Does on-site adequacy evaluation reduce the nondiagnostic rate in endoscopic ultrasound-guided fine-needle aspiration of pancreatic lesions?

BACKGROUND: This retrospective study compared the nondiagnostic rate for endoscopic ultrasound-guided (EUS) fine-needle aspiration (FNA) of pancreatic lesions in 2 settings: 1 with and 1 without on-site evaluation.
METHODS: The authors reviewed 381 consecutive cases and divided them into groups with and without on-site adequacy evaluation. For the group with on-site evaluation, cytopathology personnel prepared and evaluated Diff-Quik-stained direct smears and rinsed the remaining material in CytoLyt solution (Cytyc Corporation, Marlborough, Mass). The group without on-site evaluation was divided into 2 subgroups: the clinical team either prepared an air-dried smear for each FNA pass and then rinsed the remaining material in CytoLyt, or the entire sample was rinsed in CytoLyt. The cytologic diagnoses were reviewed and the nondiagnostic rates for each group were calculated.
RESULTS: On-site evaluation was provided for 167 cases with a nondiagnostic rate of 25.8% (43 of 167 cases). On-site evaluation was not provided for 214 cases with a nondiagnostic rate of 24.3% (52 of 214 cases). The nondiagnostic rate for the subgroup with air-dried smears prepared by the clinical team was 25.6% (43 of 168 cases) and that for the subgroup with the entire sample rinsed in CytoLyt was 19.6% (9 of 46 cases). There were no significant statistical differences in nondiagnostic rates noted among the different groups or subgroups.
CONCLUSIONS: The results of the current study indicate that when experienced operators perform EUS FNA of pancreatic lesions, on-site adequacy evaluation offers no benefit in reducing the nondiagnostic rate. Optimizing visualization of the sampled material by omitting the preparation of direct smears and rinsing the entire sample in liquid-based media demonstrated a trend toward improving the diagnostic rate.