The genetic sonogram: its use in the detection of chromosomal abnormalities in fetuses of women of advanced maternal age.

Real-time and color Doppler ultrasound were used to examine 103 second trimester fetuses with abnormal chromosomes (trisomies 13, 18, 21 and sex aneuploidy =86; other =17) and 2000 controls from women of advanced maternal age who electively underwent genetic amniocentesis. Ten ultrasound markers were analyzed and likelihood ratios were computed for each abnormal ultrasound finding and for a normal ultrasound study if none of the ten markers were present. Abnormal ultrasound markers were present in 81% of fetuses with abnormal karyotypes. The false-positive rate was 13%. The likelihood ratios and the 5% and 95% confidence limits for each of the ultrasound markers were as follows: choroid plexus cyst(s) 1.5 (0.7-3.6); central nervous system abnormalities 16.2 (4.4-60.3); abnormal nuchal skin fold 20.9 (8.4-52.1); ventricular septal defect 8.3 (4.7-14.9); outflow tract defects of the heart 3.6 (0.9-14.6); right-to-left chamber disproportion of the heart 36.9 (14.4-94.5); pericardial effusion 7.2 (3.2-16.1); tricupsid regurgitation 4.7 (2.1-10.7); hyperechoic bowel 3.7 (1.8-7.7); and pyelectasis 2.7 (1.0-7.7). All ultrasound markers were independent of each other. The likelihood ratio following a normal ultrasound study was 0.20. Isolated ultrasound markers were present in 20.4% (n=21) of fetuses. When all markers were compared to non-cardiovascular markers, the detection rate for fetuses with a chromosomal abnormality decreased from 81% to 52% (p<0.01). Given the above data, the posterior risk following an ultrasound examination using the ultrasound markers evaluated in this study can be used to compute the risk for an abnormal karyotypes in women of advanced maternal age.