Fig. 25.1
Foley catheter task trainer. This penile task trainer aids in simulating proper urethral catheter insertion
Medical students perceive genital and rectal examinations as threatening [9]. Standardized patients have been used to teach rectal examinations for decades, although the use of mannequins has been proposed [10, 11]. Randomized controlled trials have demonstrated that medical students who trained using mannequin-based simulation had better bedside confidence and rapport for female pelvic exams as well as some benefit in male digital rectal exams [10, 11]. Siebeck et al. [11] evaluated the effect of low-fidelity simulation (mannequins) versus high-fidelity simulation (standardized patients) on student inhibition and acquisition of knowledge for male digital rectal examination. Both types of simulation were found to facilitate the acquisition of knowledge, but the standardized patients reduced inhibition more than low-fidelity simulation. The study focused on the social skills required to perform rectal examination. The authors did note that the low-fidelity simulator may aid in acquiring skills to detect pathology on rectal examination.
One problem with learning the digital rectal examination (DRE) is that the procedure being performed is hidden from instructor view. Low-Beer et al. [12] attempted to overcome this problem by cutting away the proximal portion of rectum from a standard benchtop male DRE simulator. They then recorded the learners’ technique. This allowed the authors to deconstruct the procedure into 49 procedural steps and aided in teaching the steps that may be omitted during standard teaching of digital rectal examination. In general, there is a small but useful place for these sorts of simulations in medical education.
Transurethral Resection of Prostate (TURP) and Bladder Tumor (TURBT) Simulation
Transurethral resection techniques are commonly used in urology. With these techniques, one is able to resect prostate (TURP) or bladder tumor (TURBT) tissue, using a transurethral approach and an electrocoagulatory knife.
TURP
The goal of performing a TURP is to resect benign prostatic hyperplastic tissue, aiming to reduce the bulk of the prostatic tissue causing the bladder outlet obstruction and lower urinary tract symptoms. Several new, minimally invasive prostate resection techniques have been developed in the past years, including holmium laser enucleation of the prostate, photoselective vaporization, transurethral needle ablation, and transurethral microwave therapy. Although these new techniques have demonstrated safety and short-term efficacy, data on long-term efficacy are currently lacking, and the conventional transurethral resection of the prostate remains the gold standard [13]. Common complications are: bleeding, undermining the bladder neck, inadvertent peritoneal puncture during suprapubic catheter insertion, and capsular perforation with entry into the periprostatic venous plexus causing TURP syndrome [14].
A number of TURP simulators have been described in the literature [15–17]. Some of these were early prototypes of current simulators or were simulators which, to our knowledge, were not further developed and are not available on today’s market [18–20]. In Table 25.1, a list of simulators is shown. The AMS/CREST simulator does not actually replicate TURP, but contains a photoselective vaporization of the prostate (PVP) module, where endoscopic instrument tracking, haptic rendering, and a web/database curriculum management modules are integrated into the system [21]. The development is based on the same prototype as the University of Washington TURP trainer. The Uro Trainer includes a TURBT module as well.
Table 25.1
Simulators for transurethral resection of prostate (TURP) and investigated validity
Simulator | Alias | Face validity | Content validity | Construct validity | Criterion validity |
|---|---|---|---|---|---|
METI/CAE SurgicalSIM | University of Washington TURP trainer | Y | Y | Y | Y |
VirtaMed | TURPSim Simbionix trainer | N | N | N | N |
CREST | AMS/PVP | Y | N | N | N |
Uro Trainer | Storz trainer | Y | Y | N | N |
PelvicVision | Melerit Medical trainer | Y | Y | Y | Y |
TupperTM | Homemade TUR trainer | N | N | N | N |
Dr. Forke’s resection trainer | Samed GmbH | N | N | Y | N |
Validation studies have been performed to investigate the educational value of the available simulators. Most validation studies used the definitions of face, content, construct, and criterion validity similar to those described by McDougall [22]. Table 25.1 summarizes TURP simulators and validity described in literature.
