title: False positive morphologic diagnoses at the anomaly scan: marginal or real problem, a population-based cohort study.
abstract: BACKGROUND
  Congenital malformations occur in 3-4% of live births. Their prenatal detection is performed by ultrasound screening. Any announcement about a suspected malformation is a source of stress for the parents, and misdiagnosis during ultrasound screening can lead to expensive and sometimes iatrogenic medical interventions. In this study, we aim to determine the false-positive rate, first overall and then by anatomical system, of ultrasound screening for congenital malformations in the second and third trimesters of pregnancy.
  
  
  METHODS
  Our sample includes all children born between 1 January, 2006, and 31 December, 2009, in the French region of Auvergne, whose mother had a prenatal ultrasound diagnosis of a congenital malformation during the second or third trimester of pregnancy confirmed by a follow-up ultrasound examination by an expert consultant ultrasonographer. The study included 526 fetuses, divided in 3 groups: false positives, diagnostic misclassifications, and true positives. The rates of false positives and diagnostic misclassifications were calculated for the sample as a whole and then by anatomical system.
  
  
  RESULTS
  Overall, the false-positive rate was 8.8% and the rate of diagnostic misclassification 9.2%. The highest false-positive rates were found for renal and gastrointestinal tract malformations, and the highest diagnostic misclassification rates for cerebral and cardiac malformations. The diagnostic misclassification rate was significantly higher than the false-positive rate for cardiac malformations.
  
  
  CONCLUSIONS
  The false-positive rate during prenatal ultrasound is not insignificant; these misdiagnoses cause psychological stress for the parents and overmedicalisation of the pregnancy and the child.
authors.affiliation: Service de Génétique Médicale, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France. alegrand@chu-clermontferrand.fr.
authors.forename: Anne
authors.initials: A
authors.lastname: Debost-Legrand
authors.forename: Hélène
authors.initials: H
authors.lastname: Laurichesse-Delmas
authors.forename: Christine
authors.initials: C
authors.lastname: Francannet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Perthus
authors.forename: Didier
authors.initials: D
authors.lastname: Lémery
authors.forename: Denis
authors.initials: D
authors.lastname: Gallot
authors.forename: Françoise
authors.initials: F
authors.lastname: Vendittelli
mesh_terms: D000328:Adult; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging* / Q000453:epidemiology; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D005602:France / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D012042:Registries; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D016216:Ultrasonography, Prenatal / Q000379:methods*