Clinical significance of amniotic-fluid-cell culture failure

Recent reports suggest an increased incidence of chromosomal abnormalities in pregnancies with amniotic fluid-cell culture failure. We retrospectively reviewed the cytogenetic results of 14,165 amniotic fluid samples processed in our laboratory from 1987 to 1996. Ninety-eight per cent of the samples were obtained before 24 weeks' gestation, mainly because of advanced maternal age; 2 per cent were obtained after or at 24 weeks because of the ultrasonographic finding of fetal structural defects. Amniotic-fluid-cell culture failure occurred in 62 cases (0.44 per cent). Culture failure was more common in samples obtained after or at 24 weeks' gestation (10 per cent) than in those obtained before 24 weeks (0.27 per cent) (P < 0.001, chi-square test). This difference was also observed when the results were analysed according to the cases with known normal or abnormal karyotypes. The frequency of culture failure did not differ significantly between the groups with normal and abnormal karyotypes. We conclude that amniotic-fluid-cell culture failure is more common in advanced pregnancy with an ultrasonographic finding of fetal structural defects and is not associated with a higher incidence of chromosomal abnormalities.