Of the available TURP simulators, the METI/CAE Healthcare SurgicalSIM (alias: the University of Washington TURP trainer) has been most frequently described and most comprehensively investigated [23–29]. The simulator has been developed and improved over several years, and several prototypes of the simulator have been validated in the stages of development. Validation studies have been performed by the developers [23–27, 29] as well as by an external research group [28]. Studies included between 19 and 136 participants. However, this simulator is not available on the commercial market anymore.
The Uro Trainer (Storz, Germany) has been investigated for face and content validity by two study groups, which included 19 and 97 participants, respectively [30, 31]. Both groups concluded that face and content validity of this simulator could not yet be established, and further modification of the Uro Trainer was recommended before initiating further experimental validity studies. The virtual reality VirtaMed simulator has recently been developed and face, content, and construct validation studies are currently underway.
The PelvicVision trainer has been developed and evaluated by one Swedish study group; their face, content, construct, and criterion studies included 9–24 participants [32–35]. Based on these results, the authors conclude that criterion-based training of the TURP procedure on the PelvicVision trainer significantly improves operative performance and raises the level of skill dexterity of inexperienced urology residents compared to no training at all [32].
The TupperTM simulator consists of 7 cm of a 30 ft garden hose, a suprapubic tube, a TupperwareTM box, three catheter plugs, and silicone gel [36]. Costs are below $40 US. Different transurethral procedures, such as mono- and bipolar resection, as well as laser vaporization, can be carried out on the model [36].
Dr K. Forke’s resection trainer (LS 10-2/S) is a mobile device, consisting of a penis simulator, featuring a urethra, a specifically constructed device for the insertion of a different training prostate, a bladder chamber, and simulated suprapubic access, as well as optional intermittent or continuous-flow irrigation [37]. Two different training prostates are offered: one with and one without anatomical structures. In their construct validity study, the resection results of the one non-experienced resident showed a distinct learning curve during supervised training on the model. Also, the trained residents showed a more constant progress rate in the post-training phase compared to the results of three non-trained experienced residents. In the past, the company Limbs & Things produced a TURP and TURBT model for resection skill training. This device however was most commonly used by industry to demonstrate endoscopic equipment, and not for residency training. No validation studies were ever published on the model, which is currently off the market.
TURBT
Bladder tumors are very common tumors of the genitourinary system; therefore, transurethral resection of such tumors is often performed [14]. The goal is to remove the tumors, as well as to determine depth of invasion. Common complications are bleeding and perforation. Although several endourologic training models, such as animal models, virtual reality models, and synthetic models, have been developed for transurethral resection of the prostate and for urethrocystoscopy, only a few models or modules exist for the TURBT procedure. The Uro Trainer described in the TURP section also contains a TURBT module. In the past, the company Limbs & Things has also developed a TURBT module using synthetic materials, which is, however, no longer on the market. Furthermore, three low-cost, low-fidelity models have been described in the literature, but they were not validated (Table 25.2).
Table 25.2
Simulators for transurethral resection of bladder tumor (TURBT) and investigated validity
Simulator | Alias | Face validity | Content validity | Construct validity | Criterion validity |
|---|---|---|---|---|---|
Uro Trainer | Storz trainer | Y | Y | Y | N |
Glass globe | N | N | N | N | |
Pig bladder model | N | N | N | N | |
TupperTM | Homemade TUR trainer | N | N | N | N |
Validity studies have only been performed for the Uro Trainer (Storz, Germany). Study participants varied from 12 to 150 medical students, residents, or urologists. Conclusions of face and content validity investigations of this simulator differed between the two research groups. Reich et al. found an overall positive opinion of urologists towards the simulator with scores of 5.0–8.0 on a scale of 0–10 (0, insufficient/very unrealistic; 10, very good/extremely realistic) [38], whereas Schout et al. concluded that, measured against face and content criteria of other studies, only 3, 5, and 8% of the parameters could be interpreted as positive, moderately acceptable, and good, respectively [31]. Construct validity investigations showed improvement of medical students’ results, but no improvement of residents’ performances on the simulator [38].
