Introduction

Since its introduction, endoscopic ultrasound (EUS) has evolved as a vital endoscopic procedure for the diagnosis and staging of pancreaticobiliary and luminal gastrointestinal (GI) malignancies. EUS-guided fine-needle aspiration (EUS FNA) and EUS-guided fine-needle biopsy (FNB) are standard practice for EUS-guided tissue acquisition (EUS TA) for diagnostic purposes from pancreatic masses, lymph nodes, mediastinal and subepithelial lesions, and other lesions within the region of the upper and lower GI tract. The diagnosis, staging, and treatment of GI cancers have evolved into a multidisciplinary approach often using EUS as a central tool for both diagnosis and staging. EUS is the most sensitive imaging modality for the detection of pancreatic masses and is particularly useful when results of other cross-sectional imaging modalities are inconclusive. In addition, the accuracy of EUS FNA has been evaluated in several studies in patients with pancreatic cancer and other GI malignancies. Recently, the role of EUS has expanded from a diagnostic modality to one that is capable of guiding therapeutic interventions (interventional EUS). Numerous advances have been made in the field of interventional EUS, and some of these applications include drainage of pancreatic fluid collections, biliary and pancreatic access and drainage, angiotherapy for varices, treatment of premalignant and malignant conditions including pancreatic cystic lesions, fiducial marker placement, and celiac plexus neurolysis and block, and anastomosis creation.

The clinical effectiveness of EUS and EUS TA depends on the judicious use of these techniques and competency of the performing endosonographer. The increasing sophistication of this technique, higher-risk profiles for some of the EUS-guided interventions, and the need for additional interventions or repeat procedures following a failed or nondiagnostic EUS underscore the importance of adequate training. As the applications for EUS have become increasingly recognized, the demand for well-trained endosonographers has increased and the limited availability of EUS is largely due to a lack of skilled endosonographers. It is clear that EUS is operator dependent and that additional training is required for the development of technical, cognitive, and integrative skills beyond those required for standard endoscopic procedures. Several guidelines have been published for EUS training, based primarily on expert opinion and limited published data. This chapter highlights the current status of training in EUS and the methods of EUS training and recommendations for training programs. It will also review the current state of competency assessment during EUS training and discuss the shifting paradigm from procedure volume as a surrogate of competency to validated competency thresholds. The current guidelines in training, credentialing, and privileging will be reviewed, and, finally, the importance of quality metrics in EUS during training will be highlighted.

Training in Endoscopic Ultrasound

Training in endoscopy entails both cognitive and technical elements that are required to safely and proficiently perform these procedures. Over the past decade, training in EUS has evolved from a self-directed training model to a formal and supervised training model. The consensus opinion on the ideal format for EUS training is through a structured, hands-on experience with patients in a supervised setting. The duration of training can vary; however, self-education, reliance on animal models or computer-based courses, or short training courses as the sole method of training are discouraged. A core curriculum for training in EUS has been established by the American Society for Gastrointestinal Endoscopy (ASGE). Prior to embarking on learning EUS, trainees are required to master standard upper endoscopy and colonoscopy. Trainees are expected to have completed at least 18 months of standard GI training and should have expertise in basic endoscopy, including thorough visualization of the GI tract, minimizing patient discomfort, proper identification of normal and abnormal findings, and proficiency in basic therapeutic techniques. Although some trainees may be exposed to EUS during their standard GI training, procedural exposure should not be equated with procedural competence.

EUS training should focus on the cognitive and technical aspects of the procedure. Understanding procedural indications, contraindications, risks and limitations, in addition to learning how to interpret EUS findings (normal and abnormal) and incorporating them into management algorithms, is an integral part of this process. Cognitive education is also achieved through reading, reviewing videos and atlases, and attending lectures and conferences, combined with supervised hands-on experience under the mentorship of expert endoscopists. The training process usually begins by observing a primary endoscopist perform EUS and becoming acquainted with the unique endoscopic and EUS view of the echoendoscope. The trainee should have the understanding of how relevant equipment works, including the processors, and ultimately gain proficiency in the use of radial array and curvilinear array echoendoscopes. As with general endoscopy, one of the initial challenges is intubating the esophagus. Trainees are expected to safety intubate and traverse the esophagus, the gastroesophageal junction, intubate, and traverse the duodenal sweep. Trainees should be proficient in evaluating structures visualized at various stations during EUS ( Table 3.1 ). Trainees should be adept at TNM staging (tumor, node, and metastasis). Proficiency in EUS TA using EUS FNA and EUS FNB needles is expected at the end of training. Trainees are also expected to understand the advantages and limitations of different EUS TA techniques. Understanding the basics of specimen handling and the role of on-site cytopathology evaluation is critical. Trainees should maintain a procedure log of only those procedures during which they had hands-on training. This log should include the indication and the end points achieved by the trainee. This will not only be helpful for credentialing purposes but also allows for competency assessment. The key end points of training in EUS are highlighted in Table 3.1 .

