In 2011, cf DNA from the maternal serum became commercially available to screen for fetal aneuploidy. Overall, about 3% of test results will detect an aneuploidy, and false positive results are only seen in 0.05% to 0.1% of tests. Evolving data, however, suggest that in women who have more than one aneuploidy suspected by cfDNA testing but who are found by diagnostic testing to carry a genetically normal fetus may harbor a higher risk of occult maternal malignancy. In this session, we will review published data on the risk of maternal malignancy in women who have discordant cfDNA test results.