High recurrence rate at 5-year followup in children after upper urinary tract stone surgery

Risk factors for recurrence in pediatric urinary stone disease

BACKGROUND

Children's urinary system stones may develop from environmental, metabolic, anatomical, and other causes. Our objective is to determine the recurrence and prognosis, demographic, clinical, and etiological characteristics of children with urolithiasis.

METHODS

Medical records of patients were evaluated retrospectively. Patients' demographic data and medical history, serum/urine biochemical and metabolic analysis, blood gas analysis, stone analysis, imaging findings, and medical/surgical treatments were recorded.

RESULTS

The study included 364 patients (male 187). Median age at diagnosis was 2.83 (IQR 0.83-8.08) years. The most common complaints were urinary tract infection (23%) and urine discoloration (12%). Sixty-two percent had a family history of stone disease. At least one metabolic disorder was found in 120 (88%) of 137 patients having all metabolic analyses: hypercalciuria was found in 45%, hypocitraturia in 39%, and hyperoxaluria in 37%. Anatomical abnormalities were detected in 18% of patients. Of 58 stones analyzed, 65.5% were calcium and 20.6% were cystine stones. Stone recurrence rate was 15% (55/364). Older age (> 5 years), family history of stone disease, stone size (≥ 5 mm), and urinary system anatomical abnormalities were significantly associated with stone recurrence (p = 0.027, p = 0.031, p < 0.001, and p < 0.001, respectively). In adjusted logistic regression analysis, stone size ≥ 5 mm (OR 4.85, 95% CI 2.53-9.3), presence of urinary system anatomical abnormalities (OR 2.89, 95% CI 1.44-5.78), and family history of stone disease (OR 2.41, 95% CI 1.19-4.86) had increased recurrence rate.

CONCLUSIONS

All children with urolithiasis should be evaluated for factors affecting stone recurrence. Children at higher risk of recurrence need to be followed carefully.

Using structured problem solving to promote fluid consumption in the prevention of urinary stones with hydration (PUSH) trial

BACKGROUND

Structured Problem Solving (SPS) is a patient-centered approach to promoting behavior change that relies on productive collaboration between coaches and participants and reinforces participant autonomy. We aimed to describe the design, implementation, and assessment of SPS in the multicenter Prevention of Urinary Stones with Hydration (PUSH) randomized trial.

METHODS

In the PUSH trial, individuals with a history of urinary stone disease and low urine output were randomized to control versus a multicomponent intervention including SPS that was designed to promote fluid consumption and thereby prevent recurrent stones. We provide details specifically about training and fidelity assessment of the SPS coaches. We report on implementation experiences related to SPS during the initial conduct of the trial.

RESULTS

With training and fidelity assessment, coaches in the PUSH trial applied SPS to help participants overcome barriers to fluid consumption. In some cases, coaches faced implementation barriers such as variable participant engagement that required tailoring their work with specific participants. The coaches also faced challenges including balancing rapport with problem solving, and role clarity for the coaches.

CONCLUSIONS

We adapted SPS to the setting of kidney stone prevention and overcame challenges in implementation, such as variable patient engagement. Tools from the PUSH trial may be useful to apply to other health behavior change settings in nephrology and other areas of clinical care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT03244189.

One and done: Feasibility and Safety of Primary Ureteroscopy in a Pediatric Population

BACKGROUND

Pediatric urolithiasis has been increasing at rate of 4-10 % annually in the United States, most notably within adolescents and females. A significant number of patients will require surgical management of their stones. Primary ureteroscopy (URS) affords the opportunity to treat stones under a single anesthetic with lower re-treatment rates or anatomical and stone characteristic limitations compared to shockwave lithotripsy. Previous studies evaluating primary URS have been largely underpowered, are limited by stone location, and/or are not representative of the stone population in the United States.

OBJECTIVES

Primary study outcomes were the success of primary URS and patient characteristics associated with success. Secondary outcomes were the stone-free rate (SFR), 30-day emergency department (ED) visits, 30-day readmissions, and complications.

METHODS

We performed a retrospective cohort study of patients less than 18 years of age from 2011 to 2023 who underwent primary URS. Patients were excluded if a ureteral stent was placed prior to URS or diagnostic URS was performed. A successful primary URS was considered if access to the ureter was obtained and treatment of the stone(s) completed. In failed primary URS, a ureteral stent was placed for staged management.

RESULTS

A total of 196 patients were included and primary URS was performed or attempted on 224 renal units. The median age was 15.8 (IQR 13.4-16.9) years and median follow up 8.4 (IQR 1.1-24.6) months. The success rate of primary URS was 79 %. No significant characteristics were appreciated for successful primary URS based on: overall age, <14 vs > 14 years of age, sex, body mass index, history of stones, history of endourologic procedures, preoperative alpha blockade, location of stone(s), multiple stones, type of URS, or acute treatment. In successful primary URS, the SFR was 88 % with stone size (p = 0.0001) the only predictor of having residual stones. The 30-day ED rate was 21.4 %, 30-day unplanned readmission rate was 12.5 %, and complication rate was 7.5 %. No long-term complications were appreciated.

DISCUSSION

Our success of primary URS compares favorably to previously published literature. Our SFR rate, 30-day ED visits, 30-day unplanned readmission, and complication rates are similar to other studies. Limitations of the study are its retrospective design, selection bias, and intermediate follow-up.

CONCLUSIONS

Primary URS can be completed safely in the majority of pediatric patients without any patient characteristics associated with success. We advocate for primary URS when possible due to the excellent SFR and potential of treating stones under a single anesthetic.

Pediatric Nephrolithiasis

The prevalence of pediatric nephrolithiasis has increased dramatically in the past two decades for reasons that have yet to be fully elucidated. Workup of pediatric kidney stones should include metabolic assessment to identify and address any risk factors predisposing patients to recurrent stone formation, and treatment should aim to facilitate stone clearance while minimizing complications, radiation and anesthetic exposure, and other risks. Treatment methods include observation and supportive therapy, medical expulsive therapy, and surgical intervention, with choice of treatment method determined by clinicians' assessments of stone size, location, anatomic factors, comorbidities, other risk factors, and preferences and goals of patients and their families. Much of the current research into nephrolithiasis is restricted to adult populations, and more data are needed to better understand many aspects of the epidemiology and treatment of pediatric kidney stones.

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.

Symptomatic recurrence rate of upper urinary tract calculi in children after endourological procedures

INTRODUCTION

The recurrence rate of paediatric urolithiasis was less reported, especially in Asians. Our aim was to verify the symptomatic recurrence rate of Chinese paediatric urolithiasis and to determine the predictive factors for stone recurrence.

MATERIALS AND METHODS

We performed a retrospective review of children who presented with first upper urinary tract calculi from June 2014 to September 2019. For the follow-up, we generated Kaplan-Meier plots with time to stone recurrence and Cox proportional hazard regression analyses were applied. The recurrence was defined as a new symptomatic stone on ultrasound and/or computerized tomography.

RESULTS

A total of 230 children with a median age of 5 yr (IQR 4-8) were included. Calcium oxalate was found in 72% of stones, and calcium apatite was found in 32% of stones. After a median follow-up of 39.5 months, 34 (14.8%) children had stone recurrence. Median time to stone recurrence was 31 months. Among them, 31 (91.2%) required surgical intervention. Older children (P < 0.01), higher BMI (HBM) (P < 0.01) and higher stone burden (P < 0.01) were shown to be associated with stone recurrence in the univariate analysis. The multivariate Cox regression analysis showed that children with stone burden > 2 cm³ had a higher risk of recurrence (HR 4.84, 95%CI 2.28-10.3). Children with HBM had an increased recurrence rate compared to normal BMI children (HR 2.99, 95%CI 1.36-6.56).

CONCLUSIONS

The symptomatic recurrence rate of paediatric urolithiasis in Chinese is not as high as that reported in Caucasians. HBM and higher stone burden are associated with higher recurrence rates.

Ultra-mini-percutaneous nephrolithotomy in flank-free modified supine position versus prone position in treatment of pediatric renal pelvic and lower calyceal stones

OBJECTIVES

To report the safety and efficacy of ultra-mini-percutaneous nephrolithotomy (UMPCNL) in flank free modified supine (FFMS) and prone positions in management of pediatric renal calculi.

PATIENTS & METHODS

This prospective randomized study included 55 pediatric patients with symptomatic renal stones and suitable for ultra-mini-percutaneous nephrolithotomy. They were randomized into two groups. Group A included 28 patients who were treated by UMPCNL in FFMS position (with a pad below the ipsilateral shoulder and buttocks, putting ipsilateral upper limb over the chest, and crossing the extended ipsilateral lower limb over the flexed contralateral one) and Group B included 27 patients treated by UMPCNL in the prone position. In both groups dilatation was done to 13 French sheath allowing the introduction of 6/7.5 French semi-rigid ureteroscope and fragmentation of stones by Ho:YAG laser with a 550-μm fiber laser lithotripter.

RESULTS

The operation time in FFMS position UMPCNL group was significantly shorter than prone position UMPCNL group (84.3±9.87 vs. 99.3±8.75) minutes with p=0.022. There was no significant difference between both groups in terms of stone free rate (89.3% vs. 88.9%), overall complication rate (including transient fever) (21.4% vs. 18.5%), post-operative pain (VAS score) (3.4±0.8 vs. 3.3±0.9), or hospital stay (3.53±0.8 vs. 4.1±1.1) days.

CONCLUSION

Both ultra-mini-percutaneous nephrolithotomy in FFMs and prone positions are feasible, safe and effective in treatment of pediatric renal stones with relatively shorter operative time in FFMS position.

24-Hour urine collection for first time pediatric stone formers: Is it worth it?

INTRODUCTION/OBJECTIVE

24-h urine collections are recommended for motivated first-time stone formers. Given that children have a lifetime potential for recurrences, metabolic work-up has been recommended. 24-hour urine collections can be problematic, especially in children. We sought to study the benefits of 24-h urine collections in children with stones.

STUDY DESIGN

We performed a single center, retrospective chart review of the most recent pediatric nephrolithiasis patients under age 18 at our center who supplied their first 24-h urine collection. We assessed whether 24-h urine results led to a change in management and if those patients were adherent to the recommendations.

RESULTS

Seventy pediatric nephrolithiasis patients who had 24-h urine collection were reviewed. Recommendations other than standard dietary and fluid intake changes were made in 8/70 (11%). A low citrate/calcium ratio (327 vs. 525, p < 0.03) and whether the test was ordered by nephrology vs. urology (26% vs. 2%, p < 0.003) were predictive of an additional recommendation. Of the 8 patients who had changes recommended only 1/8 completed a repeat 24-h urine collection, 3/8 never returned for followed up and 2/8 stopped the medicines prior to follow up. There was no difference in early stone recurrence rates, 55% of the studies were incorrectly collected, and total costs are estimated at $9800.

DISCUSSION

Our study aimed to evaluate the impact and value of 24-h urine collection in first time pediatric stone formers. We found that 24-h urine collections altered management from standard dietary recommendations in only 11% of cases. These collections were fraught with challenges - 55% of our samples appeared to be incorrectly collected, there was at least one abnormality noted in 100% of collections, these tests are expensive, and patients were poorly compliant with recommendations based on test results. Additionally, changes made based on the 24-h urine results seemed to vary depending on who evaluated the test results. Among cases in which changes were made, nephrologists made alterations at a far greater rate than urologists did. We do acknowledge there are several limitations to our study. First, this is a retrospective chart review. Second, for the urology patients, we were only able to review patient records that were available due to a transition from one electronic medical record to another, resulting in a loss of some earlier patient records. We highly doubt that those records we could not review were significantly different than those we did review. Third, this is a single center design and includes the practice patterns of the providers here. We acknowledge that our local practice patterns may or may not be reflective of national practice patterns, however, most clinicians are likely faced with similar interpretation issues and poor rates of compliance and could benefit from guidelines.

CONCLUSION

24-h urine collection for first time pediatric stone formers is expensive, difficult to accomplish and infrequently leads to treatment changes. Our data suggest it adds little for most children with stones and may be better reserved for those children with recurrent stone disease.

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.

Patient Characteristics Associated With Completion of 24-hour Urine Analyses Among Children and Adolescents With Nephrolithiasis

OBJECTIVE

To inform the development of strategies to improve adherence to guidelines, we sought to identify characteristics of pediatric patients with nephrolithiasis associated with completing 24-hour urine analyses.

MATERIALS AND METHODS

We performed a retrospective cohort study of patients with nephrolithiasis aged 3-18years treated in a large pediatric healthcare system from May 2012 to May 2017. Multivariable Cox models were fit to estimate the association between patient characteristics and completion of a 24-hour urine analysis.

RESULTS

Among 623 patients, 317 (50.9%) completed a 24-hour urine collection. Median age was 14.4years (interquartile range [IQR] 10.5, 16.3). In adjusted analyses, age at diagnosis (hazard ratio [HR] 1.03; 95% confidence interval [CI] 1.01-1.07), renal colic on presentation (HR 1.72; 95% CI 1.15-2.58), and family history of nephrolithiasis (HR 1.50; 95% CI 1.17-1.93) were associated with an increased likelihood of completion of a 24-hour urine. Public/government assistance insurance (HR 0.68; 95% CI 0.48-0.96) was associated with decreased likelihood of completing a 24-hour urine.

CONCLUSION

Patients who had prior painful experiences with stones (renal colic), and potential better understanding of nephrolithiasis (family history, older age on presentation) were more likely to complete a 24-hour urine. Those patients with public insurance/government assistance were less likely to complete a 24-hour urine. These results can be used to develop strategies to improve pediatric patients' adherence to completing 24-hour urine collections.

Predictive ability of Guy's stone score in pediatric patients undergoing percutaneous nephrolithotomy

BACKGROUND

Several authors have evaluated, in a number of external validation and predominantly adult studies, Guy's stone score (GSS) as a predictive tool for the assessment of stone clearance after percutaneous nephrolithotomy (PCNL). However, there are limited and conflicting data investigating whether GSS could be a potential independent factor associated with residual stone rates and complications of PCNL for children.

OBJECTIVE

The aim of the current study was to evaluate the ability of GSS, as an independent factor, to predict residual stone rates and complications in pediatric patients undergoing PCNL.

STUDY DESIGN

The records of the pediatric patients who had undergone PCNL for stone disease at the current department were retrospectively reviewed. Variables included patient, stone, and treatment parameters. The GSS was used for assessment of stone complexity. Univariate and multivariate analyses were performed to evaluate factors associated with residual stone rates and complications of pediatric PCNL.

RESULTS

The study group consisted of 114 children (63 boys and 51 girls) with a median (interquartile range) age of 6 (3-11) years and who had undergone 122 PCNLs (eight bilateral). Multivariate logistic regression analysis (Summary Table) demonstrated that the independent risk factors for increased residual stone rate following pediatric PCNL monotherapy were GSS (OR 3.14, 95% CI 1.31-7.49, P = 0.01) and number of calyces involved (OR 4.02, 95% CI 1.11-14.53, P = 0.033). Multivariate logistic regression analysis demonstrated that the independent risk factors for complications following pediatric PCNL were surgical experience (OR 2.72, 95% CI 1.09-6.82, P = 0.032), and operation time (OR 1.01, 95% CI 1.00-1.03, P = 0.040).

DISCUSSION

A prediction model is needed to pre-operatively counsel patients and evaluate outcomes for measuring treatment success of PCNL. The GSS provides a simple, reliable and reproducible tool for describing the complexity of PCNL while predicting postoperative stone-free status, despite its limitations. However, little research has been conducted on the applicability of GSS in pediatric patients undergoing PCNL. In addition, conflicting results have been reported about its association with complications of pediatric PCNL.

CONCLUSIONS

The current study found that although GSS had a significant predictive ability for residual stone rates after pediatric PCNL revealed by multivariate logistic regression, the results did not conclude that complexity of GSS was directly proportional to complications of pediatric PCNL. The factors, including calyceal involvement and surgeon experience, may need to be incorporated in GSS to further improve its ability to predict outcomes of pediatric PCNL.

IRB APPROVED PROTOCOL NUMBER

1422.

Lime powder regimen supplement alleviates urinary metabolic abnormalities in urolithiasis patients

BACKGROUND

Urolithiasis has high recurrent rate after surgical removal within 3 years. Potassium citrate compound is used to prevent stone recurrence but it has intolerable gastrointestinal adverse effects. We conducted a phase 2 clinical study of lime power regimen (LPR), a limeade-based supplement containing potassium and citrate for 6 months period of treatment, to evaluate its effects on biochemical and clinical aspects of recurrent urolithiasis.

METHODS

Seventy-four urolithiasis patients were randomly allocated to receive either LPR or placebo for 6 months in a double-blinded manner. Plasma and 24 h urine samples were collected to measure urinary pH, mineral excretion and urinary total antioxidant status , plasma for creatinine and plasma protein carbonyl, and stone for elemental analysis at the initiation and end-of-treatment (6 month). Adverse effects were recorded.

RESULTS

Administration of LPR significantly increased urinary pH, citrate and potassium excretion. Urinary levels of calcium and oxalate, and plasma protein carbonyl content were reduced, while urinary total antioxidant status was elevated by LPR treatment. Urinary supersaturation was decreased and urinary protein excretion was ameliorated in LPR-treated patients. Gastrointestinal adverse effects were rarely observed. None of the participants developed stone recurrence for the duration of the trial.

CONCLUSION

Lime power regimen is a potential drug to correct urinary metabolic disorders associated with urolithiasis in high risk stone recurrent patients. A phase 3 clinical trial is underway to validate anti-stone recurrence property of LPR in long-term treatment.

Clinical application of super-mini PCNL (SMP) in the treatment of upper urinary tract stones under ultrasound guidance

PURPOSE

To present the safety and efficacy of totally ultrasonography-guided Super-mini percutaneous nephrolithotomy (SMP) in the treatment of upper urinary tract stones both in children and adults.

PATIENTS AND METHODS

We carried out SMP in 104 patients (including 48 children and 56 adults) with upper urinary tract stones between June 2015 and February 2017. All steps of renal access were performed by ultrasonography. The lithotripsy was performed using either Holmium laser or pneumatic lithotripter. Perioperative and postoperative parameters along with operative data were recorded in detail.

RESULTS

The mean age of children and adult patients were 4.4 ± 3.6 and 44.3 ± 15.7 years old, respectively. The stone burden was comparable for both groups (1.72 ± 0.66 vs 1.74 ± 0.56 cm, p = 0.852). Mean operation time was not significant different between two groups (p = 0.052), while the mean haemoglobin drop in children was much lower in adult patients (6.3 ± 6.9 vs 10.9 ± 8.69, p = 0.004). Both groups had similar SFRs in postoperative 1 day and at 1-month follow-up (p = 1.000, p = 0.912). Mean hospital stay of children and adult patients was 2.3 ± 0.8 and 2.2 ± 0.76 days (p = 0.484). The total complication rate was significantly lower in two groups (p = 1.000); none of the patients required blood transfusion.

CONCLUSIONS

Ultrasonography-guided SMP was a safe and effective treatment option for moderate-sized upper urinary tract stones, and has the advantage of preventing radiation hazard, especially for pediatric stone patients.

Comparison of outcomes of tubed versus tubeless percutaneous nephrolithotomy in children: A single center study

Objective

To evaluate and compare the effectiveness of tubeless percutaneous nephrolithotomy (PCNL) and tubed PCNL by using small bore nephrostomy tube (12Fr) in children for the management of nephrolithiasis.

Material and methods

This study was a retrospective analysis of 35 children where tubed PCNL (Group 1) was done in 18, and tubeless PCNL (group 2) in 17 patients from January 2010 to December 2016. Charts were reviewed for age, mass, stone size, operative time, hospital stay and stone-free rates. These variables were compared between the two groups. SPSS version 21 was used for data analysis. The data were shown as mean±standard deviation for continuous variables. Categorical variables were presented in percentages.

Results

There is no difference in terms of age, stone sizes, operative times, hospital stays, stone-free rates and post-PCNL complications between the two groups (p>0.05). The mean drop in hemoglobin level was 0.7±0.1 g/dL and 1.3±0.2 g/dL in Groups 1 and 2, respectively (p=0.01).

Conclusion

Tubeless PCNL in children is a safe option in well selected cases.

