EUS-guided through-the-needle microforceps biopsy for pancreatic cysts: Why no widespread adoption?

EUS-guided through-the-needle microforceps biopsy (TTNB) has been shown to have an accuracy, sensitivity, and specificity of 78.8%, 82.2%, and 96.8%, respectively, for diagnosing pancreatic cyst subtypes.[1–7] However, despite data showing the efficacy and clinical value of this device, TTNB has not seen widespread clinical adoption by the EUS community. Why is this the case? It has been over a decade since the first use of TTNB to perform direct intracystic biopsy was reported by Aparicio et al.[8] This initial report was followed by a number of studies on its diagnostic performance.[1–8] TTNB has demonstrated histological adequacy with regard to tissue acquisition in comparison to other tools to investigate pancreatic cysts such as fine-needle aspiration, cyst fluid analysis, and cyst fluid cytology. These earlier techniques have been shown to have, in many cases, limited diagnostic value. This is particularly true among patients with suspected intraductal papillary mucinous neoplasms without obvious communication with the main pancreatic duct and in cases with very viscous fluid that cannot undergo standard chemical analysis.[9,10] Pancreatic cyst fluid is usually only scantly cellular. By comparison, TTNB samples contain tissue from the lining of the cyst wall, including both epithelial cells and associated connective tissue.[11] The safety profile of EUS-TTNB is reasonable, with an overall pooled adverse rate of 8%. Serious adverse events were reported to occur in about 1% of patients. Intracystic bleeding and procedure-related acute pancreatitis are the most feared adverse events.[12] The 2018 American College of Gastroenterology guidelines recommend obtaining cyst fluid cytology for analysis in patients with known or suspected mucinous pancreatic cystic lesions. However, the median diagnostic accuracy and sensitivity are less than 50%, significantly lower than those of EUS-TTNB.[12] The guideline only briefly mentions TTNB and calls for larger, prospective, multicenter trials, a comment that offers little guidance to the practicing clinician.[13,14] Multiple factors could explain the apparent reluctance to use TTNB in the diagnostic workup of Pnacreatic cyst lesions (PCLs). Available studies of TTNB show heterogeneity with regard to the technique used. Most studies on TTNB have used 3 passes for sample collection, but this number is arbitrary, and endosonographers may be unsure of how to best, or even properly, utilize TTNB. Tacelli et al reported higher accuracy and diagnostic yield with an increasing number of passes, but this comes with an increased risk of adverse events.[7] EUS-TTNB is a relatively new the procedure in the field of advanced endoscopy. The intricacies of EUS-TTNB demand specific training and the development of a high level of experience and expertise, which may not be widely available. The perceived complexity and limited expertise in many regions might contribute to this reluctance to adopt EUS-TTNB. In many instances, there could be a correlation between the hesitancy and the fear of adverse events. This highlights the importance of specialized training programs and continuous professional development for newer procedures, maximizing both patient safety and diagnostic accuracy. However, many practitioners may prefer to continue with what they know and tend to be conservative when adopting new techniques such as EUS-TTNB, that is, "My old tools have worked for me all these years, so I do not have to change." Critically, TTNB does not have a specific billing code, so there is no additional reimbursement in the United States for use of this device. This alone may account for much of the limited adoption of this technology. Increases in procedure time as well additional risks of adverse events without concomitant increase in reimbursement almost certainly play a role in the thought processes of clinicians. Finally, the lack of broad clinical usage of EUS-TTNB may simply reflect that PCLs are no longer a "hot topic" in EUS or even pancreatology at this point. Once the source of frequent lectures at national meetings, innumerable publications, and frequent surgical debates regarding proper medical and surgical management, PCLs may simply be felt to be largely a "settled" issue, and endosonographers may be less than enthusiastic about revisiting this topic for additional research studies. Although EUS-TTNB appears to be a useful tool for more detailed characterization of pancreatic cystic lesions, it has not crossed over into widespread use by the EUS community. It would be interesting to see if this situation were affected by the development of an appropriate Current Procedural Terminology (CPT) code. Unless some new data on this device emerge, and with progress in competing technologies such as genomic pancreatic fluid analysis, this is unlikely to change going forward. Ethical Approval This is an editorial from already published studies/data; therefore, it does not involve active human participants and/or animals. Hence, a formal consent, informed consent, institutional review board approval, and ethics approval are not applicable and/or not required.