The financial costs of the virtual reality simulators are not clearly stated in the literature. In general, virtual reality simulators account for some tens of thousands of US dollars, whereas the box pig bladder model costs $160 US [39], the TupperTM costs below $40 US, and the glass globe costs around $10 US [40].
Ureteroscopy Simulation
Adequate performance of basic endourological skills is of crucial importance in urological practice. Ureterorendoscopy (URS) is a widely used procedure that has diagnostic and therapeutic purposes in ureteric stone management and other abnormalities of the urinary tract [41]. For URS training outside the operating room, several models have been developed in past years ranging from low- to high-fidelity models. Simulators of animate and inanimate materials are available for various prices. Practicing on live animals or animate models has limitations, since it requires strict hygiene and can only be done in specialized laboratories. In general, animate models can be reused less frequently than inanimate ones, leading to increased financial costs. Moreover, ethical considerations increasingly restrict the use of animal models.
In 2008, Schout et al. published a review of the literature concerning existing training models in endourology [39]. More recent updates on training in ureteroscopy are described by Skolarikos and Olweny et al. [42, 43]. The most frequently described models are listed in Table 25.3.
Table 25.3
Most frequently described Ureterorendoscopy (URS) training models
Simulator | Manufacturer | Material | Fidelity | Content validity | Construct validity | Criterion validity | Virtual instructor |
|---|---|---|---|---|---|---|---|
URO Mentor | Simbionix | Computerized | High | Y | Y | Y | Y |
Adult Ureteroscopy Trainer | Ideal Anatomic Modeling | Inanimate | High | Y | Y | N | N |
Uro-Scopic Trainer | Limbs & Things | Inanimate | High | Y | Y | N | N |
Scope Trainer | Mediskills | Inanimate | High | Y | Y | N | N |
Bench model | Liske et al. | Animal | High | Y | N | N | N |
Bench model | Matsumoto et al. | Inanimate | Low | Y | Y | N | N |
Virtual Reality Simulators
In the last decade, computerized models, including virtual reality (VR) simulators, have been further developed and used for training surgical skills. A URS model which has often been described is the URO Mentor (Simbionix, Israel), a computer-based virtual reality (VR) model offering semirigid and flexible URS modules as well as rigid and flexible urethrocystoscopy (UCS) modules. In addition, a percutaneous access simulator can be added to the URO Mentor platform.
A personal computer is linked to a male mannequin with lifelike endoscopes. Computer-based graphics provide realistic images of the male genitourinary system. Various learning modules are included, which contain virtual patients with background, laboratory, and radiographic information. Trainees can choose appropriate instruments and record their performance for later evaluation. Several performance parameters like time, minutes of X-ray exposure, occurrence of perforations, and percentage of laser misfires are measured to evaluate a trainees performance.
The URO Mentor has proven effective as a tool for learning endoscopic skills. Parameters of performance on this VR simulator can distinguish inexperienced urologists from experienced ones. Furthermore, training on the URO Mentor has shown to improve real-time performance of URS and UCS procedures on patients and cadavers, although the number of studies and participants are limited [44–55].
Bench Models
Low-Fidelity Bench Models
Matsumoto et al. described a low-fidelity ureteroscopy model which consisted of a Penrose drain, an inverted cup, molded latex in a portable plastic case and two straws approximately of 8 mm. in diameter as substitutes for urethra, bladder dome, bladder base and bilateral ureters, respectively. Openings were cut midway up straws to facilitate placement of mid ureteral stones. It costs CAD$20 to manufacture [50].
