Non-Invasive Prenatal Screening (NIPS): Benefits and Limitations
Non-invasive prenatal screening (NIPS), also referred to as non-invasive prenatal testing (NIPT), has become an increasingly popular prenatal genetic screening tool in recent years as it offers a relatively simple, noninvasive method of checking for certain conditions during pregnancy with a high degree of accuracy. However, as with all screening tests, there are limitations to noninvasive prenatal screening that are important to consider. Read on to learn more about the benefits and limitations of NIPS to see whether this test may be a good option for you.
Benefits of non-invasive prenatal screening:
Because NIPS is a simple blood test, it doesn’t carry any health risks for the pregnant person or the baby. Completing the test is completely safe for both!
Non-invasive prenatal screening can be done as early as 9 weeks gestation, and results are typically available in less than a week. This means patients are able to get genetic screening information about their pregnancy early in the first trimester, which can give them peace of mind or allow them time to prepare or perform follow-up testing after increased risk results.
Most NIPS labs quote a high level of accuracy based on high test sensitivity and specificity, meaning that while false positive and false negative results on NIPS are possible, they are rare.
Limitations of NIPS (or NIPT):
- NIPS is a screen. Noninvasive Prenatal Screening is meant to identify pregnancies at an increased risk for certain chromosomal conditions, but NIPS is not able to definitively diagnose any conditions during pregnancy. Therefore, false positive or false negative results can occur, and follow-up prenatal diagnostic testing, such as amniocentesis or chorionic villus sampling (CVS), is recommended to confirm a diagnosis after receiving increased risk NIPS results. No irreversible pregnancy decisions should be made based on the results of NIPS alone.
- NIPS screens for a limited number of chromosomal or genetic conditions. While NIPS can look for some of the more common chromosomal conditions seen during pregnancy, it is not able to look for all possible chromosomal or genetic disorders in a fetus. This means it is possible for a pregnancy to be affected with a genetic condition yet receive a low-risk NIPS result because that particular genetic condition was not tested by noninvasive prenatal screening.
- Incidental findings or inconclusive results are possible. While the focus of NIPS is on identifying chromosomal conditions in the pregnancy, occasionally unexpected findings may be seen. Incidental findings could include results indicative of a chromosomal difference in the pregnant person rather than the fetus, or in very rare cases, non-invasive prenatal screening may identify DNA from other sources besides the pregnancy, such as a tumor. NIPS results may also be labeled as “inconclusive” in cases where the results don’t match up with any of the expected result categories.
Are there alternatives to NIPS?
Yes! NIPS is one option for prenatal genetic screening, but other forms of screening are available during pregnancy too, such as ultrasound assessment or maternal serum screening. Instead of screening, some families may choose to pursue prenatal diagnostic testing to get a clear “yes” or “no” answer about chromosomal conditions in the pregnancy.
Others may choose not to do any prenatal genetic screening at all. In a guideline released in 2020, the American College of Obstetricians and Gynecologists (ACOG) recommended that NIPS be made available to all pregnant people, regardless of age or baseline risk, but not everyone will choose to pursue this testing. Speaking with a genetic counselor or your prenatal care provider can help you determine whether NIPS is right for you.
- Authored by Kelly Miller, MS, LCGC | Genetic Counselor
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