Endoscopic Ultrasound-Guided Fine-Needle Aspiration of Gastrointestinal and Pancreatic Tumors: Is Negative Pressure Helpful or Does It Suck?

Abstract

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) facilitates endoscopic tissue acquisition. The technique is affected by two major categories of factors: that influencing sample acquisition and that influencing sample interpretation, some subject to controversy [1]. The former factors include: the degree of technical difficulty (location of the lesion), the type of lesion (solid or cystic), the diameter of the needle (19-, 22-, or 25-gauge), the number of punctures, the use of negative pressure (presence and amount including capillary aspiration, namely slow-pull technique), the presence of stylets, the presence of rapid on-site evaluation (ROSE), the type of needle (a dedicated biopsy needle, with or without a side hole at the needle tip, and with or without a core trap at the needle tip), any special maneuvers (‘‘fanning’’ technique) used, and the experience and skills of the endosonographer. The factors affecting interpretation are contamination and mimicry of other types of lesions. There is current controversy concerning the use of negative pressure suction, with regard to the decision of whether or not to use suction and the selection of an appropriate target and force of suction. In EUS-FNA, negative pressure is applied using suction with a 10or 20-mL syringe, which increases the quantity of the extracted sample at the expense of occasionally increasing the probability of blood contamination. In general, the outcome of a specimen gathered during EUS-FNA is determined based on the diagnostic ability of cytologist or pathologist, acquisition of an appropriate and sufficient specimen (cellularity), contamination from the gastrointestinal (GI) tract, and observed blood contamination on slides. In the two randomized controlled trials (RCTs) that have so far evaluated the contribution of negative pressure during EUS-FNA for lymph nodes [2] or solid lesions [3], the use of negative pressure did not improve diagnostic accuracy, but did increase blood contamination. In one RCT, although the use of negative pressure increased the cellularity of the specimens obtained (P = 0.01), the diagnostic accuracy did not significantly differ from that of EUS-FNA without negative pressure (P = 0.73) [2]. Therefore, based on the available data, EUS-FNA without negative pressure is recommended by most experts [1]. If the obtained specimen is minimal, such as in cases of chronic pancreatitis, negative pressure can be used to enable the acquisition of a larger specimen [1]. Nonetheless, while most reports focus on cytology, histological tissue quality has rarely been investigated. In this issue of Digestive Diseases and Sciences, Aadam et al. [4] hypothesized that negative pressure still persists in the aspirating needle despite closing the suction-syringe stopcock. They first examined the effect of stopcock closure and the removal of the syringe itself using an in vitro model system that confirmed the presence of residual negative pressure inside and up to the tip of the needle after closing the stopcock that was successfully neutralized by removing the syringe. In the next step, in a prospective, single-blinded, randomized, crossover pilot study in patients with solitary pancreatic masses, EUS-FNA was performed in 60 patients using a 22-gauge needle. After the first puncture and back-and-forth strokes, the syringe was either stopcock-shut but attached, or removed entirely, and a second pass was performed in a crossover fashion. The samples obtained with the syringe still connected contained & Hiroshi Kawakami hiropon@med.hokudai.ac.jp