Epidemiology of pediatric urolithiasis

Comparative efficacy of different surgical techniques for pediatric urolithiasis-a systematic review and meta-analysis

Background

Prior research has assessed a range of surgical treatments for pediatric urolithiasis, emphasizing the necessity of tailor-made therapeutic approaches. These studies also show the adaptability of percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery (RIRS), and shock wave lithotripsy (SWL) in managing diverse stone dimensions. The goal of this research was to examine the effectiveness of these varying surgical methods in treating pediatric urolithiasis.

Methods

Seven digital databases were explored to gather pertinent studies, following the guidelines established by the PRISMA protocol. The retrieved studies were subsequently scrutinized to draw comparisons between the stone-free rate (SFR) and the rate of complications associated with PCNL, RIRS, and SWL.

Results

The SFR evaluation revealed no notable disparity between PCNL and RIRS [odds ratio (OR) 1.43, 95% confidence interval (CI): 0.67-3.05, P=0.36]. However, it was observed that both PCNL and RIRS outperformed SWL in terms of effectiveness (OR 2.51, 95% CI: 1.19-5.29, P=0.02 and OR 2.42, 95% CI: 1.41-4.14, P=0.001 respectively). Regarding the complication rates, no significant differences were observed among the three surgical methods (OR 0.67, 95% CI: 0.49-1.59, P=0.05), albeit with various forms of complications being reported. Certain studies associated PCNL with an elevated rate of complications, specifically urinary tract infections (UTIs) and severe hematuria.

Conclusions

Though PCNL and RIRS demonstrated higher effectiveness than SWL in achieving SFR, there was no significant disparity in the rates of complications across all three procedures. The study underscores the significance of personalized treatment plans, taking into account aspects such as the dimension and location of the stone, along with patient-specific characteristics.

Is Stent on a String the New Gold Standard for Postureteroscopy Ureteral Drainage? Evidence from a Systematic Review

Introduction: Ureteral stents are widely used throughout urologic surgery, most commonly following ureteroscope (URS) procedures. This systematic review aims to assess the current evidence concerning stent on string (SOS) placed after URS and compare it with stents without strings (SWOSs). Methods: A systematic review was conducted on several databases using the preferred reporting items for systematic review and meta-analysis (PRISMA) methodology for studies in English language, for patients of all age groups, who had an SOS after URS for stone disease. Results: Of 1210 records identified, a total of 22 studies (20 adult and 2 pediatric studies) were included, with a total of 8382 patients. Of these, 3427 (40.9%) had SOSs inserted and 434 (11%) were in the pediatric age group. Our results show that SOS provides several advantages, and compared with SWOS, they were in situ for less time, with no difference in complications such as urinary tract infection or urinary symptoms. Furthermore, significant cost savings, less pain on removal, and high rates of safe home removal were reported in SOS, with >90% patients reporting that they would be happy to remove their SOSs at home. However, a small risk of stent dislodgment must be considered when making decisions regarding SOS placement after URS. Conclusion: SOS provides an excellent option after URS, especially in those patients with no intraoperative complication, and their placement is done as a routine insertion based on surgeon preference. These stents reduce dwell time, pain, cost, risks, and suffering involved from prolonged stenting, and majority of patients are happy to remove it themselves at home. Although their use seems to be still restricted in the current endourology practices, they are likely to become the new gold standard for routine URS in future, with more shared decision making and patient-reported outcome measures coming into the mainstream.

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.

Current Status of Protein Biomarkers in Urolithiasis-A Review of the Recent Literature

Urolithiasis is an increasingly common clinical problem worldwide. The formation of stones is a combination of metabolic status, environmental factors, family history and many other aspects. It is important to find new ways to quickly detect and assess urolithiasis because it causes sudden, severe pain and often comes back. One way to do this is by exploring new biomarkers. Current advances in proteomic studies provide a great opportunity for breakthroughs in this field. This study focuses on protein biomarkers and their connection to kidney damage and inflammation during urolithiasis.

In focus: perplexing increase of urinary stone disease in children, adolescent and young adult women and its economic impact

Background

Urinary stone disease (USD) historically has affected older men, but studies suggest recent increases in women, leading to a near identical sex incidence ratio. USD incidence has doubled every 10 years, with disproportionate increases amongst children, adolescent, and young adult (AYA) women. USD stone composition in women is frequently apatite (calcium phosphate), which forms in a higher urine pH, low urinary citrate, and an abundance of urinary uric acid, while men produce more calcium oxalate stones. The reasons for this epidemiological trend are unknown.

Methods

This perspective presents the extent of USD with data from a Canadian Province and a North American institution, explanations for these findings and offers potential solutions to decrease this trend. We describe the economic impact of USD.

Findings

There was a significant increase of 46% in overall surgical interventions for USD in Ontario. The incidence rose from 47.0/100,000 in 2002 to 68.7/100,000 population in 2016. In a single United States institution, the overall USD annual unique patient count rose from 10,612 to 17,706 from 2015 to 2019, and the proportion of women with USD was much higher than expected. In the 10-17-year-old patients, 50.1% were girls; with 57.5% in the 18-34 age group and 53.6% in the 35-44 age group. The roles of obesity, diet, hormones, environmental factors, infections, and antibiotics, as well as the economic impact, are discussed.

