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

Which method would best prevent inaccurate karyotype analysis?

1. Using outdated staining techniques

2. Properly timed trypsinization

3. Comparing with older results

4. Conducting tests at ambient temperature

The correct answer is: Properly timed trypsinization

Properly timed trypsinization is crucial for accurate karyotype analysis because it ensures optimal chromosomal structure preservation during the preparation of metaphase spreads. Trypsinization involves the use of enzymes to digest protein coatings on chromosomes, which helps in dispersing the chromatin to allow for clearer visualization under a microscope. If this process is not timed correctly, either too early or too late, it can lead to the degradation of chromosomal integrity or result in suboptimal staining patterns. This ultimately affects the clarity and quality of the karyotype analysis, making it difficult to identify chromosomal abnormalities accurately. In contrast, using outdated staining techniques can lead to poor visualization of chromosomes, thus compromising the analysis. Comparing with older results may not be relevant or beneficial, especially if there have been changes in the sample or the techniques used over time. Conducting tests at ambient temperature could also negatively impact the preparation and preservation of the chromosome samples, as temperature can influence the enzymatic activity involved in the trypsinization process. Therefore, ensuring the correct timing of trypsinization directly aids in obtaining high-quality karyotypes for analysis.