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Table of Contents
Year : 2020  |  Volume : 31  |  Issue : 6  |  Page : 244-252

Recent literature on the minimally invasive management of pediatric urolithiasis: A narrative review

1 Department of Surgery, Division of Urology, University of Toronto; Department of Surgery, Division of Urology, Hospital for Sick Children, Toronto, Canada
2 Department of Surgery, Division of Urology, Hospital for Sick Children, Toronto, Canada
3 Department of Urology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei, Taiwan
4 Department of Surgery, Division of Urology, University of New Mexico, Albuquerque, NM, USA
5 Department of Urology, University of Wisconsin, Madison, WI, USA

Date of Submission26-Jun-2020
Date of Decision03-Oct-2020
Date of Acceptance08-Oct-2020
Date of Web Publication26-Dec-2020

Correspondence Address:
Stephen Shei-Dei Yang
Department of Urology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/UROS.UROS_91_20

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Although the surgical management of pediatric urolithiasis does not differ significantly from that of adults, there are anatomical and physiological differences that necessitate special considerations. This review aims to summarize the existing high-level evidence (systematic review, meta-analysis, randomized controlled trials) for surgical management of pediatric urolithiasis, with a discussion on different technical tips to make these surgical approaches achievable. A PubMed web-based medical literature search was performed on May 26, 2020, using the search strategy (Pediatric or children) and (urolithiasis or stone) and Urology. The search was limited to meta-analysis, systematic reviews, and randomized controlled trials published in the past 10 years. Only studies that focused on surgical management of pediatric urolithiasis were included. Fifty-seven records were identified and 47 were excluded as these records were duplicates, did not assess surgical management, or were trials that were included in systematic reviews/meta-analyses that were included in this study. Ten studies were included in this review. Depending on the review/trial, the stone-free rate (SFR) had wide ranges for all of the surgical management options assessed (shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy). There are many considerations in choosing the appropriate surgical management for a patient presenting with pediatric nephrolithiasis–SFRs, radiation exposure, and adverse events being some of these features. All three procedures assessed had different characteristics, with advantages and disadvantages unique to each procedure. As each surgical technique for pediatric urolithiasis provides its advantages and disadvantages, surgeons should discuss all options to provide the best-informed decision-making process to a patient or family who may require surgical management of pediatric nephrolithiasis.

Keywords: Pediatric, surgical management, urolithiasis

How to cite this article:
Kim JK, Chua ME, Yang SS, Ming JM, Santos JD, Farhat WA. Recent literature on the minimally invasive management of pediatric urolithiasis: A narrative review. Urol Sci 2020;31:244-52

How to cite this URL:
Kim JK, Chua ME, Yang SS, Ming JM, Santos JD, Farhat WA. Recent literature on the minimally invasive management of pediatric urolithiasis: A narrative review. Urol Sci [serial online] 2020 [cited 2023 Feb 5];31:244-52. Available from: https://www.e-urol-sci.com/text.asp?2020/31/6/244/305100

  Introduction Top

The prevalence of urolithiasis among children varies widely from 5% to 15% reported in low- to middle-income countries to 1%–5% among high-income countries.[1] Although the surgical management of pediatric urolithiasis does not differ significantly from that of adults, there are anatomical and physiological differences that necessitate special considerations.[2] Hence, this investigation aims to provide a comprehensive update on the topic of surgical management of pediatric urolithiasis by summarizing the available high-level evidence on this topic published in the past 10 years and also to discuss different technical tips to make these surgical approaches achievable.

  Methodology Top

A PubMed web-based medical literature search was performed on May 26, 2020, using the search strategy (Pediatric or children) and (urolithiasis or stone) and Urology. The search was limited to meta-analysis, systematic reviews, and randomized controlled trials published in the past 10 years.

Only studies that focused on surgical management of pediatric urolithiasis were included. All duplicated studies were identified and excluded from the review. If an overlap in a topic covered in ≥2 systematic reviews or meta-analyses were found, only the record with the most recent search date was included. For randomized control trials (RCTs), only those that were not included in identified systematic reviews or meta-analyses were included. The pooled effect estimates or between-group comparison statistics outcomes reported by the meta-analysis or RCTs were included to support the intervention efficacy. The efficacy of surgical approaches of shockwave lithotripsy (SWL), retrograde intrarenal surgery (RIRS) or ureteroscopy lithotripsy, and percutaneous nephrolithotomy was summarized in a cluster. Each surgical approach was compared to each other.