Interpretation

We confirm the significant increase in USD among women. We offer potential explanations for this sex disparity, including microbiological and pathophysiological aspects. We also outline innovative solutions - that may require steps beyond typical preventive and treatment recommendations.

Utilization of Flexible Ureteroscopy in Renal Stones Management in Pediatrics: Single Tertiary Center Experience

Objectives. To assess the effectiveness and safety of flexible ureteroscopy in children treated at our center during the last 5 years. Methods. Retrospectively, we have studied 41 children that suffered 51 stone episodes, and FURS for renal calculi <2 cm. Preoperative, operative, and postoperative data were gathered. Results. The mean age of the 41 kids who experienced 51 stone episodes was 9.6 [2.8] years (4.2-16 years). The mean stone diameter was 12.8 [3.3] mm (6-20 mm). The mean operative time was 79.9 [19.9] minutes. The mean hospital stay was 27.6 [12.9] hours. The SFR after the first session was 64.7% and 80.4% after the second session. The overall complications had been recorded in 25 cases (49%) with low morbidity (Clavien grade I-III). Conclusions. Pediatric FURS is a minimally invasive option with a high SFR and a low percentage of high-grade complications in the management of pediatric renal stones.

Paediatric nephrology in under-resourced areas

BACKGROUND

Nearly 50% of the world population and 60% of children aged 0 to 14 years live in low- or lower-middle-income countries. Paediatric nephrology (PN) in these countries is not a priority for allocation of limited health resources. This article explores advancements made and persisting limitations in providing optimal PN services to children in such under-resourced areas (URA).

METHODS

Medline, PubMed and Google Scholar online databases were searched for articles pertaining to PN disease epidemiology, outcome, availability of services and infrastructure in URA. The ISN and IPNA offices were contacted for data, and two online questionnaire surveys of IPNA membership performed. Regional IPNA members were contacted for further detailed information.

RESULTS

There is a scarcity of published data from URA; where available, prevalence of PN diseases, managements and outcomes are often reported to be different from high income regions. Deficiencies in human resources, fluoroscopy, nuclear imaging, immunofluorescence, electron microscopy and genetic studies were identified. Several drugs and maintenance kidney replacement therapy are inaccessible to the majority of patients. Despite these issues, regional efforts with support from international bodies have led to significant advances in PN services and infrastructure in many URA.

CONCLUSIONS

Equitable distribution and affordability of PN services remain major challenges in URA. The drive towards acquisition of regional data, advocacy to local government and non-government agencies and partnership with international support bodies needs to be continued. The aim is to optimise and achieve global parity in PN training, investigations and treatments, initially focusing on preventable and reversible conditions.

Role of Multi-Detector Computed Tomography Indices in Predicting Extracorporeal Shockwave Lithotripsy Outcome in Patients With Nephrolithiasis

Background

Nephrolithiasis is one of the most common renal pathologies and is routinely encountered in daily practice. Non-contrast computed tomography (NCCT) is the gold standard diagnostic imaging modality for urolithiasis. The role of HU (Hounsfield units) in calculus as a predictor of extracorporeal shock wave lithotripsy (ESWL) has been studied in the past. This study aims to evaluate the role of HU value and various other NCCT indices in predicting the outcome of ESWL.

Material and methods

This was a prospective observational study that included 45 patients suffering from nephrolithiasis who underwent NCCT-KUB (kidney, ureter, and bladder) followed by ESWL. The NCCT indices were evaluated and correlated with the outcome of ESWL. NCCT-KUB was performed using multidetector SIEMENS® SOMATOM EMOTION 16-slice CT scanner (SIEMENS, Munich, Germany).

Results

In our study, the HU value turned out to be a statistically significant predictor of ESWL success (p <0.05), and the renal pelvis also proved to be a good prognostic indicator for ESWL success. The cut-off value of <1179 HU favored a successful outcome of ESWL, while if >1179 HU, ESWL is likely to fail. Hence, the successful outcome of ESWL is inversely proportional to the HU value. Renal pelvic calculi (n=14) showed a 100% success rate, which was better than all other calculus locations (p<0.05). However, the rest of the indices did not show any statistical significance.

Conclusion

Multi-detector NCCT-KUB indices can help in the selection of patients with a good prognosis for ESWL, which will prevent the patient from undergoing undesired invasive procedures.

Quantitative phase analysis and microstructural characterization of urinary tract calculi with X-ray diffraction Rietveld analysis on a Caribbean island

In the twin-island state of Trinidad and Tobago, urinary stone analysis is not routinely performed. This study investigates, via powder X-ray diffraction, 52 urinary tract calculi collected from hospitals in Trinidad. Of these, 46 stones were analysed with Rietveld refinement for quantitative analysis and materials characterization. Refined unit-cell, microstructural and weight fraction parameters were obtained, with the last being used for stone classification. The results revealed seven distinct mineralogical phases of varying frequency: calcium oxalate monohydrate (COM, 58%), calcium oxalate dihydrate (COD, 23%), carbonated apatite (APA, 48%), brushite (BRU, 6%), struvite (STR, 42%), uric acid (UA, 23%) and ammonium acid urate (AAU, 19%). The average refined crystallite sizes were 1352 ± 90 Å (COM), 1921 ± 285 Å (COD), 83 ± 5 Å (APA), 1172 ± 9 Å (BRU), 1843 ± 138 Å (STR), 981 ± 87 Å (UA) and 292 ± 83 Å (AAU). Subsequently, 36.5% of stones were categorized as phosphates, 34.6% as oxalates, 13.5% as uric acid/urates and 15.4% as mixed compositions. The study findings highlight the importance of stone analysis as a necessary step towards disease management of local patients, and endorse the application of Rietveld refinement as a natural extension to diffraction-based kidney stone investigations.

