Several countries across the globe have introduced cervical cancer screening program based on human papillomavirus (HPV) detection test or visual inspection with acetic acid (VIA) test and many more are contemplating to do so. Both the tests score over cytology in test sensitivity and certain logistic conveniences. However, specificity of either of the tests is mediocre and triaging of the test positives with colposcopy leads to large number of false positive diagnoses. In cytology screening prior knowledge of the grade of cytological abnormality guides the colposcopist to arrive at a diagnosis, an advantage that is absent in HPV or VIA based screening. As a consequence, the agreement between the colposcopy and the histopathology diagnoses is poor when colposcopy is performed on HPV or VIA positive women and the specificity is significantly reduced. Colposcopy tends to over-diagnose lesions and treatment based only on colposcopy diagnosis can potentially lead to significant number of over-treatments. Cytology triaging of the HPV positive women is the standard of care in the developed countries, which avoids the problems of false positive diagnosis or over-treatment to a great extent. However, most of the developing countries will have to depend on stand-alone HPV or VIA test in absence of quality cytology facilities and colposcopy will continue to be challenging.
In some studies random biopsies from cervix of HPV positive women without any colposcopically apparent lesion detected significant number of high grade lesions. Some authors put forward the concept of ‘thin’ CIN to account for the non-visualization of the lesions though this theory is debatable. It is more likely that the colposcopists failed to recognize small lesions or erosions.
HPV test is likely to detect more glandular lesions. In cytology screening the morphological diagnosis of a glandular abnormality guides the colposcopist to evaluate the cases adequately. This advantage will not be available in HPV detection based programs and the colposcopy may miss glandular lesions.
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Colposcopy on women with abnormal cytology has been practiced widely for decades and as a result the management algorithms for different case scenarios are well standardized. Practice of colposcopy on HPV or VIA positive women is not yet standardized with certain unsettled management issues e.g. management of screen positive women with type-3 transformation zone or of low grade lesions extending inside the canal.
There is an urgent need for a broad consensus on quality indicators for colposcopy as the same quality indicators and standards may not be applicable when colposcopy is performed on HPV or VIA positive women.