Clinical effectiveness in the diagnosis and acute management of pediatric nephrolithiasis

Radiation exposure associated with computed tomography for pediatric urolithiasis evaluation: A scoping review of the literature

INTRODUCTION

Computed tomography (CT) imaging is used for assessment of pediatric urolithiasis in cases where ultrasound is inconclusive. The utility of CT imaging must be considered alongside the potential risks of radiation exposure in this patient population due to the increased risk of cancer development. The purpose of this review is to investigate the radiation exposure associated with standard-dose and low-dose computed tomography (CT) imaging for the assessment of pediatric urolithiasis.

METHODS

A scoping literature review over a 23 year period between 2000 and 2023 was conducted of all English-language studies reporting on the use of non-contrast CT imaging for assessment of pediatric urolithiasis. Patients that were specified as pediatric with age ≤20 years at time of intervention and undergoing standard-dose or low/ultra-low-dose CT were included. Low-dose and ultra-low-dose CT were defined as a radiation dose ≤3.0 mSv and ≤1.9 mSv, respectively.

RESULTS

A total of 8121 articles were identified and after screening, 6 articles representing 309 patients were included in this scoping review. Of the articles reviewed, standard non-contrast CT radiation doses for pediatric urolithiasis evaluation ranged from 2.9 to 5.5 mSv and low-dose CT radiation dose was reported to be 1.0-2.72 mSv. Only 2 studies directly evaluated low-dose CT imaging compared to standard-dose CT imaging for pediatric urolithiasis assessment. Radiation reduction approaches did not negatively impact urolithiasis detection or characterization in 2 studies reviewed.

CONCLUSIONS

CT radiation doses for suspected or known pediatric urolithiasis are underreported and vary greatly with underutilization of low-dose/ultra-dose protocols for pediatric urolithiasis especially in comparison to the adult population. Results from this scoping review support that low-dose CTprotocols for pediatric stone disease are feasible to reduce radiation exposure.

Is There Any Effect of Retrograde Intrarenal Stone Surgery on Renal Functions in Childhood?

Purpose In this study, we aimed to demonstrate whether retrograde intrarenal stone surgery (RIRS) performed due to renal stones during the childhood period has any detrimental impact on renal functions. Materials and methods We retrospectively analyzed 121 patients aged 2 to 16 years who underwent RIRS for renal stones between March 2018 and February 2023. Data were available for 41 patients. The estimated glomerular filtration rate (eGFR) was computed using the modification of diet in renal disease (MDRD) formula on the day preceding the surgery and the third month after the surgery. We employed the National Kidney Foundation's chronic kidney disease (CKD) classification to categorize the glomerular filtration rate (GFR) into five groups. Preoperative and postoperative eGFR values of pediatric patients were compared by analyzing changes in CKD groups. Results Of the patients included in the study, 21 (51.2%) were male, while 20 (48.8%) were female children. No significant difference was found between the preoperative median eGFR and the postoperative median eGFR values (p=0.958). In the 3rd month after surgery, it was observed that 5 (12.1%) patients showed an improvement in their CKD stage, while deterioration was noted in 1 (2.4%) patient. Although a negative correlation was observed between the median eGFR change and both the operation time and the stone volume in Pearson correlation analysis, it was determined that this change did not create a significant difference (p=0.213 and p=0.295, respectively). Conclusion Stone surgery conducted with RIRS appears to yield positive outcomes on kidney function in the pediatric population. Nevertheless, being particularly attentive to patients with prolonged operation times and larger stone volumes is essential.

Use of whole-exome sequencing to identify novel monogenic gene mutations and genotype-phenotype correlations in Chinese Han children with urolithiasis

The incidence of urolithiasis (UL) in children has been increasing. Although the pathogenesis of pediatric UL is controversial and remains unclear, multiple monogenic causes of UL have been identified. We aim to investigate the prevalence of inherited UL causes and explore the genotype-phenotype correlation in a Chinese pediatric group. In this study, we analyzed the DNA of 82 pediatric UL patients using exome sequencing (ES). The data of metabolic evaluation and genomic sequencing were subsequently analyzed together. We detected 54 genetic mutations in 12 of 30 UL-related genes. A total of 15 detected variants were described as pathogenic mutations, and 12 mutations were considered likely pathogenic. Molecular diagnoses were made in 21 patients with pathogenic or likely pathogenic variants. Six novel mutations that were not previously reported were identified in this cohort. Calcium oxalate stones were detected in 88.9% cases (8/9) with hyperoxaluria-related mutations, while 80% of individuals (4/5) with cystinuria-causing defects were diagnosed with cystine stones. Our study highlights the significant genetic abnormalities in pediatric UL and demonstrates the diagnostic power of ES for screening patients with UL.

Role of Pediatric Ureteral Access Sheath and Outcomes Related to Flexible Ureteroscopy and Laser Stone Fragmentation: A Systematic Review of Literature

Context

Flexible ureteroscopy and laser lithotripsy (FURSL) represent a good treatment option for pediatric urolithiasis. Scarce evidence is available about the safety and efficacy of the concomitant use of a ureteral access sheath (UAS) in the setting of pediatric ureteroscopy (URS).

Objective

To acquire all the available evidence on UAS usage in pediatric FURSL, focusing on intra- and postoperative complications and stone-free rates (SFRs).

Evidence acquisition

We performed a systematic literature research using PubMed/MEDLINE, Embase, and Scopus databases. The inclusion criteria were cohorts of pediatric patients <18 yr old, submitted to URS for FURSL, reporting on more than ten cases of UAS placement. The primary outcomes were prestenting rates, operating time, ureteric stent placement rates after surgery, rates and grades of complications, ureteral injuries, and overall SFR. A total of 22 articles were selected.

Evidence synthesis

In total, 26 intraoperative and 130 postoperative complications following URS with UAS placement were reported (1.8% and 9.18% of the overall procedures, respectively). According to the Clavien-Dindo classification, 32 were classified as Clavien I, 29 as Clavien II, 43 as Clavien I or II, six as Clavien III, and one as Clavien IV. Twenty-one cases of ureteral injuries (1.59%) were noted in the whole cohort; most of them were ureteral perforation or extravasation, and were treated with a temporary indwelling ureteric stent. The overall SFR after a single URS procedure was 76.92%; after at least a second procedure, it was 84.9%.

Conclusions

FURSL is a safe and effective treatment option for pediatric urolithiasis. UAS use was associated with a low rate of ureteric injuries, mostly treated and resolved with a temporary indwelling ureteric stent.

Patient summary

We performed a systematic literature research on the utilization of a UAS during ureteroscopy for stone treatment in pediatric patients. We assessed the outcomes related to the rates of intra- and postoperative complications and the rates of efficacy of the procedure in the clearance of stones. The evidence shows a low rate and grade of complications associated with UAS placement and good stone-free outcomes. A ureteric injury may occur in 1.6% of cases, but it is usually managed and resolved with a temporary indwelling ureteric stent.

The effect of preoperative tamsulosin on ureteroscopic access in school-aged children

INTRODUCTION

Flexible ureteroscopes are not tailored for pediatric ureteral size and may not pass at first attempt into the pediatric ureter. Administration of tamsulosin preoperatively in adults has been shown to facilitate ureteral access sheath placement. Several studies have shown tamsulosin to be safe and effective when utilized for medical expulsive therapy in pediatric patients, but its utility for preoperative ureteral dilation has not been studied to date.

OBJECTIVE

We hypothesized that preoperative tamsulosin reduces failed ureteroscopic access in children.

MATERIALS AND METHODS

We conducted a retrospective review of patients aged 0-18 years undergoing flexible ureteroscopy (URS) from 2014 to 2019 at a single institution. Patients were divided into those taking 0.4 mg of tamsulosin daily for at least 1 week prior to surgery and those not taking tamsulosin. The primary outcome was failure to pass a 7.95 Fr flexible ureteroscope on initial attempt, requiring stent placement and staged management. Patients undergoing URS or stent placement within the prior year, requiring semi-rigid URS, or with genitourinary anomalies were excluded.

RESULTS AND DISCUSSION

A total of 49 patients met inclusion criteria. The tamsulosin group (n = 13) and non-tamsulosin group (n = 36) were similar with respect to demographic data. The percentage of prepubertal patients was 53% vs 33% (p = 0.19). The tamsulosin group had lower failed URS (38% vs 61%, p = 0.20). When stratified by age, both prepubertal and postpubertal patients in the tamsulosin group had lower failed URS (43% vs 67%, p = 0.67 and 33% vs 58%, p = 0.38). These clinically significant results suggest initial passage of a flexible ureteroscope is more successful in pediatric patients on preoperative tamsulosin. This study was largely limited by its low power and flaws inherent to its retrospective design.

CONCLUSION

Our results have implications for prescribing tamsulosin preoperatively to reduce multiple procedures and anesthetics in children. Adequately powered prospective trials are warranted to confirm preoperative tamsulosin reduces failed first-attempt flexible URS in children.