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.

Animal, Human, and 23Na MRI Imaging Evidence for the Negative Impact of High Dietary Salt in Children

PURPOSE OF THE REVIEW

Conditions typically prevalent in adults such as hypertension, kidney stones, osteoporosis, and chronic kidney disease are increasing among adolescents and young adults (AYA). The purpose of this review is to describe the association of these conditions to a high salt diet among pediatric patients.

RECENT FINDINGS

We present animal, human, and 23Na MRI evidence associated with the negative impact of high dietary salt in children. Special focus is placed on novel 23Na MRI imaging which reveals the important concept of a third compartment for sodium storage in soft tissue. Finally, we make recommendations on who should not be on a low salt diet.

SUMMARY

A high salt intake predisposes children and AYA to considerable morbidity. We exhort the reader to engage in advocacy efforts to curve the incidence and prevalence of high salt-related life-limiting conditions.

Distribution of APOE gene polymorphism in the Chinese Uyghur children & its association with urolithiasis

BACKGROUND & OBJECTIVES

This study was to survey the apolipoprotein E (APOE) gene polymorphism distribution among Chinese Uyghur children and to explore the relationship between APOE gene polymorphism and the occurrence of urolithiasis.

METHODS

A total of 144 Uyghur children with urolithiasis and 274 without the history of urolithiasis were enrolled in this study. Venous blood samples were collected from all participants, and APOE genotyping, derived from rs429358 and rs7412, was performed using Sanger sequencing.

RESULTS

Among the 418 children, the most prevalent genotype was E3/3, accounting for 71.3 per cent in the urolithiasis group and 71.4 per cent in the control group, followed by E3/4 and E2/3. Higher frequencies of the ɛ2 and ɛ4 alleles and lower frequencies of the ɛ3 allele were observed in the test group, and the unusual allele ɛ1 was also found in them. However, there were no significant differences between cases and controls at both rs429358 and rs7412 genotype and allele frequencies [odds ratio (OR)=0.98, 95% confidence interval (CI): 0.57-1.67; 0.98 (0.59-1.63); 1.43 (0.75-2.74) and 1.40 (0.74-2.62), respectively]. Likewise, none of significant differences was found between cases and controls at both APOE genotype and allele frequencies [OR=0.88, 95% CI: 0.51-1.53; 0.74 (0.33-1.64); 1.10 (0.73-1.66); 1.13 (0.76-1.67) and 1.14 (0.76-1.70), respectively].

INTERPRETATION & CONCLUSIONS

The present study does not support any association between APOE genotyping and urolithiasis in Uyghur children.

A 13 year hospital based study on the Trend of Urinary Stone Disease in Uttarakhand, India

Background

The present retrospective study on urinary stone disease in the Uttarakhand state was necessitated as no study has been done yet.

Methods

A 13 year retrospective study (from 2005 to 2018) was conducted on the urinary stones removed from the patients, admitted at Himalayan Institute of Medical Sciences, Dehradun. The incidence of the disease, site of stones in urinary tract upon diagnosis, composition of removed stones and occurrence of a possible co-relationship between the incidence of the urinary stone disease at different times, age, sex, religion of the patients was investigated.

Results

The frequency of occurrence of urinary stones in males was found to be almost three times more as compared to their female counterparts. The above trend was consistent over the entire period of the study. Interestingly, in the Muslim and Sikh population of the area, females were found to be less prone to the problem as compared to their Hindu counterparts. However, in all religious groups, 21-40 years old subjects were found to be most susceptible to the problem and approximately 90% of the urinary stones were recovered from the kidneys and primarily composed of calcium oxalate.

Conclusion

The co-relationship between the occurrence of urinary stones with age, sex of the patients, their religion & site of stones on diagnosis was found to be statistically significant.

Metabolic risk factors and the role of prophylaxis in pediatric urolithiasis

Suppose that the recurrence in pediatric urolithiasis has a close relationship with metabolic abnormalities and is affected by residual burden and prophylaxis. If so, the recurrence rates could be reduced with effective surgery and appropriate prophylaxis. Here we retrospectively evaluate the metabolic risk factors data of 148 children who were operated on between January 2005 and March 2013 due to kidney stones. All patients underwent percutaneous nephrolithotomy (PCNL), and all were children. Thirteen children had a history of surgery performed to treat urological anomalies. Twenty-four-hour urine analysis, the residual status of surgery, BMI levels, and the number of metabolic abnormalities were noted. Only 18 (15%) of 122 patients without residual stones after PCNL had recurrence at follow-up whereas; nine (26%) of 26 patients with residual stones developed recurrence (p = 0.017). Recurrence was observed in 14 (16%) of 89 patients with a metabolic abnormality, and 13 (30%) of 44 patients with two or more metabolic abnormalities had recurrence at follow-up (p = 0.024). Those patients with no metabolic abnormalities did not develop recurrence. Stone recurrence was seen in six (8%) of 78 children who were given metabolic prophylaxis, compared to 21 (30%) of 70 patients who did not receive metabolic prophylaxis (p = 0.02). No stone recurrence was seen in nine children who were given Shohl's, whereas four (67%) of six patients who did not take Shohl's had recurrence (p = 0.022). Complete removal of stones by a suitable surgical method is essential to avoid recurrences. Detailed clinical and laboratory evaluations should be performed in children with urolithiasis. Appropriate specific prophylactic treatment (e.g., potassium citrate and Shohl's) and non-specific prophylactic treatment (e.g., avoiding animal proteins, salt, simple sugars, and increased water intake) should be given to prevent reformation of stones in patients with pediatric urolithiasis.

