urologists have traditionally received their surgical training through the halstedian apprenticeship model of  see one , do one , teach one. despite the original success of this model , it relied heavily upon the accumulation of considerable operating experience gathered during several years of demanding training . over the last few decades
, there has been a significant increase in the number of minimally invasive urological procedures .
as these complex operations often possess steep learning curves , it is of some concern that trainee operating exposure has recently been limited by the introduction of initiatives such as the european working time directive .
furthermore , with a growing debate about whether it is safe and/or ethical to train on patients , there is a clear need for change to traditional surgical education .
simulation is an appealing tool for modern urology training , allowing trainees to repeatedly practice a procedure , as a result bypassing the early , error - prone phase of the learning curve in an environment which does not jeopardize patient safety .
furthermore , with high fidelity simulators , it is possible to also teach non - technical skills , such as leadership , communication and teamwork which complement technical urological skills .
this article will review the current role of urological simulators by discussing how they can best be incorporated into training programs , by assessing the availability and validity of current models and by considering what current challenges and limitations they face .
the author performed a thorough literature review of the electronic databases medline , embase and google scholar .
it is important to stress that simulation is an adjunct rather than a replacement of clinical training . to fully exploit the benefit of simulation
simulation thus becomes a safe means to maximize the effectiveness of training in the restricted number of hours possible .
an optimal simulation program would involve trainees receiving repeated exposure to the simulator over an extended period of time .
it is vital that the student receives feedback on their performance , enabling them to target their learning appropriately .
trainees can often start with low fidelity simulators to grasp basic surgical skills before moving onto full - procedural simulations as they progress through their training . in the uk , trainees can now log simulator experience into the intercollegiate surgical curriculum program logbook .
furthermore , the feasibility and acceptability of a centrally - coordinated simulation - based urology training program named simulate has been determined , describing a potential way in which to deliver technical and non - technical skills in a structured manner . for the endourological procedures of cystoscopy and ureterorenoscopy ,
numerous high - fidelity bench - top models and virtual reality ( vr ) simulators have been created .
high - fidelity simulators , such as the uro - scopic trainer ( limbs and things , uk ) , consist of physical mannequins and allow trainees to practice using the standard operating instruments .
brehmer and swartz found that repeated training on a bench - top simulator for semi - rigid ureteroscopy significantly improved resident performance and made trainees feel more comfortable with the instruments and procedures .
other studies have confirmed the face , content and construct validity of numerous high fidelity ureterorenoscopy and cystoscopy simulators .
virtual reality trainers , such as the uro - mentor ( simbionix , usa ) , simulate surgical procedures through interactions with computer interfaces .
demonstrated that repeated exposure of novices to the uro - mentor simulator ( for flexible cystoscopy ) produced encouraging results ; global rating scale score and time for procedure completion improved , with a decrease in the amount of trauma caused . additionally , good construct validity was noted . an essential factor in determining the usefulness of simulation as
an educational tool is whether the skills learnt from simulation are actually transferable to the clinical setting . in a randomised controlled trial ,
schout et al . showed that trainees who received cysto - urethroscopy training on the uro - mentor vr performed significantly better than those with no vr training when performing cysto - urethroscopy on real patients . when comparing simulators , chou et al .
showed that there was no significant difference in ureteroscopy performance ( on a porcine model ) between medical students trained on the uro - mentor vr simulator compared to a high fidelity model .
interestingly , some authors have queried whether these highly - technical expensive models are necessary .
matsumoto et al . showed that whilst simulation improves endourological performance , there was no significant difference between the groups that trained with a low fidelity model which cost  14 compared to the high fidelity model costing  2600 .
turp is a commonly performed , but challenging procedure . as errors during this procedure can cause serious complications , it is concerning that the mean number of turps completed by residents over the course of their training was halved from 120 to 60 between the time period of 1990 and 2000 . as a result
bright et al . demonstrated the face and construct validity of the turpsim vr simulator ( simbionix , usa ) with novices improving turp performance upon repeated training , but experts still performing significantly better .
kllstrm et al . showed that following training on the pelvicvision turp vr simulator ( meleritmedical ab ) , trainees performed significantly better turp on patients , with a 65% increase in the number of residents able to perform a turp .
aydin et al . recently confirmed the construct validity of the greenlight simulator ( american medical systems inc , usa ) for photoselective vaporization of the prostate .