In addition, EUS training should take place at a center fitted with all the basic equipment necessary to perform EUS and where an adequate number of experienced trainers are present who have a track record of adequate case volume and effective endoscopic teaching. An ideal environment also provides interaction with a multidisciplinary team that includes surgeons, oncologists, radiation oncologists, cytopathologists, and radiologists. Training programs should educate trainees on preparing a comprehensive written report of important normal and abnormal findings, and communication of findings and results to referring physicians, patients, and family members. The trained endosonographer should be able to deliver bad news in a clear and comprehensive manner. A recent survey study showed that the comfort level for disclosing a pancreatic cancer diagnosis after EUS was higher among experienced (>5 years in practice) and high-volume endosonographers. Although the vast majority of endosonographers felt obligated to share the diagnosis of cancer, the lack of proper training and time were limiting factors. This highlights the need for formal communication skills training during GI fellowship training. Unfortunately, the majority of EUS programs across the United States have limited, if any, extramural funding and may require additional clinical responsibilities to help support the trainee’s salary. While understanding the financial limitations of most institutions, training programs should strive to limit the clinical responsibilities unrelated to EUS when developing their core curriculum. Ideally, programs should provide protected research time and encourage academic pursuits such as designing research protocols, preparing manuscripts, writing grant proposals, and attending EUS courses. Creating an environment emphasizing endoscopic research and clinical investigation should be a fundamental goal for each training program. Exposure to endoscopy unit management including scheduling, staffing, equipment maintenance, and management skills is also a valuable asset to any training program. Many trainees in EUS may pursue future academic positions, and these are invaluable skills to acquire early in an academic career. Although a common goal for most training programs is the development of future academic endosonographers, some trainees may express different career interests that conflict with the goals of the training program. Understanding and recognizing the program’s expectations and trainee’s career interests is crucial to an enjoyable and successful training experience.

Current Status of Endoscopic Ultrasound Training

In the United States, training in EUS has shifted to dedicated advanced endoscopy fellowships, occurring in a fourth year of training after a standard GI fellowship. The number of advanced endoscopy fellowship programs (typically a 1-year training program of combined training in EUS and ERCP) has increased dramatically. A total of 62 programs offering EUS training were listed in the 2016–17 Advanced Endoscopy Fellowship match program through the ASGE ( http://www.asgematch.com ), some of which train more than one trainee per year. These programs are typically offered to physicians who have completed formal GI fellowship training. The number of programs listed may be an underestimate because there are programs and applicants that do not participate in the match. It should be noted that these programs are not recognized by the Accreditation Council for Graduate Medical Education (ACGME). Due to the lack of a fixed mandatory curriculum, there are limited data on the composition and outcomes of EUS training among advanced endoscopy trainees completing these programs. Results from a recent prospective multicenter study evaluating competence among advanced endoscopy trainees showed that the median number of EUS exams performed per trainee was 300 (range: 155 to 650). In terms of indications, suspected pancreatic mass accounted for 24.5% of the graded procedures, and pancreatic cyst (17.8%), subepithelial lesion (7%), and luminal malignancy (6.9%) represented the other major indications. The majority of the graded EUS exams were performed using the linear echoendoscope (67.5%) and in the ambulatory setting (82.6%). At the end of training, nearly all trainees felt comfortable with independently performing EUS, EUS FNA, EUS-guided celiac plexus block and neurolysis, and EUS-guided pseudocyst drainage. However, 50% of trainees were not comfortable placing fiducials and performing interventional EUS procedures such as biliary and pancreatic drainage. Nearly half of the trainees planned to practice at an academic center and expected a majority of their practice to be in advanced endoscopy.

