Background: A Pap test result of atypical squamous cells of undetermined significance (ASCUS) presents a clinical challenge. Only 5–10% of women with ASCUS harbour serious cervical disease.
Methods: We screened 3619 women, who attended to Mirza Koochak Khan Hospital at Tehran University of Medical Sciences with Pap smears, of whom 100 returned with ASCUS. After six months, each subject underwent a standard cytology (conventional Pap smear), human papillomavirus (HPV) DNA testing (identifying high-risk HPV types with polymerase chain reaction) and colposcopy with multiple cervical biopsies.
Results: Mean age was 44.09 ± 8.6 years. The estimated prevalence of cervical intraepithelial neoplasia (CIN) II or higher was 4%. When histologically verified high-grade lesions (≥ CIN II) were observed, the relative sensitivity of HPV DNA testing was 100% compared with conventional Pap smear, which performed 75% versus 100% relative sensitivity, respectively, using cytological diagnosis high-grade squamous intraepithelial lesion, or low-grade squamous intraepithelial lesion (LSIL) as the cut-off. Negative and positive predictive values (NPV and PPV) of Pap test were 98.9% and 100%. The NPV and PPV of HPV DNA testing were 100%.
Conclusions: Although less complicated than colposcopy, the repeat Pap smear triage algorithm for ASCUS may underdiagnose some women with high-grade CIN, when compared with colposcopy. Considering the high sensitivity of HPV testing, it may be useful as an alternative to the current policy of six-month repeat cytology for women with ASCUS results.