High-Fidelity Bench Models
The Uro-Scopic Trainer (Limbs & Things, United Kingdom) is a high-fidelity bench model that offers training with real-time instruments [51, 53, 56, 57]. There was no difference in the performance of a basic ureteroscopic stone management procedure between trainees who trained on the URS training model from Limbs & Things and the URO Mentor VR simulator [53]. On the other hand, in the study described by Matsumoto et al., there was no difference in performance between trainees who trained on the low-fidelity bench model and the trainees who trained on the high-fidelity Uro-Scopic Trainer, measured in a laboratory environment using a checklist, global ratings score, pass rating, and time needed to perform the procedure [57].
Another bench model for URS is the Scope Trainer, which is developed by Mediskills Limited (United Kingdom). This model has an expandable bladder with vessels and contains a few bladder tumors. It has life-size ureters, and two anatomically accurate kidneys with renal pelvises and calyces. Through a tap from the bladder, irrigation fluid can be infused, and the bladder can be emptied [44, 58]. In a study by Brehmer et al., the performance of 26 urology residents was assessed on the bench model before and after training on this model. The participants were assessed by an experienced endourologist who used a task-specific checklist and global score. The study was performed in an operating room using the same instruments as in real life, and the model was covered with drapes to make the experience more realistic. The participants performed significantly better on the model after training, and the authors concluded that training on this bench model in a realistic setting enhanced the manual dexterity as well as familiarity with the method among urology residents [59].
More recently, in 2010, White et al. reported on the Adult Ureteroscopy Trainer (Ideal Anatomic Modeling, USA) [60]. This high-fidelity model has not been fully validated; however, results suggest face, content, and construct validity after the evaluation of 46 participants. The model claims to have anatomical accuracy, durability, and portability. In addition to inanimate bench simulators, porcine models have also been used for training ureteroscopic skills [61, 62]. In 2009, Liske et al. describe a bench model using a porcine urinary tract on which 150 urologists have trained; however, reports on validation studies are not available [63].
Costs of high-fidelity models range from $3,000 to $60,000 US [60]. Costs of the adult ureteroscopy trainer are $485 US. However, the costs and maintenance of the ureteroscope, basket retrieval devices, and phantom stones remain unclear. Most models require the presence of an instructor, since there is no virtual instructor, as in the URO Mentor. This could add to the overall cost of the simulation training.
Since all types of simulators have been shown to improve trainees’ performance, it can be assumed that animate, inanimate, and virtual reality simulators, separately or in combination, can all be suitable for training purposes. Since high-fidelity models are not necessarily superior to low-fidelity models in all situations, the usefulness of a model may be better defined using the concept of functional fidelity, indicating the extent to which the skills required for the real task are performed during the simulated tasks [64].
Studies concerning the effect of simulator training on patient outcome are limited for the URS procedure. Furthermore, not all simulators have been validated. The choice for a particular model will partly depend on the instructors and resources, which are available in a hospital or training institution. Whether a low- or high-cost simulator is purchased, it is of paramount importance to provide optimal learning conditions for the trainee. A first step for structured implementation of simulator training for URS is to define which learning goals should be achieved and to create opportunities for trainees to practice skills on a regular basis. More research is needed to determine the optimal interval training scheme for simulator training for URS to achieve sustained learning. Conditions to optimize learning include feedback to the learner, repetitive practice, integration in the curriculum, different levels of difficulty, the use of multiple learning strategies, variety of clinical conditions, a controlled environment, individualized learning, the presence of clearly stated goals, and the use of validated simulators [2].
