Evaluation of the ThinPrep Pap test as an adjunct to the conventional Pap smear

OBJECTIVE: To evaluate the ThinPrep Pap test as an adjunct to the conventional Pap smear. DESIGN AND SETTING: Prospectively collected cervical samples were split for independent screening at a large specialised private gynaecological pathology practice in Sydney. MAIN OUTCOME MEASURES: Detection of additional significant abnormalities (cervical intraepithelial neoplasia 1, or more severe); changed management recommendations from "repeat smear in 12 months" or "...six months" to "colposcopy", a reduction in unsatisfactory reports. RESULTS: 35,560 paired (split-sample) conventional and ThinPrep slides were prepared. Significant abnormalities were detected in 724 conventional smears (2%). Additional significant abnormalities were found in 85 ThinPrep slides whose corresponding conventional smear was negative or unsatisfactory even after review, representing a 12% increase in the detection of significant abnormalities. As a result of the addition of ThinPrep, management recommendations were changed from "repeat smear in 12 months" or "...six months" to "colposcopy" for 89 of 1669 women whose conventional Pap smears showed minor non-specific changes or papillomavirus. There were 1258 conventional smears (3.5%) that were unsatisfactory compared with 235 ThinPrep slides (0.7%); for only 74 samples (0.2%) were both slides unsatisfactory. CONCLUSIONS: The addition of the ThinPrep Pap test improves detection and clinical management of cervical abnormalities, and reduces the number of unsatisfactory samples which would otherwise require repeat tests.