title: Second-trimester fetal aberrant right subclavian artery: original study, systematic review and meta-analysis of performance in detection of Down syndrome.
abstract: OBJECTIVE
  First, to estimate the prevalence of fetal aberrant right subclavian artery (ARSA) in our population and its association with Down syndrome. Second, to determine the feasibility of ultrasound to visualize ARSA in the three planes. Finally, to carry out a systematic review of the literature on the performance of second-trimester ARSA to identify fetuses with Down syndrome.
  
  
  METHODS
  ARSA was assessed by ultrasound in the axial plane and confirmed in the longitudinal and coronal planes during the second half of pregnancy in women attending our unit (from February 2011 to December 2012). A search of diagnostic tests for the assessment of ARSA was carried out in international databases. Relevant studies were subjected to a critical reading, and meta-analysis was performed with Meta-DiSc.
  
  
  RESULTS
  Of the 8781 fetuses in our population (mean gestational age: 24 ± 5.4 weeks), 22 had Down syndrome. ARSA was detected in the axial view in 60 cases (0.7%) and confirmed in the coronal view in 96.7% and in the longitudinal view in 6.7% (P < 0.001). Seven cases with ARSA had Down syndrome and all were in the non-isolated-ARSA group. The estimates of positive likelihood ratio (LR) were 0 for isolated ARSA and 199 (95% CI, 88.9-445.2) for non-isolated ARSA. In the systematic review, six studies were selected for quantitative synthesis. The pooled estimates of positive and negative LRs for global ARSA were, respectively, 35.3 (95% CI, 24.4-51.1) and 0.75 (95% CI, 0.64-0.87). For isolated ARSA, the positive and negative LRs were 0 (95% CI, 0.0-14.7) and 0.98 (95% CI, 0.94-1.02), respectively.
  
  
  CONCLUSIONS
  The prevalence of ARSA seems close to 1%. The coronal plane is the most suitable for its confirmation after detection in the axial plane. Detection of isolated or non-isolated ARSA should guide decisions about karyotyping given that isolated ARSA shows a weak association with Down syndrome.
authors.affiliation: Department of Obstetrics and Gynecology, Hospital General Gregorio Marañón, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: De León-Luis
authors.forename: F
authors.initials: F
authors.lastname: Gámez
authors.forename: C
authors.initials: C
authors.lastname: Bravo
authors.forename: J M
authors.initials: JM
authors.lastname: Tenías
authors.forename: Á
authors.initials: Á
authors.lastname: Arias
authors.forename: R
authors.initials: R
authors.lastname: Pérez
authors.forename: E
authors.initials: E
authors.lastname: Maroto
authors.forename: Á
authors.initials: Á
authors.lastname: Aguarón
authors.forename: L
authors.initials: L
authors.lastname: Ortiz-Quintana
mesh_terms: D000328:Adult; D000783:Aneurysm / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D018376:Cardiovascular Abnormalities / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D002869:Chromosome Aberrations; D000013:Congenital Abnormalities / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D003680:Deglutition Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D004314:Down Syndrome / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D004452:Echocardiography / Q000379:methods; D005260:Female; D005333:Fetus / Q000002:abnormalities; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D013348:Subclavian Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000196:embryology; D016216:Ultrasonography, Prenatal / Q000379:methods
keywords: Down syndrome; aberrant right subclavian artery; chromosomal abnormalities; meta-analysis; systematic review; ultrasound marker