Six consecutive false positive cases from cell-free fetal DNA testing in a single referring centre.

Recent studies have proposed the introduction of cell-free fetal DNA testing (NIPT - Non Invasive Prenatal Testing) in routine clinical practice emphasizing its high sensibility and specificity. In any case, false positive and false negative findings may result from placental mosaicism, because cell-free fetal DNA originates mainly from placenta. Case: we report six cases of women who underwent chorionic villus sampling (CVS) or amniocentesis to confirm the results from NIPT: two Turner syndromes, two Triple X, one Patau syndrome, one Edward syndrome. Results: using classic cytogenetic analysis and, also, Array - Comparative Genomic Hybridization(Array CGH) the karyotype of all 5 fetuses was found to be normal. Conclusion: results from NIPT must always be confirmed by invasive prenatal diagnosis. It is mandatory to inform the patient that the CVS and amniocentesis still represent the only form of prenatal diagnostic test available.