Cellular contamination during automatic and manual staining of cytological smears.

Three routine cervical smears were contaminated with adenocarcinoma cells from a malignant serous effusion which was being processed simultaneously in an automatic staining machine. Further investigation showed that cells were transferred in up to 17% of cases. However, with manual staining, the figure could be as high as 30%. The possibility of misleading cellular transfer should therefore always be considered. Serious fluids should not be processed with routine cervical smears.