Pediatric Stone Disease

Is percutaneous nephrolithotomy effective and safe in infants younger than 2 Years old? Comparison of mini standard percutaneous nephrolithotomy

BACKGROUND

In this study, we aimed to compare the operative outcomes, postoperative outcomes, stone-free status and complications of SPCNL and MPCNL in infants younger than two years of age.

METHODS

We retrospectively analyzed 163 patients younger than two years of age who underwent percutaneous nephrolithotomy (PCNL) in our institution between September 1999 and March 2022. The patients were divided into two groups depending on the tract size. The MPCNL group consisted of 73 patients with a tract of 22 Fr or less, and the SPCNL consisted of 90 patients with a tract greater than 22 Fr.

RESULTS

The median age of 163 patients included in the study was 17.3 (range 7-24) months. Although the median stone size was lower in the SPCNL group, no statistically significant difference was found between the two groups in terms of stone size (p = 0.073). The median operative time was 74.8 min in the MPCNL group and 62.8 min in the SPCNL group, with a statistically significant difference (p = 0.002). Stone free rates (SFR) were 89 % and 90.8 % in the MPCNL and SPCNL groups, and the clinically insignificant residual fragments (CIRF) rates were 11 % and 4.6 %, respectively (p = 0.064). The fluoroscopy time, nephrostomy withdrawal time, and hospitalization stay were similar in the two PCNL groups (p = 0.535, p = 0.253, and p = 0.143, respectively). Postoperative fever was similar in MPCNL and SPCNL groups (p = 0.504). Although bleeding (6.7%-2.7 %) and blood transfusion (3.3%-1.4 %) rates were higher in the SPCNL group, there was no statistically significant difference (p = 0.248 and p = 0.420, respectively). Prolonged urinary leakage occurred in 6 (8.2 %) patients in the MPCNL group and 1 (1.1 %) patient in the SPCNL group, with a statistically significant difference (p = 0.026).

CONCLUSIONS

With the development of MPCNL, the use of SPCNL in infants has decreased considerably. However, SPCNL continues to be an effective and reliable method when needed in suitable patients. Although PCNL in infants shows some differences from adults, it is an effective and safe method for suitable patients.

LEVEL OF EVIDENCE

Although we created our study by retrospectively examining the pediatric urology data that we created prospectively, our study is of a retrospective nature. Therefore the Level of Evidence is 3.

Deciding on a novel predictive value to gauge how well patients with lower ureteric stones respond to medical expulsive therapy

This study, conducted over 4 years in Baghdad, Iraq, aimed to determine the importance of ureteric jet assessment in medical expulsive therapy (MET) for distal ureteral stones. A total of 156 patients with distal ureteral stones (≤ 10 mm) participated, and their ureteric jets were observed using a color Doppler scanner before and after 2 weeks of MET. The main focus was the success rate of stone expulsion. Our results showed that 50% of patients had detectable ureteric jets after 2 weeks of MET, and 21.8% experienced successful stone expulsion. After 4 weeks, 23.7% achieved stone expulsion, while 54.5% still had remaining stones. Patients who had a positive baseline ureteric jet were significantly more likely to successfully expel their stones. This study highlights the importance of monitoring ureteric jet movement in MET for distal ureteral stones.

Clinical patterns and implications of prescription opioid use in a pediatric population for the management of urolithiasis in the emergency room

Extrapolations from the adult population have suggested that opioids should be avoided in the management of pediatric urolithiasis, but the literature is sparse with regards to actual practice patterns and the downstream implications. We sought to investigate the rate of oral opioid administration for children presenting to the emergency room (ER) with urolithiasis and to identify associations between opioid administration and return visits and persistent opioid use. The TriNetX Research and Diamond Networks were used for retrospective exploratory and validation analyses, respectively. Patients <18 years presenting to the emergency room with urolithiasis were stratified by the receipt of oral opioids. Propensity score matching was performed in a 1:1 fashion. Incident cases of opioid administration and risk ratios (RRs) for a return ER visit within 14 days and the presence of an opioid prescription at 6 to 12 months were calculated. Of the 4672 patients in the exploratory cohort, 11.9% were prescribed oral opioids. Matching yielded a total of 1084 patients. Opioids at the index visit were associated with an increased risk of return visits (RR 1.51, 95% CI 1.04-2.20, P = 0.03) and persistent opioid use (RR 4.00, 95% CI 2.20-7.26, P < 0.001). The validation cohort included 6524 patients, of whom 5.7% were prescribed oral opioids. Matching yielded a total of 722 patients and demonstrated that opioids were associated with an increased risk of return visits (RR 1.50, 95% CI 1.04-2.16, P = 0.03) but not persistent opioid use (RR 1.70, 95% CI 0.79-3.67, P = 0.17). We find that the opioid administration rate for pediatric urolithiasis appears reassuringly low and that opioids are associated with a greater risk of return visits and persistent use.

Mini-versus standard percutaneous nephrolithotomy in pediatric population: A randomized controlled trial

INTRODUCTION

Mini PCNL has gained popularity in adult patients due to reduction in the complication rate with comparable stone free rate. There is paucity of level 1 evidence regarding the benefit of mini PCNL in the pediatric group.

