title: Second-trimester ultrasound markers for detection of trisomy 21: which markers are best?
abstract: OBJECTIVE
  To investigate which second-trimester ultrasound markers for aneuploidy are the most diagnostically efficient in detecting fetal trisomy 21.
  
  
  METHODS
  All second-trimester genetic sonograms performed since November 1, 1992 for women at increased risk for fetal trisomy 21 were analyzed retrospectively. Statistical analysis included descriptive statistics, the test of proportions, and univariate and multivariable logistic regression analysis using trisomy 21 as the dependent variable and ten aneuploidy ultrasound markers as independent variables.
  
  
  RESULTS
  There were 581 normal fetuses, 23 with trisomy 21 and four with other chromosomal abnormalities. When one or more abnormal ultrasound markers were present, the sensitivity and false-positive rate for trisomy 21 were 87% and 13.4%, respectively. After adjusting for confounders, multivariate logistic regression analysis showed the best combination of ultrasound markers for detecting trisomy 21 to be nuchal fold thickening (relative risk [RR] 85.5; 95% confidence interval [CI] 20.4, 357.7), pyelectasis (RR 25.2; 95% CI 6.7, 95.0), and short humerus (RR 20.4; 95% CI 4.5, 92.1). The model combining these three ultrasound markers yielded a sensitivity of 87% and a false-positive rate of 6.7%.
  
  
  CONCLUSIONS
  By using only three ultrasound markers (combination of nuchal fold thickening, pyelectasis, and short humerus) the false-positive rate is decreased from 13.4% to 6.7% without any compromise in the sensitivity (87%). The clinical usefulness of evaluating the various second-trimester ultrasound markers needs to be evaluated in prospective studies.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School/St. Peter's Medical Center, New Brunswick, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Vintzileos
authors.forename: W A
authors.initials: WA
authors.lastname: Campbell
authors.forename: E R
authors.initials: ER
authors.lastname: Guzman
authors.forename: J C
authors.initials: JC
authors.lastname: Smulian
authors.forename: D A
authors.initials: DA
authors.lastname: McLean
authors.forename: C V
authors.initials: CV
authors.lastname: Ananth
mesh_terms: D016001:Confidence Intervals; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D016015:Logistic Models; D015999:Multivariate Analysis; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012189:Retrospective Studies; D012306:Risk; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal