First- and second-trimester screening: Detection of aneuploidies other than Down syndrome

Fionnuala M. Breathnach, Fergal D. Malone, Lambert Messerlian Geralyn, Howard S. Cuckle, T. Flint Porter, David A. Nyberg, Christine H. Comstock, George R. Saade, Richard L. Berkowitz, Susan Klugman, Lorraine Dugoff, Sabrina D. Craigo, Ilan E. Timor-Tritsch, Stephen R. Carr, Honor M. Wolfe, Tara Tripp, Diana W. Bianchi, Mary E. D'Alton

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


OBJECTIVE: To evaluate the performance of first- and second-trimester screening methods for the detection of aneuploidies other than Down syndrome. METHODS: Patients with singleton pregnancies at 10 weeks 3 days through 13 weeks 6 days of gestation were recruited at 15 U.S. centers. All patients had a first-trimester nuchal translucency scan, and those without cystic hygroma had a combined test (nuchal translucency, pregnancy-associated plasma protein A, and free β-hCG) and returned at 15-18 weeks for a second-trimester quadruple screen (serum alpha-fetoprotein, total hCG, unconjugated estriol, and inhibin-A). Risk cutoff levels of 1:300 for Down syndrome and 1:100 for trisomy 18 were selected. RESULTS: Thirty-six thousand one hundred seventy-one patients completed first-trimester screening, and 35,236 completed second-trimester screening. There were 77 cases of non-Down syndrome aneuploidies identified in this population; 41 were positive for a cystic hygroma in the first trimester, and a further 36 had a combined test, of whom 29 proceeded to quadruple screening. First-trimester screening, by cystic hygroma determination or combined screening had a 78% detection rate for all non-Down syndrome aneuploidies, with an overall false-positive rate of 6.0%. Sixty-nine percent of non-Down syndrome aneuploidies were identified as screen-positive by the second-trimester quadruple screen, at a false-positive rate of 8.9%. In the combined test, the use of trisomy 18 risks did not detect any additional non-Down syndrome aneuploidies compared with the Down syndrome risk alone. In second-trimester quadruple screening, a trisomy 18-specific algorithm detected an additional 41% non-Down syndrome aneuploidies not detected using the Down syndrome algorithm. CONCLUSION: First-trimester Down syndrome screening protocols can detect the majority of cases of non-Down aneuploidies. Addition of a trisomy 18-specific risk algorithm in the second trimester achieves high detection rates for aneuploidies other than Down syndrome. LEVEL OF EVIDENCE: II.

Original languageEnglish (US)
Pages (from-to)651-657
Number of pages7
JournalObstetrics and gynecology
Issue number3
StatePublished - Sep 2007
Externally publishedYes

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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