OBJECTIVE

We performed a randomised study to compare mini PCNL (mPCNL) with standard PCNL (sPCNL) for the management of renal calculi in patients less than 18 years of age in terms of safety, efficacy, and stone-free rate (SFR).

MATERIALS AND METHODS

A randomised controlled trial was performed on 50 children who underwent PCNL from June 2015 to March 2021, who were divided into two groups. Group I had 25 patients managed with mPCNL (sheath size 16.5 Fr) and Group II had 25 patients who underwent sPCNL (sheath size 26 Fr). Primary outcomes including stone free rates (SFR) and hemoglobin drop and secondary outcomes like operative time, complications, pain score, need of analgesia, incidence of nephrostomy site leak, hospital stay in days were compared between the two groups.

RESULTS

The mean age of patients in groups I and II was 9.4 ± 2.6 and 10.4 ± 2.26 years, respectively (p = 0.15). The mean stone sizes in both groups I and II were 18.6 ± 2.56 and 20.2 ± 3.58 mm, respectively (p > 0.05). The stone free rate for group I was 88% and for group II, 92% (p = 0.64). The average drop in hemoglobin was higher in group II compared to group I (1.1 ± 0.31 g/dl and 1.7 ± 0.23 g/dl respectively; p < 0.0001), however the mean blood transfusion rate was not significantly different in both groups. The operating time was shorter in group II compared to group I (p-value - 0.0030). The pain scores were lesser for the group I. Grade I complications were higher in group II as compared to group I (p-0.047); however, grade II complications were comparable in both groups. The mean hospital stay was not significantly different in both groups.

DISCUSSION

This study confirms the role of mini PCNL in pediatric patients with renal stones. The stone clearance rate of mini PCNL is equivalent to standard PCNL, with lesser blood loss and postoperative complications, however with longer operative time during mPCNL. The small number of the participants in both arms is a limitation of this study and may also reflect fewer children with urolithiasis being treated surgically even in a tertiary care referral centre.

CONCLUSIONS

Mini-PCNL offers equivalent stone free outcome with lower complications rate compared to the standard PCNL for all types of renal stones.

Nur MA, Mohamed FY, Mohamud AK, Hassan J. The prevalence of urolithiasis in subjects undergoing computer tomography in selected referral diagnostic centers in Mogadishu, Somalia

Introduction and objectives

Somalia was predicted to be in the global stone belt with high urolithiasis prevalence. We aimed to determine the prevalence of urolithiasis and their demographic and computer tomography (CT) characteristics among subjects under CT scans in Mogadishu, Somalia. Materials and Methods: From March 2014 to November 2022, a total of 7,276 patients who underwent an abdominopelvic non-contrast CT scan for various indications were retrospectively reviewed. The mean age was 45.6 years with a standard deviation of 21.1 (range, 0.2-110 years). Patients were subdivided into two categories: adults (≥18 years) and pediatric (≤17 years).

Results

Of the 7,276 patients, 1,075 (14.8%) were diagnosed with urolithiasis. Among those with urolithiasis, 702 (65.3%) were male patients, and 373 (34.7%) were female patients. Among them, adults accounted for 92.7%, while children were 7.3%. Renal stones (nephrolithiasis) were the most common, representing 57% followed by ureteric stones at 35.5%, making upper urinary stones 92.5%. Approximately 70 patients (6.5%) had bladder stones; of these, 26 of them (37%) were accompanied by benign prostatic hyperplasia (BPH). There were 10 urethral stones (0.9%) recorded in the study, all were found in male patients, 8 localized in prostatic urethra, and 2 in the bulbar urethra. The overall mean stone size was 13.2 mm, and 60% of them ranged from 5 to 22 mm. Only 24% of the patients were asymptomatic. Single stones were almost 70%, while staghorn calculi were 8.2%. More than 60% of the patients with urolithiasis showed some degree of hydronephrosis ranging between mild to severe.

Conclusion

A CT scan-based urolithiasis prevalence indicates 14.8% in Mogadishu, Somalia, and these results are consistent with the probability calculation of the weights-of-evidence (WofE) methodology based on several risk factors including temperature, climate change, mineral deposit, drinking water quality, and distribution of carbonated rocks. Considering the high prevalence of the disease, Somalia needs to invest more in prevention and treatment facilities while also training urologists that are capable of utilizing minimally invasive techniques in the country.

Pediatric Stone Disease: Current Trends and Future Directions

Pediatric nephrolithiasis is less common in children than in adults but the incidence has been rising rapidly, and it is now a public health and economic burden in the United States. There are challenges unique to children that should be taken into consideration when evaluating and managing pediatric stone disease. In this review, we present the current research on risk factors, emerging new technologies for treatment of stones and recent investigations on prevention of stones in this population.

