Effectiveness of Liquid-Based Cytology and Papanicolaou Tests in a Low Risk Population

OBJECTIVE: To compare sensitivity an effectiveness of ThinPrep vs. Pap Test and determine whether the Hybrid Capture System II (HCII) for detection of human papillomavirus (HPV) could increase the sensitivity and effectiveness of cervical screening in a low risk population. STUDY DESIGN: We present a comparative observer, blind, "split sample" study of ThinPrep and Papanicolaou staining in a population of 2026 consecutive women. RESULTS: Conventional Papanicolaou stain detected lesions in 62 cases (3.06%), including 1 atypical glandular cell of undetermined significance (AGUS), 34 atypical squamous cells of undetermined significance (ASCUS) (1.73% of atypias), 20 (0.99%) low grade squamous intraepithelial lesions (LSIL), and 7 (0.35%) high grade squamous intraepithelial lesions (HSIL). ThinPrep detected lesions in 63 cases (3.11%), including 26 (1.28%) ASCUS, 27 (1.33%) LSIL and 10 (0.49%) HSIL. Despite this overall similarity, only 35 had a coincident cytopathologic result by both methods. The kappa concordance index between ThinPrep and Pap was 0.546. Sensitivity and specificity were 74.6 and 45.0 in ThinPrep and 69.5 and 25.0 in Papanicolaou-stained smears. High risk HPV (HR-HP 17) was positive in 13 of ZOASCUS and in 21 of 22 SIL. CONCLUSION: Technologies now widely available such as Thin Prep and viral detection aim to improve accuracy of screening.