MATERNAL CELL CONTAMINATION IN UNCULTURED AMNIOTIC-FLUID

The presence of maternal cells in uncultured amniotic fluid may result in error in the interpretation of prenatal tests such as direct DNA a nalysis and rapid aneuploidy detection by fluorescence in situ hybridi zation (FISH). Using simultaneous dual colour X and Y FISH, we assesse d maternal cell contamination in uncultured amniotic fluids from 500 w omen carrying male fetuses, The presence of maternal cells was correla ted with the amount of blood present in the amniotic fluid as defined by visual examination of the cell pellet after centrifugation. The ove rall rate of maternal cell contamination in uncultured amniotic fluid as identified using X and Y-specific probes was 21.4 per cent, compare d with 0.2 per cent in cultured fluid. Sixteen per cent of slightly bl oody and 55 per cent of moderately bloody uncultured fluids had at lea st 20 per cent maternal cells and were classified as uninformative acc ording to our protocol for rapid aneuploidy detection. Maternal and fe tal cells could not be distinguished based on morphological characteri stics alone.