Epidemiology of Kidney Stones

In the past two decades, major breakthroughs that improve our understanding of the pathophysiology and therapy of kidney stones (KS) have been lacking. The disease continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of kidney stones. Our expanding knowledge of the epidemiology of kidney stones is of paramount importance and largely upgrades the modern management of the disease. In this paper, we review the variables affecting prevalence and incidence, including age, gender, race, ethnicity, occupation, climate, geography, systemic diseases, diabetes, vascular disease, chronic kidney disease, and dietary risk factors relevant to kidney stones.

Dietary management of hypocitraturia in children with urolithiasis: results from a systematic review

PURPOSE

Hypocitraturia is a low urinary excretion of citrate and a well-known risk factor for kidney stone development in children. This systematic review aimed to evaluate the dietary management of hypocitraturia in children with urolithiasis.

METHODS

Literature search was performed on 30th September 2022 using Embase, PubMed, and Cochrane Central Controlled Register of Trials. Studies were included if children with stones and hypocitraturia were managed with diet supplements.

RESULTS

Six papers were included. Four studies evaluated the role of oral potassium citrate associated with high fluid intake on stone resolution and recurrence. Two studies assessed the impact of oral potassium citrate on long-term stone recurrence after percutaneous nephrolithotomy and shock wave lithotripsy. All studies demonstrated that the association of potassium citrate and high fluid intake was well tolerated with no side effects and restored normal urine citrate excretion, allowed a reduction in stone size, and, following definitive treatments, was associated with a lower rate of stone regrowth and recurrence compared with controls. These effects were demonstrated across all pediatric ages.

CONCLUSIONS

Our review infers that oral potassium citrate and high fluid assumption are safe and effective in restoring urine citrate excretion, treating and preventing stone recurrence with no serious adverse events, and should probably be the first-line treatment of pediatric patients with asymptomatic stones and hypocitraturia.

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.

Diagnosis and Management of Nephrolithiasis in Children

The incidence of kidney stones in children is increasing. Approximately two-thirds of pediatric cases have a predisposing cause. Children with recurrent kidney stones have an increased higher risk of developing chronic kidney. A complete metabolic workup should be performed. Ultrasound examination is the initial imaging modality recommended for all children with suspected nephrolithiasis. A general dietary recommendation includes high fluid consumption, dietary salt restriction, and increased intake of vegetables and fruits. Depending on size and location of the stone, surgical intervention may be necessary. Multidisciplinary management is key to successful treatment and prevention.

Enteral nutrition and the risk of nephrolithiasis in complex pediatric patients

PURPOSE

Medically complex, non-ambulatory children can often suffer from nephrolithiasis. The purpose of this study is to determine risk factors which are predictive for recurrent stone formation in this patient population.

MATERIAL AND METHODS

A retrospective cohort study was performed on non-ambulatory patients with cerebral palsy and/or severe developmental delay presenting to a high-volume Pediatric Stone Center from 2015 to 2019. Two 24-hour urine collections were performed as a baseline prior to pharmacotherapeutic and/or dietary intervention. Healthy stone-forming children served as a control group.

RESULTS

28 non-ambulatory subjects and 38 healthy controls were evaluated. The study group had a higher rate of bilateral nephrolithiasis but a similar history of previous surgical procedures. 89% of the non-ambulatory children were fed via a gastrostomy. The median calcium excretion was the same in both groups (3.0 mg/kg/day). The median 24-hour excretion of oxalate was significantly increased in the study group (54 vs 31 mg/1.73 m²/day, p = 0.0001). Urinary citrate and phosphorus excretions, and the supersaturations of calcium oxalate and calcium phosphate were similar between study subjects and controls. Calcium oxalate stones were noted in 57% of those with known stone composition in the study group. Enteral feeding formulas were primarily based on soy protein, a known high oxalate food.

CONCLUSIONS

Urinary oxalate excretion is significantly increased in a cohort of medically complex, non-ambulatory stone-forming children. Urinary calcium excretion was not elevated between study subjects and healthy controls. Further analysis is needed to assess if dietary intervention to limit oxalate excretion results in decreased stone formation.

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.

Extracorporeal shock wave lithotripsy for urinary tract stones in pediatric patients: Our 11 years of experience

Background/Aim: Urinary system stone disease creates a significant burden on the health system. Many treatment methods are available, including extracorporeal shock wave lithotripsy (ESWL), endourological procedures, and open and laparoscopic procedures. In recent years, in parallel with technological developments, endourological devices have become more usable in the renal system. For this reason, urologists are opting for endourological procedures more frequently. ESWL is the least invasive procedure for urinary system stone disease, and it has a higher success rate in pediatric patients than in adults. In this retrospective cohort study, we analyzed the data from the pediatric cases in which we used ESWL treatment in our clinic. We aimed to reveal the effectiveness of ESWL and the factors that will increase the success rate of this procedure in light of the current literature. Methods: The files of patients aged 16 years and under who underwent ESWL at the Urology Clinic of University of Health Sciences Sanliurfa Mehmet Akif Inan Training and Research Hospital between January 2010 and December 2021 were retrospectively reviewed. Age, gender, stone area, stone localization, number of sessions, energy and frequency used, complete stone-free status, and secondary intervention requirement were recorded. The absence of stone fragments or the presence of fragments smaller than 3 mm only in imaging after ESWL was considered a success. Results: This study included 433 pediatric patients. The mean age of the patients was calculated as 12.02 (4.67) (range: 1–16) years. The most important factors affecting the number of residual stones were stone localization (P = 0.045) and size (P < 0.001). When stone localization was compared according to patient age, the older patients were found to have a significantly higher rate of stones in the proximal ureter than in the lower calyx of the kidney (P = 0.045) and renal pelvis (P = 0.048). Conclusion: Although there are continual advances in other minimally invasive surgical methods today, ESWL is a treatment method that can be safely applied in pediatric patients. Stone size and stone localization are the two most important factors affecting its success rate.