likewise , the face and content validity for a new holmium laser enucleation of the prostate ( holep ) simulator has been determined , with 84% of the participants believing that the simulator would be useful for training . it has been reported that during percutaneous nephrolithotomy , as few as 11% of urologists routinely obtain percutaneous renal access without the aid of a radiologist .
therefore , as trainees may not receive training from their seniors on how to achieve access , simulation could potentially enhance training in this area .
mishra et al . proved the validity of the perc mentor vr renal access simulator ( mentor graphics , usa ) .
they found that while experts were faster and more efficient at gaining access on the simulator , novices improved their performance over the course of training for numerous metrics , such as fluoroscopy time .
furthermore , they then compared the abilities of five novices to attain renal access in a pig before and after training on the vr simulator . whereas only one of the pre - trained group achieved access , all five did so safely after training , thus confirming predictive validity .
an inexpensive , fluoro - less , physical c - arm trainer ( simportal ) has also been described , but awaits validation .
as laparoscopic procedures become more common in urology , a variety of simulators have been developed . while the training of general laparoscopic skills on low - fidelity box trainers may improve performance of individual skills such as suturing time
, studies suggest that it has limited impact on the overall operative performance of trainees during in vivo laparoscopic nephrectomy .
brewin et al . confirmed the validity of the first vr laparoscopic nephrectomy simulator with experts rating it to be a useful training tool with above average realism . with repetition
, trainees improved their overall simulator performance , with faster , more efficient and safer task execution .
given the increasing adoption of complex robotic - assisted urological procedures with steep learning curves , the role of simulation to train qualified and trainee urologists in these skills is sure to play a big part in the future of urological simulation .
cho et al . demonstrated that virtual reality simulation with the dv - trainer ( mimic technologies , inc .
, seattle , wa ) improved surgeon performance on the da vinci surgical system ( intuitive surgical , inc . ,
it is now apparent that for a positive patient outcome in urological surgery , technical surgical ability must be complemented by excellent , non - technical skills such as decision making , teamwork and communication .
non - technical skills can be improved by simulation in mock operating theatres with full - participation from the entire surgical , anaesthetic and nursing teams
. between 94 - 100% of trainees noted this type of high fidelity simulation to be useful for developing communication skills .
interestingly , non - technical skills have not been found to necessarily correlate with experience , suggesting that more advanced trainees may also benefit from training upon these simulators .
structured , simulation - based curricula , incorporating both technical and non - technical skills has been shown to be feasible and effective for teaching ureteroscopy to trainees .
life - threatening emergency situations can also be simulated with studies demonstrating a significant reduction in the time taken to initiate resuscitation protocols .
one consideration tutors need to consider is that simulation can be resource demanding , with a need for faculty , equipment and a location to be provided .
another consideration is that there is no agreed consensus on how to validate simulation tools , with different investigators adopting different approaches . given the difficult , expensive and potential ethical challenges of conducting randomised trials to determine whether specific simulators actually improve the operating performance of trainees , educators often have to select simulators based on their own judgement .
more work is needed to compare different simulators and to identify which ones are more effective at training students .
for example , the learning curve for prostate cancer recurrence after radical prostatectomy does not plateau until approximately 250 procedures have been performed .
therefore , it is important to appreciate that simulation training alone will not be sufficient for trainees to bypass this curve and to meet the requirements for certification at the end of training .
rather , simulation should complement other essential components of urology training programs such as participation in mentorship schemes and clinical fellowships , which also aid progression along the learning curve .
urology trainees consistently claim clinical fellowships to be a necessary undertaking in order to achieve clinical competence .
fellowships help trainees to improve both procedural confidence and competence , while also allowing the development of super - specialist skills . indeed , 5-day mini fellowship programs are effective at teaching urologists new procedures such as robot - assisted laparoscopic prostatectomy , with skills learnt retained in both the short and long - term .
indeed , fellowships undertaken at high - volume centers of excellence are useful to ensure trainees accumulate an adequate procedural caseload necessary to develop the surgical skills essential for a positive surgical outcome [ 40 , 41 ] .
it is important to stress that simulation is an adjunct rather than a replacement of clinical training . to fully exploit the benefit of simulation
simulation thus becomes a safe means to maximize the effectiveness of training in the restricted number of hours possible .
an optimal simulation program would involve trainees receiving repeated exposure to the simulator over an extended period of time .
it is vital that the student receives feedback on their performance , enabling them to target their learning appropriately .
trainees can often start with low fidelity simulators to grasp basic surgical skills before moving onto full - procedural simulations as they progress through their training . in the uk , trainees can now log simulator experience into the intercollegiate surgical curriculum program logbook .
