When there is a NIPT false-positive result that is highly unlikely to have a fetal cause, there is an understandable concern. Before alarming the patient, there may be some additional information available from the NIPT laboratory that might help. First, was this the only abnormality found? Some NIPT laboratories may be able to establish whether there other genomic regions with imbalances. Multiple imbalances are often seen in malignancies but this would be unlikely as a confined placental mosaicism or other cause of a false-positive result. Second, was the fraction of cell-free DNA with the imbalance measured and was that compatible with an assessment of fetal fraction for other parts of the genome? Again, the availability of these data will be dependent on the NIPT method used. Third, what specific region of chromosome 13 was involved? Some regions of chromosome 13 are associated with malignancy (e.g. the Rb gene region at 13q14) while other deletions may be nothing more than clinically benign copy number variant. A microarray analysis of the mother’s lymphocytes or other tissue might be informative in establishing whether the deletion was an insignificant copy number variant.

More information is urgently needed to assess risk for maternal malignancy when there is a false-positive result. Pre-test counseling should address whether patients wish to be informed about any findings that relate to their own personal health.