The first epidemiology study of urolithiasis in New Brunswick

INTRODUCTION

Understanding the composition of a kidney stone is crucial in leading to proper treatment and preventing reoccurring urolithiasis. This study aimed to investigate the prevalence of urolithiasis in the province of New Brunswick (NB), Canada.

METHODS

A total of 3828 kidney stone analysis reports from October 1, 2016 to September 30, 2019, were reviewed from laboratory information systems. Among them, 3311 were identified as new cases. Stone compositions were analyzed by the Fourier transform infrared spectrometry. Incident rates were compared using Chi-squared analysis of different age, sex, and regional health authority (RHA) zones.

RESULTS

The prevalence of urolithiasis in NB was 147.8 per 100 000 person-years. Males had a significantly higher (X²=254, p<0.001) incident rate of 189 (95% confidence interval [CI] 182-198) than females (107 [95% CI 102-114]) per 100 000 person-years. Zone 1 had significantly higher (245 per 100 000 person-years, p<0.001) prevalence compared to other RHA zones. Age group over 65 years had the highest incidence rate of 253 per 100 00 person-years of all groups. The predominant kidney stone types in NB were calcium oxalate monohydrate (60.68%) and calcium oxalate dihydrate (11.58%). Those patients aged 0-18 years had a high percentage of struvite (4.32%) vs. the provincial average (2.19%) (p<0.001).

CONCLUSIONS

The prevalence of NB's urolithiasis is slightly higher than that of Ontario. Since both zones 1.1 and 1.2 have significantly high prevalence and are situated in the Moncton area (combined zone 1), it may suggest that geographical factors play a role in the prevalence of urolithiasis in NB.

Role of Mini-Percutaneous Nephrolithotomy in the Management of Pediatric Stone Disease: A Systematic Review of Literature

Introduction: Kidney stone disease in the pediatric setting is rare, but the incidence is rising. Mini-percutaneous nephrolithotomy (mPCNL) is one of the newer surgical interventions to have been developed in recent decades. The aim of this study was to carry out a systematic review (SR) to formally evaluate the safety and efficacy of pediatric mPCNL, which was defined as PCNLs using tract size between 15F and 20F. Methods: An SR was carried out in accordance with Cochrane guidelines and A MeaSurement Tool to Assess systematic Reviews (AMSTAR) checklist. Original studies reporting on outcomes of mPCNL with 20 or more patients (aged ≤18 years) were included. Results: Eight studies were finally identified, which satisfied our predefined criteria. This included two randomized trials and six cohort studies. A total of 384 patients with a weighted mean age of 7.5 years (range: 0.5-18 years) and a male:female ratio of 3:2 underwent mPCNL. The weighted mean stone size was 1.2 cm (range: 0.8-3.5 cm). The weighted mean operative time and length of hospital stay were 76.8 minutes (range: 20-120 minutes) and 4.6 days (range: 1-33 days), respectively. The most common location(s) of stones were lower pole (57%) and renal pelvis (24.3%). The weighted mean initial and overall stone-free rates were 87.9% (range: 76%-97.5%) and 97% (range: 91.3%-100%), respectively. None of the cases required intraoperative conversion to standard PCNL. Complications occurred in 19% (n = 73) of patients. The weighted mean transfusion rate reported across studies was 3.3% (range: 0%-10.3%). Conclusions: mPCNL is safe and effective in the pediatric population. Further randomized studies will help determine its formal role in pediatric endourology and help guideline recommendations accordingly.

Current update and future directions on gut microbiome and nephrolithiasis

The incidence of nephrolithiasis is increasing worldwide. Understanding how gut microbiome influences oxalate homeostasis has the potential to offer new strategies to prevent nephrolithiasis. The literature was reviewed to gather the evidence on the association between gut microbiome, hyperoxaluria and nephrolithiasis, and to identify the therapeutic interventions focused on the gut microbiome that could decrease hyperoxaluria and prevent nephrolithiasis. Gut microbiome is constituted by a plethora of microbiota including Oxalobacter formigenes (Oxf) and lactobacilli. Oxf can degrade dietary oxalate and induce enteral oxalate secretion. Animal studies suggested an association between oral Oxf supplementation and a decrease in hyperoxaluria. However, human studies have showed inconsistent results. Oral supplementation of lactobacilli did not show benefit in decreasing the hyperoxaluria. Antibiotic exposure, by affecting the gut microbiome, has been associated with an increase in nephrolithiasis. In vivo studies suggest fecal transplantation as a potential treatment option for reducing nephrolithiasis, but needs further evaluation in clinical studies. The current evidence suggests an association between gut microbiome and nephrolithiasis. However, the strategies focused on modulating gut microbiome for decreasing hyperoxaluria and preventing nephrolithiasis need further research. Judicious use of antibiotics in those predisposed to nephrolithiasis offers a preventative strategy for decreasing nephrolithiasis.