furthermore , the feasibility and acceptability of a centrally - coordinated simulation - based urology training program named simulate has been determined , describing a potential way in which to deliver technical and non - technical skills in a structured manner .
for the endourological procedures of cystoscopy and ureterorenoscopy , numerous high - fidelity bench - top models and virtual reality ( vr ) simulators have been created .
high - fidelity simulators , such as the uro - scopic trainer ( limbs and things , uk ) , consist of physical mannequins and allow trainees to practice using the standard operating instruments .
brehmer and swartz found that repeated training on a bench - top simulator for semi - rigid ureteroscopy significantly improved resident performance and made trainees feel more comfortable with the instruments and procedures .
other studies have confirmed the face , content and construct validity of numerous high fidelity ureterorenoscopy and cystoscopy simulators .
virtual reality trainers , such as the uro - mentor ( simbionix , usa ) , simulate surgical procedures through interactions with computer interfaces .
demonstrated that repeated exposure of novices to the uro - mentor simulator ( for flexible cystoscopy ) produced encouraging results ; global rating scale score and time for procedure completion improved , with a decrease in the amount of trauma caused . additionally , good construct validity was noted . an essential factor in determining the usefulness of simulation as
an educational tool is whether the skills learnt from simulation are actually transferable to the clinical setting . in a randomised controlled trial ,
schout et al . showed that trainees who received cysto - urethroscopy training on the uro - mentor vr performed significantly better than those with no vr training when performing cysto - urethroscopy on real patients . when comparing simulators , chou et al .
showed that there was no significant difference in ureteroscopy performance ( on a porcine model ) between medical students trained on the uro - mentor vr simulator compared to a high fidelity model .
interestingly , some authors have queried whether these highly - technical expensive models are necessary .
matsumoto et al . showed that whilst simulation improves endourological performance , there was no significant difference between the groups that trained with a low fidelity model which cost  14 compared to the high fidelity model costing  2600 .
turp is a commonly performed , but challenging procedure . as errors during this procedure can cause serious complications , it is concerning that the mean number of turps completed by residents over the course of their training was halved from 120 to 60 between the time period of 1990 and 2000 . as a result
bright et al . demonstrated the face and construct validity of the turpsim vr simulator ( simbionix , usa ) with novices improving turp performance upon repeated training , but experts still performing significantly better .
kllstrm et al . showed that following training on the pelvicvision turp vr simulator ( meleritmedical ab ) , trainees performed significantly better turp on patients , with a 65% increase in the number of residents able to perform a turp .
aydin et al . recently confirmed the construct validity of the greenlight simulator ( american medical systems inc , usa ) for photoselective vaporization of the prostate .
likewise , the face and content validity for a new holmium laser enucleation of the prostate ( holep ) simulator has been determined , with 84% of the participants believing that the simulator would be useful for training .
it has been reported that during percutaneous nephrolithotomy , as few as 11% of urologists routinely obtain percutaneous renal access without the aid of a radiologist . therefore ,
as trainees may not receive training from their seniors on how to achieve access , simulation could potentially enhance training in this area .
mishra et al . proved the validity of the perc mentor vr renal access simulator ( mentor graphics , usa ) .
they found that while experts were faster and more efficient at gaining access on the simulator , novices improved their performance over the course of training for numerous metrics , such as fluoroscopy time .
furthermore , they then compared the abilities of five novices to attain renal access in a pig before and after training on the vr simulator . whereas only one of the pre - trained group achieved access , all five did so safely after training , thus confirming predictive validity .
an inexpensive , fluoro - less , physical c - arm trainer ( simportal ) has also been described , but awaits validation .
as laparoscopic procedures become more common in urology , a variety of simulators have been developed . while the training of general laparoscopic skills on low - fidelity box trainers may improve performance of individual skills such as suturing time
, studies suggest that it has limited impact on the overall operative performance of trainees during in vivo laparoscopic nephrectomy .
brewin et al . confirmed the validity of the first vr laparoscopic nephrectomy simulator with experts rating it to be a useful training tool with above average realism . with repetition
, trainees improved their overall simulator performance , with faster , more efficient and safer task execution .
given the increasing adoption of complex robotic - assisted urological procedures with steep learning curves , the role of simulation to train qualified and trainee urologists in these skills is sure to play a big part in the future of urological simulation .
cho et al . demonstrated that virtual reality simulation with the dv - trainer ( mimic technologies , inc .
