We used the 22-gauge needle for FNAs other than transduodenal procedures for two reasons: first, the 22-gauge needle has the added advantage of procuring better histologic samples than do 25-gauge needles,3 and second, its technical performance equals that of the 25-gauge needle for all FNAs except transduodenal cases. However, because of limited data, the decision to use a 22- or 25-gauge needle for FNA of lesions that do not require a transduodenal route should be based on operator preference and experience. Despite the disadvantages that are inherent in its size, 19-gauge needles are indispensible

for certain indications: (1) for therapeutic procedures that require the passage of a 0.035-inch guidewire; (2) for aspiration of large cyst lesions, particularly if they are mucoid; and (3) for procurement of core tissue. In phase I of the present study, we had technical Obeticholic Acid molecular weight difficulty with the 19-gauge needle when therapeutic interventions or cyst aspirations were undertaken via the transduodenal route. This was because it was either difficult to exit the needle out of the sheath, the needle was severely bent precluding good sonographic visualization, or it was difficult to remove the stylet from the needle assembly Selleckchem isocitrate dehydrogenase inhibitor once the lesion was accessed. In order to circumvent this problem, in phase II of the study, we used the newly developed Flexible 19-gauge needle for all transduodenal interventions and cyst

aspirations. This new needle is made of nitinol, which enhances the flexibility of the FNA assembly and facilitates ease of access for interventions and tissue procurement via the transduodenal route.15

Although the Flexible 19-gauge needle also can be used for any transgastric and/or esophageal or transrectal procedure, the cost of the needle is more than that of a standard 19-gauge needle and does not confer any added benefit. With regard to CPN, although 22-gauge needles can be used, in both phases of this study we used FER the standard 19-gauge FNA and 20-gauge CPN needles and found no difference in technical performance between needle types. There are a few limitations to this study. First, this is a single-center study in which all procedures were performed by expert endosonographers, and the findings therefore may not be applicable to less-experienced endoscopists. However, the technical outcomes, even within our center, were significantly better after incorporation of this algorithm. Some practice patterns, such as use of a 19-gauge needle for diagnostic cyst aspiration, are unique to endosonographers and institutions. We prefer the 19-gauge needle because it is more time efficient and can aspirate mucin better, whereas other endosonographers might prefer to use the 22-gauge needle for the same indication. Second, the diagnostic adequacy reported was based on on-site analysis and not on long-term clinical follow-up.