Cervical cytology

Author: Mikael Häggström
Cytology of the cervix:

Clinical information

It is not necessary to look through more than readily available reports from previous cervical cytologies.

Magnification

While being fairly new to cervical cytology, preferably start looking at a high magnification such as 20x objective (with 10x eye piece). For suspicious findings, you may magnify up to maximum. On the other hand, once the pattern feels repetitive you can try switching to a slightly lower magnification such as 10x.

Adequacy

Adequacy should always be stated, either as "Satisfactory" or "Unsatisfactory". For estimating the number of cells, determine the following:

• The area of your field of view at high power (see the Evaluation chapter)
• The total size of the relevant area on the microscope slide. A ThinPrep is about 360 mm².
• Look at 10 representative high power fields (HPFs) within that area, and calculate the average number of cells per high power field.

HPF example on a ThinPrep (about 360 mm²). If 10 fields gives a total of 40 cells, it will be 4 cells per HPF. The area of this field is 0.23 mm². Therefore, total cellularity is estimated to be:
4 cells * 360mm² / 0.23mm² = 6260 cells.

• You may count 10 fields either across the slide, or 5 fields in each direction.[1]
  You may count 10 fields either across the slide, or 5 fields in each direction.

Total number of cells = Average number of cells per HPF *

Total size of area HPF area

Conventional smear cellularity should be at least 8,000 cells. Liquid-based cytology cellularity should be at least 5,000 cells. Also a conventional smear is inadequate if >75% of cells are obscured by blood, exudate or air-drying artefact.

Eventually you will be able to tell when most cases are adequate or inadequate without performing a detailed calculation.

Endocervical cells

Squamous metaplasia also counts as endocervix. Typical features are annotated. Pap stain.

State whether the endocervical/transformation zone is present or absent. Count an endocervical component as present if there are 10 or more endocervical or squamous metaplastic cells.

• Endocervical cells can be viewed from the side as nuclear polarity (margination towards the same side as others) in a “picket-fence” configuration.
  Endocervical cells can be viewed from the side as nuclear polarity (margination towards the same side as others) in a “picket-fence” configuration.
• 
  Sheets of endocervical cells have a honeycomb pattern.

Very common findings

• 
  For reporting, acute inflammation should be a background of ample dispersed neutrophils, and not only aggregates of neutrophils with cells or mucus.
• Vaginal squamous cell with normal vaginal flora versus bacterial vaginosis on Pap stain. Normal vaginal flora (left) is predominantly rod-shaped Lactobacilli, whereas in bacterial vaginosis (right) there are clue cells, covered in bacteria. A significant amount of clue cells can be reported as "Shift in vaginal flora suggestive of bacterial vaginosis".
  Vaginal squamous cell with normal vaginal flora versus bacterial vaginosis on Pap stain. Normal vaginal flora (left) is predominantly rod-shaped Lactobacilli, whereas in bacterial vaginosis (right) there are clue cells, covered in bacteria. A significant amount of clue cells can be reported as "Shift in vaginal flora suggestive of bacterial vaginosis".
• 
  Candida, seen as pseudohyphae.

Main conditions to exclude or confirm

Squamous atypia, seen mainly as cells with increased nucleus/cytoplasm ratio, nuclear hyperchromasia and irregular nuclear outline.

• 
  Atypical squamous cells of undetermined significance (ASCUS), with only few slightly atypical cells
• 
  Low-grade squamous intraepithelial lesion (LSIL), here compared to an unremarkable intermediate squamous cell.
• 
  High-grade squamous intraepithelial lesion (HSIL), showing even more prominent features, and decreased cytoplasm, causing a high nuclear/cytoplasmic ratio.

Other findings

• 
  Chlamydia trachomatis, with granular cytoplasm with multiple intracytoplasmic inclusions with central small coccoid bodies.

Report

Example in a normal case:

Cervical/endocervical ThinPrep: Negative for intraepithelial lesion or malignancy (NILM).

Main page

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