  Results Top

Summary of literature characteristics

Fifty-seven records were retrieved from the literature search [Figure 1]. Twelve duplicated studies were removed. Thirty-five records were excluded as they did not assess a surgical approach or have been included in another systematic review or meta-analysis that were included in this study. Ten relevant studies were included for the summary of the recent evidence on the surgical approach of pediatric urolithiasis management [Table 1].
Figure 1: PRISMA flow diagram of the literature search

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Table 1: Summary of results from identified studies

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Shockwave lithotripsy

In a systematic review and meta-analysis by Lu et al., SWL had an overall stone-free rate (SFR) of 90%, with a higher SFR when used for stones <10 mm in size, when compared to stones >10 mm in size (relative risk [RR] 1.14, 95% confidence interval [CI] 1.07–1.21) and stones in proximal ureter, and when compared to stones in mid-to-low ureters (RR 1.077, 95% CI 1.005–1.154).[3]

An RCT of 300 patients by AbdelRazek et al. suggested that SFR is higher when hydronephrosis is artificially induced by using a 4Fr ureteric catheter with continuous inflow of saline at 100 cm above the SWL table–those who had induced hydronephrosis (n = 153) had 90.8% SFR, whereas the control group (n = 147) had 75.5% SFR (P = 0.001).[4]

Another RCT of 60 patients by Salem et al. suggested that when using Dornier Lithotripter S, those who received slow shocks (80 shocks/minute, n = 30) had higher SFR when compared to those who had rapid shocks (120 shocks/minute, n = 30) for stones measuring 10–20 mm (90% vs. 73.3%, respectively). The technique reported by authors involved a gradual increase in energy from 14 to 20 KV and up to 2500 total shocks. There was no difference in post-SWL fevers between the compared groups.[5]

Retrograde intrarenal surgery

According to the systematic review by Whatley et al., the overall efficacy of flexible ureteroscopy and laser lithotripsy for pediatric renal stones (various stone locations, size range 1.5–30 mm) has an average SFR of 87% (range 58%–100%) following the initial procedure. Seventy-six percent of patients required a postprocedural ureteral stent, and the average complication rate was 12.6%.[6]

According to the systematic review by De Coninck et al., using ureteral access sheaths during RIRS allows an increase in irrigation flow by 35%–80% while decreasing intrapelvic pressure by 57%–75%. Even with high irrigation pressures of 200 cmH2O through the ureteroscope, the intrapelvic pressure can be maintained below 20 and 30 cmH2O when using 12/14Fr and 10/12Fr ureteral access sheaths, respectively. Ureteral access sheaths also lower the rates of infectious complications such as urinary tract infections and sepsis (18.6% vs. 23.9%, 4.3% vs. 15.2%, respectively). No robust data were available to conclude additional benefits of ureteral access sheaths for SFR, insertions, scope damage, ureteral injury, and postoperative pain.[7]

An RCT by Fahmy et al. showed that when comparing laser fragmentation and dusting techniques, the operative time is significantly lower for the fragmentation technique (mean 28 min vs. 36 min, P = 0.007, respectively). However, fragmentation and dusting had similar SFR on follow-up (96 vs. 98%, P = 0.2) and minor complication rates (3 vs. 5, P = 0.6; respectively).[8]

Percutaneous nephrolithotomy

The systematic review by Jones et al. evaluating the minimally invasive PCNL (defined as <15Fr tract) showed that the overall SFR ranges from 80% to 100% for micro-PCNL (<10Fr) and from 85% to 100% for ultra-mini-PCNL (12–14Fr). The overall complication rates were 11.2%. Postprocedural renal colic and fragment obstruction were reported among micro-PCNL studies, while renal pelvicalyceal perforation was reported in ultra-mini-PCNL studies.[9]

When comparing tubeless versus standard PCNL for pediatric urolithiasis, Nouralizadeh et al. report that the patients undergoing tubeless PCNL may have shorter hospital stays, although this was not statistically significant (mean difference −1.57 days, 95% CI: −3.2–0.07). There were no significant differences for operative time, perirenal fluid collection, postprocedural fever, stone clearance, and need for further procedure.[10]

Comparison of the surgical approaches

A systematic review by He et al. that included 13 comparative studies concluded that SWL provides a shorter hospital stay and procedure time, with lower SFR, higher retreatment, and a higher need for the adjunctive procedure. PCNL has a higher SFR than SWL but is associated with more radiation exposure and procedure time than SWL and RIRS. RIRS has a higher single session SFR and a lower retreatment rate compared to SWL, while it has shorter hospital days than PCNL. Reported complication rates were equivalent between the three surgical approaches. Fluoroscopy time was assessed in this review and it was found that PCNL has longer fluoroscopy time than the other two procedures (PCNL vs. SWL: Weighted mean difference 93.36, 95% CI: 79.44–107.28, P < 0.0001; PCNL vs. RIRS: 65.30, 95% CI: 29.32–101.27, P < 0.0001).[11]

