A Comparison of Detection Rates between Conventional Pap Smears and the Liquid Based Pap Tests in Dysplasia Clinic
SK Galfione, D Smith, DR Mody, DM Coffey. The Methodist Hospital, Houston, TX
Background: In the United States, there has been a trend of decreased use of conventional Pap smears with an increase in liquid based pap tests. The purpose of this study is to compare the detection rates of HSIL, LSIL and ASCUS/AGUS on conventional Pap smears versus liquid based Pap tests.
Design: The statistics of Pap tests from a dysplasia clinic population were compared from the years 1998-1999 (when only conventional Pap smears were performed), 2001-2002 (when the same high-risk clinic completely switched to ThinPrep Pap test); and 2006 (the clinic switched to SurePath Pap test and currently uses it exclusively). The Pap smears/tests were performed or supervised by the same gynecologists during the years studied and the same pathologists and cytotechnologists group evaluated all of the Paps manually. The Paps were categorized into six groups: Atypical Squamous Cells of Undetermined Significance/Atypical Glandular Cells of Undetermined Significance (ASCUS/AGUS), Low grade Squamous Intraepithelial Lesion (LSIL), High grade Squamous Intraepithelial Lesion (HSIL), Negative for Intraepithelial Lesion or Malignancy/Within Normal Limits (NILM/WNL), unsatisfactory and carcinoma.
Results of Conventionals, ThinPrep and SurePath Pap Tests
|Categories:||Conventional (Total: 34,649)||ThinPrep (Total: 16,310)||SurePath (Total: 6,585)|
The ASCUS/AGUS rates increased from 5% in conventional to 8% in ThinPrep and 7% in SurePath (two tailed P value is less than 0.0001 for the conventional versus liquid based, which is considered to be statistically significant). The LSIL rates increased from the conventionals (3%) to ThinPrep (7%) to SurePath (11%) (Two tailed P value is less than 0.0001 between conventional versus liquid based Pap tests). The detection rate of HSIL doubled from the conventionals (2%) to ThinPrep and SurePath (both 4%)(P value of less than 0.0001 for the conventional versus liquid based Pap tests). The unsatisfactory rates and carcinoma detection rates were similar, with all pap tests having less than 1% in either category.
Conclusions: The study shows that there was a statistically significant difference between the detection rates of abnormal Paps on conventional and liquid based Pap tests. There was only a statistical difference on LSIL detection rates between the two FDA approved liquid based systems in our high risk dysplasia clinic population.
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 147, Monday Morning