Risk factors for repeat surgical intervention in pediatric nephrolithiasis: A Pediatric Health Information System database study

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

A population-based retrospective cohort study of surgical trends and outcomes of pediatric urolithiasis in Ontario, Canada (2002-2019)

INTRODUCTION

The worldwide incidence of pediatric urinary stone disease (PUSD) is increasing. However, there is no commensurate data on whether this translates to an increasing need for surgical intervention for PUSD, given the role of conservative management.

OBJECTIVE

We aimed to evaluate the trends and outcomes of clinically significant PUSD, using administrative databases to identify patients surgically treated for PUSD.

STUDY DESIGN

This retrospective population-based cohort study assessed the incidence and trends of surgically treated PUSD and outcomes in Ontario, Canada in patients <18 years of age who underwent their first PUSD procedure between 2002 and 2019 utilizing administrative databases held at the Institute of Clinical Evaluative Sciences (ICES). We assessed the incidence of surgically treated PUSD, demographics, initial surgical treatment and imaging modality, and risk factors for repeat intervention within 5 years. Statistical analyses summarized demographics, surgical trends, and logistic regression was used to identify risk factors for repeat surgical intervention.

RESULTS

We identified 1149 patients (mean age 11.3 years), with 59.6% older than 12 years. There was a decrease in the number of PUSD procedures performed per year that was close to statistical significance (p = 0.059) and a trend towards increased utilization of ureteroscopy (URS) compared with Shockwave Lithotripsy (SWL). In addition, there was a significant increase in the proportion of females surgically treated with PUSD (p = 0.001). In the 706 patients followed for 5 years, 17.7% underwent a repeat procedure within 6 months, while 20.4% underwent a repeat procedure from 6-months to 5 years. Renal stone location (OR 2.79, 95% confidence interval (CI) 1.62-4.80, p = 0.0002) and index SWL (OR 1.66, 95% CI 1.20-2.31, p = 0.0025) were risk factors for repeat surgical intervention within the first 6-months. There was an increasing utilization of ultrasound (US) compared to computerized tomography (CT) (p = 0.0008).

DISCUSSION

Despite the literature reporting increasing PUSD incidence, we observed a non-significant decrease in the number of surgical PUSD procedures performed. Exclusion of those treated conservatively may explain our results. The increase in the proportion of females treated reflects the narrowing gender gap in stone disease. A trend towards increased URS utilization was observed and re-intervention rates were similar to previous studies.

CONCLUSION

The overall rate of surgically treated PUSD did not show an increasing trend in Ontario, Canada from 2002 to 2019. URS was the most common surgical treatment modality, with a corresponding decline in SWL rates. PUSD was associated with a high surgical re-intervention rate within 6 months.

Atypical clinical presentation and management of urinary stone disease in non-verbal non-ambulatory children

INTRODUCTION

Management of kidney stones primarily depends on various factors such as the presence of urinary tract obstruction, pain, stone size, location, impact on renal function, and the existence of infection. Renal colic is the classic presentation of an obstructive kidney stone. However, in this study, we present a cohort of non-verbal non-ambulatory (NVNA) patients who exhibit a distinct and uncommon presentation of kidney stones due to their medical conditions. Information about kidney stone disease in this gropup of complex pediatric patients is, scarce and their associated risk factors are not well understood. Therefore, we aim to summarize the clinical presentation, and management challenges in this unique group of NVNA patients to identify potential variables for prospective studies.

METHODS

A retrospective chart review was completed for all NVNA patients seen at the pediatric multidisciplinary kidney stone clinic between July 2020 to August 2022. Demographic variables, clinical presentation data, metabolic evaluation, radiological imaging, and surgical management was included for analysis.

RESULTS

A total of 224 pediatric patients were referred to the multidisciplinary stone clinic. Of those, 27 were identified to be NVNA. The most common primary diagnosis was Cerebral Palsy followed by Lennox-Gastaut syndrome. Average age at first kidney stone presentation was 11.5 years ± 5.7 years. An obstructing stone was diagnosed in 18 (66%) patients, 4 (22.2%) of these presented with sepsis. Average stone burden was 9.2 mm ( ± 5.8 mm). Of the obstructing stones, 13 (72%) were in the kidney. All patients with an obstructing stone underwent surgical management with retrograde endoscopic approach. Metabolic 24-h-urine analysis was completed in 24 (89%) patients. 17 (62%) had an elevated urine density, 15 (55%) demonstrated calcium oxalate supersaturation, 12 (44%) met criteria for acidosis, and 7 (26%) had significant hypocitraturia.