Outcomes of Ureteroscopy vs Mini-Percutaneous Nephrolithotomy for Pediatric Upper Urinary Tract Calculi: Comparative Nonrandomized Outcomes from Two Tertiary Endourology Referral Centers

Introduction: Pediatric upper urinary tract calculi can be treated by ureteroscopy (URS) or mini-percutaneous nephrolithotomy (mPCNL). We wanted to compare outcomes of URS and mPCNL from two tertiary referral centers that specialized in one of these treatments for pediatric stone disease. Materials and Methods: Data were collected from two tertiary centers for a 10-year period (2010-2019); one center specializing in URS and the other in mPCNL for consecutive patients ≤16 years undergoing either of these minimally invasive interventions. Upper urinary tract stones included stones in the kidney, pelviureteral junction, and proximal ureter, whereas mid or distal ureteral stones were excluded. Data were collected on patient and stone demographics. Outcomes of interest included stone-free rate (SFR) and complication rates. Results: During the study period, 55 patients underwent URS (group 1) and 40 patients underwent mPCNL (group 2). The mean stone size for groups 1 and 2 were 11.4 and 14.5 mm, respectively, whereas twice as many patients in group 1 had multiple stones. The final SFR and complication rates for groups 1 and 2 were 100% and 97.5%, and 5.4% and 12.5%, respectively. Although there were two Clavien II and one Clavien IV complication in the URS group, all five complications in mPCNL group were Clavien I. Conclusions: Our study shows excellent outcomes for upper urinary tract stones with both URS and mPCNL. Although treatment choices should be tailored to patients, each modality carries different advantages and our results reflect that high-volume centers specializing in a particular technique offer best outcomes, and this must also be borne in mind when counseling patients.

Shockwave lithotripsy for kidney stones as a first-line therapy in children younger than 2 years

BACKGROUND

The incidence of urolithiasis in children has risen worldwide over the last decades with geographical varieties. As pediatric patients begin forming stones earlier in life, they have high risk of recurrence. Extracorporeal shockwave lithotripsy (SWL) is a non-invasive treatment modality that is preferred in the management of pediatric stones. Reports about the safety and efficacy of SWL in patients younger than 24 months are scarce in the literature.

OBJECTIVE

The aim of the study was to evaluate the effectiveness and safety of SWL in patients younger than 24 months. The authors also aimed to assess the validity of the Dogan nomogram in predicting stone-free rates.

STUDY DESIGN

Between January 2009 and March 2019, data of 247 patients younger than 24 months at the time of SWL were retrospectively collected. Analysis was performed on 260 renal units. Success was considered in patients who were completely free of stones after the first session.

RESULTS AND DISCUSSION

The female/male ratio was 103/157, with a median age of 15 (5-24) months, a median stone size of 8 (3-30) mm and a median follow-up period of 7 (3-20) months. Multiple stones and lower calyx stones were observed in 19.6% (51/260) and 23.4% (61/260) of patients, respectively. Complications were detected in 5.8% (15/260) of patients (9 with steinstrasse, 3 with UTI, 2 with vomiting, 1 with hematuria). After the first session, 56.9% (148/260) of patients were stone-free. Forty-six of the failed 112 first sessions underwent second session. A total of 5 patients had a third session. The efficacy quotient was 57%. On univariate analysis, younger age (≤16 months), single stone, small stone size (<10 mm), and non-lower pole location were significant predictors of stone clearance. On multivariate analysis, younger age (=<16 months) and single stone remained significant. The Dogan nomogram score lower than 150 was found to be a good cutoff point to predict better stone clearance (Table).

CONCLUSION

Shockwave lithotripsy is a safe and effective treatment modality in patients younger than 24 months and could be the first option in this particular age-group in whom the other endourological modalities are not always applicable. The Dogan nomogram is reliable in predicting the stone-free rate in this age-group.

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

BACKGROUND

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

OBJECTIVE

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

RESULTS

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

CONCLUSIONS

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

Feasibility of dusting and pop-dusting using high-power (100W) Holmium YAG (Ho:YAG) laser in treatment of paediatric stones: results of first worldwide clincial study

Introduction

As the role of paediatric ureteroscopy (URS) for stone disease increases, new methods of stone treatment such as dusting and pop-dusting have emerged. However, outcomes of treatment using these laser settings in paediatric age group is still largely unknown. We aimed to look at the feasibility and outcomes of URS and pop-dusting using a high-power 100W laser for paediatric stone patients.

Material and methods

Outcomes from a prospective stone database were reviewed over a period of 30 months from February 2016–July 2018. All paediatric patients (≤16 years) treated with dusting and pop-dusting were included in our study. Dusting and pop-dusting were performed using Ho:YAG laser with the energy setting ranges of 0.2–0.5 J and 0.5–0.7 J respectively with a frequency of 20–50 Hz.

Results

Twelve patients underwent URS and treatment using this method with mean age of 6.5 years and a male:female ratio of 7:5. The mean and cumulative single stone size was 7.1 mm (3–10 mm) and 11.9 mm (6–40 mm) respectively with half of all patients having multiple stones. Eleven patients were stone free on follow-up with no intra or post-operative complications noted.

