Rapid rescreening of cervical smears for internal quality control.

OBJECTIVE

To assess the performance of quick rescreening as an internal quality control for cervical smears previously screened as negative and to compare this method with clinically indicated rescreening of negative smears and with further 10% random rescreening.

STUDY DESIGN

In a small-workload laboratory with many different types of indications for cytology, during a three-month period, all gynecologic cytology smears considered negative for significant findings (anything above atypical squamous cells of undetermined significance (ASCUS)/atypical glandular cells of undetermined significance (AGUS) in the Bethesda System) or inadequate were quickly rescreened using a 10 x objective.

RESULTS

Of the total 2,188 smears processed, 164 (7.5%) were excluded from rapid review because they were positive on routine screening, and 2,024 cases were subjected to rapid rescreening: 1,925 (95.1%) cases were considered negative and 99 (4.9%) positive for significant findings; 58 of the latter were confirmed and 41 not confirmed by the cytopathologist's detailed examination. The 58 confirmed cases were classified as: 43 ASCUS/AGUS, 14 of low grade squamous intraepithelial lesion and 1 of invasive cancer. No cases of high grade squamous intraepithelial lesion were detected.

CONCLUSION

Considering that the routine screening and internal quality control of the laboratory had detected 117 positive cases, the additional 58 represent a definite increase in the efficiency of a small-workload laboratory. In such a clinical setting, no additional case of a high grade lesion was detected by rapid rescreening. The increase in cost and time was considered very reasonable, and the method was incorporated as quality control for the laboratory. Clinically indicated rescreening of negative smears and random 10% rescreening after random rescreening did not add significantly to quality assurance.