American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

Why is a specimen for cold agglutinin analysis unacceptable if incubated at 37 degrees C?

1. It did not reach room temperature

2. The sample should have been pre-warmed for 30 minutes

3. It must be collected in a red top tube

4. It needs to be frozen before testing

The correct answer is: The sample should have been pre-warmed for 30 minutes

The specimen for cold agglutinin analysis is unacceptable if incubated at 37 degrees Celsius because it must be appropriately handled to maintain the conditions under which cold agglutinins are stable and detectable. Cold agglutinin testing specifically requires that the specimen be preserved at lower temperatures, typically around room temperature or colder, to prevent the agglutination from being disrupted by elevated temperatures. By incubating the specimen at 37 degrees Celsius, the warm conditions can alter the agglutination reactions. Cold agglutinins are antibodies that can agglutinate red blood cells at lower temperatures, often around 4 degrees Celsius. If the specimen is incubated at a higher temperature, it may lead to false-negative results due to changes in the antigen-antibody interaction that happens when the temperature rises. Therefore, pre-warming the sample for a specific period, such as 30 minutes, would not be appropriate for a test that relies on the preservation of cold agglutinins, making that the reason the analysis could be considered unacceptable.