Multicenter Randomized Controlled Trial Comparing the Performance of 22 Gauge Versus 25 Gauge EUS-FNA Needles

Tissue acquisition by Endoscopic ultrasound plays a central role in diagnosis of several pathologies; this is achieved by obtaining cytological material with fine needle aspiration (FNA) needles that are able to provide smears of malignant cells. Several needles are at present available including 19 Gauge, 22 Gauge and 25 Gauge needles. A 22 Gauge needle is at present the standard needle and most of the EUS-FNA results are based on FNA with this needle.

Twenty five Gauge needles presently available on the market are distinctly small, highly flexible and may be easier to penetrate hard pancreatic tumors. There even is anecdotal messages that this size of needle may be able to traverse relatively large vascular structures without major risk. However, there is very scant data on whether a 25 G needle is comparable to a standard 22 G needle in terms of specimen cellularity and quality. There is only one small randomized trial published as an abstract by Lee et al reporting no statistical significant difference in cellularity between the two groups of needle size as judged by 2 different cytologists. However, the conclusion is dubious because considerable bias may be present since both needles were used in the same lesion. There is therefore a need for a properly designed randomized study comparing different needle sizes.

This study is a prospective randomized multicenter study. Patients referred to one of the participating departments for an EUS examination will be included prospectively. Linear EUS examination will be done with a linear echoendoscope for lymph nodes, mediastinal, pancreatic and other intra-abdominal masses.

Tumor and lymph node characteristics will be carefully described: size (long axis), echogeneity (hypoechoic, hyperechoic, mixed), and echostructure (homogenous, in-homogenous, calcifications), shape (round, oval, triangular), border (regular, irregular).

EUS-guided cell sampling will be performed with a 22 G (Medi-Globe, Sonotip II) and 25 G (Medi-Globe, Sonotip II) needles under EUS and Colour-Doppler guidance.