Endoscopic ultrasonography (EUS) has become an important diagnostic and - recently
- also therapeutic tool in gastrointestinal endoscopy, mostly complementary to other
primary investigations. Its application in oncology as well as in a variety of benign
conditions, the mixture of endoscopy and ultrasound as an imaging technique as well
as the complexity of instrument handling to generate adequate visualization have all
raised the necessity to define competence and hence design respective training programmes.
The following review shall give an overview on current programmes and the limited
evidence of how to define competence and how to organize training. It has to be added
that in most other areas of endoscopy with the recent possible exception of colonoscopy,
data are scant as well.
Any training and its practical aspects have to be founded on the basis of sound theoretical
and clinical knowledge not only of the technique under consideration including its
potential complications, but also of the indications of EUS and the incorporation
into clinical management of EUS and EUS-FNA as well as associated methods. No training
programme whatsoever should only consist of teaching of practical application and
technical aspects. Since this is a rather self-evident aspect, this is not dealt with
further in the following, also with respect to the fact, that no standardization on
the precise content of theoretical teaching exists, but at least clinical evidence
can be collected from reviews, metaanalyses and textbooks.
EUS training programmes and recommendations
Formal EUS training programmes exist in only few countries. In Europe, France has
by far the most advanced training curriculum, although this is still not officially
accepted for credentialing. Nevertheless, a two years intensive programme has been
described, involving theoretical introduction, 4 weeks of theoretical training and
20 one-day practical sessions per year [1]. Up to now, with the programme running since 1991, 20 - 25 doctors each year have
undergone this curriculum, but data on outcome have not been published at least in
the English speaking medical literature. In Germany, suggestions were made by a regional
working group and included as prerequisites 1000 forward viewing and 200 side viewing
endoscopies and 1000 abdominal ultrasound examinations, followed by specific requirements
for EUS training, namely 200 examinations, of those 150 done by the trainees, backed
up by courses and other teaching materials [2].
In the US, the ASGE has provided guidelines for credentialing and granting hospital
privileges to perform routine gastrointestinal endoscopy [3] as well as advanced endoscopic procedures, which also includes EUS [4]. It was agreed that EUS should be dealt with separately from other endoscopic procedures.
Attempts to create objective criteria by giving minimum numbers does not obviate the
need for ultimately assessing competency the by training director or other independent
tutor. The debate whether privileging in one or more of the various areas of EUS makes
sense, may be considered separately, but adequate training has to be undergone in
the areas for which privileging is requested. Nevertheless, a general consensus by
EUS experts concluded that luminal (GI) EUS requires at least 3-6 months of intensive
training to establish competency, whereas pancreaticobiliary EUS and FNA may need
training for up to 1 year [5]
[6]. From the Asian-Pacific area, not many structured training programmes have come
to the international attention.
Evidence for EUS competence from the literature
Logically, pre-EUS knowledge inlcudes sufficient expertise and safe handling of endoscope
introduction (both forward and side-viewing) into the duodenum as well as knowledge
in transabdominal ultrasound. The latter statement - beyond basic knowledge of principles
of ultrasound and tissue visualization as well as artefacts - is not based on evidence.
Non-systematic experience from countries in which ultrasound is integral part of gastroenterology
training and from those in which ultrasound is firmly in the hands of radiologists
shows that EUS examiners do not seem to perform differently at large. However, it
is not analysed and reported in detail, which ultrasound training the trainees in
non-ultrasound countries actually receive. US examiners have at least in the initial
phase, used the advice and expertise of GI radiologists, which might have helped in
image interpretation but surely not in instrument positioning to achieve these. As
far as the author is aware, this is mostly not the case anymore in EUS training, and
might only have helped the initial trainers to develop their knowledge.
Further to these basic facts, the next question is, how can competence be measured?
By assessment of a trainee by an ”experienced” examiner or by benchmarking of EUS
accuracy in relation to acknowledged standards, e. g. surgical staging results? If
the latter is the standard to be adhered to, we have to define accuracy limits which
should be reached. These however, are hampered by a variety of facts and assumptions:
-
Published data on accuracy mostly come from expert centers where enthusiastic researchers
have usually reached results well over 80 % for staging accuracy. This however has
been somewhat flawed by recent data on poor results in rectal and gastric cancer staging
looking at average EUS application by variety of EUS examiners also including those
with low numbers [7]
[8]. However, also data from speciality centers on rectal and pancreatic cancer staging
[9]
[10] have shed some doubts on high accuracy levels as reproducible gold standard.
-
Detailed definition of features defining EUS diagnoses are especially relevant for
staging but have only rarely been systematically examined. Criteria were mostly defined
in prospective studies measuring tumor staging accuracy, but at later stages never
been systematically looked at : Does a slightly irregular outer tumor border already
define stage T3, is this different in esophagus and stomach with their different T
stage definitions, and what is irregular. There are studies on interobserver variability
of EUS staging [11]
[12]
[13], but they have not systematically focused on image criteria aspects. Only one study
on parameters of defining vascular involvement, although retrospective, has shown
disappointing results [10]. The lack of precise data in this field is a major obstacle in defining training
goals and quality assurance measures.
