NIPT vs Traditional Screening Tests What Expecting Parents Should Know

When considering NIPT vs traditional screening tests, expectant parents may find it hard to decide which option offers better screening performance for chromosomal problems during pregnancy. These are both screening tests that use different approaches and provide different results.

NIPT, which is also known as a non-invasive prenatal test, uses cell-free DNA found in the mother’s blood. On the other hand, traditional prenatal screening tests include maternal blood tests and ultrasound measurements. If the parents want to choose screening for a broader range of chromosomal abnormalities, LifeCell’s NIPT (All Chromosomes) can be done via the mother’s blood.

Table of Contents

How Does NIPT Work?

NIPT analyses small fragments of cell-free DNA (cfDNA) present in the mother’s blood during pregnancy. Some of this DNA originates from the placenta and can be analysed to assess the probability of certain chromosomal conditions.

There is a large amount of evidence on NIPT for detecting trisomy 21, which is also called Down’s Syndrome, 18, also called Edwards’ Syndrome, and 13, also called Patau’s Syndrome.

According to ACOG, cell-free DNA testing represents the most sensitive and specific screening test for common fetal aneuploidies. Scientific studies have also shown a high detection rate of these chromosomal conditions.

Which is More Accurate: NIPT or Traditional Testing?

While comparing the efficiency of NIPT and traditional testing methods, it can be said that NIPT provides more accurate results for common fetal aneuploidies.

A large-scale prospective study showed that cell-free DNA screening resulted in a better detection rate of trisomy 21 along with a lower false-positive rate compared to conventional screening in a certain population group.

In another meta-analysis, high detection rates of trisomies 21, 18 and 13 were observed when using cell-free DNA as the method of screening. These results may partly help explain why professional bodies regard NIPT as a highly effective screening method for the above-mentioned conditions.

When Can NIPT and Traditional Screening Be Performed?

Timing is another factor parents may want to consider.

NIPT can be performed from around 10 weeks of pregnancy. This allows parents to obtain screening information relatively early.

Traditional combined screening follows a different timetable. According to the NHS, the combined test is usually carried out between 10 and 14 weeks and includes both a blood test and an ultrasound scan.

If the combined screening window is missed, the NHS states that a quadruple blood test can be offered between 14 and 20 weeks, although this is less accurate than the combined test for Down’s Syndrome screening.

The appropriate option can therefore depend partly on the stage of pregnancy when screening is being considered.

What Does a Low-Risk NIPT Result Mean?

A low-risk NIPT result considerably lowers the chances of developing any of the chromosome disorders that the test screens for. Nevertheless, it does not mean that the baby will be free from any form of genetic or structural abnormalities.

The NIPT test evaluates only the abnormalities screened by the particular selected panel. It cannot detect all possible genetic and structural problems.

This explains why ultrasound tests should still be carried out even when the NIPT is low risk.

Therefore, one should not see a low-risk NIPT result as a comprehensive assessment of the health of the baby.

What About Expanded NIPT Panels?

It should be mentioned that NIPT panels vary in their scope since they do not always analyse the same genetic disorders. While some panels test for trisomy 21, 18, and 13 only, other panels may test for extra conditions.

LifeCell’s NIPT (All Chromosomes) represents a more comprehensive prenatal screening that detects most common fetal aneuploidy disorders (trisomy 13, trisomy 18, trisomy 21 [Down syndrome], Turner syndrome, sex chromosome aneuploidies [XXX, XXY, XYY]) and rare autosomal aneuploidies. The report will indicate the probability of a baby being born with the screened chromosomal conditions

Conclusion

Knowledge of NIPT vs traditional screening tests will help pregnant women to become better informed in their decision on how to screen their pregnancy. The NIPT is based on cell-free DNA from maternal blood and provides higher screening performance for common fetal aneuploidies including trisomies 21, 18 and 13. The traditional screening test is based on maternal blood markers plus an ultrasound and can also give more information about the fetus.

NIPT is still regarded as a screening process and not a diagnostic one, and a high-risk outcome needs to be followed up by further testing. On the other hand, a low-risk outcome also cannot replace ultrasound investigations since certain fetal structural defects cannot be diagnosed using chromosomal screening.