Compositional analysis of various layers of upper urinary tract stones by infrared spectroscopy

The objective of the present study was to determine the composition of various layers of upper urinary stones and assess the mechanisms of stone nucleation and aggregation. A total of 40 integrated urinary tract stones with a diameter of >0.8 cm were removed from the patients. All of the stones were cut in half perpendicularly to the longitudinal axis. Samples were selected from nuclear, internal and external layers of each stone. Fourier transform infrared spectroscopy (FT-IR) was adopted for qualitative and quantitative analysis of all of the fragments and compositional differences among nuclear, internal and external layers of various types of stone were subsequently investigated. A total of 25 cases of calcium oxalate (CaOx) stones and 10 cases of calcium phosphate (CaP) stones were identified to be mixed stones, while 5 uric acid (UA) calculi were pure stones (purity, >95%). In addition, the contents of CaOx and carbapatite (CA.AP) crystals in various layers of the mixed stones were found to be variable. In CaOx stones, the content of CA.AP in nuclear layers was significantly higher than that of the outer layers (32.0 vs. 6.8%; P<0.05), while the content of CaOx was lower in the inner than in the outer layers (57.6 vs. 86.6%; P<0.05). In CaP stones, the content of CA.AP in the nuclear layers was higher than that in the outer layers (74.0 vs. 47.3%; P<0.05), while the content of CaOx was lower in the inner than in the outer layers (7.0 vs. 40.0%; P<0.05). The UA stones showed no significant differences in their composition among different layers. In conclusion, FT-IR analysis of various layers of human upper urinary tract stones revealed that CaOx and CaP stones showed differences in composition between their core and surface, while all of the UA calculi were pure stones. The composition showed a marked variation among different layers of the stones, indicating that metabolism has an important role in different phases of the evolution of stones. The present study provided novel insight into the pathogenesis of urinary tract stones and may contribute to their prevention and treatment.

What is the fate of insignificant residual fragment following percutaneous nephrolithotomy in pediatric patients with anomalous kidney? A comparison with normal kidney

Pediatric population has increasing incidence of renal calculus and it is estimated to be around 50/10,000 population. The treatment of choice for large and complex stone in anomalous kidney is percutaneous nephrolithotomy (PCNL). The fate of insignificant residual fragment after PCNL in pediatric patients is not well documented. Here, we are reporting our long-term experience and follow-up of insignificant residual fragment in pediatric patients with anomalous kidney in comparison to normal kidney. Intuitional ethical approval was taken. A retrospective analysis of PCNL in pediatric (<18 years) anomalous kidney was performed from 2001 to 2013. The data of 52 pediatric patients with anomalous kidney (group B) have been compared to 251 normal kidneys (group A). The mean age of the patients was 7.83 + 3.45 (range 3-18) in group A and 8.21 ± 3.25 (range 5-18) in group B. The mean size of the insignificant residual fragment was 2.2 + 0.5 mm (1-4) in group A and 2.1 + 0.6 mm (range 1-4) in group B. Most of these residual fragments were single in number (72.55 vs. 67.30%, respectively). 54.98% children in group A and 67.30% in group B were symptomatic in the follow-up. Stone size was increased, stable and spontaneously passed in 49.8 vs. 71.15, 22.7 vs. 19.23 and 27.49 vs. 9.61% (p < 0.03), respectively, over mean follow-up of 50.34 months. Insignificant residual fragments in children are notorious for regrowth (49.8% in normal and 71.15% in anomalous kidney) in future. Most of the children will require symptomatic treatment (55.37 vs. 82.69%) or reintervention (39 vs. 46%) for insignificant residual fragment.

Ureteroscopy and laser stone fragmentation (URSL) for large (≥1 cm) paediatric stones: Outcomes from a university teaching hospital

INTRODUCTION

The treatment of large renal stones (≥1 cm) in paediatric patients is challenging. The usual treatment options include percutaneous nephrolithotomy (PCNL) or shockwave lithotripsy (SWL). There is a rise in the use of ureteroscopy and laser stone fragmentation (URSL) for paediatric stones; however, outcomes of treatment for large renal stones in this age group are still largely unknown.

OBJECTIVE

To investigate the outcome of URSL for large paediatric renal stones ≥1 cm treated at the present institution over the last 5 years.

METHODS

A retrospective review was performed of outcomes from the prospectively maintained stone database. Only paediatric patients undergoing ureteroscopic (rigid or flexible ureteroscopy (URS)) procedures for stones ≥1 cm were included. Patient demographics, operative details, stone burden, hospital stay, complications and stone clearance were recorded and analysed.

RESULTS

From April 2010 to June 2015, 18 paediatric patients with a mean age of 10.4 years (range 3.6-15) underwent 35 ureteroscopic procedures for large stones (≥1 cm). The stone location was in the kidney (n = 14), ureter (n = 1), and in both the kidney and ureter for the remaining three patients. Nine patients had multiple stones. There was a preceding history of PCNL in four patients, with one patient having URS combined with a PCNL. The mean follow-up was 2.7 years (range 0-5). A postoperative stent was inserted in 21 (60%) patients. The overall stone-free rate (SFR) was 89% for a mean of 1.8 procedures per patient (range 1-4) - see Summary Table below. There was an inability to access stone within a lower pole calyx in one patient, despite maximum deflection of the ureteroscope. No intra- or post-operative complications were noted, and mean hospital stay was 1.1 days (range 0-5).

