Journal of Ultrasound in Medicine, Vol 18, Issue 7 469-473, Copyright © 1999 by American Institute of Ultrasound in Medicine
Best second trimester sonographic markers for the detection of trisomy 21
P. Vergani, A. Locatelli, M. G. Piccoli, P. Ceruti, E. Mariani, J. C. Pezzullo and A. Ghidini
Divisione di Ostetricia e Ginecologia, Istituto di Scienze Biomediche San Gerardo, Monza, Italy.
We analyzed all genetic sonograms obtained during a 6 year period to
establish the independent ability of the following sonographic markers of
aneuploidy in the diagnosis of trisomy 21: structural anomalies, cardiac
abnormalities, nuchal fold thickness of 6 mm or greater, bowel
echogenicity, choroid plexus cysts, and renal pyelectasis. With the
exception of bowel echogenicity and choroid plexus cysts, the sonographic
markers were more common in trisomy 21 than euploid fetuses (all P <
0.001). Logistic regression analysis demonstrated that cardiac anomalies
(odds ratio = 255; 95% confidence interval, 25, 2592), other structural
anomalies (odds ratio = 25; 95% confidence interval, 6, 97), and nuchal
fold thickness of 6 mm or greater (odds ratio = 13; 95% confidence
interval, 3, 50) were the only independent predictors of trisomy 21. The
false-positive rate and sensitivity were 5.3% (48 of 898) and 59.2% (13 of
22), respectively, when any of the sonographic markers significant at
univariate analysis was considered, and 3.1% (28 of 898) and 54.5% (12 of
22), respectively, when any of the predictors at multivariate analysis was
present. Because a considerable overlap of sonographic markers exists among
trisomy 21 fetuses, use of those that are not independent predictors leads
to an increase in false-positive rate without a gain in sensitivity.
