Real-time, high-definition, three-dimensional microscopy for evaluating problematic cervical Papanicolaou smears classified as atypical squamous cells of undetermined significance

BACKGROUND. The perceived inadequacies of the cervical Papanicolaou (Pap) smear have been attributed to sampling, screening, or interpretive errors. Within this type of cytologic preparation, there are thick cell clusters in which the cells are obscured. It may not possible to evaluate these areas by conventional microscopy. The authors clinically tested the hypothesis that high-definition, three-dimensional (3-D) microscopy based on multiple oblique illumination (MOI), with its ability to penetrate into thick areas, would be useful in evaluating problematic cervical Pap smears, particularly those diagnosed as atypical squamous cells of undetermined significance (ASCUS). METHODS. ASCUS Pap smears and corresponding surgical biopsy specimens were evaluated prospectively using standard, axially illuminated microscopes and a new high-definition, 3-D microscope employing MOI. The Pap smears were reviewed in a blinded fashion with both types of microscopy. The rendered diagnoses were then compared with the subsequent tissue biopsies, which also were blinded, as the definitive end point. RESULTS. It was immediately apparent that the high-definition, 3-D MOI microscope had better resolution compared with the standard microscopes. Pap smears and biopsy diagnoses were correlated significantly for MOI (P < 0.001), and there were significant improvements (P = 0.0108) in accuracy when 3-D, high-definition microscopy was compared with conventional microscopy. The authors found no statistically significant correlation between ASCUS diagnoses that were rendered by using standard microscopes compared with the subsequent biopsy. CONCLUSIONS. Due to enhanced visualization through thick cell clusters, an increased depth of field, light penetration, and resolution, high-definition, 3-D microscopy based on MOI produced superior accuracy compared with conventional light microscopy in evaluating cervical Pap smears.