-
Especially for tumor staging, but also for other indications, histological control
is difficult to obtain since patients are either not (submucosal tumors) or not primarily
(neoadjuvant therapy) operated on in the vast majority of cases. So, simple benchmarking
by obtaining accuracy data comparing EUS and histopathological results after surgery,
are difficult or in some centers almost impossible.
-
Homogeneous accuracy data exist in other areas, especially in diagnosis of common
bile duct stones [14]
[15]
[16]
[17]; here however, accuracy concerning negative findings can only be tested by careful
follow-up [16]
[17], whereas positive EUS findings are usually easily controlled by ERCP with sphincterotomy.
-
Benchmarking of endoscopic results may raise a variety of other problems such as quality
of data acquisition and external control mechanisms since these data inevitably will
also be (ab)used for individual marketing of physicians or units.
For these and other reasons, its seems unrealistic, that each new EUS candidate delivers
his/her accuracy rates based on data including follow-up of his/her patients for credentialing.
Similarly, it will mean a great effort for established endosonographers to provide
these data for recredentialing. Some surrogate parameter or as mentioned assessment
by trainers might help but these have still to be defined.
At least, a few data exist on learning curves. Some studies have measured the accuracy
in relation to EUS examination numbers in the GI tract. For visualization of normal
structures, controlled by an experienced examiner, a prospective study has demonstrated
that competent intubation of the esophagus, stomach, and duodenum was achieved in
a median of 1 - 2 procedures (range 1 to 23), whereas visualization of the gastric
or esophageal wall was achieved after a mean of 10 - 15 EUS examinations (range 1
to 47). Adequate evaluation of the celiac axis region required some 10 - 15 EUS procedures
(range 8 - 36) [18].
As early as 1996, Paul Fockens has reported on his learning curve of EUS staging of
esophageal cancer between 1991 and 1993. After the first 36 cases, T staging accuracy
was 58 %, rising to 83 % in the subsequent 35 cases. The authors conclusion that 100
cases would be necessary, is based on these 71 cases but we do not know whether a
further 30 cases would have further increased the T staging accuracy [19]. Another paper published in 1999 compared different years of EUS staging done by
one examiner which were 64.5 for 1989, 90 % and 86 % for 1997 and 1998 from a total
of 112 traversable tumors staged between 1989 and 1998. An accuracy of 68 % after
49 cases rose to 90 % after 74, but it is not clear why these cut-offs were selected
[20]. At least the study suggests, that once a stable accuracy level (here between 85
and 90 %) is achieved, it will probably not be increased further. Both studies let
us conclude that for esophageal cancer staging, often thought to be one of the easiest
EUS applications, staging accuracy well above 80 % is only reached after some 70 -
75 cases. Given the limited number of such cases outside speciality centers for esophageal
cancer, competence will obviously take quite some time to be achieved. In a pretty
small study on rectal cancer staging, 58 percent of the initial 12 studies were staged
correctly compared with 87.5 percent accuracy in the remaining 24 examinations [21].
What does expert opinion suggest? A survey of the American Endosonography Club in
1995 suggested an average of 43, 44 and 37 EUS examinations for esophageal, gastric
and rectal imaging [22]. The ASGE currently recommends a minimum of 75 supervised cases, at least two-thirds
in the upper gastrointestinal tract, before competency for evaluating mucosal tumors
can be assessed [4]; similar recommendations were given, based on expert opinion, also by the ESGE [23].
The situation in the pancreatobiliary area has always been regarded the most difficult
one. A multicenter, 3-year prospective study reported that adequate imaging of the
pancreatic and bile ducts required less cases to be done than of the pancreatic parenchyma
(median 34 vs. 55, ranges 15 - 74 vs. 13 to 135 cases) [18]. No studies exist on the learning curve in diagnosing pancreatobiliary disease.
A survey from the American Endosonography Club suggests that interpretative competence
of pancreatic images may require additional procedures, namely a total of 120 cases
[22]. Other expert opinion suggests a higher threshold of 150 cases before assessing
interpretative competence [24]. Currently, the ASGE Standards of Practice Committee recommend a minimum of 75 pancreatobiliary
EUS examinations before competence can be assessed [4].
Finally, a prospective study assessing 4 physicians as well as one nurse evaluated
visualization of GI and pancreatobiliary area and found competence as assessed by
an experienced evaluator after approximately 25 esophageal, 35 gastric but 78 duodenal
(including pancreatobiliary) examinations. The nurse, by the way, was tested only
for esophageal/ mediastinal scanning and performed equally well [25].
There are only limited data on EUS-guided fine needle aspiration (FNA) - and those
only for pancreatic puncture - which has evolved as a crucial addendum to the imaging
capability of EUS, almost similarly to the relevance of biopsy for luminal endoscopy.
