Educational Potential of Technologies Facilitating Percutaneous Nephrolithotomy Access - Beyond the Abstract

Last year, as a first-year medical student, I observed percutaneous nephrolithotomy (PCNL) in what was one of my first ever exposures to urology. At the end of the procedure, I asked what seemed to be an innocent question to the attending surgeon, Dr. Naeem Bhojani: “Is there any technology facilitating PCNL access?”. This question stemmed from me thinking that the triangulation technique could possibly be modeled by software after a single image registration instead of multiple shots. Such technology could reduce the number of fluoroscopic images needed and the amount of radiation exposure prior to gaining access. While Dr. Bhojani answered that other imaging modalities such as ultrasound were being adopted, he suggested that I review the literature to find an exhaustive answer to my question. This led to a systematic review of existing technologies that can facilitate PCNL access.1

While previous systematic reviews covering innovations in PCNL discussed everything from new techniques to new tools2–4, we focused exclusively on technologies developed that enhance the urologist’s ability to gain access intraoperatively, which is the crucial step of the procedure. Our review thus excluded innovations used prior to the surgery (such as those used to better plan the surgery) and those not involved in the access step of the surgery (such as miniperc).

In this review, we explored technologies such as the Automated Needle Targeting with X-Ray (ANT-X) system, a robot-assisted device automating the access step of PCNL, as well as software such as SonixGPS which projects the puncture tract on an ultrasound screen.5,6 While these technologies demonstrate benefits compared to unenhanced approaches, the added advantages of these technologies at the present time, do not warrant the purchase of these tools.

While this may sound disappointing, our findings have potential implications for medical education and surgical training. Ultrasound-guided access is slowly but surely becoming the new standard for PCNL access as it reduces radiation exposure to zero and allows for examination of adjacent organs/structures while at the same time being relatively affordable. However, it presents with two major challenges that hinder its widespread adoption: 1. Clear imaging of the kidney with accurate interpretation as well as 2. Visualization of the needle and coordination of the needle hand with the imaging hand to advance the needle within the imaging plane into the chosen renal target.7 While this remains to be seen, we hypothesize that the added advantages of the PCNL access technologies, while limited, may reduce the learning curve for techniques such as ultrasound-guided access.

Taking the example of technologies tracking and projecting the needle tract on the ultrasound screen, these innovations can be employed as “training wheels” for novices wishing to obtain access using ultrasound, potentially reducing the learning curve needed to gain this skill. As previously mentioned, these hypotheses remain to be tested, and we look forward to doing so in the near future.

Written by: David-Dan Nguyen, Department of Medicine, McGill University, Montreal, Quebec, Canada and Naeem Bhojani, MD, Division of Urological Surgery, Université de Montréal, Montreal, Quebec, Canada

1. Nguyen D-D, Luo JW, Tailly T, Bhojani N. PERCUTANEOUS NEPHROLITHOTOMY ACCESS: A SYSTEMATIC REVIEW OF INTRAOPERATIVE ASSISTIVE TECHNOLOGIES. J Endourol. March 2019:end.2019.0085. doi:10.1089/end.2019.0085
2. Basok EK, Donmezer S, Ali E. Recent advances in percutaneous nephrolithotomy. EMJ Urol. 2014;1(May):83-89.
3. Rassweiler J, Rassweiler M-C, Klein J. New technology in ureteroscopy and percutaneous nephrolithotomy. Curr Opin Urol. 2016;26(1):95-106. doi:10.1097/MOU.0000000000000240
4. Tailly T, Denstedt J. Innovations in percutaneous nephrolithotomy. Int J Surg. 2016;36(Pt D):665-672. doi:10.1016/j.ijsu.2016.11.007
5. Oo MM, Gandhi HR, Chong K-T, et al. Automated Needle Targeting with X-ray (ANT-X) – Robot-assisted device for percutaneous nephrolithotomy (PCNL) with its first successful use in human. J Endourol. April 2018:end.2018.0003. doi:10.1089/end.2018.0003
6. Li X, Long Q, Chen X, He D, He H. Assessment of the SonixGPS system for its application in real-time ultrasonography navigation-guided percutaneous nephrolithotomy for the treatment of complex kidney stones. Urolithiasis. 2017;45(2):221-227. doi:10.1007/s00240-016-0897-2
7. Usawachintachit M, Masic S, Allen IEE, Li J, Chi T. Adopting Ultrasound Guidance for Prone Percutaneous Nephrolithotomy: Evaluating the Learning Curve for the Experienced Surgeon. 2016;30(8):856-863. doi:10.1089/end.2016.0241

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