Maternal cell-free DNA (cfDNA) results that are discordant with the diagnostic fetal karyotype should prompt further investigation. If deeper analysis of the cfDNA results demonstrates a "saw-tooth" pattern characteristic of genome-wide imbalance, maternal malignancy is suggested. Identifying the maternal malignancy can, however, be difficult.
Keywords: Cell‐free DNA; metastatic neoplasm; multiple monosomies; prenatal diagnosis.