, seattle , wa ) improved surgeon performance on the da vinci surgical system ( intuitive surgical , inc . ,
it is now apparent that for a positive patient outcome in urological surgery , technical surgical ability must be complemented by excellent , non - technical skills such as decision making , teamwork and communication .
non - technical skills can be improved by simulation in mock operating theatres with full - participation from the entire surgical , anaesthetic and nursing teams
. between 94 - 100% of trainees noted this type of high fidelity simulation to be useful for developing communication skills .
interestingly , non - technical skills have not been found to necessarily correlate with experience , suggesting that more advanced trainees may also benefit from training upon these simulators .
structured , simulation - based curricula , incorporating both technical and non - technical skills has been shown to be feasible and effective for teaching ureteroscopy to trainees .
life - threatening emergency situations can also be simulated with studies demonstrating a significant reduction in the time taken to initiate resuscitation protocols .
one consideration tutors need to consider is that simulation can be resource demanding , with a need for faculty , equipment and a location to be provided .
another consideration is that there is no agreed consensus on how to validate simulation tools , with different investigators adopting different approaches . given the difficult , expensive and potential ethical challenges of conducting randomised trials to determine whether specific simulators actually improve the operating performance of trainees , educators often have to select simulators based on their own judgement .
more work is needed to compare different simulators and to identify which ones are more effective at training students .
for example , the learning curve for prostate cancer recurrence after radical prostatectomy does not plateau until approximately 250 procedures have been performed .
therefore , it is important to appreciate that simulation training alone will not be sufficient for trainees to bypass this curve and to meet the requirements for certification at the end of training .
rather , simulation should complement other essential components of urology training programs such as participation in mentorship schemes and clinical fellowships , which also aid progression along the learning curve .
urology trainees consistently claim clinical fellowships to be a necessary undertaking in order to achieve clinical competence .
fellowships help trainees to improve both procedural confidence and competence , while also allowing the development of super - specialist skills . indeed , 5-day mini fellowship programs are effective at teaching urologists new procedures such as robot - assisted laparoscopic prostatectomy , with skills learnt retained in both the short and long - term .
indeed , fellowships undertaken at high - volume centers of excellence are useful to ensure trainees accumulate an adequate procedural caseload necessary to develop the surgical skills essential for a positive surgical outcome [ 40 , 41 ] .
to conclude , there are numerous simulators available to teach both technical and non - technical urological skills . despite the need for more validation and comparative studies
, evidence suggests that these simulators help trainees to bypass the early steps of the learning curve . in order to maximize the efficiency of these simulators ,
they should be incorporated within proficiency - based curricula alongside other initiatives such as clinical fellowships . by deepening the understanding of how simulation improves trainee performance
, we can be sure to optimize the training for urology trainees in an increasingly restrictive educational environment .
 introductionsimulation is becoming an increasingly popular educational tool in numerous surgical specialities , including urology . 
 this article reviews the current role of urological simulators ; discussing their need , availability , incorporation and current limitations.material and methodsa literature review of the electronic databases medline , embase and google scholar was performed.resultsfor increasingly limited urological training programs , simulation can act as a valuable adjunct to clinical training . 
 evidence suggests that simulation enables the trainee to bypass the early , error - prone part of the surgical learning curve . 
 it should be incorporated into proficiency - based curricula , with junior trainees initially beginning with low fidelity simulators to grasp basic surgical skills before moving onto full - procedural simulation as they progress through their training . 
 a wide variety of simulators of differing fidelity are currently available , teaching both technical ( eg . cystoscopy ) and non - technical ( eg . communication ) urological surgical skills . 
 whist numerous studies have assessed the face , content and construct validity of various urological simulators , further work needs to be undertaken to determine whether the skills learnt actually improve trainee performance in the operating room . 
 then , educators will be able to make informed decisions about whether these resource demanding ( financially and in terms of demands on faculty ) simulators are a worthwhile educational tool.conclusionsalthough further investigation is required , urological simulators appear to have a considerable role for developing both technical and non - technical urological skills in an increasingly restricted educational environment in modern urogynecology . 
INTRODUCTION
MATERIAL AND METHODS
RESULTS AND DISCUSSION
How should simulation be incorporated into surgical education?
Currently available urological simulators
Transurethral resection of the prostate/bladder tumour (TURP/TURBT)
Percutaneous renal access
Laparoscopic and robotic urological simulation
Non-technical urological skills
Challenges of simulation training
CONCLUSIONS
CONFLICTS OF INTEREST