SurePath Research Articles

Non‐gynecologic cytology on liquid‐based preparations: A morphologic review of facts and artifacts

Liquid-based preparations (LBP) are increasingly being used both for gynecologic (gyn) and non-gynecologic (non-gyn) cytology including fine needle aspirations (FNA). The two FDA-approved LBP currently in use include ThinPrep (TP), (Cytyc Corp, Marlborough, MA) and SurePath (SP), (TriPath Imaging Inc., Burlington, NC). TP was approved for cervico-vaginal (Pap test) cytology in 1996 and SP in 1999 and both have since also been used for non-gyn cytology. In the LBP, instead of being smeared, cells are rinsed into a liquid preservative collection medium and processed on automated devices. Even after a decade of use, the morphological interpretation of LBP remains a diagnostic challenge because of somewhat altered morphology and artifacts or facts resulting from the fixation and processing techniques. These changes include cleaner background with altered or reduced background and extracellular elements; architectural changes such as smaller cell clusters and sheets, breakage of papillae; altered cell distribution with more dyscohesion and changes in cellular morphology with enhanced nuclear features, smaller cell size and slightly more three-dimensional (3-D) clusters. Herein, we review the published literature on morphological aspects of LBP for non-gyn cytology.

Evolution of Pap testing at a community hospital—A ten year experience

Over a 10-year period the Pap program at our community hospital laboratory progressed from the use of 100% conventional smears to predominantly ThinPrep (TP) and then to nearly 100% SurePath (SP). During this period the annual Pap volume grew from less than 20,000 to nearly 50,000. This retrospective review focuses on improvements in high-grade squamous intraepithelial lesion (HSIL) detection rates and specimen adequacy rates during the 10-year period. The laboratory database was used to identify 310,080 Pap test records between 1995 and 2004 inclusive. Pap type differences in HSIL detection rates and specimen adequacy rates were examined using the Cochran-Mantel-Haenszel test, with year as the stratification variable. The Breslow-Day test was used to evaluate the consistency of differences across the years. The overall results are summarized below in tabular format. Results of Combined 10-Year Data for Total Number of Cases, HSIL Rate, and Unsatisfactory Specimen Rate by Pap Method are given: [table: see text]. HSIL detection rates were significantly higher for liquid-based Pap tests compared with conventional smears (P < 0.0001). In addition, SP was associated with higher HSIL detection rates than TP with an estimated common odds ratio (OR) of 1.37 (95% confidence interval (CI), 1.10 - 1.71; P = 0.005), and higher specimen adequacy compared with TP or conventional Pap methods (P < 0.0001).

Human papillomavirus testing using hybrid capture II with surepath collection

Testing for human papillomavirus (HPV) is an integral part of equivocal cervical cytology triage. Clinical validation of non-FDA (Food and Drug Administration)-approved methods is therefore important because of the high volume of such tests and the implications for missed high-grade lesions if test performance is not optimal. A preinitiation study and 17 months of follow-up data using Hybrid Capture II (HC II) HPV detection with SurePath (SP) sample collection were analyzed. Results of HPV tests on abnormal cytology samples were collected and compared with follow-up results. HPV-positive rates were determined in cases of low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL), and follow-up rates of cervical intraepithelial neoplasia (CIN) were determined in HPV-positive and -negative cases of atypical squamous cells of unknown significance (ASC-US). Rates were compared with published data using FDA-validated methods. The preinitiation study showed the test method to be 100% sensitive for the detection of LSIL (20 cases) and HSIL (8). The ASC-US follow-up study (2319 cases with 625 having biopsy results) showed that the rate of CIN III+ in HPV +/- cases was 7.8%/1.4%, and of CIN II+ was 17.5%/4.3%, respectively. The positive predictive values/negative predictive values (PPV/NPVs) (CIN II+) for the test were 17.5%/95.7%, respectively. Published FDA-validated HPV testing follow-up data show that the expected rates of CIN III+ and CIN II+ in the HPV-negative ASC-US population are 1.4% and 5%, respectively, with PPV/NPVs (CIN II+) of 20%/99%, respectively. By comparison, the present data using HC II with SP show strong similarity, indicating clinical validity for the use of this method.