DISCUSSION

Published papers in adult literature have shown that ureteroscopy and laser fragmentation (URSL) is a viable alternative to PCNL. Newer equipment and improved techniques have resulted in SFRs being comparable with PCNL. A recent systematic review reported an SFR of 91% for large adult stones (>2 cm) for a mean 1.45 procedures per patient, and an overall complication rate of 8.6%. The present study has also demonstrated excellent outcomes in the use of ureteroscopy and laser fragmentation for the management of large paediatric stones with no complications.

CONCLUSION

The results show that paediatric URSL for large stones achieves a good SFR with minimal morbidity and is a good treatment option in established endourological units.

Kidney Stone Recurrence among Children and Adolescents

PURPOSE

Kidney stone disease has become increasingly common during childhood and adolescence. However, the rate of symptomatic kidney stone recurrence for pediatric patients is uncertain. We sought to determine the recurrence rate of symptomatic kidney stones in a cohort of children with incident symptomatic nephrolithiasis.

MATERIALS AND METHODS

We performed a retrospective cohort study of patients 3 to 18 years old without anatomical abnormalities or genetic causes of nephrolithiasis who presented with a first symptomatic kidney stone between 2008 and 2014. We determined recurrence rates of symptomatic nephrolithiasis, defined as a new kidney stone on ultrasound and/or computerized tomogram associated with pain and/or vomiting. We also estimated associations between completing 24-hour urinalysis and symptomatic kidney stone recurrence using Kaplan-Meier curves and multivariable Cox regression models.

RESULTS

A total of 285 children with a median age of 14.8 years (IQR 11.3-16.6) at nephrolithiasis diagnosis were followed for 492 person-years. A total of 86 symptomatic recurrent stones developed in 68 patients (24%) during the followup period. The probability of symptomatic stone recurrence was 50% at 3 years after the index kidney stone. Median time to stone recurrence was 3 years at the first recurrence and 5 years at the second. Adjusting for confounders including adherence to followup, completing a 24-hour urinalysis after a kidney stone episode was associated with a 60% decreased risk of recurrence (hazard ratio 0.40, 95% CI 0.18-0.91).

CONCLUSIONS

The risk of kidney stone recurrence is high during childhood, with approximately 50% of children presenting with symptomatic recurrence within 3 years of the first stone. The role and usefulness of analyzing 24-hour urine chemistries in decreasing kidney stone recurrence should be explored in future prospective studies.

Metabolic disturbances in Chinese children with urolithiasis: a single center report

Urinary stones and urine composition are the first steps in the process of recurrence prevention, but data concerning the association between the two compositions are scarce in Chinese children with urolithiasis. We retrospectively analyzed the records of children (age range 0-18 years) with urolithiasis in our center between March 2004 and December 2013. Stone analysis was carried out in 382 children and 24-hour urine analysis in 80 children. Analysis of both stone and 24-hour urine composition was completed in 56 children. Stone samples were analyzed by Fourier transform-infrared spectrometry. The major stone constituents were calcium oxalate (78.8 %). Of 80 children with 24 h urine analysis, only 2.5 % were without urinary metabolic abnormalities. Hypocitraturia was recorded in 97.5 %, high sodium excretion in 50.0 %, cystinuria in 48.7 %, hypercalciuria in 18.8 %, small urine volumes in 12.5 %, hyperoxaluria in 5.0 % and hyperuricosuria in 1.3 %. Interestingly, higher urine volumes were recorded in girls than in boys (73.2 ± 58.5 vs 51.3 ± 45.3 mL/kg, p = 0.036). Urine sodium (p = 0.002) and oxalate (p = 0.004) were significantly higher in children >9 year old. Moreover, compared with calcium oxalate stone formers, the urine volume (p = 0.040), citrate (p = 0.007) and cystine (p = 0.004) were higher in patients with cystine stones. Hypocitraturia was the common abnormality among Chinese children with urolithiasis. The surprisingly high incidence of cystinuria is of note.

If You Twinkle When You Tinkle, Stones Are Found on Ultrasound

Urolithiasis in children is an underrecognized cause of pediatric abdominal pain. Our case describes a child who presented to the emergency department with right lower quadrant pain, in whom a point-of-care ultrasound detected an ureterovesicular stone, which obviated the need for any further radiographic studies. We review the current literature on pediatric urolithiasis with a focus on sonographic diagnosis.

Tracking of radiation exposure in pediatric stone patients: The time is now

BACKGROUND

Despite the increasing incidence of pediatric nephrolithiasis, there is little data quantifying the radiation exposure associated with treatment of this disease. In this study, pediatric patients with nephrolithiasis who were managed at a single institution were identified, and the average fluoroscopy time and estimated radiation exposure associated with their procedures were reported.

METHODS

Stone procedures performed on pediatric patients between 2005 and 2012 were retrospectively identified. Procedures were classified as primary ureteroscopy (URS), stent placement prior to ureteroscopy (SURS), percutaneous nephrolithotomy (PCNL), and bilateral ureteroscopy (BLURS). Patient demographic information, stone size, stone location, number of radiographic images, and fluoroscopy times were analyzed.

