Stepwise sequential screening for fetal aneuploidy

• Published in: American journal of obstetrics and gynecology 2007-09, Vol.197 (3), p.312.e1-312.e5
• Main Authors: Benn, Peter A., DSc, Campbell, Winston A., MD, Zelop, Carolyn M., MD, Ingardia, Charles, MD, Egan, James F.X., MD
• Format: Article
• Language: English
• Subjects: Adult; amniocentesis; Aneuploidy; Biological and medical sciences; chorionic villus sampling; Chromosome aberrations; Down syndrome; Female; Fetal Diseases - diagnosis; Fetal Diseases - genetics; Genetic Testing - methods; Gynecology. Andrology. Obstetrics; Humans; Medical genetics; Medical sciences; Obstetrics and Gynecology; Pregnancy; Prenatal Diagnosis; prenatal screening; trisomy 18
• ISSN: 0002-9378; 1097-6868
• DOI: 10.1016/j.ajog.2007.06.054

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.