Effect of a stylet on a histological specimen in EUS-guided fine-needle tissue acquisition by using 22-gauge needles: A multicenter, prospective, randomized, controlled trial

Background EUS-guided FNA (EUS-FNA) has become the most efficacious way to obtain specimens from a solid lesion adjacent to the GI tract. Previous reports regarding the use of a stylet during EUS-FNA were all based on cytological diagnosis and have showed no significant superiority in terms of diagnostic yield. Objective To clarify the noninferiority of EUS-FNA without a stylet (S-) compared with EUS-FNA with a stylet (S+) on histological assessment. Design A prospective, single-blind, randomized, controlled crossover study. Setting Five tertiary referral centers in Japan. Patients Patients referred for EUS-FNA of a solid lesion. Intervention EUS-FNA S+ and S- in a total of 4 alternate passes with randomization to S+ first or S- first. Main Outcome Measurements The primary endpoint was the acquisition rate of an appropriate and sufficient specimen for histological assessment. The secondary endpoints were cellularity, contamination, bloodiness, diagnostic ability, and diagnostic accuracy. Results We enrolled 107 patients (110 lesions) and analyzed 220 specimens each in the S+ and S- groups. The acquisition rate of appropriate and sufficient specimens in the S+ group was 121 of 220 (55.0%) and 122 of 220 (55.5%) in the S- group. The difference in the acquisition rate of the specimen (S- minus S+) based on the generalized estimating equation was 0.42% (95% confidence interval, -6.72% to 7.56%), which was less than 10% of the prespecified noninferiority margin of this study. With regard to cellularity, contamination, bloodiness score, diagnostic ability, and diagnostic accuracy, there were no significant differences between both groups. There were no dropouts in the study. Limitations A variety of target lesions, multiple pathologists, lack of an assessment of intraobserver and interobserver variability, and a single-blind study for the pathologists. Conclusion EUS-FNA S- is noninferior to EUS-FNA S+ on histological assessment. (Clinical trial registration number: UMIN000008695.)