2. Introduction
Specimens from screening for cervical cancer are conventionally prepared (CP)
for cytology by smearing collected cells directly onto a glass slide and then fixing
them with alcohol.
With liquid-based cytology (LBC), cells that have been stored in preservative fluid
are collected and a specimen is prepared from the liquid cytology
LBC uses an automated specimen processing system that clearly displays
cytologic features of a specimen despite the limitations on the area that can be
viewed.
Infact countries like UK has switched to LBCs for purpose of screening
Some study shows even decrease in inadequate samples from 9.1 % to 1.6%
3. For LBCs we prefer two FDA approved systems
1. Sure Path
Centrifugation and sedimentation through a pressure gradient
1. Thin prep
Filtration and collection of vaccum packed cells on membrane and
transferring to slide
These methods of PAP preparation is better since it efficacy than traditional
methods are good and also specificity and sensitivity is 90% fro the same
4. Morphology
Clean background
Cells are shrunken
Cytoplasmic and nuclear features are more easily identified
Cells with low grade dyskaryosis, especially koilocytosis
Lower nuclear hyperchromasia
Glandular neoplasms show characteristic picture in thin film cytology
5. SurePath
Sample collection is done by using SurePath special kit, which includes a
SurePath preservative fluid collection vial and the sampling device
8. The enriched cell pellet is now transferred to settling chamber, further mounted on
slide and then staining is done to obtain a smear
The image shown is the instrument used to mount the slide while other image
shows the mounted slide with help of settling chamber
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10. Thin Prep method
Cervical sample is collected and rinsed into the Thin prep vial
Cells preserved and sent to lab using which smear is prepared
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15. Advantages
● Immediate fixation with enhanced nuclear and cytoplasmic detail
● All material collected is available for microscopic evaluation
● A representative sample is prepared for cytological evaluation but multiple
samples can be prepared as necessary
● Clearer background so that epithelial cells of interest are less likely to be
obscured
● A thin layer of dispersed cells are spread over a fixed area so that the area to
be screened is small and the preparation takes less time to screen than a
conventional smear
● Unsatisfactory rate decreased
● LBC samples is suitable for other tests e.g. HPV testing
● LBC slides are suitable for automated analysis
16. Disadvantages
● Smear patterns altered because of randomization of cells
● Abnormal cells are dispersed
● Scanty LBC preparations can be difficult to screen and interpret
● Blood mucous inflammation and malignant diathesis are still present but
appear slightly different
● Epithelial cells appear mostly as single cells and are slightly smaller than
they appear in conventional smears especially endocervical cells and
immature metaplastic cells.
● LBC is more expensive than conventional test
17. The Bethesda criteria for determination of adequacy of LBC Samples
● Any specimen with abnormal cells is by definition satisfactory for evaluation
● A minimum of 5,000 well-visualized/preserved squamous cells should be
seen in the slide
● A minimum of 10 fields should be counted usually at x40 objective along a
diameter that includes the center of the preparation.
● Slides with fewer than 5000 cells should be examined to determine the
reason
● The average cell number per microscopic field to achieve 5000 cells is shown
in the following table. If there are hypocellular or empty areas on the
preparation the percentage of the hypocellular areas should be estimated
18. LBC modification of cell morphology
The main effects of LBC on the morphology of epithelial cells in the samples are :
● Loss of relationships between cells and random spread of cells
● Dispersal of abnormal cells
● Scanty monolayers can be difficult to screen and interpret
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20. This how adequate smears will look on LBC while other figure gives us idea that how cells are free and not
overlapping hence helping us to know clear morphology of cells in LBCs.
