Atypical squamous cells of undetermined significance in a high-risk population

We set out to develop a benchmark for our use of the term atypical squamous cells of undetermined significance (ASCUS), to compare our ASCUS rate to rates reported by others, and to determine the correlation between ASCUS and histologically-proved cervical intraepithelial neoplasia (CIN) in our population.

All Papanicolaou (Pap) smears and associated cervical biopsies or endocervical curettages interpreted by the University of Florida Department of Pathology between 1992 and 1995 were reviewed.

Of 28,494 Pap smears; 17% were classified as "epithelial cell abnormality, squamous," with 7.4% ASCUS, 5.6% low-grade squamous intraepithelial lesion, and 4.0% high-grade squamous intraepithelial lesion. Of the 2,100 ASCUS cases, 753 had timely biopsies; 45.8% were benign, 53.8% showed CIN, and 0.4% showed carcinoma. Of the CIN cases, 39.2% were CIN1, 8.1% were CIN2, and 6.5% were CIN3.

Our 7.4% ASCUS rate is similar to published rates. Our high rate of neoplasia associated with ASCUS (54.2%) and our low ASCUS-squamous intraepithelial lesion ratio (0.77) indicate that we do not overuse the ASCUS classification.