Table 11:
Prenatal Screening Pathways for Pregnant People, Summary
| Strategy | Screening Test | Second Testa | Third Testb |
|---|---|---|---|
| Strategy 1: Traditional Prenatal Screening Without NIPT | |||
| First trimesterc | eFTSd | CVS (70%) or amniocentesis (30%) | NA |
| Second trimestere | MSSf | Amniocentesis (100%) | NA |
| Strategy 2: Second-Tier NIPT | |||
| First trimesterc | eFTSd | NIPT or amniocentesis for very high-risk pregnanciesg | Amniocentesish |
| Second trimestere | MSSf | NIPT or amniocentesis for very high-risk pregnanciesg | Amniocentesish |
| Strategy 3: First-Tier NIPT | |||
| First trimesterc | NIPT + NT ultrasound | CVS (70%) or amniocentesis (30%) | Not applicable |
| Second trimestere | NIPT | Amniocentesis (100%) | Not applicable |
Abbreviations: CVS, chorionic villus sampling; eFTS, enhanced first-trimester screening; MSS, maternal serum screening (also known as quadruple screening); NA, not applicable; NIPT, noninvasive prenatal testing; NT, nuchal translucency.
CVS and amniocentesis are diagnostic tests for confirming the results of a positive first test. Second-tier NIPT is still a screening test.
Amniocentesis is for confirming the results of a positive NIPT test.
90% of people who receive prenatal screening.
eFTS consists of a single blood test, which includes pregnancy-associated plasma protein A, free β-human chorionic gonadotrophin, placental growth factor, and α-fetoprotein. As well, eFTS includes NT ultrasound.
10% of people who receive prenatal screening.
MSS (quadruple screening) consists of a single blood test, which includes α-fetoprotein, unconjugated oestriol, free β-human chorionic gonadotrophin, and inhibin-A.
People who have a trisomy 21 risk > 1/10 or nuchal translucency ≥ 3.5 mm.
Only for people who had second-tier NIPT.