Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

Which reagent is used to fix a cytology smear?

1. 10% formalin

2. Hematoxylin

3. Physiological saline

4. Cytospray

The correct answer is: Cytospray

Cytospray is the appropriate reagent used to fix a cytology smear. This reagent is specifically designed for the preparation of cytology samples, as it efficiently preserves cellular morphology and structure. Proper fixation is crucial in cytology to ensure that the cells can be accurately evaluated under a microscope, as it prevents degradation and maintains the integrity of cellular components. In contrast, while 10% formalin is a commonly used fixative in histology for tissue samples, it is not typically employed for cytology smears due to its potential to create artifacts, which may interfere with the evaluation of individual cells. Hematoxylin, on the other hand, is a staining reagent rather than a fixative, and it is used to stain the nuclei of cells after they have been fixed. Physiological saline is primarily used for rinsing or diluting but does not have the properties necessary to fix cells appropriately for cytological examination. Using Cytospray allows for rapid and effective fixation, making it optimal for preparing smears that will undergo microscopic analysis, ensuring that the cells remain intact and the diagnostic quality is preserved.