Blinded Prospective Comparison of the Performance of 22-Gauge and 25-Gauge Needles in Endoscopic Ultrasound-Guided Fine Needle Aspiration of the Pancreas and Peri-pancreatic Lesions

Both 22- and 25-gauge needles are used for endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) of lesions, yet limited data exist on whether either offers an advantage over the other in terms of specimen cellularity and quality.

The aim of this study was to compare sample quality for 22- and 25-gauge needles in EUS-guided FNA of pancreatic and peri-pancreatic lesions.

Between October 2005 and June 2006, 12 patients with pancreatic or peripancreatic lesions underwent EUS-guided FNA with both 22- and 25-gauge Wilson-Cook Echotip needles. All procedures were performed with an Olympus linear echoendoscope by the same endoscopist to eliminate operator-dependent variability. Needle order was selected randomly, and two passes were made with each needle, consisting of ten uniform to-and-fro movements on each pass with 10-ml syringe suction. The specimens were immediately stained and independently reviewed by two cytopathologists, who were blinded to the needle used. Cellularity was graded as 0 to 6, with 6 being most cellular.

No statistically significant difference in cellularity was detected between the two needle size groups by cytologist 1 (mean difference, 0.04; 95% confidence interval [CI], −1.22 to 1.30; p = 0.94) or by cytologist 2 (mean difference, 0.2; 95% CI, −1.23 to 1.65; p = 0.76). When the data from both cytologists were combined, no significant difference in cellularity was detected between the two needle sizes (mean difference, 0.125; 95% CI, −1.22 to 1.47; p = 0.84). No significant difference in cellularity was detected between cytologists 1 and 2 (mean difference, 0.17; 95% CI, −0.15 to 0.48; p = 0.27). When the order in which needles were used was compared, no significant difference in cellularity was detected (p = 0.75). Three mechanical failures occurred with 25-gauge needles, but none occurred with 22-gauge needles. The visibility of the needles on EUS did not differ. Cytologic diagnoses were achieved in all cases: seven pancreatic adenocarcinomas, one pancreatic giant cell carcinoma, one pancreatic neuroendocrine tumor, one metastatic non-small cell carcinoma, one metastatic colon carcinoma, and one pancreatitis. There were no procedure-related complications.

Both FNA needles provided accurate diagnoses in all patients. There was no significant difference between the 22- and 25-gauge needle groups in the independent interpretation of two cytopathologists with respect to cellular yield and ability to render a diagnosis.