Diana L. Gray, M.D.

DEPARTMENT OF Obstetrics & Gynecology
Keywords: prenatal diagnosis, Down syndrome screening, ultrasound

We have analyzed the sensitivity, specificity and positive predictive value of many noninvasive predictors of fetal Down syndrome over the past few years in our division. We encounter increasing numbers of patients who decline invasive testing but wish to receive the benefits of noninvasive screening methods such as maternal age, serum biochemical markers and ultrasound imaging of fetal biometry and anatomy. The next step toward improved prediction is to combine the above predictors in a user-friendly format of a computerized algorithm. We currently are working toward this goal.

We have analyzed thousands of second trimester gestations with complete pregnancy outcome information for maternal age, biochemical markers indicating increased risk for Down syndrome and fetal sonographic indicators of increased risk for Down syndrome. Logistic regression was used to determine the independent significance of predictors, sensitivity, specificity and positive predictive values.

Independent predictors of Down syndrome were confirmed. These combined predictors generated a sensitive model with good specificity and much improved predictive values as compared to the current use of maternal age alone or maternal age plus serum biochemical screening. Ongoing prospective collection of maternal serum screening results is planned for enhancement of the above model.