Comparison of the Sensitivity of Conventional Cytology and the ThinPrep Imaging System for 1,083 Biopsy Confirmed High-Grade Squamous Lesions

Liquid-based cytology continues to be utilized as an adjunct to conventional cytology in most Australian laboratories, even though a direct-to-vial Thin Prep protocol has been introduced in many countries with established cervical screening programs. Manual screening of Thin Prep slides has been widely practiced for more than 10 years and the recent introduction of the ThinPrep Imaging System (TPI) has been reported as being more sensitive than the conventional smear (CS) in the identification of high-grade cervical disease. We report our experience with Thin Prep Imaging since its introduction into our routine gynecological cytology service. 87,284 split sample pairs reported using the Imaging System demonstrated a decrease in unsatisfactory reports (3.65% for CS and 0.87% for TPI) and an increase in possible high grade and definite high-grade squamous reports (1.57% for CS and 1.62% for TPI). For 1,083 biopsy confirmed high-grade lesions, the correct diagnosis of high grade or possible high-grade squamous disease was made on the Thin Prep imaged slide in 61.0% (6611 1,083) of cases and on the CS in 59.4% (64311,083). This was not statistically significant. When all abnormalities identified on cytology were considered, including possible low grade and definite low-grade abnormalities, the difference in sensitivity for Thinprep imaged slides of 96.0% (1,040/1,083) and CSs of 91.6% (992/1,083) was statistically significant. Diagn. Cytopathol. 2010;38:318-326. (C) 2009 Wiley-Liss, Inc.