Browse the corpus
Walk the evidence base by book and chapter — the raw source passages that ground Ask, Differential, and the rest.
1 passage
Cell-Free DNA Screening for Aneuploidy and Microdeletion Syndromes. Cell-free DNA (cfDNA) screening for the common aneuploidies is an accurate noninvasive screen for the common autosomal and sex chromosome aneuploidies. However, cfDNA screening should not be considered a diagnostic test, and the positive predictive value should be used in counseling women with a positive test regarding the option for diagnostic testing. Compared with traditional screening, cfDNA may not detect as many chromosomal abnormalities of importance. Furthermore, due to the low prevalence of recurrent copy number variants, the clinical utility in screening for microdeletions and duplications is uncertain and is not recommended for the general obstetric population.