Update on Urinary Stones in Children: Current and Future Concepts in Surgical Treatment and Shockwave Lithotripsy

Cystinuria Complicated by Anuria From Bilateral Obstructing Stones Requiring Bilateral Mini Percutaneous Nephrolithotomy in a 22-Month-Old

Pediatric nephrolithiasis is increasing in incidence and presents differently compared to adults. We report a case of nephrolithiasis in a pediatric patient, presenting with complaints of emesis, anuria, hematuria, and abdominal distension, leading to a diagnosis of bilateral obstructing cystine stones requiring bilateral percutaneous nephrolithotomy. Pediatric patients with anuria should be evaluated for bilateral nephrolithiasis as an etiology. Calculous anuria requires prompt recognition of the pathologic process and relief of the obstruction with close follow-up and supportive care until definitive stone management. Bilateral percutaneous nephrolithotomy can provide definitive surgical intervention without significant morbidity.

Is supine a preferred position for percutaneous nephrolithotomy in the pediatric age group? A randomized controlled study

BACKGROUND

The aim is to evaluate supine versus prone position in mini-percutaneous nephrolithotomy in pediatric renal urolithiasis management.

METHODS

A randomized controlled trial was constructed to evaluate supine versus prone position in pediatric PCNL. Seventy pediatric patients with a stone burden ≥1.5 cm were randomized into two groups.

RESULTS

Sixty-three patients were available for evaluation in our study with no significant difference in the perioperative demographic data. The supine group showed a shorter operation time of 43.9 min compared to 73.5 min in the prone group. The stone-free rate was higher in the supine group, with a 93.9% SFR compared to 83.3% in the prone group. The supine group showed a shorter hospital stay of 2.0±1.0 days, compared to 3.20±1.56 days in the prone group. No significant difference was seen in the perioperative complication rate and fluoroscopy time between both groups.

CONCLUSIONS

Supine mini-percutaneous nephrolithotomy is safe and effective in managing pediatric renal stones, with a higher stone-free rate, less operative time, and less hospital stay compared to the prone position.

Pediatric cystine stone successfully treated by mini-percutaneous nephrolithotripsy and antegrade ureteroscopy

Introduction

Cystinuria is often diagnosed by large renal stone for pediatric patients. The patients suffer from recurrence of stone disease, develop the chronic kidney disease and fall into end-stage renal failure. Total removal of stone at the first intervention and prevention of recurrence are essential. Although, it is difficult to treat the pediatric stone patients for their anatomical feature.

Case presentation

We report three cases of pediatric cystine stone patients (two 4-year-old boys and a 9-year-old girl) successfully treated by mini-percutaneous nephrolithotripsy and antegrade ureteroscopy. We could remove stones completely in all three cases, and the patients did not suffer from major complications.

Conclusion

It is essential to select the surgical approach, the endourological device, and the patient's position which is suitable for the age, the body size, and the condition of stones at the initial intervention of pediatric cystine stone.

Minipercutaneous Nephrolithotomy in the Management of Large and Complex Renal Calculi in Children: How Effective Is It?

Purpose: To evaluate the efficacy and safety of minipercutaneous nephrolithotomy (PCNL) in the management of large and complex calculi in children. Patients and Methods: From May 2017 to April 2021, a total of 41 pediatric cases were diagnosed with large/complex renal stones (partial-total staghorn) and following a detailed biochemical evaluation and thorough radiological examination (plain abdominal radiograph, urinary ultrasound, noncontrast and/or computed tomography), all cases underwent mini-PCNL procedure for the minimal invasive management of these calculi. Preoperative, intraoperative, and postoperative data were analyzed and reported in detail. Results: A total of 41 procedures were performed in 26 boys and 15 girls (male/female = 1.73). While the age of the kids ranged from 2.5 to 10 years (mean 6.74 ± 2.76), mean size of the stones was 16.28 ± 3.43 mm (range 11-24) with a mean stone density value of 816 HU (range 550-1350). Evaluation of the success rates in terms of complete stone clearance on postoperative day 1 revealed that while 73.2% (30/41), residual fragments have been noted in 11 cases (26.8%). Size of the residual fragments ranged from 2 to 7 mm (mean 4.3). Of those children, 10 cases required flexible ureteroscopy for stone removal, and in 1 case, placement of Double-J was adequate for spontaneous passage. During a 3-month follow-up, the stone-free rate (SFR) increased to 100% without any residual fragment left. Conclusions: Mini-PCNL with holmium laser lithotripsy is an effective and safe treatment alternative in the minimal invasive management of large/complex kidney stones in children with high SFRs.