Comparison between prone and supine nephrolithotomy in pediatric population: a double center experience

PURPOSE

Stone disease in the pediatric age is an increasing issue. Percutaneous Nephrolithotomy (PNL) can be used for larger and complex stones. As in adults it can be performed in the supine or prone position.

METHODS

We retrospectively reviewed two centers' experience in prone and supine PNL in children to analyze its results and complications.

RESULTS

33 patients underwent prone and 19 supine procedures. Patients in the prone group were younger than in the supine, while no significant differences were found in stone burden, access size, operative time or complications. Complications were: 8 and 4 Clavien 1 for the prone and supine group, respectively, one case of urosepsis (4b) in the prone and 2 cases of Clavien 3 in the supine group (double J stent placement for renal colic and ureteroscopy for steinstrasse). Tubeless procedures and mean nephrostomy time were in favor of the supine group, whereas fluoroscopy time and ureteral drainage stay were in support of the prone group. Stone free rate was better in the supine group (83.3 vs 66.6%), possibly reflecting the capability to perform a combined approach in 12 patients (allowing to reach all the calyx with simultaneous anterograde and retrograde access) or younger age in the prone group (13 vs 2 patients ≤5 years), with no differences in stone burden.

CONCLUSIONS

Supine approach seems to guarantee higher stone-free rates. Larger series are necessary to determine what the best technique is in terms of X-ray exposure, operative time and complications.

Paediatric stone management: innovations and standards

PURPOSE OF REVIEW

The aim of this study was to discuss current trends and recent developments in the surgical management of paediatric urolithiasis.

RECENT FINDINGS

Medical expulsive therapy (MET) is considered as an option for the treatment of children with ureter stones. Extracorporeal shockwave lithotripsy (SWL) remains as a first option for majority of kidney stones and upper ureter stones. Advances in endourology have led to increased adoption of retrograde intrarenal surgeries (RIRS) and percutaneous nephrolithotomy (PCNL/mini-PCNL/ultra-mini-PCNL/micro-PCNL).

SUMMARY

Management of paediatric stone disease has developed significantly in the past decade. However, the evidence in the literature remains disproportional to these advances. Well designed multicentric studies are still needed to compare effectiveness and safety of these procedures.

Comparison of infants and children with urolithiasis: a large case series

We evaluated the demographic features, etiologic risk factors, treatment strategies, and outcome of the infants and children with urolithiasis (UL). A retrospective multicenter study was conducted including 23 Pediatric Nephrology centers in Turkey. The medical records of 2513 children with UL were reviewed. One thousand, three hundred and four boys and 1209 girls (1.1:1) were reported. The mean age at diagnosis was 39.5 ± 35 months (0.4-231 months), and 1262 patients (50.2%) were in the first year of life (infants). Most of the cases with infantile UL were diagnosed incidentally. Microlithiasis (< 3 mm) was found in 794 patients (31.6%), and 64.5% of the patients with microlithiasis were infants. Stones were located in the pelvis-calyces in 63.2% (n: 1530) of the cases. The most common stone type was calcium oxalate (64.6%). Hypocitraturia was the most common metabolic risk factor (MRF) in children older than 12 months, but in infancy, hypercalciuria was more common. Fifty-five percent of the patients had received at least one medical treatment, mostly potassium citrate. At the end of a year's follow-up, most of the patients with microlithiasis (85%) showed spontaneous remission. The rate of spontaneous stone resolution in infants was higher than in children. Spontaneous remission rate was higher in cases with MRF ( - ) stones than in MRF ( +) stones. However, remission rate with medical treatment was higher in cases with MRF ( +) stones. This study represents the results of a large series of infants and children with UL and showed that there are several differences such as underlying metabolic and anatomic abnormalities, clinical course, and stone remission rates between infants and children with urinary stone disease.

Association between Temperature and Inpatient Stone Admission in a Pediatric Population

BACKGROUND

Higher temperatures have been associated with increased stone formation and subsequent utilization of hospital resources, including inpatient admission. However, these observations have been derived from the adult population. We sought to examine if this purported association extends to the pediatric population.

METHODS

We used the 2016 Kids' Inpatient Database to identify nationwide pediatric inpatient admissions related to nephrolithiasis. Temperature data from the National Oceanic and Atmospheric Administration was linked to each admission. Comparative statistics analyzed patient and admission characteristics. Multivariable logistic regression analyzed associations between stone-related admissions and temperature. As a frame of reference, this analysis was replicated using the National Inpatient Sample from 2016 to evaluate associations in the adult population.

