American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

Which cell type is most problematic if found in a chorionic villus sample?

1. Fetal tissue

2. Decidua

3. Amniotic cells

4. Fibroblasts

The correct answer is: Decidua

The presence of decidual tissue in a chorionic villus sample is particularly problematic because chorionic villus sampling (CVS) is specifically designed to analyze fetal tissue for genetic abnormalities. Decidua is the tissue that lines the uterus during pregnancy and originates from maternal tissue, meaning it does not provide any useful genetic information about the fetus. When decidual cells are present, they can contaminate the sample, making it difficult to obtain accurate fetal-specific results. This can lead to misinterpretation of the genetic analysis, potentially resulting in unnecessary anxiety or incorrect clinical decisions regarding the health of the fetus. In contrast, fetal tissue is the primary focus of CVS, and the detection of amniotic cells can be helpful in certain contexts, as they also originate from the fetus. Fibroblasts, although less commonly encountered, are typically associated with tissue culture and can be identified without significant concerns of contamination, provided they are derived from fetal sources. In summary, the concern regarding decidual tissue in a CVS sample stems from its origin and the resultant implications it has on the accuracy and interpretation of genetic tests aimed at assessing fetal health.