Postoperative outcomes of ureteroscopy for pediatric urolithiasis: A secondary analysis of the National Surgical Quality Improvement Program Pediatric

INTRODUCTION

Incidence of pediatric urinary stone disease (PUSD) has increased over recent decades. Innovations in ureteroscopic technology has expanded the role of endourologic stone management in children. However, there is currently no consensus on the optimal use of ureteroscopy (URS) within the heterogenous PUSD population.

OBJECTIVE

The primary objective was to investigate the rate of 30-day unplanned readmissions in pediatric patients after URS. The secondary objective was to examine the influence of demographic, perioperative, postoperative, and reoperation variables as predictors of an increased risk of unplanned readmission in this sample.

STUDY DESIGN

A secondary analysis was performed on retrospectively collected data from the National Surgical Quality Improvement Program Pediatric between 2015 and 2018. Pediatric patients diagnosed with PUSD and treated with URS were identified. Patients undergoing concurrent or additional surgeries during the URS procedure were excluded. Data on demographic, perioperative, postoperative, and unplanned reoperation variables were examined for their possible influence on 30-day unplanned readmissions. Descriptive statistics were used to characterize the study cohort. Continuous and categorical variables were analyzed using independent samples t-test, one-way ANOVA with Tukey post-hoc test, and Chi-square Tests or Fisher's Exact Test, respectfully. Multivariate analysis was performed using stepwise logistic regression.

RESULTS

A total of 2510 patients were identified within the study period. The majority of children undergoing URS were between 12 and 18 years of age (66.1%), female (56.9%), and had renal calculi (45.2%). Of these, 162 (6.5%) experienced a 30-day unplanned readmission related to the URS procedure. The most common reasons for an unplanned readmission was urinary tract infection (31.4%), new/unresolved stone (28.3%), and postoperative pain (8.2%). Multivariate modelling showed that females (Relative Risk [RR]: 2.03; 95% Confidence Interval [95%CI]: 1.34-3.07), patients with renal stones (RR: 1.77; 95%CI: 1.10-2.83), and inpatients at the time of surgery (RR: 1.61; 95%CI: 1.03-2.51) were more at risk of an unplanned readmission within 30-days of an URS procedure.

CONCLUSION

This study reports on short-term unplanned readmission rates in pediatric patients who underwent an URS procedure. Further it highlights possible predictors of unplanned readmission rates within a sampling of patients from NSQIP affiliated institutions. The findings from this study can be used to guide future studies around the safe use of URS in pediatric patients.

Proximal ureteral access for symptomatic stone removal using ultrathin semirigid ureterorenoscope in preschool-age children: Is it possible?

INTRODUCTION AND OBJECTIVES

We aimed to point out the ureteral access facility and obstruction removal efficiency of mini-URS in the use of proximal ureteral stone management in children under five-year-old.

PATIENTS

We retrospectively reviewed the data of 26 children who underwent mini-URS-LL for obstructive stones in proximal ureter between January 2016 and August 2018. The effectiveness of the mini-URS-LL was assessed based on the feasibility, reliability, and success of the technique.

RESULTS

Mean age was 3 ± 1.3 years, and 11 (42.3%) patients were ≤2 years old, remaining 15 (57.7%) were aged 3-5 years. Mean stone size was 9.11 ± 3.02 mm. A stone-free status was obtained at the end of 31 ureteroscopic procedure in 24 (92.3%) patients. The mean age was found significantly higher in patients who had the procedure without pre-stenting than the others who did (P = .027). No perioperative complication was experienced.

CONCLUSION

In preschool-age children, laser lithotripsy with mini-URS may be a safe technique in the hands with advanced endo-urological skills but it has low efficacy with higher rates of prestenting causing additional anesthesia sessions.

Proximal ureteral access for symptomatic stone removal using ultrathin semirigid ureterorenoscope in preschool-age children: Is it possible?

INTRODUCTION AND OBJECTIVES

We aimed to point out the ureteral access facility and obstruction removal efficiency of mini-URS in the use of proximal ureteral stone management in children under five-year-old.

PATIENTS

We retrospectively reviewed the data of 26 children who underwent mini-URS-LL for obstructive stones in proximal ureter between January 2016 and August 2018. The effectiveness of the mini-URS-LL was assessed based on the feasibility, reliability, and success of the technique.

RESULTS

Mean age was 3±1.3 years, and 11 (42.3%) patients were≤2 years old, remaining 15 (57.7%) were aged 3-5 years. Mean stone size was 9.11±3.02mm. A stone-free status was obtained at the end of 31 ureteroscopic procedure in 24 (92.3%) patients. The mean age was found significantly higher in patients who had the procedure without pre-stenting than the others who did (P=.027). No perioperative complication was experienced.