RESULTS

Of the 2,496,257 pediatric admissions, 8,453 (0.33%) were related to nephrolithiasis. Temperatures at the time of stone admission were higher than those during non-stone admission (55.9°F vs. 54.8°F, P<0.001). The stone admission group had a higher proportion of females than the non-stone admission group (64.8% vs. 55.4%, P<0.001). Stone admission was significantly associated with temperature (OR 1.025 per 10°F, 95% CI 1.003-1.049, P=0.03) and female sex (OR 1.097, 95% CI 1.027-1.171, P=0.006). In the adult population, 380,520 out of 30,000,941 patients (1.3%) were admitted with a stone. The effect of temperature on stone admissions was similar to that in the pediatric population (OR 1.020, 95% CI 1.014-1.026, P<0.001), but women were over 20% less likely to be admitted for stones than men (OR 0.770, 95% CI 0.757-0.784, P<0.001).

CONCLUSIONS

Increased temperatures were associated with an increased risk of stone-related admission in both the pediatric and adult populations. Females were at increased risk for stone-related admissions during childhood, but this trend reverses in adulthood.

Risk factors for subsequent stone events in pediatric nephrolithiasis: A multi-institutional analysis

INTRODUCTION

Children with nephrolithiasis have a 50% risk of recurrence 3 years following an index urinary stone event. The American Urological Association guidelines for medical management of nephrolithiasis suggest metabolic evaluations be stratified according to risk of future stone events. However, no such risk stratification exists across the pediatric population with urinary stone disease. We aim to assess the risk factors among pediatric patients for a subsequent stone event (SSE).

MATERIALS AND METHODS

A retrospective review for children <17 years of age with a diagnosis of nephrolithiasis and at least one completed follow-up at two tertiary-care children's hospitals within our state between 2012 and 2017 was performed. Children with known monogenic stone disease were excluded as well as those with follow-up less than 1 year. SSEs following initial diagnosis and treatment for nephrolithiasis were defined as follows: subsequent surgical intervention, new stone on imaging, reported stone passage, or ED evaluation for renal colic. Clinical and demographic factors were compared between patients with and without SSEs and analyzed using univariate and multivariate analyses via Cox proportional hazard models. Survival curves for significant associations for SSEs were generated and evaluated using Log-Rank and Wilcoxon comparisons.

RESULTS

A total of 200 patients with median clinical follow-up of 2.9 years were analyzed. Median age was 11.5 years (IQR: 6.0-15.5), with 109 (54.5%) males and 91 (45.5%) females, 94 (47%) of whom had a relevant comorbidity. An SSE occurred in 82 patients (41.0%). Age >12 (HR 2.21, 95%CI 1.42-3.45), reported stone event prior to enrollment encounter (i.e. personal history of nephrolithiasis) (HR 1.82, 95%CI 1.14-2.89), and family history of nephrolithiasis (HR 1.62, 95%CI 1.05-2.51) were associated with SSE on univariate analysis while age >12 (HR 2.09, 95%CI 1.33-3.27) and personal history of nephrolithiasis (HR 1.63, 1.02-2.6) retained significance on multivariable analysis. Survival analysis shows increased risk of recurrence with accumulation of risk factors (Summary Figure). Sensitivity analysis accounting for missing family history data retained significance for all three variables.

CONCLUSIONS

Adolescent age and a personal history of nephrolithiasis are independent risk factors for SSE in children. Understanding these risk factors and the nature of SSE among the pediatric population can potentially enhance counseling for further metabolic work-up and tailored clinical follow-up.

Detection of urinary tract calculi on CT images reconstructed with deep learning algorithms

BACKGROUND

Deep learning Computed Tomography (CT) reconstruction (DLR) algorithms promise to improve image quality but the impact on clinical diagnostic performance remains to be demonstrated. We aimed to compare DLR to standard iterative reconstruction for detection of urolithiasis by unenhanced CT in children and young adults.

METHODS

This was an IRB approved retrospective study involving post-hoc reconstruction of clinically acquired unenhanced abdomen/pelvis CT scans. Images were reconstructed with six different manufacturer-standard DLR algorithms and reformatted in 3 planes (axial, sagittal, and coronal) at 3 mm intervals. De-identified reconstructions were loaded as independent examinations for review by 3 blinded radiologists (R1, R2, R3) tasked with identifying and measuring all stones. Results were compared to the clinical iterative reconstruction images as a reference standard. IntraClass correlation coefficients and kappa (k) statistics were used to quantify agreement.

RESULTS

CT data for 14 patients (mean age: 17.3 ± 3.4 years, 5 males and 9 females, weight class: 31-70 kg (n = 6), 71-100 kg (n = 7), > 100 kg (n = 1)) were reconstructed into 84 total exams. 7 patients had urinary tract calculi. Interobserver agreement on the presence of any urinary tract calculus was substantial to almost perfect (k = 0.71-1) for all DLR algorithms. Agreement with the reference standard on number of calculi was excellent (ICC = 0.78-0.96) and agreement on the size of the largest calculus was fair to excellent (ICC = 0.51-0.97) depending on reviewer and DLR algorithm.

