Combo Screen 98% Sensitive for Down Syndrome.

RENO, NEV. -- The use of ultrasound plus maternal serum screening in women 35 and older is a "very powerful" tool for detecting Down syndrome with an overall sensitivity of 97.6%, Dr. James Egan said at the annual meeting of the Society for Maternal-Fetal Medicine.

He based this statement on the results of his search of computerized perinatal data bases containing data from January 1992 through January 2000 for three medical centers. The search found 83 women of advanced maternal age who had a fetus with Down syndrome and who had undergone ultrasound screening between 14 and 24 weeks' gestation. In this cohort, 73 women were found to have ultrasound markers present, for a sensitivity of 88%.

These markers included major structural anomalies, short femur or humerus, pyelectasis, nuchal fold thickening, fifth-digit abnormalities, echogenic bowel, echogenic cardiac focus, choroid plexus cysts, ventriculomegaly, and a two-vessel umbilical cord, said Dr. Egan of the University of Connecticut, Farmington.

Of these 83 women, 42 also had a maternal serum screen performed; 38 tested positive, giving serum screening a sensitivity of 90.5%.

Seven of these 42 fetuses had no ultrasound markers but they remained at risk because of the maternal serum screen findings.

Of the four women whose serum screen was negative, three had ultrasound markers present, which put them in the risk-positive category.

"Therefore, of the 42 advanced maternal age women, the overall sensitivity of age, serum screen, and genetic sonogram was 97.6%," he reported.