RESULTS

A total of 152 stone procedures were included in the final analysis (92 URS, 38 SURS, eight BLURS and 14 PCNL). Mean patient age at time of stone treatment was 15.94 ± 4.1 years. Median fluoroscopy times were 1.6 (IQR 0.8-2.4), 2.1 (IQR 1.6-3.0), 2.5 (IQR 2.0-2.9), and 11.7 (IQR 5.0-18.5) minutes for URS, SURS, BLURS and PCNL, respectively. There was a moderate correlation between stone size and fluoroscopy time (r = 0.33). When compared with ureteroscopic procedures, PCNL was associated with a significantly higher fluoroscopy time (11.7 vs 2.1 min, P < 0.001). The estimated median effective dose was 3 mSv for ureteroscopic procedures and 16.8 mSv for PCNL. In addition to radiation exposure during treatment, patients in this cohort were exposed to an average of one (IQR1-3) CT scan and three (IQR 1-8) abdominal X-rays. No new malignancies were identified during the limited follow-up period.

CONCLUSIONS

Radiation exposure during treatment of pediatric stone disease is not trivial, and is significantly greater when PCNL is performed. Given the recommended maximum effective dose of 50 mSv in any one year, urologists should closely monitor the amount of fluoroscopy used, and consider the potential for radiation exposure when choosing the operative approach. Prospective studies are currently underway to elucidate precise dose measurements and localize sites of radiation exposure in children during stone treatment.

A comparison of outcomes after percutaneous nephrolithotomy in children and adults: a matched cohort study

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) has surpassed open stone surgery as the operation of choice for large and complex stone burdens (figure). Although the procedure was developed in adults, its principles have been extrapolated to children. There is a paucity of literature comparing outcomes of PCNL in adults and children for similar stone burdens.

OBJECTIVE

The purpose of this study was to evaluate outcomes following PCNL among children and adults with similar stone burdens.

PATIENTS AND METHODS

Data on patient characteristics and outcomes for 2196 consecutive patients undergoing PCNL at a single institution were collected prospectively from January 1992 to July 2013. Thirty-one pediatric patients undergoing 39 PCNLs were identified. Each pediatric PCNL was matched in a ratio of 1:4 to adult PCNLs by year of surgery and stone burden characteristics (staghorn, partial staghorn, number of stones). All PCNLs were performed by two fellowship-trained endourologists who operate on both adult and pediatric patients. Ultrasonic lithotripsy was used primarily. The primary outcome measure was stone-free rate (SFR) at hospital discharge. Secondary outcomes included the need for second-look nephroscopy, length of hospital stay, complication rate, and blood transfusion rate. The Student t test was used for continuous variables and the Fisher exact for categorical variables.

RESULTS

The median age for the pediatric group was 13.9 ± 4.30 years and for the adult group was 55.4 ± 15.1 years. Pediatric patients tended to present with metabolic stones, with no difference in rates of infection stones. No difference was found in SFR at time of hospital discharge (86.1% vs. 86.4%, p = 0.2). More pediatric patients required a second access tract than adult patients (15.4% vs. 4.52%, p = 0.02). There was no significant difference in the need for second-look nephroscopy, length of stay, or complication rates (overall and by Clavien classification subgroup) between both groups. The rates of blood transfusion were low in both groups (0% vs. 0.6%, p = 0.80).

DISCUSSION

There was no difference in primary and secondary outcomes among children compared with adults undergoing PCNL in our study. The outcomes reported in this study were similar to published literature. A limitation of this study is the low number of pediatric patients. However, it is unique to have a single-center study that compares PCNL outcomes in both adult and pediatric patient and accounts for stone burden characteristics.

CONCLUSIONS

Although principles of PCNL were developed in adults, this study affirms the safety and efficacy of PCNL in both pediatric and adult patients.

Our Experience with Totally Ultrasonography-Guided Percutaneous Nephrolithotomy in Children

Purpose: To present the safety and efficacy of totally ultrasonography-guided percutaneous nephrolithotomy (PCNL) for managing urinary stones in pediatric patients. Patients and Methods: Ten children with a mean age of 5.4 (3-11) years underwent totally ultrasonography-guided PCNL from March 2013 to November 2013. The pyelocaliceal system was punctured with the patient in the prone position by using ultrasonographic guidance, and the tract was dilated using a single-shot dilation technique. All steps of renal access were performed by using ultrasonography; no fluoroscopy was used. PCNL in all cases was performed by using adult instruments. Results: The mean stone size was 28.9±6.7 mm (range 17-35 mm). The mean access time to stone was 4.45±2.25 minutes (range 3-10 min). The mean nephroscopic time was 45.9±17 minutes (range 20-80 min). The stone-free rate was 83%. Mean hospital stay of patients was 3 days (range 2-5 days). No major complications were happened. Only one patient needed ureteral stent insertion because of urinary leakage from the nephrostomy tract. Conclusion: Our experience with totally ultrasonography-guided PCNL using adult size instruments in children revealed proper results and acceptable complications compared with the standard technique of PCNL. Likewise, this alternative method has the advantage of preventing radiation hazard.

Bladder calculi in the augmented bladder: a follow-up study of 160 children and adolescents

INTRODUCTION

Bladder augmentation (BA) has been used for various congenital and acquired conditions to create a low pressure, continent catheterizable reservoir. The prevalence of calculi within the BA have been reported to be from 3 to 52.5%. The present study reports the prevalence and risk factors of bladder calculi in patients with BA.