CONCLUSION

In preschool-age children, laser lithotripsy with mini-URS may be a safe technique in the hands with advanced endo-urological skills but it has low efficacy with higher rates of prestenting causing additional anesthesia sessions.

Comparison of Renal Stones and Nephrocalcinosis in Children: Findings From Two Tertiary Centers in Saudi Arabia

Background: Renal stones (nephrolithiasis and urolithiasis) and nephrocalcinosis are uncommon in children; however, their incidences in pediatric populations have been increasing. Patients and Methods: This multicenter retrospective study compared the clinical presentation, etiology, and outcomes of childhood nephrolithiasis or urolithiasis with those of nephrocalcinosis. Results: The study included 144 children: 93 with renal stones and 51 with nephrocalcinosis. The mean age at presentation was 72 months and 54 months for children with renal stones and nephrocalcinosis, respectively. A history of consanguinity was found in 65% and 76% of the cases of renal stones and nephrocalcinosis, respectively. Congenital anomalies of the kidneys and urinary tract (CAKUT) were present in 28 and 9.8% of the patients with renal stones and nephrocalcinosis, respectively. The most common symptoms of renal stones were flank pain (29%), hematuria (15%), and dysuria (11%). Urinary tract infection was the primary presentation in the nephrocalcinosis group (18%), followed by failure to thrive (16%), polyuria (12%), and dehydration (12%). The majority of renal stone cases were caused by metabolic disorders, including hyperoxaluria (18%), cystinuria (18%), hypercalciuria (12%), and hyperuricosuria (2%). In contrast, the most common underlying disorders in cases of nephrocalcinosis were familial hypomagnesemia, hypercalciuria, nephrocalcinosis (35%), distal renal tubular acidosis (23%), and Bartter syndrome (6%). Clinical outcomes were significantly better in children with nephrolithiasis/urolithiasis than in those with nephrocalcinosis, who showed radiological evidence of worsening/persistent calcinosis and progressed more frequently to chronic kidney disease (stage II-IV) and end-stage kidney disease. Conclusion: The average age at presentation for children with renal stones was greater than that for those presenting with nephrocalcinosis. More than 25% of the children with renal stones were found to have CAKUT. Nephrocalcinosis was associated with worse clinical outcomes related to kidney function and disease resolution than nephrolithiasis.

What predicts spontaneous passage of ≤1 cm ureteral stones in children?

PURPOSE

The aim of this study is to determine what factors predict spontaneous passage of ≤1 cm ureteral stones in children.

METHODS

Files of the patients diagnosed with a single ureteral stone on a given side between 2008 and 2017 were retrospectively reviewed. Patients with congenital obstructive uropathy, neurogenic bladder, vesicoureteral reflux and those with a stone diameter of >1 cm were excluded. Detection of ureteral stones was done using ultrasonography (US) primarily, and computed tomography when US findings were inconclusive. Patients were treated either conservatively or surgically. Conservative treatment included adequate hydration and pain management whereas surgical treatment included ureteroscopic intervention. Apart from those who required urgent intervention, patients were referred for surgical treatment after 2-4 weeks of follow-up with no spontaneous passage. Factors analyzed for association of spontaneous passage included age, gender, type of hematuria, stone localization, laterality, presence of concomitant kidney stone, degree of hydronephrosis, stone size and stone composition.

RESULTS

A total of 70 patients (38 males, 32 females); median age 4.7 years had a ≤ 1 cm ureteral stone (median diameter 7 mm). US was able to diagnose the ureteric stone in 47 patients while computed tomography was required in 23 patients. Spontaneous passage was observed in 40 patients (57.1%). Median time for stone passage was 8 days (3-34 days). Stone size and presence of hematuria (macroscopic and microscopic combined) were factors associated with spontaneous passage and 6.7 mm was found to be the cut-off (AUC = 0.953; 95% CI 0.905-1.000; sensitivity 96.7%, specificity 82.5%, p < 0.001). Moreover, age, degree of hydronephrosis or stone location were not associated with spontaneous passage.

CONCLUSION

Patients with a ureteric stone size <6.7 mm can safely be followed conservatively, with a spontaneous passage rate of 82.5%. Type of Study Case series with no comparison group. Level of Evidence IV.

Educational review: role of the pediatric nephrologists in the work-up and management of kidney stones

BACKGROUND

The incidence of nephrolithiasis in children and adolescents is increasing and appears to double every 10 years. The most important role of the pediatric nephrologist is to diagnose and modify various metabolic and non-metabolic risk factors, as well as prevent long-term complications especially in the case of recurrent nephrolithiasis.

OBJECTIVE

The purpose of this review is to summarize the existing literature on the etiology and management of pediatric nephrolithiasis.

