Fixation of exfoliated cytology test specimens – clinical test basis

1. Purpose of fixation of exfoliated cytology specimens
Mainly to maintain the natural shape of cells, prevent cell autolysis and spoilage caused by bacteria; fixation can precipitate and coagulate proteins in cells, and can destroy lysosomes in cells, so that the cell structure is clear and easy to color, so fixation is more effective. Faster, the fresher the cells, the better the staining effect.
2. Commonly used fixatives
(1) Diethyl ether ethanol fixative solution: This solution has strong permeability, and the collection and fixation effect of the medical education network is good. Suitable for HE staining and Papanicolaou staining.
(2) 95% ethanol fixative: suitable for large-scale cancer prevention census. The preparation is simple, but the penetration ability is poor.
3. Fixing method
(1) Wet fixation: that is, the smear is fixed before it is dry. It is suitable for viscous specimens such as sputum, cervical scraping and esophageal brush.
(2) Drying and fixing: that is, after the smear is naturally dried, it is fixed again. It is suitable for thinner specimens, such as urine, serous cavity effusion, etc.
4. Fixed time
Usually 15 to 30 minutes. For specimens containing more mucus, such as sputum, cervical brush, etc., the fixation time should be appropriately extended; for samples without mucus, such as urine, pleural and ascites, etc., the fixation time can be shortened as appropriate.