Is Triple D Score Effective to Predict the Stone-Free Rate After Shockwave Lithotripsy in Pediatric Population?

Introduction: Triple D score was developed using skin-to-stone distance (SSD), stone density (SD), and stone volume (SV) for prediction of extracorporeal shockwave lithotripsy (SWL) outcomes in adults. SWL is the first-line treatment method for kidney stones <2 cm in children, however, it was not validated in the pediatric population. This article aims to validate Triple D score in pediatric patients. Materials and Methods: Of the 269 children treated with SWL between 2007 and 2021, a total of 147 children who had adequate follow-up data and evaluated with noncontrast CT before SWL were included in the study. Parameters were calculated for each of the SV, SSD, and SD variables. Receiver operator characteristic analysis was used to set cutoff values. Triple D scores were calculated, and success rates were determined for each score. Stone-free status was determined as complete clearance after 3 months of final SWL. Results: The median age of the study group was 7 years (range 1-16). Ninety-three of the 147 (63%) children had stone-free status. Mean SV, SSD, and SD values were significantly higher in the SWL-failed group than in the stone-free group after detecting cutoff values of 155 mm³, 6.5 cm, and 550 HU, respectively. Stone-free rates were detected as 23.8%, 35.1%, 74.0%, and 92.0% with the Triple D scores of 0, 1, 2, and 3 points. Conclusions: Our study confirms that Triple D scores support the SWL outcomes in the pediatric population. We believe that our research on Triple D score validation in children is of great clinical importance although various factors may affect to predict the success of SWL. IRB Approval: 2021/514/194/14.

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

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

Minimally invasive surgery for pediatric renal and ureteric stones: A therapeutic update

The incidence of pediatric urolithiasis (PU) is growing worldwide. The corresponding therapeutic methods have become a research hot spot in pediatric urology. PU has the characteristics of abnormal metabolism, easy recurrence, and immature urinary system development, which make its treatment different from that of adults. Pediatric urologists should select the optimal treatment modality to completely remove the stones to prevent recurrence. Currently, the curative treatments of PU include extracorporeal shock wave lithotripsy (ESWL), ureteroscopy, retrograde intrarenal surgery, percutaneous nephrolithotomy (PCNL), laparoscopic, robot-assisted laparoscopic, and open surgery. This review aims to conduct a therapeutic update on the surgical interventions of both pediatric renal and ureteric stones. It accentuates that pediatric surgeons or urologists should bear in mind the pros and cons of various minimally invasive surgical treatments under different conditions. In the future, the treatment of PU will be more refined due to the advancement of technology and the development of surgical instruments. However, a comprehensive understanding of the affected factors should be taken into account by pediatric urologists to select the most beneficial treatment plan for individual children to achieve precise treatment.

Pediatric stone disease: Current management and future concepts

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

Classification and standardized reporting of percutaneous nephrolithotomy (PCNL): International Alliance of Urolithiasis (IAU) Consensus Statements

BACKGROUND

The aim of this study was to reach a consensus in the classification and standardized reporting for the different types of PCNLs.