CONCLUSION

Deep learning reconstruction of unenhanced CT images allows similar renal stone detectability compared to iterative reconstruction.

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.

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.

Diet-related urine collections: assistance in categorization of hyperoxaluria

Hyperoxaluria, one of the major risk factors for calcium oxalate urolithiasis and nephrocalcinosis, causes significant morbidity and mortality and should therefore be detected and treated as soon as possible. An early, consequent and adequate evaluation, but also a distinction between primary (PH) and secondary hyperoxaluria (SH) is therefore essential. We evaluated the usefulness of three consecutive 24-h urine collections under different diets [usual diet, (A), low oxalate diet, (B), high oxalate diet, (C)] to prove SH, or to find evidence of PH by changes in urinary oxalate excretion (Uox). We retrospectively analyzed results from 96 pediatric patients (47 females and 49 males, age 3–18 years) who presented with a history of nephrolithiasis, nephrocalcinosis and/or persistent hematuria in whom hyperoxaluria was found in an initial urine sample. The typical pattern of SH was found in 34 patients (mean Uox (A) 0.85 ± 0.29, (B) 0.54 ± 0.15 and (C) 0.95 ± 0.28 mmol/1.73m²/d). PH was suspected in 13 patients [(A) 1.21 ± 0.75; (B) 1.47 ± 0.51 and (C) 1.60 ± 0.82 mmol/1.73m²/d], but genetically proven only in 1/5 patients examined. No hyperoxaluria was found in 16 patients. Data were inconclusive in 33 patients. Urine collection under different diets is helpful to diagnose secondary hyperoxaluria and may provide evidence, that urinary oxalate excretion is normal. We have now established this procedure as our first diagnostic step before further, more extensive and more expensive evaluations are performed.

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.

European Association of Urology and European Society for Paediatric Urology Guidelines on Paediatric Urinary Stone Disease

CONTEXT

Paediatric stone disease is an important clinically entity and management is often challenging. Although it is known that the condition is endemic in some geographic regions of the world, the global incidence is also increasing. Patient age and sex; the number, size, location, and composition of the stone; and the anatomy of the urinary tract are factors that need to be taken into consideration when choosing a treatment modality.

OBJECTIVE

To provide a general insight into the evaluation and management of urolithiasis in the paediatric population in the era of minimally invasive surgery.

EVIDENCE ACQUISITION

A nonsystematic review of the literature on management of paediatric urolithiasis was conducted with the aim of presenting the most suitable treatment modality for different scenarios.

EVIDENCE SYNTHESIS

Because of high recurrence rates, open surgical intervention is not the first option for paediatric stone disease, except for very young patients with very large stones in association with congenital abnormalities. Minimally invasive surgeries have become the first option with the availability of appropriately sized instruments and accumulating experience. Extracorporeal shockwave lithotripsy (SWL) is noninvasive and can be carried out as an outpatient procedure under sedation, and is the initial choice for management of smaller stones. However, for larger stones, SWL has lower stone-free rates and higher retreatment rates, so minimally invasive endourology procedures such as percutaneous nephrolithotomy and retrograde intrarenal surgery are preferred treatment options.

CONCLUSIONS

Contemporary surgical treatment for paediatric urolithiasis typically uses minimally invasive modalities. Open surgery is very rarely indicated.

PATIENT SUMMARY

Cases of urinary stones in children are increasing. Minimally invasive surgery can achieve high stone-free rates with low complication rates. After stone removal, metabolic evaluation is strongly recommended so that medical treatment for any underlying metabolic abnormality can be given. Regular follow-up with imaging such as ultrasound is required because of the high recurrence rates.

Nephrolithiasis during the first 6 months of life in exclusively breastfed infants

BACKGROUND

We investigated etiology and prognosis of infantile nephrolithiasis, including whether lithogenic and anti-lithogenic content of breast milk affects its formation.

METHODS

Thirty infants with nephrolithiasis and 30 healthy infants exclusively breastfed for the first 6 months of life were included in this prospective cohort case-control study. At entry, age, sex, and timing of birth of patients and controls were recorded. All patients were diagnosed and followed up periodically using ultrasonography. All infants received oral vitamin D (400 units/day). Lithogenic (calcium, oxalate, uric acid, phosphate) and anti-lithogenic (citrate, magnesium) components of maternal milk, serum calcium, phosphate, magnesium, 25-hydroxy vitamin D and parathormone, as well as spot urine calcium, uric acid, cystine, oxalate, magnesium, citrate/creatinine ratio, and calcium/citrate ratio were compared.

