Unsatisfactory Pap Test Results: A Critical Patient Management Problem Pre-Analytically Addressed by the Cytopathology Laboratory.

Background: The unsatisfactory rate of Pap tests (PT) is an important quality assurance (QA) metric for a cytopathology laboratory. At our institution, an unsatisfactory PT slide is followed by a second ThinPrep (TP) slide. The aim of this study is to evaluate this QA practice.

Methods: Our laboratory processes an unsatisfactory TP PT with a follow-up second TP slide with or without glacial acetic acid. The correlation between the unsatisfactory rate and the second slide rate test was examined.

Results: A total of 2739 cases with a second TP slide were prepared for an unsatisfactory initial TP PT. After second slide preparation, 780 cases (28%) remained unsatisfactory. Using Spearman's rank correlation test, there was a notable negative correlation between the unsatisfactory rate and the second slide rate (rho = -0.42). Of those PTs recategorized as satisfactory TP, 1742 were negative for intraepithelial lesion or malignancy (NILM) (89%), 135 as atypical squamous cells of undetermined significance (ASC-US) (7%), 37 as low-grade squamous intraepithelial lesion (LSIL) (1.9%), 11 as atypical squamous cells cannot exclude high-grade squamous intraepithelial lesion (ASC-H) (0.6%), 8 as high-grade squamous intraepithelial lesion (HSIL) (0.4%), and 20 as atypical glandular cells (AGC) (1%). The final Bethesda categorization for all cases and the human papilloma virus (HPV) data was tabulated.

Conclusions: A second slide preparation significantly reduced the unsatisfactory rate of the PT. This also had a significant impact by detecting clinically significant lesions. HPV testing can also be performed on slides reclassified from unsatisfactory to ASC-US or higher.