P‐4 TRANSFORMATION ZONE COMPONENT IN LIQUID BASED CERVICAL CYTOLOGY

Introduction: Quality assurance guidelines for the UK cervical screening programme recommend that more than 80% of cervical samples from women aged 20–50 years should contain adequate numbers of Transformation zone (TZ) cells i.e. 10 or more endocervical or squamous metaplastic cells. This study was conducted to assess the frequency of TZ component in Liquid Based Cytology (LBC) both for ThinPrep (TP) and SurePath (SP) LBC. Also to assess the degree to which this is recorded by individual screeners and to determine the percentage of samples with evidence of TZ component for the different smear takers.Method: All LBC cervical specimens received at a tertiary cytology centre in the year 2004 from women aged 20–50 years were included in the study. Evidence of TZ sampling was recorded as: TP = TZ present (10 or more TZ cells)TA = TZ absentTS = TZ scanty (less than 10 TZ cells)TN = atrophic smears, TZ cells not recognisableResults: The total number of LBC cervical cases was 7445. TP = 4300 (mostly primary care) and SP = 3145 (mostly colposcopy). Overall TZ sampling rate in LBC was 82%. TP = 77.17%; SP = 88.24%. When scanty TZ was included, the standard was met for both systems (TP = 93.7%; SP = 88.24%). Presence/absence of TZ component was recorded in 6370 cases (85.1%); range 0%–97.79%. 56.7% of smear takers achieved the minimum standard for TZ sampling.Discussion: The percentage of ThinPrep samples containing adequate TZ cells was 77.17% compared to SurePath, which was 88.24%. This may be due to different patient populations i.e. primary care versus colposcopy. Screeners recorded TZ sampling in approximately 85% of samples. 56.7% of smear takers met the standard for TZ sampling.

O‐3 A STUDY TO DETERMINE WHETHER THERE IS SIGNIFICANT CELL LOSS ON THE DISCARDED THINPREP BROOM WHEN USED FOR CERVICAL CYTOLOGY

Introduction: The aims of this study were to find out whether cells could be lost on the discarded ThinPrep (TP) broom. A similar study with SurePath (SP), whose methodology recommends leaving the broom in the vial, showed that cells were lost if the broom was discarded and that the amount was operator dependent.1Methods: Three experienced colposcopists (C1, C2 and C3) collected TP samples from 306 women. The broom was rinsed thoroughly in a vial (V1) and then rinsed and retained in a second vial (V2). Slides from each case were randomised as A or B to conceal whether they were from V1 or V2, double‐screened and a cytological diagnosis and cell count recorded for each one. Cells were counted in 10 high‐power fields (HPF) and the cellularity classified as follows: high (HC) &gt; 20 per HPF, intermediate (IC) 10–20 per HPF and low (LC) &lt;10 in order to quantitate the cells potentially discarded in V2.Results: The percentages with high‐grade and low‐grade abnormal cytology decreased with the degree of cellularity of the slide. Abnormal cytology was found in 96/133 (72.2%) of HC, 85/131 (64.9%) of IC and 15/42 (35.7%) of LC in V1 and in 5/8 (62.5%) of HC, 35/54 (64.8%) of IC and 86/244 (35.2%) of LC in V2. The cellularity of V2 was HC or IC in 62/306 (20.3%) and varied between the colposcopists: C1 39/109 (35.8%); C2 20/103 (19.4%); C3 3/94 (3.2%). C1 would have discarded the most cells but had the lowest percentage with LC in V1: 9/109 (8.3%) while the average was 42/306 (13/7%). Abnormal cytology in V2 was also found in V1 in 113/126 (89.1%).Discussion: Abnormal cells would have been discarded with the TP broom and the amount varied between the colposcopists. This finding could have an affect on adequacy of the sample used for routine diagnosis.Reference: 1. Bigras G, Rieder MA, Lambercy J‐M et al. Keeping collecting device in liquid medium is mandatory to ensure optimized liquid‐based cervical cytology sampling. J Lower Genital Tract Dis 2003;7:168–74.