ThinPrep Pap Test - Accuracy for glandular disease

OBJECTIVE: Although the ThinPrep Pap Test is replacing conventional Pap smears in many clinical practices, experience with the identification of glandular lesions is limited. In this study, ThinPrep cytology of glandular lesions was evaluated in a large, inner city teaching hospital with high rates of glandular abnormality. STUDY DESIGN: Six months of ThinPrep diagnoses in 1998, following nearly 100% conversion of the laboratory to the ThinPrep Pap Test, were compared to January-December 1997 conventional smear diagnoses for glandular disease. Biopsy confirmation was evaluated for these cases. Findings on all biopsy-confirmed glandular cases were also compared to findings on cytology. RESULTS: Similar overall rates of glandular cytology were found. For conventional smears (12 months), 46 cases were diagnosed out of 43,289 smears (0.11%). For ThinPrep cytology (six months), 36 cases were diagnosed out of 25,783 slides (0.14%, P = NS). In the year 1997, 9 biopsy-confirmed conventional smear diagnoses of adenocarcinoma in situ (AIS) or adenocarcinoma were noted versus 10 for six months of 1998 for the ThinPrep method. A statistically significant reduction in the number of miscellaneous nonglandular (squamous) biopsy diagnoses were found with ThinPrep glandular cytology (14 vs. 4 cases, P < .05). For known biopsy-confirmed glandular cases of AIS or adenocarcinoma, a statistically significant reduction in the cytology false negative rate was noted with the ThinPrep method (17 vs. 4 cases, P < .02). CONCLUSION: The ThinPrep method provides more accurate diagnoses of glandular disease, with an increase in both sensitivity and specificity for glandular lesions.