RESUMO
OBJECTIVE: To identify prenatal fetal sex and chromosomal aneuploidies by FISH using isolation of fetal nucleated RBCs. METHODS: peripheral blood samples was collected from 37 women between 11 and 24 weeks of gestation. we tried to enrich nucleated RBCs morphologically by Kleihaur-Betke staining after double gradient centrifugation and magnetic activating cell sorting (MACS) from maternal blood. Fluorescence in situ hybridization (FISH) analyses with CEP X and CEP Y probes for K-B positive nucleated RBCs were performed to detect whether fetal cells were existed among nucleated RBCs by observation of sex chromosomes. RESULTS: The average number of K-B positive nucleated RBCs separated from 10ml of maternal blood was 17.3 (+/-17.2) and the maximum number of nucleated RBCs was 54. We observed FISH signals in nucleated RBCs separated from 18 pregnant women, and Y probe signals were observed in 67.3% of nucleated RBCs separated from 10 pregnant women. CONCLUSION: We confirmed that separated nucleated fetal RBCs can be used to identify fetal sex and chromosomal aneuploidies by FISH. Since nucleated RBCs from maternal origin were not excluded, further studies are needed to overcome this limitation.