Cytology and colposcopy in the diagnosis of cervical neoplasia

Accuracy of the Papanicolaou test in screening for and follow-up of cervical cytologic abnormalities: a systematic review

PURPOSE

To evaluate the accuracy of conventional and new methods of Papanicolaou (Pap) testing when used to detect cervical cancer and its precursors.

DATA SOURCES

Systematic search of English-language literature through October 1999 using MEDLINE, EMBASE, other computerized databases, and hand searching.

STUDY SELECTION

All studies that compared Pap testing (conventional methods, computer screening or rescreening, or monolayer cytology) with a concurrent reference standard (histologic examination, colposcopy, or cytology).

DATA EXTRACTION

Two reviewers independently reviewed selection criteria and completed 2 x 2 tables for each study.

DATA SYNTHESIS

94 studies of the conventional Pap test and three studies of monolayer cytology met inclusion criteria. No studies of computerized screening were included. Data were organized by cytologic and histologic thresholds used to define disease. For conventional Pap tests, estimates of sensitivity and specificity varied greatly in individual studies. Methodologic quality and frequency of histologic abnormalities also varied greatly between studies. In the 12 studies with the least biased estimates, sensitivity ranged from 30% to 87% and specificity ranged from 86% to 100%.

CONCLUSIONS

Insufficient high-quality data exist to estimate test operating characteristics of new cytologic methods for cervical screening. Future studies of these technologies should apply adequate reference standards. Most studies of the conventional Pap test are severely biased: The best estimates suggest that it is only moderately accurate and does not achieve concurrently high sensitivity and specificity. Cost-effectiveness models of cervical cancer screening should use more conservative estimates of Pap test sensitivity.

Positive predictive rate of colposcopic examination of the cervix uteri: an overview of literature

Study of literature revealed that the positive predictive rate of the colposcopic impression is better as the cervical lesion is more severe. When directed biopsies are taken, the positive predictive rate of colposcopy increases considerably. For microinvasive disease, the positive predictive rate is quite poor, probably because of the absence of characteristic features. Large loop biopsies diagnosed all cases of microinvasive disease missed by directed biopsies, but this technique has the disadvantage of considerable "overtreatment" when integrated in the management of all patients with abnormal cytology. The restrictions of colposcopy are the invisibility of the squamocolumnar junction and observer variability in the assessment of the impression. The levels of agreement among experienced colposcopists are in the same range as those in cytological and histopathological diagnosis. It is concluded that colposcopy is an indispensable tool in the management of premalignant cervical disease, as long as the restrictions of the technique are kept in mind by the colposcopist.

The accuracy of colposcopically directed biopsy in diagnosis of CIN

During the last decade there has been an increasing interest in the use of the colposcope. A quality-control study for the evaluation and understanding of the limitations of cytology and colposcopy in our clinic is presented. The results in 132 patients are analysed and compared to previous reports from the literature. Cytologic results correlated with the histological diagnosis only in 47% of the patients. Colposcopically directed biopsies were accurate in 88.8% when the entire squamocolumnar junction was visualized. The accuracy of the directed biopsies in patients with unsatisfactory colposcopy was 58.3%. In the presence of a Gardnerella vaginalis cervicitis the colposcopic accuracy decreased to 70.9%.