title: Systematic review of accuracy of ultrasound in the diagnosis of vasa previa.
abstract: OBJECTIVE
  Vasa previa is an obstetric complication in which the fetal blood vessels lie outside the chorionic plate in close proximity to the internal cervical os. In women with vasa previa, the risk of rupture of these vessels is increased, thus potentially causing fetal death or serious morbidity. Our objective was to assess the accuracy of ultrasound in the prenatal diagnosis of vasa previa.
  
  
  METHODS
  We searched MEDLINE, EMBASE, the Cochrane Library and PubMed for studies on vasa previa. Two reviewers independently selected studies on the accuracy of ultrasound in the diagnosis of vasa previa. The studies were scored on methodological quality using the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2). Data on sensitivity and specificity were subsequently extracted.
  
  
  RESULTS
  The literature search revealed 583 articles, of which two prospective and six retrospective cohort studies were eligible for inclusion in the qualitative analysis. All studies documented methods suitable for the prenatal diagnosis of vasa previa. Four out of the eight studies used transvaginal ultrasound (TVS) for primary evaluation, while the remaining four studies used transabdominal ultrasound and performed a subsequent TVS when vasa previa was suspected. The QUADAS-2 tool reflected poor methodology in six of the eight included studies, and prenatal detection rates varied from 53% (10/19) to 100% (total of 442,633 patients, including 138 cases of vasa previa). In the two prospective studies (n = 33,795, including 11 cases of vasa previa), transvaginal color Doppler performed during the second trimester detected all cases of vasa previa (sensitivity, 100%) with a specificity of 99.0-99.8%.
  
  
  CONCLUSIONS
  The accuracy of ultrasound in the diagnosis of vasa previa is high when performed transvaginally in combination with color Doppler.
authors.affiliation: Department of Obstetrics & Gynaecology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Ruiter
authors.forename: N
authors.initials: N
authors.lastname: Kok
authors.forename: J
authors.initials: J
authors.lastname: Limpens
authors.forename: J B
authors.initials: JB
authors.lastname: Derks
authors.forename: I M
authors.initials: IM
authors.lastname: de Graaf
authors.forename: B W J
authors.initials: BW
authors.lastname: Mol
authors.forename: E
authors.initials: E
authors.lastname: Pajkrt
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D010920:Placenta / Q000000981:diagnostic imaging* / Q000473:pathology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011446:Prospective Studies; D012189:Retrospective Studies; D018615:Ultrasonography, Doppler, Color; D016216:Ultrasonography, Prenatal; D014470:Umbilical Cord / Q000000981:diagnostic imaging* / Q000473:pathology; D055949:Vasa Previa / Q000175:diagnosis*
keywords: diagnostic accuracy; ultrasound; vasa previa