Читать книгу Protocols for High-Risk Pregnancies - Группа авторов - Страница 48

[fo]Maternal serum levels of PAPP‐A are approximately 50% lower, and hCG levels (either total hCG or fβhCG) approximately twice as high, in trisomy 21 pregnancies compared with euploid pregnancies at 10–14 weeks of gestation, and these analytes can be used for assessment of trisomy 21 risk in the first trimester. The combination of maternal age, NT sonography, PAPP‐A, and hCG is referred to as first‐trimester combined screening and will detect about 85% of cases of trisomy 21, at a 5% false‐positive rate, between 10 and 14 weeks of gestation.