Table 2.
Detection rate at a fixed 2% and 5% false positive rate for protocols including maternal age and given markers based on gestation at blood draw
| Gestational age | NT/free beta hCG/PAPP-A (%) | NT/free beta hCG/PAPP-A/AFP (%) | NT/free beta hCG/PAPP-A/AFP/NB (%) |
|---|---|---|---|
| Fixed 2% false positive rate | |||
| 9 | 88 | 90 | 97 |
| 10 | 86 | 89 | 96 |
| 11 | 85 | 88 | 96 |
| 12 | 85 | 87 | 96 |
| 13 | 84 | 87 | 96 |
| Fixed 5% false positive rate | |||
| 9 | 92 | 94 | 98 |
| 10 | 92 | 94 | 98 |
| 11 | 91 | 93 | 98 |
| 12 | 91 | 93 | 98 |
| 13 | 90 | 92 | 98 |
hCG, human chorionic gonadotropin; NT, nuchal translucency; PAPP-A, pregnancy-associated plasma protein A; AFP, alpha fetoprotein; NB, nasal bone.
Ultrasound performed at 12 weeks of gestation.