An evaluation of maternal cell contamination in cultures of chorionic villi for the prenatal diagnosis of chromosome abnormalities.

Culture of chorionic villus cells provides a method of obtaining chromosomes of excellent quality for first trimester prenatal diagnosis. Concern exists that maternal cells present in the biopsy may contaminate the culture and lead to misdiagnosis. This study has confirmed that karyotypes obtained from female villus cultures were non-maternal by establishing the presence of paternal markers using Q- and C-banding. Male cultures were harvested serially to investigate the possibility of maternal cell overgrowth. Of 82 successful cultures investigated, 37 were male and 45 female and of the males 4 contained a mixture of male and female cells. Thorough dissection of the material is essential if maternal cell contamination is to be mininimised. The use of heteromorphic chromosome markers to establish that fetal cells have grown provides valuable reassurance.