There are a few possible reasons that prenatal cfDNA screening may not provide a result. It could be due to DNA quality that is suboptimal, perhaps due to a problem with the shipping of the sample. Some labs do not report out a result due to low fetal fraction (FF) (fetal fraction is the amount or % of placental DNA in mom’s blood). Sometimes there are subtle, harmless variations in an individual’s DNA code that prevent the test from working as usual.
Recent studies indicate that a no-call results may indicate an increased risk for a chromosome abnormality1 and your doctor may offer a diagnostic test, such as amniocentesis based on a no-call result.
1) Pergament E et al. Single-nucleotide polymorphism-based noninvasive prenatal screening in a high-risk and low-risk cohort. Obstet Gynecol 2014;124(2 Pt1):210-8.