Conclusions

Pop-dusting using holmium laser is a new hybrid technique that allows for more efficient dust formation even for hard stones. This is the first clinical study demonstrating the safety and efficacy of this technique in paediatric patients. It is likely there will be wider adoption of these new laser techniques for stone treatment in the paediatric age group.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Acute Urinary Retention in the Male Child from Urethral Calculi: A Report of Three Cases

Urinary stones are uncommon in children. Urethral location of calculi can give rise to various clinical manifestations. We report three cases of urethral lithiasis presenting with acute urinary retention in children.

CLINICAL-EPIDEMIOLOGICAL PROFILE OF 106 PEDIATRIC PACIENTS WITH UROLITHIASIS IN RIO DE JANEIRO, BRAZIL

Objective:

To describe the frequency, clinical profile and treatment of patients with urolithiasis in the Pediatric Nephrology Department of a public state hospital in Rio de Janeiro, Brazil.

Methods:

Retrospective study. Data from pediatric patients (age: 1 month - 18 years) with urolithiasis admitted between January/2012 and December/2014 were reviewed from hospital charts. The studied variables were: demographic and anthropometric data, clinical status, family history of urolithiasis, urinary tract infection and use of lithogenic drugs, diagnostic procedures, associated abnormalities, metabolic disorders, treatment and recurrence.

Results:

The frequency of urolithiasis was 13.6%. Main characteristics of the patients: male gender, white race, eutrophy, aged between 5 and 10 years, family history of urolithiasis, previous urinary infection and spontaneous stone passage. Abdominal and flank pain and macroscopic hematuria were the most common complaints. The most frequent metabolic disorders were hypercalciuria, hyperuricosuria and hypocitraturia. Hypocitraturia was associated with previous urinary infection (p=0.004). Abdomen/urinary tract ultrasonography was the most commonly used diagnostic test. Hydronephrosis occurred in 54.4% of the cases, 81.1% of the stones were in the kidneys, and bilateral stones were associated to a family history of urolithiasis (p=0.030). Recurrence rate was 29.3% (most patients had a metabolic disorder). In 12.3%, the patients underwent lithotripsy, 24.5% were surgically treated (mainly pyelolithotomy), and only 7.6% had their stones analyzed (calcium oxalate was the main finding in the examined stones).

Conclusions:

The frequency of urolithiasis in these pediatric patients was similar to that reported by the literature. A metabolic evaluation is required and the composition of stones should be better evaluated.

Ureteroscopy for Stone Disease in Paediatric Population is Safe and Effective in Medium-Volume and High-Volume Centres: Evidence from a Systematic Review

Purpose of Review

The incidence of urinary stone disease among the paediatric population is increasing. Whilst there has been a rise in the number of original studies published on ureteroscopy (URS) in children, critical review still remains under-reported.

Recent Findings

A Cochrane style systematic review was performed to identify all original articles on URS (minimum of 25 cases) for stone disease in paediatric patients between Jan. 1996 and Dec. 2016. Based on the number of reported cases, centres were divided into medium (25–49 cases) and high (≥ 50 cases) volume studies.

Thirty-four studies (2758 children) satisfied our search criteria and were included in this review. The mean stone size was 8.6 mm with an overall stone-free rate (SFR) of 90.4% (range 58–100). Medium-volume centres reported a mean SFR of 94.1% (range 87.5–100), whilst high-volume centres reported a mean SFR of 88.1% (range 58–98.5). Mean number of sessions to achieve stone-free status in medium-volume and high-volume groups was 1.1 and 1.2 procedures/patient respectively. The overall complication rate was 11.1% (327/2994). Breakdown by Clavien grade was as follows: Clavien I 69% and Clavien II/III 31%. There were no Clavien IV/V complications, and no mortality was recorded across any of the studies. The overall failure to access rate was 2.5% (76/2944).

Medium-volume and high-volume studies had overall complication rates of 6.9% (37/530) and 12.1% (287/2222) respectively, but there was no significant difference in major or minor complications between these two groups.

Summary

Ureteroscopy is a safe and effective treatment for paediatric stone disease. Medium-volume centres can achieve equally high SFRs and safety profiles as high-volume centres. Despite the rarity of paediatric stone disease, our findings might increase the uptake of paediatric URS procedures.

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.

The association of hypercalciuria and hyperuricosuria with vesicoureteral reflux in children

OBJECTIVES

One of the important complications of vesicoureteral reflux (VUR) is the development of urolithiasis. Identifying factors involved in development of urolithiasis in children with VUR is immensely important. This study was conducted to determine the association between hypercalciuria and hyperuricosuria with VUR in children.

METHODS

One-hundred children with VUR (case group) were compared to 100 healthy children (control group) in terms of hypercalciuria and hyperuricosuria. To measure these markers, random morning fasting urine samples were used. Data were analyzed using statistical tests.

RESULTS

Hypercalciuria and hyperuricosuria frequencies, and also urine calcium/creatinine (Ca/Cr) and urine uric acid/creatinine (UA/Cr) ratios were significantly higher in the case group compared to the control group (P < 0.05). A significant difference was found between hypercalciuria and hyperuricosuria in severity of VUR (P < 0.05). A positive correlation was observed between hypercalciuria and hyperuricosuria and severity of VUR (P < 0.05).

CONCLUSIONS

The present study showed that there is association between hypercalciuria, hyperuricosuria and VUR in children. It is recommended to adopt measures to prevent the development of urolithiasis in VUR patients.

Does extracorporeal shock wave lithotripsy cause hearing impairment in children?

