Evaluation of a new virtual-reality training simulator
for hysteroscopy
Michael Bajka Æ Stefan Tuchschmid Æ Matthias Streich Æ Daniel Fink Æ
Ga´bor Sze´kely Æ Matthias Harders
Received: 6 December 2007 / Accepted: 18 February 2008 / Published online: 24 April 2008

Springer Science+Business Media, LLC 2008
Abstract
Background To determine realism and training capacity
of HystSim, a new virtual-reality simulator for the training
of hysteroscopic interventions.
Methods Sixty-two gynaecological surgeons with various
levels of expertise were interviewed at the 13th Practical
Course in Gynaecologic Endoscopy in Davos, Switzerland.
All participants received a 20-min hands-on training on the
simulator and filled out a four-page questionnaire. Twenty-
three questions with respect to the realism of the simulation
and the training capacity were answered on a seven-point
Likert scale along with 11 agree–disagree statements con-
cerning the HystSim training in general.
Results Twenty-six participants had performed more than
50 hysteroscopies (‘‘experts’’) and 36 equal to or fewer
than 50 (‘‘novices’’). Four of 60 (6.6%) responding par-
ticipants judged the overall impression as ‘‘7 – absolutely
realistic’’, 40 (66.6%) as ‘‘6 – realistic’’, and 16 (26.6%) as
‘‘5 – somewhat realistic’’. Novices (6.48; 95% confidence
interval [CI] 6.28–6.7) rated the overall training capacity
significantly higher than experts (6.08; 95% CI 5.85–6.3),
however, high-grade acceptance was found in both groups.
In response to the statements, 95.2% believe that HystSim
allows procedural training of diagnostic and therapeutic
hysteroscopy, and 85.5% suggest that HystSim training
should be offered to all novices before performing surgery
on real patients.
Conclusion Face validity has been established for a new
hysteroscopic surgery simulator. Potential trainees and
trainers assess it to be a realistic and useful tool for the
training of hysteroscopy. Further systematic validation
studies are needed to clarify how this system can be opti-
mally integrated into the gynaecological curriculum.
Keywords Virtual reality
Training
Simulation

Hysteroscopy
Evaluation
Virtual reality (VR)-based surgical training systems [1]
have been reported to perform at least equally well as
traditional training and assessment methods such as direct
observation, animal models, videotapes, and procedure
logs in terms of reliability and validity [2]. During the last
10 years, a number of commercially available VR-based
surgical simulators for laparoscopy have been developed
and evaluated [3]. The European Association of Endo-
scopic Surgeons (EAES) actively promotes the acceptance
of VR simulators by accrediting training courses [4] and
providing guidelines for the validation of VR-based train-
ing systems [5]. In the USA, organizations such as the
Society for Simulation in Healthcare (SSIH) or Advanced
Initiatives in Medical Simulation (AIMS) help to push
public awareness of surgical simulation.
In contrast to laparoscopy, the teaching of hysteroscopic
interventions has received only little attention, with work
focusing mainly on the development of physical models
and box simulators [6]. Nevertheless, a team from the
University of Washington has put its focus on teaching in
obstetrics and gynaecology by proposing a new curriculum
for hysteroscopy [7, 8]. Therein, each resident is given the
opportunity to practise the resection of a large polyp on an
inanimate model. Work on PC-based surgical simulation
M. Bajka (&)
M. Streich
D. Fink
Clinic of Gynaecology, Dept. OB/GYN, University Hospital
Zurich, 8091 Zurich, Switzerland
e-mail: michael.bajka@hin.ch
S. Tuchschmid
G. Sze´kely
M. Harders
Computer Vision Laboratory, ETH Zurich, Zurich, Switzerland
123
Surg Endosc (2009) 23:2026–2033
DOI 10.1007/s00464-008-9927-7

