Fixation of Pap smears
Proper fixation is an essential step in the preparation of cervical smears. It ensures that the cells are well stained and clearly displayed for microscopic analysis and preserved for immediate and future review. Fixation can be achieved by complete immersion of the slide in one of alcohol fixatives listed below for 15-20 minutes after which the slide can be removed from the fixative and transported to the laboratory for staining. Alternatively,fixation can also be achieved by spray fixation. Spray fixative consist of an alcohol base and carbowax that provides a thin protective waxy coat over the slide. The carbowax must be removed by immersion in alcohol before staining
A satisfactory fixative has to meet several requirements.
1. It should penetrate the cell rapidly so that detailed cell morphology is maintained.
2. Cell shrinkage should be minimal and uniform so that morphological distortions do not occur .
3. It should allow permeability of dyes across the cell boundaries and appropriate for the staining method used
4. It should permit cell adhesion to the glass microscope slide
5. It should be bactericidal, non toxic and permanent..
The following fixatives are suitable for the fixation of cervical smears which are to be stained by the Papanicolaou method.