From the Guidelines
The Bethesda System categorizes cervical cytology results into several categories, including Negative for Intraepithelial Lesion or Malignancy (NILM), Atypical Squamous Cells of Undetermined Significance (ASC-US), Low-grade Squamous Intraepithelial Lesion (LSIL), Atypical Squamous Cell suspicion of high-grade dysplasia (ASC-H), High-grade Squamous Intraepithelial Lesion (HSIL), and Invasive carcinoma, as reported in the 2014 study 1.
Key Categories
- Negative for Intraepithelial Lesion or Malignancy (NILM)
- Atypical Squamous Cells of Undetermined Significance (ASC-US)
- Low-grade Squamous Intraepithelial Lesion (LSIL)
- Atypical Squamous Cell suspicion of high-grade dysplasia (ASC-H)
- High-grade Squamous Intraepithelial Lesion (HSIL)
- Invasive carcinoma
Management of Abnormal Results
The management of abnormal cervical cancer screening tests depends on the category of the result, with colposcopy and colposcopically directed biopsies being indicated for evaluating women with abnormal results, such as positive HPV test results and ASC-US or worse, as stated in the 2014 study 1. The guiding principle for managing abnormal test results is similar management for similar risks.
Importance of Standardized Reporting
The Bethesda System provides a standardized reporting system for classifying cytopathology results, ensuring consistent communication between pathologists and clinicians regarding cytology findings and their clinical significance, which is crucial for making appropriate management decisions based on the risk stratification provided by these categories, as noted in the 2010 study 1.
From the Research
Bethesda Category Overview
- The Bethesda System provides concise, specific descriptions for classifying cervical cytology 2
- The system has improved the quality of Pap smear diagnosis in the United States, but the number of women with abnormal Pap smear results has increased 2
Management of Abnormal Pap Smear Results
- Women with unsatisfactory Pap smears should be re-examined and retested 3
- Women with satisfactory smears and a diagnosis of "within normal limits" (WNL) or "benign cellular changes" (BCC) should be retested only at recommended screening intervals 3
- Women with diagnoses of high-grade squamous intraepithelial lesions, atypical glandular cells of uncertain significance, or malignancy should have further investigation (colposcopy) 3
HPV Triage and Management
- Adjunctive high-risk (HR)-HPV testing is useful for disease risk assessment in women with vaginal atypical squamous cells of undetermined significance (ASC-US) and atypical squamous cells, cannot exclude HSIL (ASC-H) Pap results 4
- HPV triage testing is a reasonable and cost-effective approach for women with ASC-US vaginal Pap results and also a useful option for women with ASC-H vaginal Pap results 4
- The immediate risk of having high grade squamous lesions (HSIL) in atypical squamous cells of uncertain significance (AS-CUS) and concomitant high-risk human papillomavirus (HrHPV) testing as negative is approximately 4% 5
Utility of p16 Immunohistochemistry
- p16 immunohistochemistry (IHC) can be used as an adjunct to morphologic assessment of cervical biopsies interpreted as negative or low-grade squamous intraepithelial lesion (LSIL) from patients with prior high-risk Pap test results 6
- p16 IHC can increase the detection rate of missed squamous intraepithelial lesions (SIL) and significantly increase the likelihood of HSIL on subsequent biopsy 6