Screening modality | Timing | Markers analyzed | Detection rate, % | False-positive rate, % |
---|---|---|---|---|
First-trimester combined screening | wk 11–13 | NT, PAPP-A, fbhCG | 83 | 5 |
Integrated prenatal screening | 1st phase: wk 11–13 | NT, PAPP-A | 87 | 1.9 |
2nd phase: wk 15–20 | AFP, hCG, uE3 | |||
Serum integrated prenatal screening | 1st phase: wk 11–13 | PAPP-A | 85 | 4.4† |
2nd phase: wk 15–20 | AFP, hCG, uE3, DIA | |||
Four-marker second-trimester serum screening (QUAD) | wk 15–20 | AFP, hCG, uE3, DIA | 77 | 5.2 |
Note: AFP = α-fetoprotein, DIA = dimeric inhibin-A, fbhCG = free-β subunit of human chorionic gonadotropin, hCG = human chorionic gonadotropin, NT = nuchal translucency, PAPP-A = pregnancy-associated plasma protein A, uE3 = unconjugated estriol. *Other available tests are AFP only for open neural tube defect, NT only for multiple pregnancies, and PAPP-A plus second-trimester QUAD test when NT is not available (i.e., in remote areas) in the first trimester. Noninvasive prenatal testing is available free of charge to women who have a high-risk pregnancy and for a fee to women who do not have a high-risk pregnancy. †The false-positive rate is an estimate, given the small volume of uptake of this screening test in the province.1