This chapter provides information about a genetic counselor’s role in prenatal screening, including discussing and offering options to a patient, interpreting and providing results, or managing referrals based on abnormal results. It discusses how a screen is evaluated using sensitivity, specificity, positive predictive value, negative predictive value, and personal utility. It provides a detailed description of both maternal serum screening and cell-free DNA testing. The maternal serum screening discussion includes information on multiples of median, calculating risk, timing, pattern association, limitations, and follow-up. The review of cell-free DNA testing includes fetal fraction, methodology, test performance, limitations and considerations for testing, and follow-up. This chapter also provides a list of additional resources to use for cell-free DNA testing.
OC21.05: Implications of inconclusive results in prenatal maternal serum cell-free DNA testing