Qualification of ASCUS. A comparison of equivocal LSIL and equivocal HSIL cervical cytology in the ASCUS LSIL Triage Study.

Cytologic detection of high-grade squamous intraepithelial lesions (HSILs) is critical to cervical cancer prevention. Therefore, identifying "equivocal HSIL" (ASCUS [atypical squamous cells of undetermined significance]-H) may be useful. Accordingly, we compared findings associated with "equivocal low-grade SIL" (ASCUS-L), ASCUS-H, and HSIL using data from the ASCUS LSIL (low-grade squamous intraepithelial lesion) Triage Study. The frequency of oncogenic human papillomavirus (HPV) DNA detection and underlying lesions cervical intraepithelial neoplasia (CIN) 2 or worse or CIN 3 or worse in women with ASCUS-H was intermediate between that of ASCUS-L and HSIL. Oncogenic HPV DNA was associated with 85.6% of ASCUS-H ThinPreps and 69.8% of ASCUS-H smears. Histopathologic lesions CIN 2 or worse were associated with 40.5% of ASCUS-H ThinPreps and 27.2% of ASCUS-H smears (mostly CIN 3). Nevertheless, numerically more lesions CIN 2 or worse were preceded by ASCUS-L than by ASCUS-H because ASCUS-L was more common. ASCUS-H is an uncommon interpretation that derives clinical usefulness from its high positive predictive value for lesions CIN 2 or worse.