Efficacy of automated cervical cytology screening

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Abstract
The Papanicolaou stained cervicovaginal smear (Pap smear) is a gynecologic cytologic screening tool that has dramatically reduced the incidence and mortality of cervical cancer. Recently, a number of problems with the Pap smear test, including severe cytotechnologist shortages, lack of internal quality controls, and high false negative rates have been emphasized by the scientific community and the general public. To address some of these problems, there has been increased development of a number of automated and semiautomated cytologic screening systems. A semiautomated screening system (PAPNET®) was used to retrospectively evaluate 527 conventionally prepared Pap smears from 500 consecutive unselected patients. This system scanned the slides and displayed 128 of the most “abnormal” areas of each slide on a monitor. A screener reviewed these “abnormal” images in a blinded fashion and decided whether they represented variants of normal cytology, were inadequate for evaluation, or were abnormal and warranted manual review of the material. The screener's evaluations were then compared to the previously made diagnosis and discrepancies were reviewed. After review of the images from 500 patients, 343 (69%) were deemed to be normal cytology, 140 (28%) were abnormal and needed manual review, and 17 (3%) were inadequate. Of the 343 called normal using this system, 338 were previously called normal and five patients were previously diagnosed with either atypical squamous cells of undetermined significance (ASQUS) or low grade squamous intraepithelial lesions (LGSIL). Of the 140 thought to need review, 43 were previously diagnosed with squamous or glandular disease and 97 were previously diagnosed as normal. Slides from the apparent false negatives and false positives were again reviewed in a blinded fashion. Of the 97 thought to need review by the automated system but with previously normal diagnosis, 15 additional cases were thought to have cytopathic changes (12 ASQUS and 3 LGSIL). Of the five patients that were called normal using the automated review but with previous disease, only two were felt to be true false negatives. Semiautomated Pap smear screening appears to be a sensitive as well as specific method for the identification of cervical pathology. Further, it may be incorporated as a mechanism for quality control in the laboratory.