Barreto et al. also conducted a Cochrane review, involving three studies and 153 cases with follow-up ranging from 2 weeks to 8 months, which showed that SFR for renal stones was lower for patients undergoing SWL when compared with those undergoing ureteroscopy with holmium laser or pneumatic lithotripsy (RR: 0.62, 95% CI: 0.43–0.88); the need for the second procedure was also higher for patients undergoing SWL (RR: 3.47, 95% CI: 1.32–9.15). However, serious adverse events/complications were lower in those undergoing SWL, although not statistically significant (RR: 0.56, 95% CI: 0.12–2.58).[12]

  Discussion Top

Articles of a systematic review with/without meta-analysis on surgical management of pediatric urolithiasis have been published in the past decades. However, the majority were considered the low quality of evidence with poor relatively high heterogeneity and poor precision of effect estimated. Currently, there is no available high-level evidence available to conclude the efficacy and safety of the laparoscopic procedure for pediatric urolithiasis.[13],[14] Having said that, our paper summarized what is considered the best available evidence in the surgical management of pediatric urolithiasis.

For a pediatric urologist that has a particular interest in the surgical management of pediatric urolithiasis, we strongly suggest that the approach should be individualized according to the characteristics of the patient and their stone condition. SWL is the least invasive procedure and may be an excellent option for smaller stones and stones in the proximal ureter. RIRS and PCNL both require general anesthesia, with RIRS being less invasive than PCNL but with lower SFR, especially for larger stones. PCNL is also highly skill-dependent, and many centers may not have the equipment or support to perform this procedure routinely, especially in the pediatric setting. While age is a factor that may also impact the decision making in stone management, the studies assessed in this systematic review report mean ages of 3.6–10.1 [Table 1], depending on the procedure. While older patients may have overlaps in principles of pediatric and adult stone management principles, there is lacking the body of literature supporting a specific type of procedure over another for patients younger than the reported ages. Nonetheless, each procedure should be individualized for feasibility. For example, RIRS could not be performed in an infant due to immature anatomy.

Similar principles from the adult population can be applied to the pediatric population when using SWL. This includes first choosing the patients who would benefit the most based on stone criteria, which may include stone size, multiple stones, lower pole stones, Hounsfield unit >1000, and stone type (cystine, calcium oxalate monohydrate, and matrix stones), and patient criteria, which may include skin-to-stone distance >10 cm and anatomical considerations (pelvic kidney, horseshoe kidney, and calyceal diverticulum). Technical aspects to make SWL more successful include ensuring optimal coupling of the shock by avoiding minimizing the air pockets that may form between the gel/oil. This can be done by limiting patient movement or repositioning during the procedure and using a large volume mound of medium directly from the container rather than applying it in small volumes.[15] In the pediatric population, the setting of 80 shocks per min was found to be superior to 120 shocks per min for stones measuring 10–20 mm in size when a gradual increase in energy is applied.[5] This is congruent with what was found in adult studies, which showed superior SFR with slow rates.[16] Setting the initial stone rates at lower energy, pausing, and resuming at higher energy or gradually increasing the energy may also reduce the renal injury by inducing renal vasoconstriction and reduce the rates of renal hematomas.[17],[18] One should ensure monitoring the stone location frequently to ensure that the stone is within the treatment zone.[15]

For RIRS, it is important to be mindful of surgeon positioning, instrument handling, and laser settings. These are also shared concepts between adult and pediatric populations. Standing in a 90° rotation in a lateral stance allows the surgeon to block and control the ureteroscope. Scopes should be manipulated in movements that combine rotation, deflection, and pushing (advancement/withdrawal). Macrorotations are assisted by the dominant hand and (assuming right-hand dominance) supination allows exploration of renal calyces to the right of the screen. Moreover, pronation allows the exploration of renal calyces to the left of the screen. Microrotations can be performed by the nondominant hand at the urethral meatus to further refine the rotational movements. Laser settings can be adjusted for fragmentation (high energy, low frequency), dusting (low energy, high frequency), or popcorning of stones (moderate-high energy, moderate-high frequency). Setting pulse durations to short may aid with fragmentation, while setting it to long may aid with dusting or popcorning and provide less retropulsion and improved coagulation.[19],[20]

From a senior author's experience, for pediatric patients undergoing RIRS, several techniques may facilitate the procedure. In accessing the ureteral orifice with a semirigid ureteroscope, one may meet resistance–in such cases, rotating the scope while gently dilating the ureteric orifice using a 20–60 mL syringe may make access easier [Video 1]. The size of the syringe used should depend on age (e.g., 20 mL syringe for patients <2 years of age, 60 mL syringe for patients <10–12 years of age).

