Atypical squamous cells of undetermined significance: A cytohistological study in a colposcopy clinic.

Cytohistologic correlation was performed by 3 observers on 100 atypical squamous cells of undetermined significance (ASCUS) cases from a colposcopy clinic. Our objectives were to: 1) subclassify ASCUS cases and determine their clinical significance; 2) assess the independent predictive value of different cytologic parameters for biopsy-proven dysplasia (BPD); and 3) calculate interobserver variability. The prevalence of BPD was 73% in the ASCUS favor dysplasia (AFD) group, and 27% in the ASCUS favor reactive (AFR) group (P 0.001). The sensitivity of cervical cytology (AFD) for detecting BPD was 88.5%. Using multiple logistic regression, only nuclear membrane irregularity was found to be independently predictive of BPD (P 0.0001). The interobserver agreement (kappa) was 0.41. Colposcopic smears were inferior to referring smears in detecting dysplasia, with 67% of patients having a referring diagnosis of dysplasia. In a colposcopy clinic population there is a high prevalence (73%) of BPD in the AFD group. Attention should be paid to nuclear membrane irregularity in the risk stratification of ASCUS cases. Diagn. Cytopathol. 1999;21:211-216.