Performance of the AutoPap Primary Screening System in the detection of high-risk cases in cervicovaginal smears

Quality Control of the Autopap Screening System Employed as a Primary Screening Device: Rapid Review of Smears Coded as no Further Review

Aims and background

Automated reading of smears is increasingly used in cervical screening, and quality control procedures to check its performance are required. The aim of the present study was to evaluate the usefulness of rapid review of all smears coded as “no further review'’ (NFR) by the AutoPap system as a quality control procedure.

Methods

From 2002–2005, 153, 269 smears were processed by AutoPap at the Centro per lo Studio e la Prevenzione Oncologica of Florence, Italy, and 24,503 (15.9%) were coded as NFR. All NFR smears underwent immediate rapid review by expert readers.

Results

Sixty-five of 118 NFR cases reviewed as ASCUS-R complied to recommended 6 months cytology, and 25 of 30 NFR cases reviewed as ASCUS-SIL or more severe accepted immediate colposcopy. As a result of such assessment, one single case of microinvasive carcinoma was detected in a woman aged 34 years: NFR smear had been reviewed as AGCUS, was followed by repeat AGCUS cytology and repeat negative colposcopy, and finally underwent conization.

Conclusions

NFR report at AutoPap was associated with an extremely high negative predictive value, which might suggest using AutoPap as a primary screening tool, with NFR report prompting a “return to screening'’ recommendation. Rapid review of NFR smears is not recommended as a quality control measure for the negligible yield of highgrade lesions detected.

BD focalpoint slide profiler performance with atypical glandular cells on SurePath Papanicolaou smears

BACKGROUND

The FocalPoint Slide Profiler is an automated cervical cytology screening system that is approved for primary screening. It identifies up to 25% of slides as requiring No Further Review. However, few studies have evaluated FocalPoint performance with glandular abnormalities.

METHODS

Sixty-six SurePath Papanicolaou (Pap) tests with a diagnosis of atypical glandular cells were identified. A total of 172 Pap tests with a diagnosis of "endometrial cells present" were included as controls. Follow-up histology was abnormal if diagnosed as high-grade squamous intraepithelial lesions, adenocarcinoma in situ, carcinoma, or complex endometrial hyperplasia. The FocalPoint software ranked each case into 1 of 7 categories: quintiles 1 (high risk) through 5 (low risk), No Further Review, and Process Review.

RESULTS

A total of 215 slides were qualified for review; 38 (57.6%) atypical glandular cells cases were abnormal on follow-up biopsy, and 27 (71.1%) atypical glandular cells with abnormal follow-up qualified for review; no cases were classified No Further Review, and 9 (33%) were ranked in quintile 1. Twenty-three (82.1%) atypical glandular cells with benign follow-up were qualified for review; 3 (11%) cases were classified No Further Review, and 4 (17%) were ranked in quintile 1. There was a statistically significant difference between the ranking of benign atypical glandular cells cases, abnormal atypical glandular cells cases, and control cases (P = .03). However, when collapsed into No Further Review versus all other quintiles, the differences were not significant (P = .20).

CONCLUSIONS

The FocalPoint Slide Profiler did not classify glandular lesions with abnormal follow-up in the No Further Review category. However, these cases were not preferentially ranked in quintile 1. FocalPoint-screened slides need to be carefully reviewed for glandular abnormalities, regardless of the quintile ranking.

The impact of digital imaging in the field of cytopathology

With the introduction of digital imaging, pathology is undergoing a digital transformation. In the field of cytology, digital images are being used for telecytology, automated screening of Pap test slides, training and education (e.g. online digital atlases), and proficiency testing. To date, there has been no systematic review on the impact of digital imaging on the practice of cytopathology. This article critically addresses the emerging role of computer-assisted screening and the application of digital imaging to the field of cytology, including telecytology, virtual microscopy, and the impact of online cytology resources. The role of novel diagnostic techniques like image cytometry is also reviewed.

Reliability of sparing papanicolaou test conventional reading in cases reported as No Further Review at AutoPap-assisted cytological screening

BACKGROUND

AutoPap-assisted smear reading has been proposed prior to conventional manual reading; the latter may be unnecessary for cases reported as No Further Review (NFR) and would be required for cases reported as Review (REV).

METHODS

The authors evaluated comparable concurrent screening cohorts who were undergoing a conventional manual (CONV) or an AutoPap-assisted smear reading within the same screening program. The authors evaluated the prevalence of CIN2+ at repeat screening in subjects 1) with a negative report at conventional Papanicolaou test (CONV- = 9605), 2) with a REV report at AutoPap, followed by a negative conventional reading (REV- = 17,576), and 3) with a NFR report at AutoPap, followed by a negative rapid review (NFR- = 3477) at previous (baseline) screening.

RESULTS

Crude CIN2+ detection rate was 0.176% (17 of 9605), 0.187% (33 of 17,576), or 0.02% (1 of 3477) among baseline CONV-, REV-, or NFR- subjects, respectively. No significant difference in CIN2+ detection rates was evident when comparing the whole baseline CONV- and AutoPap- cohorts (0.176% versus 0.161%; chi(2) ((df=1)) = 2.48, P = .87), or baseline CONV- with baseline REV- subjects (chi(2) ((df=1)) = 2.49, P = .96), whereas a borderline difference was evident when comparing baseline NFR- with CONV- (chi(2) ((df=1)) = 3.07, P = .079) or with REV- (chi(2) ((df=1)) = 3.61, P = .057) subjects.

