Objective: The aim of this study was to determine the strength of the correlation between colposcopic impression and biopsy histology.
Methods: In an urban referral clinic, colposcopy and directed biopsy were performed between July 1, 1996, and December 31, 1999, by residents supervised by board-certified attending obstetrician-gynecologists. Impression and biopsy were graded as benign, suggesting condyloma or koilocytosis, cervical intraepithelial neoplasia (CIN) grades 1-3, or cancer. The significance of association was assessed by chi(2) testing and the strength by kappa statistics.
Results: Colposcopies were performed on 2825 women, with colposcopic impression and biopsy grade known for 2112. Exact agreement was found in only 893 (37%) women, but results agreed within one grade in 1203 (75%). The association between impression and histology was significant (P < 0.001), but the strength of the correlation was poor (0.20). The positive predictive value of any colposcopic abnormality for any histologic abnormality was 80%. The negative predictive value of a benign colposcopic impression was 68%. The sensitivity of colposcopy with a threshold of any lesion detected was 89%, and the specificity was 52%. The sensitivity for CIN 2/3 was 56%.
Conclusion: Colposcopy is imprecise, although useful in estimating lesion grade. Management decisions require biopsy.