METHODS

The RAND/UCLA appropriateness methodology was used to reach a consensus. Thirty-two statements were formulated reviewing the literature on guidelines and consensus on PCNLs, and included procedure specific details, outcome measurements and a classification for PCNLs. Experts were invited to two rounds of input, the first enabled independent modifications of the proposed statements and provided the option to add statements. The second round facilitated scoring of all statements. Each statement was discussed in the third round to decide which statements to include. Any suggestion or disagreement was debated and discussed to reach a consensual agreement.

RESULTS

Twenty-five recommendations were identified to provide standardized reporting of procedure and outcomes. Consensual scoring above 80% were strongly agreed upon by the panel. The top treatment related outcomes were size of sheath used (99.1%) and position for PCNL (93.5%). The highest ranked Outcome Measures included definition of postoperative hospital length of stay (94.4%) and estimated blood loss (93.5%).

CONCLUSIONS

The consensus statements will be useful to clarify operative technique, in the design of clinical trials and standardized reporting, and presentation of results to compare outcomes of different types of PCNLs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Minimally Invasive Approaches in Pediatric Urolithiasis. The Experience of Two Italian Centers of Pediatric Surgery

Background: Over the last 30 years, the incidence of pediatric urolithiasis (PU) has been increasing and the surgical management has evolved toward a minimally invasive approach (MIA). We reported the experience of two Centers of Pediatric Surgery in the management of PU, focusing on MIA as first choice in treatment. Methods: Data were retrospectively analyzed from October 2009 to October 2019 in children with urolithiasis who were admitted to two referral Italian Centers of Pediatric Surgery. Demographic and clinical data of the patients, features of the urolithiasis, type of surgery were considered. Results: Seventy patients (7.3 ± 5.0 years) with normal renal function were treated for calculi in the pyelocaliceal system (45.7%), ureter (34.3%), bladder (4.3%), urethra (1.4%), and multiple locations (14.3%). Size of calculi was >10 mm in 55.7% of cases (kidney>bladder/urethra>multiple>ureter, p = 0.01). Symptoms were present in 75.7% of patients. Family history was positive in 16.9% of cases. MIA was performed in 59 patients (84.3%): 11.8% shockwave lithotripsy (kidney>ureter>multiple); 32.2% ureteral retrograde surgery (ureteral>other localizations); 30.5% retrograde intrarenal surgery (kidney>other localizations); and 25.4% other procedures including percutaneous nephrolithotomy, cystoscopic bladder stone removal or laser cystolithotripsy (kidney>bladder>multiple). Preoperative stenting was necessary in 52.8% of cases. Four MIA procedures (6.9%, kidney>ureter/multiple) were converted to open surgery. Open surgery was required as first approach in 15.7% of patients (kidney>ureter>multiple) who needed urgent surgery or had associated congenital renal anomalies. In 18/70 of children (25.7%), with prevalence of stones in kidney and multiple location (p < 0.01), a second procedure completed the treatment (88.8% MIA). Intraoperative difficulties were recorded in 8.5% of cases, without difference between location and size of calculi. Late complications (5.7%) were related to displacement and infection of the ureteral stent. Conclusions: MIA resulted to be feasible in more than 75% of primary surgery and in more than 85% of cases requiring a second procedure. Preoperative stent was mandatory in more than 50% of children. The technological evolution allowed to overcome many of the technical difficulties related to the approach to the papilla and lower calyxes. Open surgery is reserved for selected cases and endoscopic surgery represents the best choice of treatment for PU.