The ureteral sheath can be useful in visualization as one does not have to empty the bladder frequently, in addition to the benefits of reducing upper pole pressures and reducing postoperative infectious complications. Moreover, having this channel in the ureter may be especially useful if multiple stone fragments require basketing since one removes and reintroduces the ureteroscope to the same location easily [Video 2]. However, ureteral sheaths can also lead to complications such as ureteral injury. For females, an alternative to ureteral sheaths that allows one to empty the bladder during RIRS includes 5–8Fr feeding tubes that can be placed in the bladder, adjacent to the ureteroscope. This facilitates bladder drainage throughout the procedure. An assistant can aspirate fluid from the feeding tube itself if the fluid is not being drained as fast as it is being introduced to the upper tracts. In males, it is difficult to place a feeding tube next to the ureteroscope; in short cases, a large angiocatheter can be introduced suprapubically to the coil in the bladder and an assistant can periodically empty the bladder via this channel using a large syringe (e.g., 60 mL syringe).

PCNL should take into account the patient positioning, of which prone position is the standard approach. There is a lack of studies that assess the potential for supine PCNL in pediatric populations, but a future large number of prospective studies may clarify the safety and feasibility of PCNL in future.[21] One of the most important and difficult steps of PCNL is gaining access. There are many described techniques, including the bulls-eye technique, ultrasound-guided access, and endoscopic-guided access being commonly utilized techniques. As these access techniques have a steep learning curve, the experience and comfort of the endourologist or interventional radiologist are a guide to choosing the access technique.[22] The type of access sheath may also be considered based on the size of the stones and the patient. The size of the access sheath may vary from <10 Fr to 30 Fr and smaller sheaths may provide lower bleeding complications, while large sheaths allow the removal of larger stones.[23] Following gaining access, PCNL access sheath may limit the navigation of the nephroscope into renal calyces immediately adjacent to the access sheath. In such cases, the “passing the ball” technique can be helpful, whereby an RIRS can be used to access the previously inaccessible stones, fragment the stones, and pass the fragments to the PCNL access sheath side.[24]

Although the laparoscopic procedures were not discussed in this paper, this can be an option for highly selected cases, such as those with anatomic abnormalities that make conventional stone procedures difficult. Some important details with laparoscopic pyelolithotomy are to ensure the use of warm irrigation, if required, and to leave a drain postoperatively in case all of the fluids were not removed. One also has the option of using the 5-mm trocar in laparoscopic cases to insert a ureteroscope to basket stones out of the collecting system with ease. It should be noted that if employing a laparoscopic approach, the surgeon must be comfortable in suturing laparoscopically.[25] However, how laparoscopy compares to other minimally invasive management of nephrolithiasis is unclear as there are a limited number of studies assessing and comparing the efficacy of laparoscopic procedures.

This review of the recent literature on surgical management of pediatric nephrolithiasis is a concise overview of available surgical management options and respective outcomes. This can serve as a quick guide that can aid in discussions with patients and families for informed decision making.