DISCUSSION

NVNA patients represent a unique cohort whose clinical presentation is atypical. Limited ability to express symptoms makes early detection difficult to recognize. Twenty two percent of patients present with sepsis as their first manifestation of an acutely obstructing kidney stone. Pain is subjectively interpreted by caregivers and is an uncommon symptom. Our cohort demonstrates common risk factors for stones including propensity for chronic dehydration, slow urinary tract transit, ineffective bladder emptying, G-tube feeding, and lithogenic medications.

CONCLUSION

NVNA pediatric patients have atypical kidney stone clinical presentation. Awareness of this unique group of patients should support future collaborative studies to focus on understanding these atypical presentations and reflect on improving management.

Clinical Features and Surgical Outcomes of the Children With Urolithiasis at a Tertiary Care Hospital: First Report From Somalia

INTRODUCTION

There are very few studies regarding pediatric urolithiasis (PU) reported from Africa, and to date, no data have been presented from Somalia. This study evaluated the sociodemographic and radiological characteristics, treatment, and outcome data of the PU patients treated at Somalia's only tertiary care center.

METHOD

The data of all patients diagnosed with urolithiasis during a 6-year period were reviewed. Only pediatric (age <18) urolithiasis patients were included. Demographic parameters, radiological features, stone characteristics, treatment, and outcome data were collected and analyzed.

RESULTS

Overall, 227 (127 male, 100 female) patients were included. The rate of PU was 8.1%. The mean patient age was 12.7 ± 3.2. More than two-thirds of the patients (n = 161, 70.9%) were adolescents. The stones were located in the kidney in 50.7%, the ureter in 33%, and the bladder in 14.5%. Distal ureteral stones (36%) accounted for the majority of ureteral stones, followed by the ureterovesical junction (26.7%) and proximal ureteral (24%) stones. The mean stone size was 16.2 mm. Most (42.3%) stones had a 10-20 mm diameter, while 23.3% were sized between 6 and 10 mm. Renal insufficiency was present in 5.3%. Among 227 patients, 101 (44.5%) underwent minimally invasive procedures including ureterorenoscopic lithotripsy (n = 40, 18%), retrograde intrarenal surgery (n = 30, 13.2%) and percutaneous nephrolithotomy (n = 31, 14%). Open pyelolithotomy was the most common surgery performed (n = 53, 22.3%). Surgical site infection developed following 3.5% of the open surgery cases. The stone-free rate was 91.3%. It was significantly higher in open cases (98%) compared to the cases performed via a minimally invasive approach (83%) (p = 0.02).

CONCLUSION

In Somalia, PU is more common than in many other countries. Open surgery continues to be the primary treatment modality for children with urolithiasis due to the restricted endourology resources. However, minimally invasive approaches have evolved over the last years.

A simulated model for fluid and tissue heating during pediatric laser lithotripsy

BACKGROUND

Laser lithotripsy (LL) is a common modality for treatment of children and adolescents with nephrolithiasis. Recent introduction of higher-powered lasers may result in more efficacious "dusting" of urinary calculi. However, in vivo animal studies and computational simulations have demonstrated rapid and sustained rise of fluid temperatures with LL, possibly resulting in irreversible tissue damage. How fluid and tissue heating during LL vary with pediatric urinary tract development, however, is unknown. We hypothesize that kidneys of younger children will be more susceptible to changes in fluid temperature and therefore tissue damage than those of older children.

METHODS

Computational simulations were developed for LL in children utilizing COMSOL Multiphysics finite-element modeling software. Simulation parameters were varied, including the child's age (3, 8, and 12 years), flow of irrigation fluid (gravity - 5 mL/min or continuous pressure flow - 40 mL/min), treatment location (renal pelvis, ureter, calyx), and power settings (5 W - 40 W). Using a simplified axisymmetric geometry to represent the collecting space, the model accounted for heat transfer via diffusion, convection, perfusion, and heat sourcing as well as tissue properties and blood flow of the urothelium and renal parenchyma. Laminar and heat-induced convection flow were simulated, assuming room-temperature ureteroscopic irrigation. Renal size was varied by age, based on normative values. The maximum fluid temperature after 60 s of simulated LL was captured. Thermal dose was calculated using the t₄₃ equivalence of 240 min as a threshold for tissue damage, as was tissue volume at risk for irreversible cellular damage.

