Which statement best describes noninvasive prenatal testing (NIPT)?

• A. Noninvasive prenatal testing analyzes fetal DNA in maternal blood and is highly sensitive for common aneuploidies but not diagnostic; positive results require confirmatory testing.
• B. It is a definitive diagnostic test for all fetal chromosomal abnormalities.
• C. It requires an invasive procedure to obtain fetal tissue.
• D. Its positive predictive value is unaffected by disease prevalence.

Answer: (A)

NIPT is a screening method that analyzes fetal cell-free DNA circulating in the mother's blood to estimate the risk of common fetal aneuploidies, especially trisomy 21, 18, and 13. It is highly sensitive for these conditions, but it is not diagnostic. Because it does not directly examine fetal cells in a way that confirms the fetal karyotype, a positive result requires diagnostic testing with invasive procedures such as amniocentesis or chorionic villus sampling to confirm the fetal chromosome status. The positive predictive value of NIPT depends on how common the condition is in the tested population, so results must be interpreted in the clinical context. The other statements aren’t accurate because NIPT does not diagnose all fetal chromosomal abnormalities, it does not require invasive tissue collection to obtain the DNA, and its PPV is influenced by disease prevalence.