Brush vs. spatula for cervical smears. Histologic correlation with concurrent biopsies

In this study we compared the results of 1,293 brush smears obtained between April 23, 1990, and April 22, 1991, with those of 1,304 consecutive spatula smears from 1989. As expected, 94.1% of brush smears revealed the presence of endocervical cells as compared to 63.04% of the spatula smears (P < .0001). The number of "normal" cases was significantly (P < .001) lower in the brush smears (58.2% for the brush vs. 73.7% for the spatula). A significantly larger number (P < .001) of "abnormal" cases and low and high grade squamous intraepithelial lesions (moderate, severe, carcinoma in situ) were demonstrated in the brush smears. In the second part of the study the results of 547 brush smears with accompanying cervical biopsies obtained during the same period were studied for concordance of interpretation and were compared with 421 biopsy-accompanied spatula smears. Of the brush cases, 17.6% cytologically reported as high grade squamous intraepithelial lesions had low grade squamous intraepithelial lesions or reactive or normal histology. This discrepancy was significantly lower (P < .05) in spatula cases (8.9%). These findings suggest that in this series, although brush sampling yielded a higher pickup, it led to a tendency toward overinterpretation by cytopathologists.