Minimally Invasive Management of Bladder Stones in Children

Background: Bladder stones (BS) are rare in children. Minimally invasive surgery (MIS) seems to be nowadays the procedure of choice to treat pediatric patients with BS. This study aimed to analyze retrospectively our experience with percutaneous cystolithotomy, endourological treatment with Holmium laser and robotic cystolithotomy in children with BS. Methods: We retrospectively analyzed the data of 13 children (eight boys and five girls) with BS who were treated at our centers between July 2013 and July 2020. The patients received three different MIS procedures for stones removal: five underwent robotic cystolithotomy, five underwent endourological treatment and three received percutaneous cystolithotomy (PCCL). We preferentially adopted endourological approach for stones <10 mm, percutaneous approach between 2014 and 2016 and robotic approach since 2016 for larger stones. Results: Mean patients' age at the time of diagnosis was 13 years (range 5-18). Ten/13 patients (76.9%) had primary BS and 3/13 patients (23.1%) had secondary BS. Mean stone size was 18.8 mm (range 7-50). In all cases the stones were removed successfully. One Clavien II post-operative complication occurred following PCCL (33.3%). All the procedures were completed without conversions. Operative time ranged between 40 and 90 min (mean 66) with no significant difference between the three methods (p = 0.8). Indwelling bladder catheter duration was significantly longer after PCCL (mean 72 h) compared with robotic and endourological approaches (mean 15.6 h) (p = 0.001). Hospitalization was significantly longer after PCCL (mean 7.6 days) compared with the other two approaches (mean 4.7 days) (p = 0.001). The endourological approach was the most cost-effective method compared with the other two approaches (p = 0.001). Conclusions: Minimally invasive management of bladder stones in children was safe and effective. Endourological management was the most cost-effective method, allowing a shorter hospital stay compared with the other procedures but it was mainly indicated for smaller stones with a diameter < 10 mm. Based upon our preliminary results, robotic surgery seemed to be a feasible treatment option for BS larger than 15-20 mm. It allowed to remove the big stones without crushing them with a safe and easy closure of the bladder wall thanks to the easy suturing provided by the Robot technology.

Effectiveness and complications of mini-percutaneous nephrolithotomy in children: one center experience with 232 kidney units

OBJECTIVE

To evaluate the efficacy and complications of mini-percutaneous nephrolithotomy (PCNL) surgery using 14-20 Fr access sheaths in pediatric patients, as well as the results of postoperative stone analysis and metabolic urine analysis.

MATERIAL AND METHODS

We retrospectively evaluated the records of 206 pediatric patients (232 kidney units) who underwent mini-PCNL for kidney stones in our clinic between February 2011 and December 2018. We evaluated the demographic characteristics, complications, stone-free rates, and the results of chemical analysis and urinary metabolic analysis.

RESULTS

The age ranged from 9 months to 16 years. The mean age was 5.1±3.9 years, and the median age was 3.5 years. The median stone burden was 200 mm² (min: 100; max: 1600). Kidney stones were most commonly located in the pelvis in 118 (50.9%) patients, followed by lower calyceal stones in 42 (18.1%) and multiple calyceal stones in 38 (16.4%) patients, respectively. While the success of mini-PCNL was 80.6% after the first session, this rate increased to 87.9% after auxiliary treatments. The total complication rate was 12.9% according to modified Clavien classification. A postoperative stone analysis showed that calcium oxalate had the highest frequency with 61.1% of patients, followed by cystine stone with 21.3% of patients. Metabolic urine analysis revealed no abnormalities in 42.8% of patients. The most common metabolic abnormality was hyperoxaluria (32%), followed by hypercalcuria (19.6%).

CONCLUSION

Mini-PCNL is a safe and effective procedure with reasonable complications for the treatment of pediatric kidney stones. All kinds of multidisciplinary efforts are required to remove kidney stones completely in pediatric patients.

Combined Laparoscope and Flexible Ureteroscope Pyelolithotomy Dealing with Large-Burden Complex Renal Calculi in Children Less Than 1 Year Old