CONCLUSIONS

The authors' findings suggested that AutoPap assisted reading is comparable to conventional reading, as the frequency of CIN2+ detected at repeat screening did not differ between baseline CONV- or AutoPap- cohorts. The baseline NFR- subgroups showed a lower, borderline significant CIN2+ detection rate when compared to the CONV- cohort. The very low observed negative predictive value of an NFR report (0.02%) suggested that these subjects may safely return to periodic screening and that quality control measures such as rapid review or full manual reading of a random sample are probably not necessary.

Comparison of DNA extraction from cervical cells collected in PreservCyt solution for the amplification of Chlamydia trachomatis

OBJECTIVE

The aim of this study was to compare and evaluate three methods of DNA extraction for the amplification of Chlamydia trachomatis in uterine cervical samples collected in PreservCyt solution. ThinPrep is the trade name for the slide preparation.

METHODS

Thirty-eight samples collected in LCx buffer medium, which were identified as C. trachomatis infected by ligase chain reaction (LCR), were selected for this study. DNA from the PreservCyt samples was extracted by three methods: (i) QIAamp kit, (ii) boiling in Tris-EDTA buffer with Chelex purification, and (iii) Proteinase K digestion with Chelex purification. Sample DNA was tested for the presence of C. trachomatis by PCR using cryptic plasmid research (CTP) primers and major outer membrane protein research momp gene (MOMP) primers. Real-time (LightCycler) PCR for relative C. trachomatis quantification following DNA extraction was performed using primers (Hsp 60) for the 60 kDa heat-shock protein hsp60 gene.

RESULTS

Amplification using CTP primers was the most successful with each of the extraction protocols. Boiling in buffer was the least successful extraction method. QIAamp was the best extraction method, yielding the most positives with both the CTP and MOMP primers. Proteinase K-Chelex extraction gave similar sensitivity to QIAamp extraction with CTP primers but lower for MOMP primers.

CONCLUSIONS

The DNA extraction method must be carefully selected to ensure that larger PCR amplicons can be successfully produced by PCR and to ensure high sensitivity of detection of C. trachomatis. In this study it was found that the QIAamp extraction method followed by PCR with the CTP primers was the most successful for amplification of C. trachomatis DNA.

Effectiveness of AutoPap system location-guided screening in the evaluation of cervical cytology smears

Location-guided screening is a feature of the AutoPap primary screening software. Areas of the smear most likely to contain an abnormality are identified for prompt review by the cytotechnologist, thereby facilitating diagnostic accuracy and reducing laboratory workload. A two-armed retrospective study comprising 6,000 conventional smears was undertaken to compare this approach with the current practice of full manual screening of conventional smears. Discrepant diagnoses between the two study arms were subject to an internal discrepancy review process to determine the final truth diagnosis. Analysis of the results show that AutoPap location-guided screening is at least equivalent to current practice when detecting high-grade or suspected high-grade smears. However, the device does not detect low-grade abnormalities, unsatisfactory smears, an endocervical component or organisms, as well as standard screening. The device also assigns a numerical score to each slide, with abnormal smears allocated a higher rank. Slide ranking was found to be of value in triaging abnormal smears for prompt screening and reporting. The performance of the primary screening software was found to be comparable to previous studies, with the majority of abnormal smears being selected by the instrument for manual review.

A feasibility study of the use of the AutoPap screening system as a primary screening and location-guided rescreening device

BACKGROUND

The AutoPap 300 QC system (Tripath Imaging, Inc., Burlington, NC) is an automated device that was designed to screen conventionally prepared cervical smears and, more recently, thin-layer slide preparations. The system has been tested in large clinical trials.

METHODS

A total of 14,145 cervical smears obtained from participants in the Florence screening program were eligible for the study. Smears were processed first with the AutoPap system and were classified into three different categories: 1) no further review (NFR), 2) review, and 3) process review (PR). Conventional manual reading was performed by 10 experienced cytopathologists.

RESULTS

After AutoPap processing, 2398 smears were classified as NFR (16.9%), and 1818 smears were classified as PR (12.8%). Overall, there were 188 inadequate smears (1.3%) at conventional review and 125 inadequate smears (0.88%) at AutoPap review. Six-month repeat smears were prompted by 330 conventional reviews (2.3%) and by 222 AutoPap reviews (1.56%). Similarly, referral to colposcopy was prompted by 179 conventional reviews (1.2%) and by 147 AutoPap reviews (1.0%). Overall, 32 patients were diagnosed with high-grade cervical intraepithelial neoplasia as a result of assessment. Conventional reading detected 31 patients (28 patients were referred for colposcopy, and 3 patients were referred for repeat cytology), and the AutoPap system detected 30 patients (27 patients were referred for colposcopy, and 3 patients were referred for repeat cytology).

CONCLUSIONS

The current experience suggested that conventional reading and AutoPap reading of cervical smears had essentially the same sensitivity, with slightly greater specificity for the AutoPap system. Thus, comparisons of the AutoPap system and conventional reading should focus mainly on cost analysis.