title: Diagnostic accuracy of noninvasive detection of fetal trisomy 21 in maternal blood: a systematic review.
abstract: BACKGROUND
  Both pregnant women and providers of obstetric care are aware of the rapid advances in noninvasive prenatal diagnosis (NIPD) of fetal trisomies, and appear to look forward to its clinical introduction.
  
  
  OBJECTIVE
  To review and critically assess the published literature on diagnostic accuracy of NIPD using cell-free fetal DNA or RNA in maternal blood to detect fetal trisomy 21.
  
  
  METHODS
  An electronic search was performed in MEDLINE, EMBASE and the Cochrane library (1997 to April 2011). Of a total of 201 citations, 9 studies were eligible for full-text analysis by 2 independent reviewers, using the QUADAS tool.
  
  
  RESULTS
  Two of the 9 analyzed studies complied with the criteria of the QUADAS tool. Combining the selected 2 studies, with a total of 681 pregnancies included, overall sensitivity was 125/125 (100%, 95% CI 97.5-100%) and specificity 552/556 (99.3%, 95% CI 98.7-99.3%).
  
  
  CONCLUSIONS
  NIPD of fetal trisomy 21, using fetal nucleic acids in maternal plasma, appears to have a high diagnostic accuracy. Large-scale prospective studies are awaited before implementation in clinical practice.
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Leiden, The Netherlands.
authors.forename: E J
authors.initials: EJ
authors.lastname: Verweij
authors.forename: J M E
authors.initials: JM
authors.lastname: van den Oever
authors.forename: M A
authors.initials: MA
authors.lastname: de Boer
authors.forename: E M J
authors.initials: EM
authors.lastname: Boon
authors.forename: D
authors.initials: D
authors.lastname: Oepkes
mesh_terms: D004247:DNA / Q000097:blood / Q000235:genetics; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood*; D011296:Prenatal Diagnosis / Q000379:methods* / Q000706:statistics & numerical data; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D012333:RNA, Messenger; D004247:DNA