RESULTS

Mean follow-up period was 56.1 ± 6.8 months. There was no difference concerning lithogenic and anti-lithogenic content of breast milk. Serum calcium, phosphorus, alkaline phosphatase, and 25-hydroxy vitamin D levels (49.1 ± 19 vs. 26.7 ± 4 ng/ml, p < 0.001) were significantly higher and parathormone level significantly lower in patients. Random urine calcium/creatinine and calcium/citrate ratios were significantly higher in patient group (0.63 ± 0.40 vs. 0.42 ± 0.10 and 0.62 ± 0.12 vs. 0.41 ± 0.25 mg/mg, respectively, p < 0.01). Three patients were lost to follow-up after the first year. At last follow-up, calculi disappeared in 25/27 remaining patients without interventions or therapy.

CONCLUSIONS

Breast milk does not have an etiologic effect in infantile nephrolithiasis. Higher serum vitamin D levels may have roles in development of lower levels of PTH and higher levels of serum and urine calcium, leading to stone formation. The prognosis for infantile stones is excellent. Graphical abstract.

Pediatric stone disease: Current management and future concepts

Treatment of pediatric urolithiasis consists of medical and surgical approaches. The main goal of the treatment is to prevent stone recurrence by avoiding multiple surgical interventions. In recent years, many innovations have been reported in the medical diagnostic evaluation protocol and in surgical treatment. According to recent reports, single mutations could be responsible for a larger proportion of renal stones. This etiologic feature holds the potential to change the management in stone prevention from metabolically directed therapy to more specific approaches. In addition, miniaturized instruments have been adopted in clinical practice. In recent years, minimally invasive endoscopic surgery is the treatment of choice in pediatric urolithiasis. This review aims to assess the current literature on medical and surgical treatment options for pediatric urolithiasis. We also aim to provide an overview of potential future advances.

Comparison of Efficiency and Safety of Retrograde Intrarenal Surgery and Micropercutaneous Nephrolithotomy in Pediatric Kidney Stones Smaller than 2 cm: A Prospective Cohort Study

Objective: To compare the safety and efficacy of two minimally invasive surgical techniques used for pediatric stone disease: retrograde intrarenal surgery (RIRS) and micropercutaneous nephrolithotomy (micro-PCNL). Materials and Methods: A prospective study was designed to include children aged <15 years with a single stone <20 mm. Sixty-four patients were assigned to undergo either an RIRS or a micro-PCNL (1:1 ratio). Demographic parameters, stone size, location, operative data, complications, stone-free status, and efficacy quotient were compared. Results: Due to anatomic considerations, seven patients were shifted to the micro-PCNL arm, thus resulting in 39 micro-PCNLs performed vs 25 RIRS in the end. Because of the deviation from planned surgery that was significantly higher in the RIRS group (p = 0.011), the analysis was done in a prospective cohort comparison. Stone-free rates were similar for micro-PCNL and RIRS groups (80% vs 82.2%). The operative (median 60 vs 90 minutes, p < 0.001), fluoroscopy (median 15 vs 30 seconds, p = 0.004), and lithotripsy times (median 15 vs 25 minutes, p = 0.007) were shorter in the RIRS group. However, despite the larger stone size, the efficiency quotient was significantly higher in the micro-PCNL group (82.1% vs 54.1%; p = 0.009). None of the patients experienced significant hematuria requiring blood transfusion, as well as no ureteral orifice obstructive complication was detected within the follow-up period. Conclusion: RIRS and micro-PCNL techniques in children have similar stone-free and complication rates. The operative, fluoroscopy, and lithotripsy times were shorter, deviation from the planned surgery, and the number of sessions under anesthesia was higher in the RIRS group. Despite the larger stone size, efficacy quotient was significantly higher in the micro-PCNL group.

Comparison of efficacy and safety of minimally invasive procedures for 10-20 mm pediatric renal Stones-A bayesian network meta-analysis

OBJECTIVE

To assess the efficacy and safety of various minimally invasive procedures for 10-20 mm pediatric renal stones by Bayesian network meta-analysis (NWA).

METHODS

We searched clinical comparative trials published in Pubmed, Embase, Cochrane Library from inception to 12 April 2020. Two researchers evaluated the quality and extracted data individually. Data was analyzed using STATA and GEMYC R package.

RESULTS

The overall network meta-analytic outcome of stone free rate (SFR) in a single session revealed that Retrograde Intrarenal Stone Surgery (RIRS), miniaturized percutaneous nephrolithotomy (mPCNL) and PCNL showed superiority to extracorporeal shockwave lithotripsy (ESWL). Statistical significance was not detected between any intervention from our pooled network analysis of complication rate. SMP was the most likely to ranking in first place to render stone free status, and it also showed the lowest risk possibility of complications. Mini-PCNL had longer operation time and hospitalization than ESWL. The global and loop inconsistency evaluation demonstrated a rather acceptable outcome apart from the comparisons of complication rate between two randomized control studies.

DISCUSSION

Herein, the authors reviewed and explored the optimal management pattern for pediatric 10-20 mm renal stones. This NWA revealed RIRS and mPCNL could render higher SFR without increasing risk of complications compared with ESWL. Although SMP was deemed to be the best choice in our study, the limited source of study and sample size implied the results required to be further validated. In addition, there were still some problems requiring to be underlined for various surgical options.

