Diagnostic yield and accuracy of a new cytology brush design compared to standard brush cytology for evaluation of biliary strictures.

Background: The sensitivity of brush cytology for biliary strictures has typically been low, usually 30%-60%. We compared the cellular yield and diagnostic accuracy using a new cytology brush (n = 16) versus standard biliary brushings (n = 16) in 32 patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) with brushings for evaluation of a biliary stricture for malignancy.

Methods: We performed retrospective chart reviews of 16 consecutive ERCPs with brushings performed for the cytologic evaluation of a biliary stricture for malignancy using the new cytology brush between January 2016 and February 2017 at our institution. Our control cohort was 16 consecutive ERCP cases performed for the same indication directly preceding the availability of the new cytology brush.

Results: The biliary brushing cases performed using the new cytology brush demonstrated a significantly increased number of total cell clusters per representative ×20 field compared with cases using the standard brush (mean 24.6 versus 14.4, P = .03). This trend continued when assessing large (>50 cells) clusters (mean 5.8 vs. 3.3, P = .02) and medium (6-49 cells) clusters (11.1 vs. 5.8, P = .03). Nonetheless, there were no statistically significant differences with regards to diagnostic accuracy for the new cytology brush versus standard biliary brushings.

Conclusion: We found that the Infinity brush significantly increased diagnostic yield with regards to total cell clusters, large (>50 cells) clusters, and medium (6-49 cells) clusters, however, this did not lead to increased diagnostic accuracy overall. Further studies of this and other brush designs are warranted to optimize biliary brushing specimens.