A Prospective Multi-center Randomized Study of the Difference in Diagnostic Yield Between EUSFNA Needles With and Without a Side Port in Pancreatic Masses

Background Endoscopic ultrasound (EUS) and EUS-guided fine needle aspiration (EUSFNA) are well established techniques in clinical practice. In routine gastrointestinal endoscopy such as gastroscopy, only the mucosal layer of the digestive tract is visualized. In the case of EUS, an ultrasonic transducer located at the tip of the echoendoscope allows the endoscopist to visualize the wall of gastrointestinal tract as a series of definable layers corresponding to histology, rather than as a single entity, and also enables detailed images of areas outside of the digestive tract, such as intra-abdominal lymph nodes, and solid organs such as liver, pancreas to be seen. EUS has a significant clinical impact because it allows assessment of submucosal GI lesions, loco-regional staging of gastrointestinal malignancy, tissue diagnosis by EUSFNA and staging of pancreaticobiliary lesions, non-small-cell lung carcinoma, and mediastinal disease. EUSFNA is a minimally invasive technique of tissue acquisition under EUS guidance. A FNA needle is inserted through the accessory channel of a curvilinear echoendoscope. Both the target lesion and the needle tip are visualized under real time ultrasound guidance, and any potential intervening vessels can be excluded by turning on the Doppler mode prior to needle puncture. The lesion is then punctured under real-time ultrasonic guidance and material aspirated by the needle for cytological assessment.

In prospective trials, EUSFNA has been clearly established to be an important diagnostic tool, with excellent safety profile. The overall diagnostic yield of EUSFNA should exceed 80%, with higher rates in EUSFNA of lymph nodes, where rates of >90% may be expected, as compared to pancreatic masses, where lower diagnostic rates were reported. The somewhat lower rates for solid pancreatic lesions compared to lymph nodes could be due to the underlying desmoplastic changes associated with pancreatic malignancies.

EUSFNA may be performed with rapid on site cytopathological assessment (ROSE) of the aspirated material to guide the number of needle passes being performed. In most practices, rapid on site cytopathological assessment is not feasible and it has been recommended that in such situation, in order to maximize the diagnostic yield, at least 3 needle passes should be performed for lymph nodes and at least 4 passes should be performed for pancreatic masses. Even without onsite cytopathological assessment, excellent results with greater than 90% diagnostic yield have been reported by expert centers.

Needles for EUSFNA are available from four manufacturers, namely Cook Endoscopy, Boston Scientific, Olympus Corporation and Mediglobe. The available needle diameters are 25, 22 and 19 gauge. These needles have a sharp tip for puncturing and a hollow core for aspiration after the puncture. The hollow needle core is covered by a stylet which is withdrawn after the puncture to facilitate aspiration. Aspiration is usually facilitated by application of suction using a syringe which is attached to the entry port of the hollow core of the needle, after the stylet has been withdrawn, although it must also be acknowledged that there are endoscopists who prefer to apply no suction in order to reduce the possibility of bloody aspirates. Olympus has recently made commercially available a new 22 gauge FNA needle with a side port at the needle tip. The theoretical basis for introduction of the side port is to facilitate the process of fine needle aspiration, and to increase the diagnostic yield. There have been preliminary unpublished retrospective data that suggested the yield might be raised. However, there are no prospective multicenter randomized controlled studies to ascertain the validity of the assumption. Currently two needles with similar designs, apart from absence and presence of side port, are available from Olympus Corporation. These are the EZ-Shot 2 (model: NA-220H-8022) and EZ-Shot 2 with side port (NA-230H-8022)

Aim The aim of this prospective randomized study is to determine whether there is a difference in diagnostic yield between EZ-Shot 2 (model: NA-220H-8022) and EZ-Shot 2 with side port (NA-230H-8022) in patients with pancreatic masses for evaluation.