A Prospective, Single Blinded, Randomized Controlled Trial of Endoscopic Ultrasound (EUS) - Guided Fine-Needle Aspiration (FNA) With and Without a Stylet

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Purpose: Background: The use of stylet during EUS-FNA is assumed to improve quality and diagnostic yield of specimens, despite lack of evidence. The use of stylet during FNA is cumbersome, time consuming and increases cost of FNA needle. Aim: To compare specimens obtained by EUS-FNA with stylet (S+) and without stylet (S-) for: 1. Cellularity, contamination, and amount of blood, and 2. Diagnostic yield of malignancy. Methods: Pts referred for EUS-FNA of solid lesions were prospectively enrolled at 2 tertiary referral centers (2 endosonographers). 22-gauge FNA needle with suction using 10 ml syringe was used. Each lesion was sampled for a minimum of 4 passes (2 S+ and 2 S-). Sequence of S+ and S- passes was determined by a preprinted randomization scheme. A cytopathologist was present in the room during the procedure. 2 slides were prepared for each needle pass (stained with Diff Quick and Pap) and numbered accordingly. Cytopathologists blinded to technique of FNA evaluated slides for: 1. Cellularity - no representative cells of target organ, representative cells in <25%, 25-50% or >50% of the slide, 2. Number of cells - <100(fair), 100-1000(good) and >1000 (excellent) per slide, 3. Contamination with cells from GI wall v none, contamination in < 25%, 25-50% or >50% of the slide, 4. Amount of blood - minimal, moderate or significant, and 5. Final diagnosis. Results: Results from the 2 groups of slides (S+ and S-) were compared using Fisher's exact test. In this pilot study, 100 pts was estimated as an adequate sample size. Results: 101 pts with 118 lesions were prospectively enrolled. Mean age 63 yrs, 69% males, 85% Caucasians. The sites of FNA were: pancreas-61, lymph node-30, liver-6, adrenal-5, others-16. Overall diagnosis was malignant in 55 lesions, benign 27, atypical/suspicious 23, inadequate specimen in 13. 236 passes each were made S+ and S-. There were no differences between S+ and S- specimens with regards to cellularity (p=0.98), no. of cells (p=0.99), contamination (p=0.92), and significant amount of blood (p=0.61). Specimen was deemed inadequate in 102/236 (43%) S+ passes vs. 89/236 (38%) S- passes (p=0.26). Diagnosis of malignancy was made in 55/236 (23%) S+ passes vs. 66/236 (28%) S- passes (p=0.74). Of the 55 malignant lesions, S+ passes were positive in 35 (64%) vs. 43 (78%) for S- passes (p=0.14). Conclusion: In this RCT comparing specimens from FNA passes made with and without stylet, no differences were seen in the cellularity, contamination, significant amount of blood and diagnostic yield of malignancy. Similar number of S+ specimens were deemed inadequate compared to S- specimens. Results of this study suggest that use of a stylet during EUS-FNA does not confer any advantage.