Objective: To evaluate the experience and result of combined laparoscope and flexible ureteroscope (f-URS) pyelolithotomy in dealing with large-burden complex renal calculi in children <1 year old. Methods: Eleven patients (7 males and 4 females) <1 year old were retrospectively reviewed between December 2015 and May 2017, who had been diagnosed with renal calculi and received combined laparoscope and f-URS pyelolithotomy. The operations were carried out under general anesthesia. Patient' characteristics, presenting symptoms, operative times, and blood loss, stone-free rate, and postoperative complications were all collected retrospectively. Results: All 11 patients received combined laparoscope and f-URS pyelolithotomy. All operations went smoothly without conversion record and blood transfusion. Average time consumed was 109 minutes (55-187 minutes), and blood loss reported was 16 mL (10-25 mL). Average hospital stay after operation was 7 days (5-11 days). On mean follow-up of 6-12 months, no symptomatic urinary tract infections and urinary calculi were detected. Conclusion: Laparoscope combined f-URS pyelolithotomy is considered safe in the treatment of large-burden multiple renal calculi in infant patients with a high stone clearance rate. It has certain advantages in the treatment of renal calculi in infants <1 year old, and it could be an alternative treatment when other treatments fail or are unavailable.

Traditional Chinese medicine on treating ureteral calculi: A systematic review and meta-analysis protocol

BACKGROUND

Ureteral calculi generally refer to the temporary obstruction of the human body after the ureteral stenosis. When the ureteral stones are not discharged in time, they can grow in the original site, causing the patient to have corresponding clinical manifestations, such as: renal colic, hematuria, etc, when severe, can cause renal obstruction and hydronephrosis, seriously endangering the patient's health. Ureteral calculi usually occur in young and middle-aged people. The peak age of the disease is between 20 and 50 years old. It also occurs in the young and middle-aged labor force. The men incidence rate is 2 to 3 times that of women. Ureteral calculi is one of the current refractory diseases, and the effect after treatment with integrated Chinese and Western medicine is remarkable.

METHODS AND ANALYSIS

We will search for PubMed, Cochrane Library, AMED, EMbase, WorldSciNet; Nature, Science online and China Journal Full-text Database (CNKI), China Biomedical Literature CD-ROM Database (CBM), and related randomized controlled trials included in the China Resources Database. The time is limited from the construction of the library to November 2018. We will use the criteria provided by Cochrane 5.1.0 for quality assessment and risk assessment of the included studies, and use the Revman 5.3 and Stata13.0 software for meta-analysis of the effectiveness, recurrence rate, and symptom scores of ureteral.

ETHICS AND DISSEMINATION

This systematic review will evaluate the efficacy and safety of Traditional Chinese medicine for ureteral. Because all of the data used in this systematic review and meta-analysis has been published, this review does not require ethical approval. Furthermore, all data will be analyzed anonymously during the review process Trial.Registration number: PROSPERO CRD42019137095.

Update on Surgical Management of Pediatric Urolithiasis

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

Successful Ultra-Minimally Invasive Endoscopic Intrarenal Surgery for 2-Year-Old Boy with Bilateral Cystine Kidney Stones Over 2 cm

Background: Treatment of upper urinary tract stones measuring >2 cm in children aged <3 years is challenging. Although adult-sized instruments are usually available, in pediatric populations such instruments seem unreasonable and unfit for children with small kidneys and narrow ureters. We use ultra-miniaturized endoscopes and instruments to reduce the damage to normal tissues in pediatric patients.

Case Presentation: We treated a 2-year-old boy with >2-cm bilateral cystine kidney stones. We decided to perform retrograde intrarenal surgery using an ultrathin (4.5F) semi-rigid ureteroscope for the right kidney stone (2.0 × 1.2 cm) in the lithotomy position and super ultra-minimally invasive endoscopy combined with intrarenal surgery with a percutaneous 8.5F to 9.5F tract sheath for the left kidney stone (3.5 × 2.4 cm) under the Barts modified Valdivia position. These procedures were successful for the bilateral kidney stones. Postoperatively, the patient was stone-free without major complications.

Conclusion: We believe that ultra-minimally invasive endoscopic intrarenal surgery is safe and efficient in pediatric patients. Furthermore, the Barts modified Valdivia position was safely utilized in our 2-year-old patient with multiple large kidney stones.