases identified in fetal medicine clinics around the world. To ensure knowledge exchange and transparency of NIPT between laboratories, we suggest a systematic recording of discordant NIPT results, as well as a quality assurance by external quality control and accreditation. © 2017 John Wiley & Sons, Ltd.
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynecology, Copenhagen University Hospital, Hvidovre, Denmark.
authors.forename: Tanja Schlaikjaer
authors.identifier: http://orcid.org/0000-0003-4220-5947
authors.initials: TS
authors.lastname: Hartwig
authors.affiliation: Department of Clinical Biochemistry, Copenhagen University Hospital, Hvidovre, Denmark.
authors.forename: Louise
authors.initials: L
authors.lastname: Ambye
authors.affiliation: Department of Clinical Biochemistry, Copenhagen University Hospital, Hvidovre, Denmark.
authors.forename: Steen
authors.initials: S
authors.lastname: Sørensen
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynecology, Copenhagen University Hospital, Hvidovre, Denmark.
authors.forename: Finn Stener
authors.initials: FS
authors.lastname: Jørgensen
mesh_terms: D002869:Chromosome Aberrations; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D062145:Maternal Serum Screening Tests; D011247:Pregnancy