  Conclusion Top

Several systematic reviews and relevant RCTs were published in the past decade that assess the minimally invasive approach in pediatric urolithiasis. Each surgical technique provides its own advantages and disadvantages, and the surgeon should discuss all options to provide the best-informed decision-making process to a patient or family who may require surgical management of pediatric nephrolithiasis.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Barreto L, Jung JH, Abdelrahim A, Ahmed M, Dawkins GPC, Kazmierski M. Reprint - Medical and surgical interventions for the treatment of urinary stones in children: A cochrane review. Can Urol Assoc J 2019;13:334-41.  Back to cited text no. 1
Taguchi K, Cho SY, Ng AC, Usawachintachit M, Tan YK, Deng YL, et al. The Urological association of asia clinical guideline for urinary stone disease. Int J Urol 2019;26:688-709.  Back to cited text no. 2
Lu P, Wang Z, Song R, Wang X, Qi K, Dai Q, et al. The clinical efficacy of extracorporeal shock wave lithotripsy in pediatric urolithiasis: A systematic review and meta-analysis. Urolithiasis 2015;43:199-206.  Back to cited text no. 3
AbdelRazek M, Hassan A, AbdelKader MS, Abolyosr A. SWL outcome in artificial hydronephrotic vs. non-hydronephrotic kidney for preschool children with high-density renal stones. World J Urol 2019;37:937-41.  Back to cited text no. 4
Salem HK, Fathy H, Elfayoumy H, Aly H, Ghonium A, Mohsen MA, et al. Slow vs rapid delivery rate shock wave lithotripsy for pediatric renal urolithiasis: A prospective randomized study. J Urol 2014;191:1370-4.  Back to cited text no. 5
Whatley A, Jones P, Aboumarzouk O, Somani BK. Safety and efficacy of ureteroscopy and stone fragmentation for pediatric renal stones: A systematic review. Transl Androl Urol 2019;8:S442-7.  Back to cited text no. 6
De Coninck V, Keller EX, Rodríguez-Monsalve M, Audouin M, Doizi S, Traxer O. Systematic review of ureteral access sheaths: Facts and myths. BJU Int 2018;122:959-69.  Back to cited text no. 7
Fahmy A, Youssif M, Rhashad H, Orabi S, Mokless I. Extractable fragment versus dusting during ureteroscopic laser lithotripsy in children: Prospective randomized study. J Pediatr Urol 2016;12:254.e1-4.  Back to cited text no. 8
Jones P, Bennett G, Aboumarzouk OM, Griffin S, Somani BK. Role of minimally invasive percutaneous nephrolithotomy techniques-micro and ultra-mini PCNL (<15F) in the pediatric population: A systematic review. J Endourol 2017;31:816-24.  Back to cited text no. 9
Nouralizadeh A, Simforoosh N, Shemshaki H, Soltani MH, Sotoudeh M, Ramezani MH, et al. Tubeless versus standard percutaneous nephrolithotomy in pediatric patients: A systematic review and meta-analysis. Urologia 2018;85:3-9.  Back to cited text no. 10
He Q, Xiao K, Chen Y, Liao B, Li H, Wang K. Which is the best treatment of pediatric upper urinary tract stones among extracorporeal shockwave lithotripsy, percutaneous nephrolithotomy and retrograde intrarenal surgery: A systematic review. BMC Urol 2019;19:98.  Back to cited text no. 11
Barreto L, Jung JH, Abdelrahim A, Ahmed M, Dawkins GPC, Kazmierski M. Medical and surgical interventions for the treatment of urinary stones in children. Cochrane Database Syst Rev 2019;10:CD010784.  Back to cited text no. 12
Sultan S, Aba Umer S, Ahmed B, Naqvi SAA, Rizvi SAH. Update on surgical management of pediatric urolithiasis. Front Pediatr 2019;7:252.  Back to cited text no. 13
Radmayr C, Bogaert G, Dogan HS, Kocvara R, Nijman JM, Stein R, et al. EAU Guidelines on Paediatric Urolog. In EAU Guidelines, Edition Presented at the Annual EAU Congress Barcelona; 2019.  Back to cited text no. 14
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McAteer JA, Evan AP, Williams JC Jr, Lingeman JE. Treatment protocols to reduce renal injury during shock wave lithotripsy. Curr Opin Urol 2009;19:192-5.  Back to cited text no. 17
Willis LR, Evan AP, Connors BA, Handa RK, Blomgren PM, Lingeman JE. Prevention of lithotripsy-induced renal injury by penetrating kidneys with low-energy shock waves. J Am Soc Nephrol 2006;17:63-73.  Back to cited text no. 18
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Somani BK, Ploumidis A, Pappas A, Doizi S, Babawale O, Dragos L, et al. Pictorial review of tips and tricks for ureteroscopy and stone treatment: An essential guide for urologists from PETRA research consortium. Transl Androl Urol 2019;8:S371-80.  Back to cited text no. 20
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Sabler IM, Katafigiotis I, Gofrit ON, Duvdevani M. Present indications and techniques of percutaneous nephrolithotomy: What the future holds? Asian J Urol 2018;5:287-94.  Back to cited text no. 22
Wright A, Rukin N, Smith D, De la Rosette J, Somani BK. 'Mini, ultra, micro' - Nomenclature and cost of these new minimally invasive percutaneous nephrolithotomy (PCNL) techniques. Ther Adv Urol 2016;8:142-6.  Back to cited text no. 23
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  [Figure 1]

  [Table 1]

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