ad. 25. Is contamination of a chorionic villus sampling sample by mother’s cells possible? Potential error in the chorionic villus sampling results.

In regard to the question: “Is contamination of a chorionic villus sampling sample by mother’s cells possible?” and to widely spread, not scientifically proven opinions of people (including physicians) concerning this issue, we will try to explain it as exhaustively as possible.

In cells culture only slight contaminations from mother’s cells may appear. According to research, it is about 1.8% – 4% of sample’s volume. Mother’s cells look different under an inverted microscope, and therefore, in an experienced laboratory they are easily detected and separated. Thus, in chorion cells growth only fetal chorionic villus samples are used. Contamination of the sample with a patient’s blood has no influence on the culture of chorion cells.

Irrespective of the culture, we always try to compare the genetic result from the chorionic villus sampling with an ultrasound scan. We encourage all patients, who underwent a diagnostic test at our centre, to have a detailed ultrasound examination in the second trimester as well. In case of any doubts concerning the health of a fetus with a normal genetic test result, we will consider collecting another sample. If a patient underwent chorionic villus sampling, this time we would suggest amniocentesis, and if a patient underwent amniocentesis, we would suggest fetal blood sampling. The situation described above hardly ever takes place and it aims to reassure our patients about the reliability of the results.