Can non-invasive prenatal testing (NIPT) replace the traditional first-trimester combined screening (i.e., “Tang screening”)?

Prenatal examinations are an essential part of every pregnancy, especially several key screening tests. Non-invasive prenatal testing (NIPT) and the traditional Down syndrome screening (often referred to as “Tang screening”) are widely known among expectant mothers. These tests aim to assess the likelihood of fetal chromosomal abnormalities—particularly Down syndrome—and are routinely performed during pregnancy. With advances in medical technology, some have proposed replacing conventional Tang screening with NIPT. So, can NIPT fully replace Tang screening? Below, we address this question.

Can NIPT Replace Tang Screening?

No, NIPT cannot replace Tang screening. Although both tests analyze maternal venous blood, NIPT is neither more cost-effective nor more accurate than Tang screening for general population screening. Tang screening evaluates specific biochemical markers in maternal serum; a low-risk result reliably indicates a very low probability of Down syndrome in the fetus, thereby obviating the need for further NIPT. Typically, early Tang screening is performed between weeks 9–13 of gestation, while mid-trimester screening occurs between weeks 15–20. In contrast, NIPT is generally conducted between weeks 12–26. Thus, NIPT is often performed only after the optimal window for Tang screening has passed.

Additional Information: Key Considerations for Tang Screening

1. Optimal Timing

The ideal time for Tang screening is between weeks 14–18 of pregnancy. Around week 15, fetal development reaches a critical peak, making this period the most appropriate for detecting structural anomalies. Screening performed during this timeframe yields the most reliable and clinically meaningful results.

2. Fasting Not Required

Fasting is not necessary before Tang screening, as the test analyzes maternal serum components unaffected by recent food intake. However, for optimal accuracy, it is advisable to schedule the blood draw before eating. Postprandial increases in blood viscosity may slightly affect serum separation during centrifugation, though this has minimal impact on final test interpretation.

Above is an overview addressing whether NIPT can replace Tang screening. We hope this information is helpful to you.