In a very small collective of 20 patients who underwent EUS-FNA by three examiners,
the initial learning (n = 9) and the later period (n = 11) was assessed and the accuracy
increased from 33 % to 91 % [26], but such a small study is probably of limited value. Another study examined the
first 57 pancreatic tumor FNA cases of one endosonographer, and again the accuracy
rose from 40 - 50 % (1 - 20) to the remaining ones (70 - 90 %) [27]. On the other side of the spectrum, for an obviously very talented endosonographer,
the diagnostic accuracy after training on 45 cases in his 3rd year fellowship did not increase overe his subsequent 300 cases, analysed by 100
cases each (92 - 95 %). Only the number of passes (from 4 to 3) and the complication
rate (from 13 - 18 % to 7 %) decreased [28].
For all other lesions lesions than in the pancreas (mediastinum, paragastric, e. g.
lymph nodes, ascites, submucosal tumors), data are missing, however, it is assumed
that pancreatic FNA may have the highest complexity and complication risk. It was
therefore recommended that a trainee be competent in non-pancreatic EUS after at least
25 supervised FNA cases. The same publication, written before the abovementioned studies,
suggested that for pancreatic FNA competence in diagnostic pancreaticobiliary EUS
(at least 75 cases) has to be acquitted, and 25 supervised FNA procedures of pancreatic
lesions have to be done [4].
From these few reports and studies we may conclude that case numbers given by experts
or committees are usually lower than those shown in actual clinical testing. Nevertheless,
practical aspects have to be taken into account, and it can be debated whether standards
should be much higher than those set for other areas of GI endoscopy. An individualized
approach in assessing competence may be superior, but has not been agreed upon as
yet.
Training tools
The usual spectrum of self-teaching by textbooks and videos or CD-ROMs is recommended
in almost all review articles and consensus statements as a basis for EUS training.
The mention of course participation is another important step considered very helpful.
A three-day educational course on EUS was assessed before and after in terms of knowledge
of EUS indications in 4 anatomic sites and with 2 participants, and the knowledge
increased by 4 - 20 %, mostly in esophagus and rectum [29]. There are courses of several levels, ranging from mere theory, to video demonstrations,
live demos or participation (observation) in patient procedures to hands-on training
in simulators and animals, and combination of some or all of the above aspects.
Training in simulators or models of various composition has been introduced quite
a few years ago with great success in various areas of GI endoscopy such as hemostasis,
polypectomy or other techniques including even therapeutic ERCP [30]
[31]
[32]. Several studies have shown its value in increasing skill [33]
[34] which can also be objectively measured [35], and, most importantly, that the learning phase in patients can be shortened. A
recent randomized study using a sigmoidoscopy simulator showed a better performance
in patients of the trainees undergoing simulation first when compared to a control
group in a recent randomized trial [36].
For EUS, a variety of simulators has been described: The Simbionix Corporation (http://www.simbionix.com)
which has several upper and lower GI as well as ERCP simulators has recently developed
the first and only EUS module providing practice of EUS procedures. The adaption of
VOXEL man for teaching EUS anatomy has been described by a German group [37]. Biomodels (EASIE, Erlangen trainer) have been modified to fit for EUS (no publications).
Simpler models for training of EUS-FNA [38]
[39] or cyst drainage [40] have been presented which are all useful to teach and train certain aspects of EUS
imaging or FNA. Finally, training in live pigs is perhaps the most realistic, but
also the most elaborate model [41]
[42]. Although not shown in randomized trials, the value of these models is likely to
improve training and shorten the learning curve patients. Most probably, the value
of the different models is rather complementary than competitive. The ideal training
center for EUS will have most if not all of them available after appropriate testing.
Suggestion for further actions
Not surprisingly, teaching in EUS is mostly self-teaching up to recently. Of the attendees
of the 12th International Symposium on EUS in October 2002 in New York, who were asked
to complete a survey questionnaire on clinical practice of EUS, 191 participated (48.9
%), 110 from the United States, 81 from 30 different other countries. 53 % of 102
endosonographers were in academic practice, a natural selection in such meetings,
and 80 % also performed ERCP. Almost half of the respondents had 1 - 5 years of experience.
Only 19 % had more than 6 months of dedicated hands-on EUS training, and more than
a third of the respondents learned EUS by observation or self teaching [43]. On the other hand, a survey among 76 EUS performers found that 93 % and 89 % felt
that they had received adequate instruction for diagnostic EUS and EUS-FNA; 81 % were
trained during advanced (67 %) or normal GI fellowship (14 %) [44].
What we may need to better approach the problem of EUS competency and training has
to be developed in consensus and may include the following
-
Definition of EUS features of various disorders, ranging from precise parameters for
tumor staging to the diagnosis of benign disorders for teaching and setting standards
of training
-
Discussion about quality programmes in EUS in relation to possible benchmark data
concerning indications, accuracy and complications; they should be easy, practicable
and reproducible
-
Definition of a training curriculum including theory, hands-on training (such curricula
have been defined for model training of GI endoscopy in Germany (www.dgvs.de) and
the US (45) and finally in patients
-
Tackling the difficult problem of how to assess competency, initially (credentialing)
and possibly also later (recredentialing)
Only if we can better standardize the performance and features of EUS as well as the
definition of competency and training we will help to improve EUS quality and finally
its incorporation into better patient care.
