The use of color Doppler ultrasound to identify fetuses at increased risk for trisomy 21: an alternative for high-risk patients who decline genetic amniocentesis.
OBJECTIVE
To compare color Doppler ultrasound with real-time ultrasound to determine whether it increased the identification of fetuses with trisomy 21.


METHODS
Consecutive fetuses with a second trimester risk greater than 1:270 for trisomy 21 were examined with real-time ultrasound (n = 1028) or real-time plus color Doppler ultrasound (n = 1028) before second trimester genetic amniocentesis. The type of abnormal ultrasound findings were compared between fetuses with normal and abnormal chromosomes. Using the Bayes theorem, the ultrasound-adjusted maternal age-related risk (posterior risk) for trisomy 21 was computed after a normal or abnormal real-time plus color Doppler examination.


RESULTS
A significantly greater number of fetuses with trisomy 21 (87% [13 of 15] versus 29% [5 of 17], P < .002) were identified with real-time plus color Doppler than with real-time ultrasound. Color Doppler ultrasound identified a significantly higher rate of cardiovascular abnormalities in fetuses with trisomy 21 (60% [9 of 15] versus 12% [2 of 17], P < .008) than did real-time ultrasound. Identification of abnormal fetal anatomy using real-time plus color Doppler in patients 35 years and older increases the likelihood of detecting trisomy 21. A normal real-time plus color Doppler examination of the fetus decreases the risk for trisomy 21 to less than 1:270 until the maternal age of 42, above which the risk for trisomy 21 is greater than 1:270.


CONCLUSIONS
Real-time plus color Doppler ultrasound examination of the fetus is an alternative for the identification of trisomy 21 for patients who may decline genetic amniocentesis based on their age-related risk.
DeVore
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GR
Fetal Diagnostic Center, Pasadena, California.
Alfi
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D000328:Adult; D000649:Amniocentesis; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018615:Ultrasonography, Doppler, Color; D016216:Ultrasonography, Prenatal / Q000379:methods*