for hysteroscopy was initiated in 1998 by the NASA/
Stanford National Biocomputation Center and the Stanford
University Medical Media and Information Technologies
(SUMMIT) group, resulting in the only hysteroscopy sys-
tem commercially available to date: the AccuTouch system
(Immersion Medical, Gaithersburg, Maryland, USA).
The HystSim (Hysteroscopic Surgery Simulator System,
http://www.hystsim.ethz.ch) project was initiated in 2001 by
the National Center of Competence in Research Co-Me
(Computer Aided and Image Guided Medical Interventions,
http://www.co-me.ch) of the Swiss National Science Foun-
dation in order to build the most realistic simulator possible for
hysteroscopic interventions by today’s VR technology. For
the successful integration of the developed simulation system
into the training curriculum, its validity has to be proven
through rigorous evaluation. Even if a widely accepted eval-
uation cascade has not been established yet, usually face
validity, defined as ‘‘the extent to which the examination
resembles real life situations’’ [2], provides the first and fun-
damental step in simulator validation [9–12]. Thereon,
construct validity, defined as ‘‘a set of procedures for evalu-
ating a testing instrument based on the degree to which the test
items identify the quality, ability and trait it was designed to
measure’’ [13], has to be investigated. Typically, it is estab-
lished by comparing the performance on the virtual-reality
simulator for groups of surgeons with different degrees of
experience. The last and most significant step of the validation
cascade is predictive validity, defined as ‘‘the extent to which
the scores on a test are predictive of actual performance’’ [13].
However, predictive validity has only been established for a
small number of surgical simulators [14–16], mainly because
of the high expense and complexity of the involved virtual
reality to operation room (VR to OR) study.
As a first step towards the establishment of the role of
the device in the gynaecological curriculum the question of
to what extent the simulation is realistic and whether
novice and expert surgeons consider it useful for training
has to be answered. Thus, this study evaluates the face
validity of the HystSim system. Obviously, both expert and
novice clinicians must accept the simulation as a realistic
and useful training aid. Expert clinicians are often teaching
hysteroscopic interventions and rely on a realistic simula-
tion in order to expose the novice surgeon to a wide range
of situations, while novices need to be willing to work with
the system. It is therefore important to know the overall
acceptance as well as finding out whether novice and
expert surgeons perceive the simulation differently.
Material and methods
In this study we investigate the acceptance of the HystSim
training simulator based on the responses of potential
trainers and trainees. The concept of comparing expert and
novice face validity as a first step in simulator validation
has been implemented by various other validation studies
in endoscopy [10, 17] and laparoscopic surgery simulation
[11, 12]. Questionnaires were used to judge realism and
training capacity on five-, seven- or ten-point Likert scale
with the aid of agree–disagree statements. For an optimal
tradeoff between differentiation and observability, we
decided to use a seven-point Likert scale as proposed in
[17]. Formal exemption of the institutional review board
had been obtained so approval for the study was not
required.
Subjects
Sixty-two gynaecological surgeons with various levels of
expertise and no prior exposure to the HystSim system
were interviewed at the 13th Annual Practical Course in
Gynaecologic Endoscopy in Davos, Switzerland, March 1–
4, 2007, organized by Gyne´cologie Suisse (Swiss Society
of Obstetrics and Gynaecology). In accordance with the
logbook of the Swiss Medical Society FMH (Foederatio
Medicorum Helveticorum) to complete specialization in
OB/GYN, participants having performed more than 50
hysteroscopies were defined as ‘‘experts’’, while those
having performed equal to or fewer than 50 interventions
were defined as ‘‘novices’’. All participants received a 20-
min hands-on training on the simulator including two dif-
ferent diagnostic interventions, rollerball ablation, and
myomectomy. Before answering the questionnaire, an
informed consent form was signed, stating that the data
gained from the questionnaire may be used for scientific
and/or teaching purposes.
Questionnaire
The questionnaire consisted of a four-page survey divided
into the categories personal settings, realism, training, and
statements. For the demographic questions, the basic items
concerning age, gender, dexterity, and prior experience
were extended with questions on prior experience with
surgical simulators in general and previously attended skills
training courses or other educational programs. Fourteen
questions with respect to the realism of the simulation were
answered on a seven-point Likert scale: ‘‘1 – absolutely not
realistic’’, ‘‘2 – not realistic’’, ‘‘3 – somewhat not realistic’’,
‘‘4 – undecided’’, ‘‘5 – somewhat realistic’’, ‘‘6 – realistic’’,
and ‘‘7 – absolutely realistic’’. Nine questions concerning
the training usefulness of the simulation were rated on a
seven-point Likert scale ranging from ‘‘1 – strongly dis-
agree’’ to ‘‘7 – strongly agree’’ with similar intermediate
steps. In addition, participants answered 11 agree–disagree
statements concerning training with the simulator.
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