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How Are Pap Smear Results Classified?

Monday, April 23, 2012 - 13:07

Contributing Author: Guy Slowik FRCS

Laboratories use one of two systems to classify Pap smear results.

Traditional Reporting System

The older system classifies each cell sample as

Class I

Normal

Class II

Atypical

Class III

Mild, moderate, or severe abnormality

Class IV

Carcinoma in situ, that is, a growth that has the characteristics of cancer cells but has not yet reached the deepest layers of the tissue

Class V

Suspicious for an invasive cancer, that is, cancer that is likely to infiltrate and destroy surrounding tissue

The Bethesda System

Developed during a conference of cancer specialists at the National Institutes of Health (NIH), this newer system is replacing the older classification method.

The Bethesda System classifies the adequacy of cell samples as

  • satisfactory
  • limited
  • unsatisfactory

It describes epithelial cells as

  • normal
  • benign or noncancerous
  • abnormal

The Bethesda System further classifies abnormal epithelial cells - the cells that make up the mucous membrane that lines the cervix - as

  • atypical squamous cells of unknown significance (ASCUS)
  • low-grade squamous intraepithelial lesion (LSIL)
  • high-grade squamous intraepithelial lesion (HSIL)

Abnormalities in cells that line the glands of the cervix may be

  • atypical glandular cells of undetermined significance (AGUS)
  • adenocarcinoma, that is, cancer of the glandular cells of the cervix

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