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Updated: Jul 11, 2026
Semiconductor Sequencing for Preimplantation Genetic Testing for Aneuploidy
Published on: August 25, 2019
Stepwise sequential screening for fetal aneuploidy
Peter A Benn1, Winston A Campbell, Carolyn M Zelop
1Division of Human Genetics, Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT, USA.
Objective:
The purpose of this study was to evaluate stepwise sequential screening for fetal aneuploidy.
Study Design:
Women who received first-trimester screening were also offered second-trimester tests with second-trimester risks that were based on both sets of markers. Screen-positive rates, use of second-trimester testing and invasive testing, sensitivity, and changes in risks were evaluated.
Results:
Of 1528 women who received first-trimester screening, 133 women (8.7%) had an indication for invasive testing that was based on first-trimester results alone; 1173 women (76.8%) received second-trimester tests, which reduced the net number of women with an indication for invasive testing to 105 (6.9%). In unaffected pregnancies, the addition of the second-trimester testing reduced the median Down syndrome risk from 1:2368 to 1:10,301. Six of 10 chromosome abnormalities (60%) were identified by first-trimester screening, and 9 of 10 chromosome abnormalities (90%) were identified by sequential screening.
Conclusion:
Sequential screening can be introduced successfully into clinical practice, is effective, and can reduce the number of invasive tests that are performed.