MATERIAL AND METHODS

A retrospective review of 160 patients was performed from January 1997 through December 2012. The various risk factors for the formation of bladder calculi such as the nature of the anatomical defect, presence of preoperative urinary calculi, type of bowel augmentation, addition of a mitrofanoff and/or bladder neck procedure, prevalence of post-operative urinary tract infections (UTIs), need for mitrofanoff revision due to stenosis/difficulty catheterization, postoperative significant hydronephrosis and bladder calculi were recorded for analysis. The children underwent open removal or endoscopic cystolithotripsy. One hundred and eight males and 52 females (average age 6.3 years) were followed up for a median of 70.5 months. All patients performed daily bladder irrigation with tap or drinking water.

RESULTS

Post-operative bladder calculi were noted in 14 (8.8%) of 160 patients following BA. Median time to stone formation was 37.5 months (11-120 months). Recurrent febrile UTIs were noted in 16 of the 160 patients following BA. The various risk factors and their outcomes are summarized in table. Eight patients underwent open cystolithotomy and four patients were treated by cystolithotripsy. Post-operative recurrent bladder calculi were noted in 2 patients. Multivariate analysis revealed that exstrophy/epispadias (OR 17.2) and recurrent UTI (OR 55.4) were independent risk factors for developing postoperative calculi in bladder augmentations. All other risk factors did not achieve statistical significance.

DISCUSSION

There seemed to be no difference in the prevalence of calculi in the ileal or colonic augmentations. Mucus secreted by the bowel segment blocks catheters leading to incomplete drainage, stagnation and UTIs. Our protocol consists of daily bladder irrigation till the effluents are clear of mucus. This is probably the key to the low prevalence of postoperative calculi (8.8%) in our patients.

CONCLUSION

Bladder exstrophy/epispadias and UTIs are independent statistically significant risk factors for the formation of bladder calculi in BA patients. Other risk factors such as preoperative calculi, bladder neck procedures and the use of mitrofanoff though not statistically significant, may contribute to the overall risk. The performance of daily bladder irrigation is an important part of our management of mucus.

Ureteroscopy for Paediatric Renal Tract Stones - Outcomes from a Tertiary European Centre

Aims: The use of ureteroscopy in treating paediatric stone disease has risen in recent years. We retrospectively reviewed the results of ureteroscopic stone management for our regional paediatric stone service. Material and Methods: Between April 2010 and October 2013, consecutive patients undergoing ureteroscopy and stone fragmentation were identified. Data were recorded from electronic records for patient demographics, pre-operative assessment, stone characteristics, and intra- and post-operative complications. Results: Twenty-one patients (mean age 8.6 years; range: 1.4-16) had 32 procedures in our series (13 males and 8 females). Five (24%) had a metabolic abnormality and 8 (38%) had an anatomical abnormality. The mean initial stone size was 9.6 mm (range: 5-20) and 10 were left sided. Of the 32 procedures, 18 (56%) had a pre-operative stent. A positive pre-operative urine culture was seen in 4 (13%). CT was used in 6 (19%) with the rest having a combination of USS and/or plain KUB. Of these 21 patients, 13 (62%) were stone free after the first procedure, 17 (81%) after a second and 20 (95%) after a third (mean 1.5 procedures/patient). One patient with a 6-mm residual fragment chose to have surveillance. Eighteen (50%) had post-operative stent insertion. The mean length of stay was 1.5 days (range: 0-5). A minor complication (Clavien 1) was observed in 1 patient. No other complications were recorded. Conclusions: Ureteroscopy for stone disease in children is feasible with a low complication rate and high stone-free rate.

Percutaneous nephrolithotomy in children: A preliminary report

Objectives:

The recurrence of pediatric nephrolithiasis, the morbidity of repeated open surgical treatment as well as our experience in percutaneous nephrolithotomy (PNL) in adult patients, all derived us to shift to PNL for managing renal stones >1.5 cm in pediatric patients. Our aim of this study is to evaluate the safety and efficacy of PNL in pediatric patients.

Materials and Methods:

During the period of the month between May 2011 and April 2013, 38 children (47 renal units) underwent PNL for renal stones 1.5-5 cm in length. Patient demographics, stone characteristics, and clinical outcome were prospectively studied. Data of those who underwent conventional and tubeless PNL were compared. Median follow-up period was 12 months (range: 6-24).

Results:

The median age at presentation was 8-year (range: 3-12). The operative time ranged from 30 to 120 min (median 90). Overall stone clearance rate was 91.5% after single PNL. The median hospital stay was 3 days. Auxiliary procedures were successful for the remaining 4 patients (nephroscopic clearance in one and shockwave lithotripsy in 3). Tubeless PNL was performed in 17 renal units with a comparable outcome to conventional ones. The perioperative complications were noted in 5/47 (10.6%) of all procedures (Clavien Grade II in 4 and Clavien Grade IIIa in 1) and were managed conservatively.

Conclusions:

Percutaneous nephrolithotomy for renal stones in pediatric patients is safe and feasible if performed by a well-experienced endourologist. Tubeless PNL is a better choice for children.