PURPOSE

We evaluated the possible effects of noise created by high energy shock waves on the hearing function of children treated with extracorporeal shock wave lithotripsy.

MATERIALS AND METHODS

A total of 65 children with normal hearing function were included in the study. Patients were divided into 3 groups, ie those becoming stone-free after 1 session of shock wave lithotripsy (group 1, 22 children), those requiring 3 sessions to achieve stone-free status (group 2, 21) and healthy children/controls (group 3, 22). Extracorporeal shock wave lithotripsy was applied with patients in the supine position with a 90-minute frequency and a total of 2,000 shock waves in each session (Compact Sigma, Dornier MedTech, Wessling, Germany). Second energy level was used with a maximum energy value of 58 joules per session in all patients. Hearing function and possible cochlear impairment were evaluated by transient evoked otoacoustic emissions test at 1.0, 1.4, 2.0, 2.8 and 4.0 kHz frequencies before the procedure, 2 hours later, and 1 month after completion of the first shock wave lithotripsy session in groups 1 and 2. In controls the same evaluation procedures were performed at the beginning of the study and 7 weeks later.

RESULTS

Regarding transient evoked otoacoustic emissions data, in groups 1 and 2 there was no significant alteration in values obtained after shock wave lithotripsy compared to values obtained at the beginning of the study, similar to controls.

CONCLUSIONS

A well planned shock wave lithotripsy procedure is a safe and effective treatment in children with urinary stones and causes no detectable harmful effect on hearing function.

Extracorporeal shockwave lithotripsy under sedoanalgesia for treatment of kidney stones in infants: a single-center experience with 102 cases

OBJECT

We present the efficacy of shockwave lithotripsy (SWL) therapy administered with sedoanalgesia in infants with kidney stones.

MATERIALS AND METHODS

We enrolled 102 patients aged 5-24 months who had kidney stones and received SWL therapy under sedoanalgesia using a Siemens Lithostar Modularis device. Patient and stone characteristics, therapy parameters, pain score, complications, discharge time, and follow-ups were registered and evaluated. Pain score was assessed using a Neonatal Infant Pain Score (NIPS). Postanesthetic discharge scoring system (PADSS) was used for the assessments of postprocedural discharge procedure.

RESULTS

Mean age of the patients was 17.2 ± 6.3 months (5-24 months). Mean stone size was 7.9 ± 3.3 mm (5-23 mm). The most common concomitant metabolic disorders were hypercalciuria and hypocitraturia. The stone-free rates of the infants were 70.6, 87.3, and 99.1 % after the first, second, and third sessions of SWL therapy, respectively. The mean NIPS scores procedure during, and at 1 h after SWL procedure were determined as 0.24 ± 0.45 and 0.34 ± 0.47, respectively. There was no statistically significant difference between two pain score values (P = 0.114). The mean discharge time of patients after the SWL procedure were 108.6 ± 27.9 min. Forty-two patients (41.1 %) were followed up. The follow-up period varied between 8 and 48 months (mean 19.5 months); none of those patients showed evidence of diabetes mellitus, hypertension, or renal function impairment.

CONCLUSIONS

SWL therapy under sedoanalgesia is a safe and efficient treatment modality that can be administered with low complication rates and high stone-free rates in the treatment of renal stones in infants.

High incidence of urinary stones in Uyghur children may be related to local environmental factors

OBJECTIVE

To analyze the causes of urolithiasis in Uyghur children from Xinjiang.

PATIENTS AND METHODS

We retrospectively evaluated the clinical features and characteristics of urinary stone composition of 220 Uyghur pediatric patients with urolithiasis between March 2009 and June 2011. The data were compared with that of 100 Uyghur children without urolithiasis who visited the Child Care Clinic for regular health check-ups. The stones were collected by endoscopy or open surgery, and analyzed using infrared spectroscopy.

RESULTS

The mean age of the 220 Uyghur children was 7.48 ± 4.73 years (range, 0.8-17.0 years). The overall sex ratio (male:female) was 2.23:1. The predominant pure stone was ammonium urate (58.9%), whereas the predominant mixed stone was calcium oxalate mixture (91.1%). Uric acid stones comprised 54% of all stones. Urinary tract infections were observed in 42.3% and 4.0% of the patient and control groups, respectively. The mean urinary pH values were 5.77 ± 0.67 and 6.42 ± 0.67, respectively (p < 0.001). pH values were <5.5 in 52.7% and 6% of the patient and control groups, respectively. On 24-h urine analysis, we found metabolic disturbances in these patients: hypercalciuria in 6.8% cases, hyperphosphaturia in 16.8% cases, hyperuricosuria in 21.4% cases, and hypomagnesiuria in 34.1% cases.

CONCLUSIONS

Urolithiasis in Uyghur children may be primarily related to local environmental factors.

