Fetal cells in the uterine cervix: a source for early non-invasive prenatal diagnosis

Various non-invasive techniques for prenatal diagnosis have been under inve stigation. We evaluated the success of fetal sexing using a non-invasive te chnique for obtaining fetal cells, uterine cervix brushing, in combination with FISH. Thirty pregnant women who completed between 6 and 10 weeks of ge station and who were scheduled to undergo pregnancy termination were includ ed in the study. A Pap smear cytobrush was inserted through the external os to a maximum depth of 2 cm and removed while rotating it a full turn. The material that was caught on the brush was spread on four microscope slides. Two-color FISH was used for fetal sexing. Following pregnancy termination, a placental sample was used for full karyotyping, In 29/30 cases FISH diag nosis was confirmed by chromosomal analysis. The only male case in which a Y chromosome was not seen was from a pregnancy of 6 weeks 6 days gestationa l age. One case was mosaic of 46,XY/47,XXY (25%). In most cases (7/13) the Y chromosome was already identified in the first analyzed slide. With the u se of a cytobrush fetal cells can be easily obtained for the purpose of pre natal diagnosis of chromosomal disorders. Copyright (C) 2001 John Wiley & S ons, Ltd.