The results from noninvasive prenatal screening (NIPS) tests should not be used alone to diagnose chromosomal abnormalities or disorders, according to the Food and Drug Administration (FDA).
In a safety communication, the Agency noted that while NIPS tests are widely used, the accuracy and performance of these tests have not been evaluated by the FDA. The tests provide information about the possibility for certain genetic abnormalities; however, they are not diagnostic tests, and therefore cannot be used to confirm or rule out a suspected genetic abnormality.
According to the FDA, multiple biological factors can influence the results of NIPS tests, which analyze cell-free DNA in a pregnant patient’s blood to determine risk. Patients should be alerted to the fact that these screening tests may not accurately reflect whether the fetus has a genetic abnormality; positive results should be confirmed with a diagnostic test.
“Without proper understanding of how these tests should be used, people may make inappropriate health care decisions regarding their pregnancy,” said Jeff Shuren, MD, JD, director of the FDA’s Center for Devices and Radiological Health. “We strongly urge patients to discuss the benefits and risks of these tests with a genetic counselor or other health care provider prior to making decisions based on the results of these tests.”
Several professional societies, including the American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine (SMFM), and the American College of Medical Genetics and Genomics (ACMG) have provided recommendations on the use of prenatal genetic screening. All encourage educating patients about the availability of these tests and their appropriate use. Additionally, ACMG recommends against testing for aneuploidies other than those involving chromosomes related to Down syndrome (21), Edwards syndrome (18) and Patau syndrome (13), while ACOG discourages the use of NIPS tests to detect microdeletions.
All NIPS tests are offered as laboratory developed tests (LDT), which are designed, manufactured and used within a single laboratory. A review of 13 studies evaluating more than 10,000 individuals undergoing NIPS testing showed that the tests generally performed well, with high negative predictive values (>99%) for NIPS tests included in the analysis. However, the evidence also indicates that the reliability of positive screening results is limited, particularly for microdeletions (positive predictive value range, 2-30%).
While initially classified as simple tests, the evolution of complex LDTs has led the Agency to reconsider its policy of enforcement discretion. Though no formal guidance has been published, the Agency continues its discussions on an appropriate oversight approach.
- FDA warns of risks associated with non-invasive prenatal screening tests. News release. Accessed April 20, 2022. https://www.fda.gov/news-events/press-announcements/fda-warns-risks-associated-non-invasive-prenatal-screening-tests
- Genetic non-invasive prenatal screening tests may have false results: FDA safety communication. News release. Accessed April 20, 2022. https://www.fda.gov/medical-devices/safety-communications/genetic-non-invasive-prenatal-screening-tests-may-have-false-results-fda-safety-communication
This article originally appeared on MPR