A prospective comparison of liquid-based cytology and traditional smear cytology in pancreatic endoscopic ultrasound-guided fine needle aspiration

Objective: To compare results of liquid-based cytology (LBC) and the conventional smear method (SMEAR) when performing endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for lesions of suspected pancreatic malignancy without an on-site cytopathologist. Study Design: Fifty-eight patients were prospectively enrolled between July and December 2009. Aspirates obtained from the first needle pass were randomized either to SMEAR or LBC. Another sample from the second needle pass was allocated to the other method. The rest of the aspirates from the third or later needle passes were used for SMEAR. Diagnostic accuracy was compared and related factors were pursued. Results: Although both methods were 100% specific, LBC was inferior to SMEAR in terms of sensitivity, negative predictive value, and accuracy. However, LBC provided correct diagnoses in 2 out of 3 cases of false negatives for malignancy by SMEAR in which blood was highly contaminated. Although no factor was identified for LBC, low blood contamination and more than 3 needle passes were related with accurate diagnosis in SMEAR. Conclusion: LBC was less accurate than SMEAR when performing pancreatic EUS-FNA without an on-site cytopathologist. However, LBC might serve as a good complement to SMEAR if blood contamination is profound.