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

For optimal results in chromosome analysis of placental tissue, from where should the technician select the tissue?

1. The maternal side

2. The fetal side

3. The central portion

4. The outer membrane

The correct answer is: The fetal side

Selecting tissue from the fetal side of the placenta for chromosome analysis is optimal because this area contains a higher concentration of fetal cells, which are essential for accurate genetic assessment. The fetal side, often characterized by its dense arrangement of chorionic villi, provides cells that are more likely to represent the genetic makeup of the fetus. In contrast, the maternal side typically consists of a different cell population that may not provide relevant information regarding the fetal chromosomes. The central portion of the placenta may not necessarily yield the best quality or quantity of fetal cells, as it can vary in cellularity and not always reflect the most informative areas for genetic testing. The outer membrane can also be more maternal in origin and thus less suitable for extracting fetal genetic material needed for chromosome analysis. Therefore, choosing tissue from the fetal side ensures that the sample is rich in appropriate cells, improving the accuracy and reliability of the cytogenetic evaluation.