Guidelines for Competency Assessment

Advanced endoscopy has traditionally been taught by apprenticeship wherein a trainee is expected to develop skill and expertise with hands-on experience. Competence in EUS has been historically assessed by the trainers’ subjective assessment of overall competence and/or meeting an arbitrary volume for procedures completed. Several guidelines for assessment of competency in EUS have been published by GI societies ( Table 3.2 ). These guidelines are primarily based on expert opinion and consensus and continue to use an absolute procedure volume to determine competence in EUS, with thresholds varying between guidelines. There are limited data regarding competency assessment for the performance of therapeutic maneuvers such as celiac plexus neurolysis/block, placement of fiducials, cyst drainage, and biliary or pancreatic access. These current guidelines lack validation with regard to competence and feasibility of training. In addition, they do not account for the fact that trainees differ considerably in the rates at which they learn and develop endoscopic skills. Available data and expert opinion suggest that the majority of trainees are not competent at the previously defined thresholds and require double the number of proposed procedures to achieve competence in EUS. Thus the number of procedures completed during training alone does not ensure competence and is a suboptimal marker for competence in EUS.

Learning Curves and Competence in Endoscopic Ultrasound

Competency is defined as the minimum level of skill, knowledge, and/or expertise acquired through training and experience, required to safely and proficiently perform a task or procedure. There have been few published reports regarding learning curves in EUS. Recognizing this goal and understanding the limitations of a 3-year curriculum has been the major impetus for establishing fourth-year fellowships in EUS.

Recent studies have focused on comprehensive evaluation of EUS competence during advanced endoscopy training. A pilot study conducted at three tertiary care referral centers prospectively defined learning curves in EUS among five advanced endoscopy trainees. In this study, trainees were graded at intervals of 10 EUS exams using a standardized evaluation tool (discussed later) and cumulative sum analysis (CUSUM). Two trainees crossed the threshold for competence at case numbers 255 and 295, and the others demonstrated the need for ongoing supervision. This study highlighted the substantial variability in achieving competence and a consistent need for more supervision in all trainees. This study was followed by a larger multicenter validation study which included 17 advanced endoscopy trainees at 15 centers. Learning curves using CUSUM confirmed the significant variation, and only two trainees crossed the threshold for competence (at cases 225 and 245) ( Fig. 3.1 ). The authors concluded that a specific number of cases performed during training does not ensure competence in EUS and that 225 cases should be considered as the minimum caseload for training because no trainee in this study achieved competence prior to this point.

Overall graphical representation of the learning curves among all trainees by using cumulative sum analysis (CUSUM). Crossing the lower limit threshold indicated the performance was within preset acceptable failure rate and competency was achieved.

Reproduced with permission from Wani S, Hall M, Keswani RN, et al. Variation in aptitude of trainees in endoscopic ultrasonography, based on cumulative sum analysis. Clin Gastroenterol Hepatol . 2015;13:1318–1325.e2.

One retrospective study showed that endosonographers with a formal supervised training experience in pancreaticobiliary EUS achieved a significantly higher sensitivity when using EUS FNA for the diagnosis of pancreatic malignancy as compared with those without formal FNA training. A crucial component to any EUS training program is focused on GI tumor staging. Studies in endosonographic staging of esophageal cancer suggested that at least 75 to 100 procedures were required before an acceptable level of accuracy was achieved. Ideally, the accuracy of EUS staging should be compared with a “gold standard,” such as surgical histopathology; however, surgical specimens are not always readily available and patients may have received preoperative radiation and chemotherapy that may affect staging. In these circumstances, staging by a trainee is compared with that of a skilled and competent endosonographer.

There are limited data on learning curves in EUS TA, and it is unclear when EUS FNA should be initiated during the training process (after the completion of a prerequisite number of EUS exams or at the initiation of training). A single center study suggested that when initiated at the onset of EUS training, attending-supervised, trainee-directed EUS FNA is safe and has comparable performance characteristics to trainer EUS FNA. The learning curves for EUS FNA for solid pancreatic lesions have been described with increasing sensitivity for the cytopathologic diagnosis of cancer with a decreasing number of passes needed to obtain adequate results.

Similarly, there are limited data on learning curves and criteria for competence in interventional EUS. These procedures are technically more challenging compared with diagnostic EUS (with or without EUS TA) and routine ERCP procedures. Endoscopists who desire proficiency in interventional EUS need to be highly skilled in EUS TA and ERCP techniques. Trainees need to understand that they may not gain proficiency in many interventional EUS procedures during their advanced endoscopy fellowship and will ultimately acquire these skills and competence in clinical practice under the guidance of a senior partner/mentor. Experts suggest the following prerequisites for interventional EUS: high volume of EUS and ERCP cases (>200 to 300 EUS and ERCPs/year), high success rate for standard ERCP, and practice at a center with pancreaticobiliary surgery and interventional radiology backup. Other experts recommend completion of at least greater than 10 EUS-guided pseudocyst drainage procedures before attempting EUS-guided pancreaticobiliary drainage and beginning with easier EUS-guided biliary techniques (EUS-guided rendezvous).