Biopsy correlates of abnormal cervical cytology classified using the Bethesda system

Abstract

Objective: The goal of this study was to determine the colposcopic findings underlying cytologic abnormalities classified according to the Bethesda system.

Methods: Women undergoing colposcopy for abnormal cytology at an urban teaching hospital between July 1, 1996 and December 31, 1999 had Papanicolaou smears repeated. Results were compared both with biopsy histology and with the worst histology reported after 8-26 months of follow-up. kappa statistics and Spearman's rho were calculated to determine the degree of agreement.

Results: Colposcopy was performed for 2263 (94%) women. Referral and repeat Pap smears were reported identically in 493 (25%) of the 1962 women with results for both. No AGUS (atypical glandular cells of uncertain significance) smears were confirmed on repeat smear, and after excluding AGUS, agreement within one grade was found in 1305 of 1854 (70%). Among the 1842 women with squamous cytologic abnormalities, biopsy revealed a lesion more severe than that suggested by referral cytology in 577 (31%) and a less severe lesion in 648 (35%); exact correspondence was found in only 646 (35%). Of 317 women with ASCUS (atypical squamous cells of uncertain significance) on referral Pap smear, a negative repeat smear, and a specific biopsy result, 95 (30%) had true negative histology, while 148 (47%) had condyloma, 56 (18%) had cervical intraepithelial neoplasia (CIN) 1, 8 (3%) had CIN 2, 10 (3%) had CIN 3, and none had cancer. Comparison of repeat smear and colposcopic biopsy yielded a kappa statistic of 0.16.

Conclusions: Cytology classified according to the Bethesda system does not accurately predict histologic diagnosis.