Management of atypical squamous cells of undetermined significance and low-grade squamous intra-epithelial lesion by human papillomavirus testing

Cervical cytological terminology varies from country to country. In the USA, the Pap smear is reported using the Bethesda system. The abnormal morphological changes described by this system include two very problematic categories: atypical squamous cells of undetermined significance (ASCUS) and atypical glandular cells of undetermined significance (AGUS). The management of ASCUS, which is similar to the British system ‘borderline’ smear, has been most problematic because the majority of women with this Pap result are normal, although approximately 5–11% have high-grade cervical intraepithelial neoplasia and 1 per 1000 has cervical cancer. Because AGUS is far less common and a significantly greater risk for high-grade cervical intraepithelial neoplasia, adenocarcinoma in situ and cancer, its management is far less controversial, but it is problematic because of clinical confusion with the ASCUS terminology. Low-grade squamous intraepithelial neoplasia is almost entirely related to human papillomavirus. Documentation that certain high-risk types of human papillomavirus are necessary in the aetiology of cervical cancer has led to investigations into the management of these equivocal and low-grade Pap smear abnormalities by testing for these human papillomavirus types.