CONCLUSIONS

ESWL was inferior to RIRS, mPCNL and PCNL for 10-20 mm pediatric renal stones, among which SMP might be the most ideal option associated with the least possibility of complications and the highest probability of stone clearance.

A Rare Case of T-Cell Lymphoma Presenting With Bilateral Nephrolithiasis and Acute Renal Failure

We present the rare case of a young boy who was found to have T-cell lymphoma after presenting with flank pain and bilateral nephrolithiasis. He initially underwent bilateral ureteral stent placement but returned with oliguria and acute renal failure. His subsequent workup revealed lymphoma involving both kidneys. He was started on chemotherapy for his lymphoma and dialysis for his renal failure. His stones ultimately dissolved with aggressive hydration and correction of serum uric acid levels. In this report, we discuss the identification and management of this rare condition.

Effect of bisphosphonates on the crystallization of stone-forming salts in synthetic urine

Purpose

We investigated the inhibitory effect of bisphosphonates (BPs) on the crystallization of calcium oxalate monohydrate (COM), calcium phosphate (CaP), and magnesium ammonium phosphate (MAP) in synthetic urine, aiming to see 1) which specific BPs work best on a particular type of crystal and 2) what is the lowest concentration of BPs that inhibits crystal formation.

Materials and Methods

Crystals from synthetic urine were exposed to different concentrations of BPs. Urinary turbidity was used as a marker of crystallization and was measured by spectrophotometry by use of a validated method in our laboratory. The percent inhibitory activity (IA) was calculated by using the formula: (a−b )/a×100, where a is baseline maximal turbidity and b is maximal turbidity with various concentrations of medication. Potassium citrate and magnesium citrate were used as positive controls.

Results

At the lowest dose of 0.001 mg/mL, risedronate induced the highest IA of 37% on CaP, whereas ibandronate had the strongest IA on COM (24%). To initiate the inhibition of MAP crystallization, risedronate required a two-fold higher concentration (0.002 mg/mL) to reach 30% IA, whereas etidronate required a four-fold higher concentration (0.004 mg/mL) to reach 42% IA.

Conclusions

BPs are good inhibitors of crystallization in synthetic urine, with risedronate and ibandronate being the most potent. At a low clinically acceptable dose, their highest inhibitory action was on CaP and COM crystals. Higher doses were needed to prevent MAP crystallization. Further investigation of the use of BPs in kidney stone prevention is warranted.

Evaluation of a child with suspected nephrolithiasis

PURPOSE OF REVIEW

As the incidence of nephrolithiasis in children doubles every 10 years it is becoming a common disease associated with significant morbidity along with considerable economic burden worldwide. The aim of this review is to summarize current data on the epidemiology and causes of renal stones in children and to provide a frame for the first clinical evaluation of a child with suspected nephrolithiasis.

RECENT FINDINGS

Dietary and environmental factors are the driving force of changing epidemiology. Diagnosis should be based on medical history, presenting signs, examination, first laboratory and radiological workup. Ultrasound should be the initial diagnostic imaging performed in pediatric patients while low-dose computed tomography is rarely necessary for management. Metabolic factors including hypercalciuria, hypocitraturia, low fluid intake as well as specific genetic diseases should be explored after the resolution of initial signs and symptoms.

SUMMARY

Appropriate initial evaluation, imaging technique, identification of risk factors and other abnormalities are essential for early diagnosis and prevention of stone-related morbidity in children with suspected nephrolithiasis.

Drug-Induced Urolithiasis in Pediatric Patients

Drug-induced nephrolithiasis is a rare condition in children. The involved drugs may be divided into two different categories according to the mechanism involved in calculi formation. The first one includes poorly soluble drugs that favor the crystallization and calculi formation. The second category includes drugs that enhance calculi formation through their metabolic effects. The diagnosis of these specific calculi depends on a detailed medical history, associated comorbidities and the patient's history of drug consumption. There are several risk factors associated with drug-induced stones, such as high dose of consumed drugs and long duration of treatment. Moreover, there are some specific risk factors, including urinary pH and the amount of fluid consumed by children. There are limited data regarding pediatric lithogenic drugs, and hence, our aim was to perform a comprehensive review of the literature to summarize these drugs and identify the possible mechanisms involved in calculi formation and discuss the management and preventive measures for these calculi.

Update on Surgical Management of Pediatric Urolithiasis

Urolithiasis has always been a fascinating disease, even more so in children. There are many intriguing facets to this pathology. This article is a nonsystematic review to provide an update on the surgical management of pediatric urolithiasis. It highlights the pros and cons of various minimally invasive surgical options such as extracorporeal shockwave lithotripsy (ESWL), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy (PCNL), laparoscopy, and robotics. This article also describes the various intracorporeal disintegration technologies available to fragment the stone, including the newer advancements in laser technology. It also emphasizes the cost considerations especially with reference to the emerging economies. Thus, this manuscript guides how to select the least-invasive option for an individual patient, considering age and gender; stone size, location, and composition; and facilities and expertise available.