Transrectal Ultrasound Simulation
Ultrasound is an important diagnostic imaging modality in many areas of clinical medicine. In transrectal ultrasound (TRUS), the prostate can be visualized by introducing the ultrasound probe into the rectum. This technique is widely used for diagnosing benign prostate hyperplasia, performing volumetry, and enabling transrectal prostate biopsies to diagnose prostate cancer [65–68]. A standardized procedure for taking prostate biopsies is needed since the presence of prostate cancer may not always be visible in ultrasound images. There is no standard for the number of prostate biopsies required to diagnose prostate cancer accurately. However, most authors recommend an extended biopsy scheme of >10 biopsies [65, 68, 69]. The procedure for TRUS-guided prostatic biopsies is not without complications. The most frequently reported complications are hematuria, hematochezia, hematospermia, fever, sepsis, urinary retention, and prostatitis [70, 71].
The performance of TRUS requires several skills. Two-dimensional images have to be mentally related to a 3D environment, and there has to be adequate hand-eye coordination of the clinician performing the procedure. Visual input and haptic feedback must be combined with knowledge of anatomy and prostate pathology, to reach satisfying diagnostic and biopsy results. Education and training are, therefore, key elements for successful application of ultrasound technology in patient care. Furthermore, TRUS and, especially, taking biopsies are uncomfortable for patients, and prolonging procedure time for educational purposes is not desirable. A training method with the use of simulators could help overcome these drawbacks of clinical training and improve efficiency and safety of the operator.
Little research has been done on TRUS simulators, and the simulators that have been described in literature are of limited validity, using the definitions of face, content, construct, and criterion validity described by McDougall [22]. Table 25.4 summarizes TRUS simulators described in the literature [72–76].
Table 25.4
Simulators for transrectal ultrasound (TRUS)
Author | Year | Material | Biopsies Y/N | Theoretical module | Content validity | Construct validity | Criterion validity |
|---|---|---|---|---|---|---|---|
Cos | 1990 | Inanimate | N | N | N | N | N |
Sclaverano | 2009 | Computerized | Y | N | Y | N | N |
Persoon | 2010 | Computerized | N | N | Y | N | N |
Chalasani | 2011 | Computerized | Y | N | Y | Y | N |
Janssoone | 2011 | Computerized | Y | Y | Y | N | N |
A 1990 paper describes a TRUS simulator in which the prostate was simulated by a Foley catheter balloon. This simple and inexpensive model can be used to learn the principles of ultrasound and to learn how to make a 3D mental composition from a 2D ultrasound image of the prostate, since it does not include real prostate images [74]. More recent simulators focus on the aspects of the prostate tissue itself. By using real patient data, it is possible for trainees to learn about normal and pathological aspects of the prostate, as well as practicing to adequately visualize all parts of the prostate [73, 75, 76]. In 2009, Sclaverano et al. described the first version of a simulator for ultrasound-guided prostate biopsy. The same simulator was described in 2011 and has been further developed. In addition to several technical improvements, the theoretical application in which exercises, knowledge, and feedback are included is of importance [72, 76]. Studies on construct and criterion validity of this simulator have not yet been described. In fact, none of the simulators described are criterion validated. Chalasani et al. describe a TRUS simulator in which construct validity is studied; however, a theoretical module was not described [75]. Other currently available ultrasound simulators used for medical training offer no option for TRUS, though developments are ongoing [77–82].
The financial costs of the TRUS simulators are not clearly stated in the literature and depend on several aspects. The simulator described by Persoon et al. is estimated to be $64,000 US, and optional devices are not included (Fig. 25.2). On the other hand, the relatively simple model, as described by Cos in 1990, seems less expensive but actually requires a real-time working ultrasound machine [73, 74]. To date, there is no accurate calculation on the financial benefits of simulator-based training for TRUS.
Fig. 25.2
TRUS simulator (MedCom, Germany). This virtual simulator allows the learner to place an ultrasound probe in a simulated rectum and practice coronal and axial viewing of the prostate
Simulator-based training for TRUS could be a helpful addition in the traditional apprenticeship-type training, especially for beginners, since all the simulators described offer basic training options for TRUS. Developments of the simulators for TRUS are ongoing and more extensive validation studies must follow before TRUS simulator training will likely be a standard part of resident training.
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