An 8-center study to evaluate the utility of mid-term genetic sonograms among high-risk pregnancies.
OBJECTIVE
A multicenter study was undertaken to evaluate the diagnostic efficacy of a genetic sonogram.


METHODS
Eight centers provided data on 176 pregnancies complicated by fetal Down syndrome. One hundred thirty-four pregnancies were considered high risk because of advanced maternal age (> 35 years), and 42 were considered high risk for having "abnormal" triple-screen results (risk > 1:250). Each center provided fetal biometric data, information regarding the presence or absence of major structural abnormalities, and between 3 and 6 additional ultrasonographic markers for trisomy 21. The heterogeneity of our 8 independent "sensitivity estimates" was evaluated by Poisson regression, and a single combined estimate of the sensitivity was calculated.


RESULTS
Of the total 176 cases of trisomy 21, 125 fetuses (71.0%) had either an abnormal long bone length (femur length, humerus length, or both), a major structural abnormality, or a Down syndrome marker. The combined diagnostic sensitivity was 71.6%, with a range of 63.6% (7 of 11) to 80% (8 of 10). Five centers had sensitivity estimates falling between 64% and 76%. The sensitivity of individual markers varied between 3% (sandal gap) and 46.5% (nuchal skin fold thickness). A condensed regimen of nuchal skin fold thickness, femur length, and a standard anatomic survey would screen in 56.8% of fetuses with Down syndrome.


CONCLUSIONS
This 8-center study that included many fetuses with Down syndrome validates the concept that the genetic sonogram can be used to better adjust the Down syndrome risk for high-risk patients.
Hobbins
John C
JC
Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Denver, CO 80262, USA.
Lezotte
Dennis C
DC
Persutte
Wayne H
WH
DeVore
Greggory R
GR
Benacerraf
Beryl R
BR
Nyberg
David A
DA
Vintzileos
Anthony M
AM
Platt
Lawrence D
LD
Carlson
Dru E
DE
Bahado-Singh
Raymond O
RO
Abuhamad
Alfred Z
AZ
D001699:Biometry; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D005333:Fetus / Q000033:anatomy & histology; D006801:Humans; D008423:Maternal Age; D016012:Poisson Distribution; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D018566:Pregnancy, High-Risk; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal