COMPARISON OF CONVENTIONAL PAPANICOLAOU SMEARS AND A FLUID-BASED, THIN-LAYER SYSTEM FOR CERVICAL-CANCER SCREENING

Objective: To compare the cytologic diagnoses and specimen adequacy of a fluid-based, thin-layer preparation and conventional Papanicolaou t ests. Methods: A total of 7360 women from six separate sites-three scr eening centers and three hospitals-participated in split-sample/matche d-pair, double-masked clinical trials. A conventional Papanicolaou tes t was performed, after which residual material on the sampling device was rinsed into a fluid preservative from which a thin-layer slide (Th inPrep) was prepared using the ThinPrep 2000 automated slide professor (Cytyc Corp., Boxborough, MA). Conventional and ThinPrep slides were read independently. Cytologic diagnoses and specimen adequacy were cla ssified using the Bethesda system. Results: For the three screening ce nters, 65% more diagnoses of low-grade squamous intraepithelial lesion s and higher were made on the ThinPrep slides (P < .001); for the thre e hospital centers, 6% more of these diagnoses were made with the Thin Prep method (P = .294). Comparison of specimen adequacy showed a signi ficant increase in satisfactory specimens and a reduction in the numbe r of ''satisfactory but limited by'' specimens using the ThinPrep meth od (P < .001). Conclusion: The fluid-based, ThinPrep method of sample preparation resulted in a statistically significant increase in cytolo gic diagnosis of cervical cancer precursors and in specimen adequacy c ompared with the conventional Papanicolaou testing method. (C) 1997 by The American College of Obstetricians and Gynecologists.