"Wet suction technique (WEST)": a novel way to enhance the quality of EUS-FNA aspirate. Results of a prospective, single-blind, randomized, controlled trial using a 22-gauge needle for EUS-FNA of solid lesions

Background: Contemporary EUS-guided FNA techniques involve the use of a needle, with an air column within the lumen, with or without suction. We describe a novel technique with an aim to improve the quality of the aspirate. Objective: To compare a novel "wet suction" technique (WEST) with the conventional FNA technique (CFNAT) of EUS-guided FNA using a 22-gauge FNA needle. Design: Prospective, single-blind, and randomized trial. Setting: Two large tertiary-care hospitals. Patients: All consecutive adult patients presenting for EUS with possible FNA of solid lesions were offered the chance to participate in the study. Methods: All lesions were sampled with the same needle by using alternating techniques. Patients were randomized to the WEST versus the CFNAT for the first pass. If the first pass was made with the WEST, the second pass was made with the CFNAT, and subsequent passes were made in an alternating manner by using the same sequence. All FNAs were performed using 22-gauge needles. Main Outcome Measurements: Specimen adequacy, cellularity, and blood contamination of EUS-guided FNA aspirates graded on a predefined scale. Results: The WEST yielded significantly higher cellularity in a cell block compared with the CFNAT, with a mean cellularity score of 1.82 +/- 0.76 versus 1.45 +/- 0.768 (P < .0003). The WEST cell block resulted in a significantly better specimen adequacy of 85.5% versus 75.2% (P < .035). There was no difference in the amount of blood contamination between the 2 techniques. Limitations: Lack of cross check and grading by a second cytopathologist. Conclusion: The novel WEST resulted in significantly better cellularity and specimen adequacy in cell blocks of EUS-guided FNA aspirate of solid lesions than the CFNAT.