Evaluation of cellular residue in the ThinPrep PreservCyt vial

The ThinPrep Pap Testtrade mark is a fluid-based method used for the collection and preparation of cervicovaginal samples. The collection device(s) is/are rinsed in Cytyc's ThinPrep PreservCyt medium and a thin-layer slide is prepared using the ThinPrep 2000 automated processor. The purpose of this study was to determine the detection rates for cervical lesions utilizing an additional ThinPrep slide. Fifty-four cervical samples processed by the ThinPrep method were reviewed. An additional thin-layer slide was obtained from the cellular residue for each case utilizing a new filter. Case selection criteria included cases with a few equivocal cells, a few diagnostic cells, or several low-grade dysplastic cells seen on the original ThinPrep slide. The original slides and repeat slides were reviewed by two cytopathologists and two cytopathology fellows. Fifty-four patients were included in the study, mean age 35 years (range: 16-76). The original diagnoses included: 17 negative cases, 22 atypical squamous cells of undetermined significance (ASCUS), 10 low-grade squamous intraepithelial lesions (LGSILs), four high-grade squamous intraepithelial lesions (HGSILs), and one case of atypical glandular cells of undetermined significance (AGUS). On the repeat slides the diagnosis remained the same in 42 (77.8%) cases, diagnostic cells were not present in 10 (18.5%) cases, fungal elements consistent with candida were detected on the repeat smear in one case (1.8%), and higher grade dysplastic cells were found in two cases (3.7%). Our study showed that the ThinPrep method provides a representative, diagnostic sample on the slide. Repeat processing adds little to the overall diagnosis.