RESULTS

Simulation with gravity flow irrigation revealed generation of thermal doses sufficient to cause tissue injury for all ages at 20 W and 40 W power settings. Higher temperatures were seen in younger ages across all power settings. Temperature increases were dampened with intermittent laser activity and continuous pressure flow irrigation.

CONCLUSIONS

Smaller renal size is more susceptible to thermal changes induced by LL. However, power settings equal to or greater than 20 W can result in temperatures high enough for tissue damage at any age. Continuous pressure flow and intermittent laser activity may mitigate the potential thermal damage from high power LL.

Imaging modalities and treatment of paediatric upper tract urolithiasis: A systematic review and update on behalf of the EAU urolithiasis guidelines panel

BACKGROUND

Prompt diagnosis and treatment of paediatric urolithiasis are required to avoid long term sequelae of renal damage.

OBJECTIVE

To systematically review the literature regarding the diagnostic imaging modalities and treatment approaches for paediatric urolithiasis.

STUDY DESIGN

PubMed, Science Direct, Scopus and Web of Science were systematically searched from January 1980-January 2019. 76 full-text articles were included.

RESULTS

Ultrasound and Kidney-Ureter-Bladder radiography are the baseline diagnostic examinations. Non-contrast Computed Tomography (CT) is the second line choice with high sensitivity (97-100%) and specificity (96-100%). Magnetic Resonance Urography accounts only for 2% of pediatric stone imaging studies. Expectant management for single, asymptomatic lower pole renal stones is an acceptable initial approach, especially in patients with non-struvite, non-cystine stones<7 mm. Limited studies exist on medical expulsive therapy as off-label treatment. Extracorporeal shock wave lithotripsy (SWL) is the first-line treatment with overall stone free rates (SFRs) of 70-90%, retreatment rates 4-50% and complication rates up to 15%. Semi-rigid ureteroscopy is effective with SFRs of 81-98%, re-treatment rates of 6.3-10% and complication rates of 1.9-23%. Flexible ureteroscopy has shown SFRs of 76-100%, retreatment rates of 0-19% and complication rates of 0-28%. SFRs after first and second-look percutaneous nephrolithotomy (PNL) are 70.1-97.3% and 84.6-97.5%, respectively with an overall complication rate of 20%. Open surgery is seldom used, while laparoscopy is effective for stones refractory to SWL and PNL. Limited data exist for robot-assisted management.

CONCLUSIONS

In the initial assessment of paediatric urolithiasis, US is recommended as first imaging modality, while non-contrast CT is the second option. SWL is recommended as first line treatment for renal stones <20 mm and for ureteral stones<10 mm. Ureteroscopy is a feasible alternative both for ureteral stones not amenable to SWL as well as for renal stones <20 mm (using flexible). PNL is recommended for renal stones >20 mm.

Outcomes of ureteroscopy (URS) for stone disease in the paediatric population: results of over 100 URS procedures from a UK tertiary centre

PURPOSE

To report the outcomes of paediatric ureteroscopy (URS) for stone disease from a specialist endourology centre in the UK. Ureteroscopy for management of stone disease has increased worldwide and is now being done more commonly in the paediatric age group.

METHODS

Data were analysed retrospectively from a database maintained between April 2010 and May 2018. Consecutive patients ≤ 16 years of age undergoing semi-rigid or flexible URS for stone disease were included. Stone size and stone-free rate (SFR) were routinely assessed using an ultrasound (USS) and/or plain KUB XR. Complications were graded according to the Clavien-Dindo classification and recorded within 30 days post-procedure and readmissions within 90 days after the procedure were also captured.

