Journal of Ultrasound in Medicine, Vol 18, Issue 8 523-528, Copyright © 1999 by American Institute of Ultrasound in Medicine
Genetic sonogram scoring index: accuracy and clinical utility
B. Bromley, T. Shipp and B. R. Benacerraf
Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, USA.
We sought to evaluate the accuracy of the genetic sonogram scoring index in
detecting Down syndrome fetuses in a high-risk population. Women referred
for genetic sonogram scoring index based on increased risk for aneuploidy
were prospectively evaluated. Each fetus was assigned a score based on our
previously published genetic sonogram scoring index. A score of 1 or
greater was an indication for karyotype determination. Of 1076 patients
(1118 fetuses) in the study group, follow-up data were available for 1030
(92%), eight of whom had Down syndrome (prevalence 0.8%). Three fetuses
with Down syndrome had a genetic sonogram scoring index of 0, and for one
of these the mother was 42 years old. One affected fetus had a score of 1
and the other four had scores of 2 or greater. Using a genetic sonogram
scoring index of 1 or greater (age not considered), five of eight fetuses
with Down syndrome (62.5%) were identified, as well as 150 of 1030 (14.6%)
of normals. Down syndrome was undetected in three fetuses of 1030 (1 in
343) or 0.29%. In addition, when all women 40 years old or older underwent
karyotype testing regardless of their sonographic findings, six of eight
Down syndrome fetuses were identified (75%), as well as 271 of 1030 (26.3%)
of normals. The number of cases of Down syndrome not detected was two in
1030 (1 in 515) or 0.19%. In conclusion, the genetic sonogram scoring index
was used to identify approximately 75% of fetuses with Down syndrome, with
amniocentesis being recommended in 26.7% of a high-risk population.
