Diagnostic value of cytology and colposcopy in patients with abnormal cervical pap smears

ABSTRACT

An optimal cancer detection system for preclinical cervical lesions should combine a cytological examination with a colposcopic follow-up examination. Detection at early pre-invasive stage provides an opportunity for treatment to prevent progression to invasive cancer. The present study aimed at evaluation of cytology, colposcopy, and combined cytology and colposcopy in predicting histopathological diagnosis of cervical intraepithelial neoplasia/squamous intraepithelial lesion [CIN/SIL] or other neoplastic changes in patients with abnormal cervical cytological findings. This prospective study was conducted in the Cyto-colposcopy Unit of Teaching Laboratories and Outpatient Department of Medical City Teaching Hospital over a period of one year [Sep. 2001- Sep. 2002]. Eighty-one married females were included in the study. A cervical smear was taken followed by a colposcopic examination of the cervix and then a punch biopsy was taken from the suspected lesions for histopathological study. Estimation and evaluation of the validity parameters of cytology, colposcopy, and combined cytology and colposcopy were performed using different cutoff points by special statistical analysis. Sensitivity, specificity and accuracy of cytology in the diagnosis of CIN/SIL were 73%, 93.2% and 84.0% respectively. The False- negative rate was 27%. Sensitivity, specificity and accuracy of colposcopy in the diagnosis of CIN were 83.3%, 58.5% and 70.1% respectively choosing doubtful findings as a cut-off point. The combination of cytology and colposcopy gave the following results: sensitivity, specificity and accuracy were 94.6%, 61.4% and 76.5% respectively; the negative predictive value [NPV] was 93.1%. When suspicious colposcopic findings were chosen as the cut-off point, the specificity and the positive predictive value [PPV] were higher at the expense of sensitivity and NPV. The conventional Pap smear, a valuable tool in the evaluation of patients with abnormal cervical cytology, was found to be of relatively low sensitivity in predicting CIN/SIL. Colposcopy is a valuable tool too. However, the validity parameters showed variable figures depending on the different cut-off points applied for the diagnosis of CIN/SIL. The ideal cut-off point was when doubtful and higher-grade colposcopic lesions are considered positive. The combination of cytology and colposcopy resulted in an increased sensitivity and NPV. The specificity could be further increased or improved when the threshold was set to distinguish higher-grade lesions [suspicious lesions] from lesser abnormalities