RESULTS

Over the 8-year period between April 2010 and April 2018, 81 patients with a mean age of 8.8 years (range 18 months-16 years) and a male to female ratio 1:1.1 underwent 102 procedures (1.28 procedure/patient to be stone free). Of the 81 patients, 29 (35.8%) had comorbidities, with 26 (32%) having multiple comorbidities. The mean (± SEM) single and overall stone size was 9.2 mm (± 0.48, range 3-30 mm) and 11.5 mm (± 0.74, range 4-46 mm) respectively, with 22 (27.1%) having multiple stones. Thirty-five (34.7%) had stent in situ pre-operatively. The stone location was in the ureter (26.6%), lower pole (35.4%), and renal pelvis (16.5%), with 22/81(27%) having multiple stones and 21/102 (20.5%) where a ureteral access sheath (UAS) was used. With a mean hospital stay of 1.2 days, the initial and final SFR was 73% and 99%, respectively, and 61/102 (60%) had ureteric stent placed at the end of the procedure. While there were no intra-operative complications, the readmission rate was less than 1% and there were only three early complications recorded. This included a case each of prolonged admission for pain control (grade I), urinary retention (grade II) and post-operative sepsis requiring a brief ITU admission (grade IV).

CONCLUSION

Our study demonstrates that in appropriate setting a high stone-free rate can be achieved with minimal morbidity for paediatric patients. There is potentially a need to factor the increasing role of URS in future paediatric urolithiasis guidelines.

Extracorporeal shock wave lithotripsy versus ureteroscopy for management of pediatric nephrolithiasis in upper urinary tract stones: multi-institutional outcomes of efficacy and morbidity

INTRODUCTION

As the incidence of pediatric nephrolithiasis rises, understanding the efficacy and morbidity of surgical treatment options is critical. Currently, there are limited comparative data assessing shock wave lithotripsy (SWL) and ureteroscopy (URS) outcomes in children.

OBJECTIVE

The objective of this study was to compare stone clearance, 30-day emergency department visits, and the number of general anesthetics required per stone treatment for both modalities.

STUDY DESIGN

A multi-institutional retrospective review of children presenting for either URS or SWL between 2000 and 2017 was performed. Stone clearance, need for retreatment, the number of anesthetics, as well as the number and reason for emergency room visit were captured and compared between groups. Multivariate statistical analysis accounting for age, stone location, stone diameter, pre-intervention stent, and provider volume was performed for adjusted analysis.

RESULTS

A total of 84 SWL and 175 URS procedures were included. Complete stone clearance and rates of residual stone fragments <4 mm after final procedure for SWL were 77.0% and 90.8% and for URS were 78.5% and 91.7%, respectively. Retreatment rates for both procedures were not significantly different (17.9% SWL vs. 18.9% URS, P = 0.85). Children who underwent SWL had lower rates of emergency room visits for infections (0% vs. 5.1%, P = 0.03) and flank pain (3.6% vs. 10.9%, P = 0.05) and required fewer general anesthetics per treatment (1.2 vs. 2.0, P < 0.01) than those who underwent URS (Figure).

DISCUSSION

Stone clearance after both the initial and final treatments and need for repeat interventions were similar between surgical modalities. However, SWL carries less morbidity than URS. Specifically, patients who underwent SWL experienced lower rates of ED visits for urinary tract infection and for flank pain, parallel to conclusions in current comparative literature. In addition, SWL requires less general anesthetics (2.0 vs. 1.2), secondary to lower rates of ureteral stent placement and removal. Data on the potential risk of general anesthetics to neurodevelopment support thoughtful utilization of these medications. Limitations of this study include its retrospective nature and the prolonged 20-year time period over which data were collected.

CONCLUSIONS

When adjusting for confounders, SWL and URS achieve similar stone clearance. In the setting of equivalent efficacy, considerations regarding necessity of repeat interventions, morbidity of anesthesia, and complications should be integrated into clinical practice.

Pediatric Stone Disease

Once considered rare, pediatric nephrolithiasis has become a critical field of study in the last decade due to the rapid increase in incidence. Understanding the changing epidemiology and lifelong implications of pediatric stone disease is critically important to effectively manage the individual patient as well as identify risk factors for childhood onset that could be modified. Determining the role of diagnostic imaging in children is a unique challenge as limiting radiation and imaging stewardship should be priorities. Approaches to management have also changed, as technology continues to evolve and both medical and surgical options expand.