title: Ultrasonographic fetal soft markers in a low-risk population: prevalence, association with trisomies and invasive tests.
abstract: OBJECTIVE
  To investigate the prevalence of soft markers identified at second trimester ultrasound in a low-risk population and the association of these markers with trisomies and invasive testing.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Swedish University Hospital.
  
  
  METHODS
  All women with fetuses examined by ultrasound at 15(+0) -22(+0)  weeks gestation between July 2008 and March 2011.
  
  
  METHODS
  Cases with soft markers were compared with non-cases with regard to trisomies and invasive testing.
  
  
  METHODS
  Prevalence of soft markers, likelihood ratio for trisomies and risk ratio for invasive tests after detection of soft markers.
  
  
  RESULTS
  Second trimester ultrasound was performed on 10 710 fetuses. Markers were detected in 5.9% of fetuses. 5.1% were isolated, 0.7% were multiple and 0.1% were combined with an anomaly. Presence of markers showed a positive likelihood ratio for Down syndrome, but the association (likelihood ratio = 7.1) was only statistically significant for the combined category of any marker (isolated, multiple or combined with anomaly). The risk ratio for invasive testing after the second trimester ultrasound was 24.0 in pregnancies with isolated soft markers compared with those without markers.
  
  
  CONCLUSIONS
  In a low-risk population, soft markers were found in 5.9% of fetuses at second trimester ultrasound. The likelihood ratio for Down syndrome was significant only for any marker (isolated, multiple or combined with anomaly). The presence of soft markers increased the incidence of invasive procedures substantially. Soft markers should be noted when information on second trimester ultrasound is formulated, and all units performing fetal ultrasound examinations should have established routines concerning information management when soft markers are identified.
authors.affiliation: Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden.
authors.forename: Annika
authors.initials: A
authors.lastname: Ahman
authors.forename: Ove
authors.initials: O
authors.lastname: Axelsson
authors.forename: Gordan
authors.initials: G
authors.lastname: Maras
authors.forename: Christine
authors.initials: C
authors.lastname: Rubertsson
authors.forename: Anna
authors.initials: A
authors.lastname: Sarkadi
authors.forename: Peter
authors.initials: P
authors.lastname: Lindgren
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers; D004314:Down Syndrome / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D015995:Prevalence; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013548:Sweden; D014314:Trisomy; D016216:Ultrasonography, Prenatal / Q000379:methods
chemical_list: D015415:Biomarkers
keywords: Pregnancy; aneuploidy; prenatal diagnosis; second trimester; ultrasonography