Demographic characteristics and metabolic risk factors in Croatian children with urolithiasis

The aim of this study was to assess demographic data, clinical presentation, metabolic features, and treatment in 76 children with urolithiasis presented from 2002 to 2011. Urolithiasis is responsible for 2.5/1,000 pediatric hospitalizations, with new cases diagnosed in 1.1/1,000 admissions. From the observed period, two-fold rise of incidence rate was observed. Compiling the data from other pediatric institutions in our country, we estimated present overall incidence rate in Croatia as 6.5/100,000 children under 18 years. There were 41 boys and 35 girls (ratio 1.17:1). The mean age at diagnosis was 9.7 (range 0.8-16) years and follow-up duration was 5.3 (range 1.8-10) years. Renal colic (75.0 %) and hematuria (57.89 %) were the main symptoms. In 65.78 % of children, stones were unilateral. Stones were located in kidney in 52.63 %, in the ureter in 26.32 %, and in bladder in 6.58 % cases. Stone analysis showed calcium oxalate in 75.0 % of the cases. Associated urinary tract abnormalities were found in 19.73 % children. Most common metabolic disturbances were hypercalciuria (47.37 %) and idiopathic or mild hyperoxaluria (18.42 %). Urine saturation (EQUIL2) was elevated in 61.84 % cases. Spontaneous stone evacuation occurred in 51.21 % children. Extracorporeal shock wave lithotripsy, surgical evacuation, and endoscopic removal of calculi were performed in 21.0, 6.58, and 5.26 % of cases, respectively. Follow-up conservative therapy, consisting of fluid/diet recommendations and additional potassium citrate and/or chlorothiazide in children with increased risk, was sufficient for stone recurrence prevention in 92.1 % of children. In conclusion, the study gave insight in epidemiology and metabolic disturbances of urinary stone disease in Croatian children.

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

PURPOSE

Pediatric urolithiasis has been treated with shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy with high success rates during short-term followup. We studied our success rate and modifiable risk factors in patients with at least 5 years of followup postoperatively.

MATERIALS AND METHODS

Retrospective chart review was performed for patients younger than 18 years who underwent upper tract stone surgery between 1999 and 2007, were stone-free afterward and had at least 5 years of followup. Recurrence rate, and anatomical and metabolic abnormalities were assessed.

RESULTS

Of 60 eligible children 30 (33 kidneys) had at least 5 years of followup. Average patient age at surgery was 10 years, 17 patients were female and 20 kidneys had anatomical abnormalities. Overall recurrence rate at 5 years was 55% (95% CI 38%-70%). Ureteral stones had a lower recurrence rate than renal stones (5 of 19 and 13 of 14, respectively, p <0.001). Patients with abnormal anatomy had a 65% (95% CI 43%-82%) chance of recurrence within 5 years vs 38% (95% CI 18%-65%) in those with normal anatomy (p = 0.17). Of the 18 recurrences 10 required a second operation, 7 demonstrated abnormal anatomy and 14 involved calcium based stones. A 24-hour urine test in 13 children revealed 10 with hypercalciuria and 11 with hypocitraturia, with 9 patients exhibiting both conditions.

CONCLUSIONS

We found a high recurrence rate in children with stones requiring surgical intervention, particularly those with abnormal anatomy. This finding should be confirmed in a larger multicenter study of recurrence rates. In the meantime our results suggest a need for aggressive diagnosis and treatment of metabolic abnormalities.

[Urolithiasis in childhood]

Urinary stone disease is relatively rare in children with an overall incidence of 1-2 %; however, it is often associated with metabolic abnormalities that may lead to recurrent stone formation. Stone analysis and subsequent metabolic evaluation is therefore mandatory for this high-risk group after the first stone event. The objectives of stone management in children should be complete stone clearance, prevention of stone recurrence, preservation of renal function, control of urinary tract infections, correction of anatomical abnormalities and correction of the underlying metabolic disorders. The full range of minimally invasive procedures is available if active stone removal is necessary. The majority of stones in children can be managed either with extracorporeal shock wave lithotripsy which has a higher efficacy in children than in adults, percutaneous nephrolithotomy, ureterorenoscopy or a combination of these modalities while open or laparoscopic surgery is limited to well-selected cases with underlying anatomical abnormalities.

Extracorporeal shock wave lithotripsy is effective in treating single melamine induced urolithiasis in infants and young children

PURPOSE

We evaluated the safety and efficacy of extracorporeal shock wave lithotripsy in the treatment of single melamine induced urolithiasis in infants and young children.

MATERIALS AND METHODS

A total of 189 infants and young children with single melamine induced urolithiasis were referred to our center for treatment with extracorporeal shock wave lithotripsy between March 2009 and July 2010. Location of the calculus was proximal ureteral in 17 patients, mid ureteral in 5, distal ureteral in 26 and kidney in 141. Stone size ranged from 3.8 to 25 mm (mean ± SD 9.79 ± 3.83).

RESULTS

All patients underwent extracorporeal shock wave lithotripsy using the same device with an energy ranging from 8 to 12 kV. Stone-free rate was 97.88%, clinically insignificant residual fragment rate was 1.59% and repeat treatment rate was 2.65%. A total of 180 patients (95.24%) required only 1 lithotripsy session and 5 (2.65%) required 2 sessions. Mean ± SD number of shock waves delivered per session was 580.36 ± 190.69 (range 65 to 950). Extracorporeal shock wave lithotripsy failed to fragment stones in only 1 infant, who had a proximal ureteral stone. A total of 181 specimens were collected and analyzed by infrared spectrum, with results demonstrating that the main composition was uric acid and melamine. All patients were followed for a mean of 28 months (range 20 to 36). No severe complication, such as renal subcapsular hemorrhage, hypertension, kidney rupture or lung injury, was observed.

CONCLUSIONS

Extracorporeal shock wave lithotripsy with low energy can effectively disintegrate melamine induced calculi. This approach has become our preferred method for treating single melamine induced urolithiasis in infants and young children.