Endosonographer's macroscopic evaluation of EUS-FNAB specimens after interactive cytopathologic training: a single-center prospective validation cohort study.

Background: In many centers, rapid on-site evaluation (ROSE) for the specimens obtained from endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) is not available. The aim of this study was to compare the diagnostic yields of EUS-FNAB in the presence or absence of ROSE.

Methods: Seventy-five patients who underwent EUS-FNAB for the pancreatic, gastric subepithelial, and mesenteric mass lesions at our institution from November 2013 to August 2014 were included. For 20 patients in the pilot cohort, EUS-FNAB was performed with ROSE, and simultaneously, training of the staff endosonographer for tissue adequacy by an on-site cytopathologist was also performed.

Results: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of EUS-FNAB in the pilot cohort were 91.7, 100.0, 100.0, 88.9, and 95.0 %, respectively. The 3.2 ± 0.8 [mean ± standard deviation (SD)] needle passes were needed in this cohort. Fifty-five patients were enrolled as a validation cohort from April 2014 to August 2014, and tissue adequacies were assessed by an experienced endosonographer without ROSE in this cohort. The sensitivity, specificity, PPV, NPV, and accuracy of EUS-FNAB in this validation cohort were 92.1, 100.0, 100.0, 85.0, and 94.6 %, respectively. The 4.5 ± 0.6 (mean ± SD) needle passes were needed in this cohort (p < 0.01 compared to pilot cohort).

Conclusions: Diagnostic accuracy of EUS-FNAB in which the adequacy of sample was assessed by an attending endosonographer was acceptable. This study suggests that on-site evaluation by a trained endosonographer may be an alternative tool to ROSE where ROSE is not available.