Comparison of Performace of 22 Gauge and 25 Gauge Needles in Endoscopic Ultrasound (EUS) Guided Fine Needle Aspiration (FNA)

Abstract

Background: Both 22 and 25 gauge FNA needles are used for endoscopic ultrasound (EUS-guided) aspiration of lesions, yet limited data exists on whether one offers an advantage over the other in terms of specimen cellularity and quality. Methods: Between October 2005-June 2006, 12 patients with pancreatic lesions and/or peripancreatic nodes underwent EUS-guided FNA with both a 22 and 25 gauge Wilson-Cooke Echotip Needle. All procedures were performed with an Olympus linear echoendoscope by one endoscopist to eliminate operator-dependent variability. Needle order was selected randomly and two passes were made with each needle, using 10 uniform to-and-fro movements on every pass with a 10 cc suction. The specimens were immediately stained and reviewed by two cytopathologists, who were blinded to the needle order and used uniform criteria for the evaluation of cellularity. Results: There were three mechanical failures noted with 25 gauge needles; one occurred without using the elevator after one try of FNA and two occurred after one pass with elevation of the needle to perform FNA of the mass in the uncinate process. None of the 22 gauge needles failed throughout the procedures. The visibility of the needles did not differ significantly. Diagnoses were achieved in all cases: 7 pancreatic adenoca, 1 panc giant cell ca, 1 metastatic non-small cell ca, 1 negative lymph node, 1 metastatic colon ca, 1 neuroendocrine tumor. Cellularity was graded in 0 to 6 system with 6 being most cellular. No statistically significant difference in cellularity was detected between the two groups of needle size 22 and 25 by cytologist 1 (mean of the difference was 0.04, 95% CI of -1.22 -1.30, p = 0.94). No statistically significant difference in cellularity was detected between two groups by cytologist 2 (mean of the difference; 0.2; 95% CI -1.23 -1.65, p = 0.76). When the data from both cytologists were combined, no statistically significant difference in cellularity was detected (mean of the difference: 0.125; 95% CI -1.22 -1.47, p = 0.84). No statistically significant difference in cellularity was detected between cytologists 1 and 2 (mean of the difference; 0.17, 95% CI -0.15 to 0.48, p = 0.27). On comparing needle order effect between the 1 st pass group and 2 nd pass group, no statistically significant difference was detected (p = 0.75). There were no procedure related complications. Conclusions: No significant difference was noted between the two needle groups in terms of cellularity, between the orders of the FNA, and between two cytologists evaluations. However, 22 gauge needle was more durable for FNA of the uncinate process with the elevator applied.