RESULTS

The incidence of kidney stones is increasing; dietary and environmental factors are probably the main causes for this increased incidence. In most pediatric patients, the etiology for the kidney stones can be identified. Metabolic factors, such as hypercalciuria and hypocitraturia, urinary tract infection, and urinary stasis, constitute leading causes. Herein, we review the etiologies, diagnostic work-up, and treatment options for the most prevalent causes of kidney stones. The detrimental effects of excessive dietary sodium, reduced fluid intake, and the benefits of plant-based over animal-based protein consumption on urinary crystal formation are discussed. We also review the long-term complications.

CONCLUSIONS

Pediatric nephrologists have an important role in the diagnostic work-up and prevention of recurring nephrolithiasis.

The Urological Association of Asia clinical guideline for urinary stone disease

The Urological Association of Asia, consisting of 25 member associations and one affiliated member since its foundation in 1990, has planned to develop Asian guidelines for all urological fields. The field of stone diseases is the third of its guideline projects. Because of the different climates, and social, economic and ethnic environments, the clinical practice for urinary stone diseases widely varies among the Asian countries. The committee members of the Urological Association of Asia on the clinical guidelines for urinary stone disease carried out a surveillance study to better understand the diversity of the treatment strategy among different regions and subsequent systematic literature review through PubMed and MEDLINE database between 1966 and 2017. Levels of evidence and grades of recommendation for each management were decided according to the relevant strategy. Each clinical question and answer were thoroughly reviewed and discussed by all committee members and their colleagues, with suggestions from expert representatives of the American Urological Association and European Association of Urology. However, we focused on the pragmatic care of patients and our own evidence throughout Asia, which included recent surgical trends, such as miniaturized percutaneous nephrolithotomy and endoscopic combined intrarenal surgery. This guideline covers all fields of stone diseases, from etiology to recurrence prevention. Here, we present a short summary of the first version of the guideline - consisting 43 clinical questions - and overview its key practical issues.

Comparison of Ultrasonography and Low-Dose Computed Tomography for the Diagnosis of Pediatric Urolithiasis in the Emergency Department

OBJECTIVE

This study aimed to compare ultrasonography (US) and low-dose computed tomography (LDCT) for diagnosing pediatric urolithiasis in the emergency department.

MATERIALS AND METHODS

This retrospective study was approved by our institutional ethics committee, and informed consent was waived. From March 2016 to March 2017, 100 consecutive patients met the selection criteria and were enrolled in the study. Patients were randomly selected in a 1:1 ratio and were allocated to one of the following two imaging groups: US or abdominal LDCT. LDCT examinations were performed using a 320-detector row CT. Radiation dose analysis was performed using Radimetrics. US examinations were performed using the Aplio 500 ultrasound system. The presence of urolithiasis, anatomical location of urolithiasis, and measurements of renal stones were evaluated and recorded.

RESULTS

There were statistically significant differences between US and standard-dose CT (SDCT) with respect to the diagnosis of urolithiasis, anatomical location of urolithiasis, and measurements of renal stones (p<0.001, p=0.005, and p=0.03, respectively). The mean effective radiation dose of LDCT was 1.44±0.34 mSv and that of SDCT was calculated to be 4.36±1.33 mSv. There was no statistically significant difference between LDCT and SDCT with regard to the diagnosis of urolithiasis, anatomical location of urolithiasis and measurements of renal stones (p=1 for all). The diagnostic accuracy of US and LDCT was 0.68 and 1.0, respectively.

CONCLUSION

Low-dose computed tomography had 1/3 SDCT radiation dose, and LDCT and SDCT accurately diagnosed pediatric urolithiasis in the emergency department. US had a lower accuracy than SDCT and LDCT for diagnosing pediatric urolithiasis in the emergency department. LDCT can be an alternative for SDCT for diagnosing pediatric urolithiasis.

Pediatric Nephrolithiasis: A Review

The incidence of pediatric nephrolithiasis is on the rise. The composition of kidney stones in children is different than in adults, as most stones in children have a composition of calcium oxalate and calcium phosphate mixed with a small amount of uric acid. The symptoms of pediatric nephrolithiasis are nonspecific. Computed tomography (CT) is the gold standard for diagnosis; however, because of radiation exposure associated with a CT scan, ultrasonography is also an accepted modality for the diagnosis. Extensive metabolic evaluation is important to rule out an underlying metabolic disorder. Urinary decompression, medical expulsion therapy, and surgical interventions such as ureteroscopy and extracorporeal shockwave lithotripsy are some of the options available for treating pediatric nephrolithiasis. [Pediatr Ann. 2017;46(6):e242-e244.].