Predicting Spontaneous Stone Passage in Prepubertal Children: A Single Institution Cohort

Pediatric Stone Disease: Current Trends and Future Directions

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

Shockwaves and the Rolling Stones: An Overview of Pediatric Stone Disease

Urinary stone disease is a common problem in adults, with an estimated 10% to 20% lifetime risk of developing a stone and an annual incidence of almost 1%. In contrast, in children, even though the incidence appears to be increasing, urinary tract stones are a rare problem, with an estimated incidence of approximately 5 to 36 per 100,000 children. Consequently, typical complications of rare diseases, such as delayed diagnosis, lack of awareness, and specialist knowledge, as well as difficulties accessing specific treatments also affect children with stone disease. Indeed, because stone disease is such a common problem in adults, frequently, it is adult practitioners who will first be asked to manage affected children. Yet, there are unique aspects to pediatric urolithiasis such that treatment practices common in adults cannot necessarily be transferred to children. Here, we review the epidemiology, etiology, presentation, investigation, and management of pediatric stone disease; we highlight those aspects that separate its management from that in adults and make a case for a specialized, multidisciplinary approach to pediatric stone disease.

Progression of asymptomatic nephrolithiasis in children: How often should patients receive follow-up ultrasound imaging?

INTRODUCTION

The natural history of asymptomatic nephrolithiasis (AN) in children is not well defined. Furthermore, there is no guidance on the utility of repeated renal ultrasound evaluations in this same population. Follow-up ultrasound studies are often obtained as frequently as every 6 months. The goal of this study is to assess the follow-up ultrasound interval in the management of these patients.

METHODS

A retrospective IRB approved chart review was performed for patients seen for non-cysteine AN between 2012 and 2019. AN was defined as patients without obstructive uropathy abdominal, flank pain and/or gross hematuria. Asymptomatic stones were discovered incidentally or after an acute stone event. Patients with pre-existing renal anomalies and the timepoints with stone passage or stone procedure were excluded. Descriptive statistics were used for demographic information. Multiple linear regression was used to analyze risk factors. Statistical significance was set to p < 0.05.

RESULTS

Twenty-nine patients had 90 ultrasounds. The average age at diagnosis was 10.8 ± 6.2 years. The average number of ultrasound studies per patient was 3.2 ± 1.7. The median time between follow-up ultrasounds was 5.2 months [IQR 2.8-10.0]. Median follow-up of patients was 10.6 months [IQR 4.9-21.9]. The change in total stone burden occurred at a rate of 0.11 mm/month (CI [-0.06-0.28], p = 0.20, r² = 0.42) or 0.66 mm/6 months. Patients with more renal stones had almost a threefold increase in stone burden compared to patients with fewer renal stones (2.98 [CI 1.34-4.62], p=0.001, r²=0.33). Patients with a family history of stones had a twofold increase in the size of their largest stone when compared to patients without a family history (1.97 [CI 0.26-3.68], p=0.02, r²=0.60.

CONCLUSION

A complex interplay of multiple factors influence the progression of AN in children. Children with a greater number of stones have a higher increase in total stone burden and children with a family history of stones have a faster increase in largest stone size. These patients may require more frequent imaging studies. The small change in stone size over time favors a longer than 6-month interval for many children.

Surgical treatment of pediatric urolithiasis

Introduction: Surgical treatment of urolithiasis in children is quite complex and specific due to certain anatomical and functional features of childhood. Methods of surgical treatment at this age are: extracorporeal lithotripsy (ESWL), intracorporeal (endoscopic) lithotripsy - pneumatic and laser, percutaneous nephrolithotripsy (PCNL) and open surgery. Aim: The aim of this study was evaluation of the effects of ureterorenoscopy and endoscopic lithotripsy in children, as methods of minimally invasive surgical treatment. Material and methods: The retrospective study was conducted at the Institute for Mother and Child Health Care of Serbia "Dr Vukan Cupic" in Belgrade from 2010 to 2020. The study included 112 patients (50 boys and 62 girls) aged 1-18 years with urolithiasis, treated by endoscopic (laser or pneumatic) lithotripsy. The retrospective study was conducted at the Institute for Mother and Child Health Care of Serbia "Dr Vukan Cupic" in Belgrade from 2010 to 2020. The study included 112 patients (50 boys and 62 girls) aged 1-18 years with urolithiasis, treated by endoscopic (laser or pneumatic) lithotripsy. Results: After one ureterorenoscopy, the calculus was successfully disintegrated in 87 (78%) patients: in the renal pelvis in 22 (79%), in the upper pole calices of the kidney in 14 (100%), in the lower pole calices in 10 (50%), in the proximal segment of the ureter in 10 (83%), in the distal segment of the ureter in 27 (79%), in the bladder in 4 (100%) cases. In 19 (17%) patients the second intervention was necessary: in the renal pelvis in 28 (100%), in the upper pole calices in 14 (100%), in the lower pole calices in 14 (70%), in the proximal segment of the ureter in 12 (100%), in the distal segment of the ureter in 34 (100%) and in the bladder in 4 (100%) patients. Conclusion: The primary treatment of pediatric urolithiasis is ureterorenoscopy in combination with pneumatic or laser lithotripsy. It is successfully used in all segments of the urinary tract. The procedure is partially limited in the lower pole calices of the kidney, due to anatomical circumstances and mechanical limitations of the instruments.

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

INTRODUCTION

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS AND DISCUSSION

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

CONCLUSION

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

Natural history of patients with infantile nephrolithiasis: what are the predictors of surgical intervention?

BACKGROUND

We evaluated the risk factors for the requirement of surgical intervention in infants with nephrolithiasis.

METHODS

The medical records of 122 (156 kidney units (KU)) infants were reviewed. The clinical features, stone characteristics, changes in stone status, and treatment protocols were noted. The stone status of the KU was categorized into 3 groups according to the change in size between the first and last ultrasound: resolution, unchanged, and growth.

RESULTS

The median age was 8 months (r: 2-12). The median length of follow-up was 16 months (r: 10-36). Resolution was detected in 94 KUs (60%). Stone growth was detected in 39 KUs (25%), and stone size was unchanged in 23 KUs (15%). Surgical intervention was required in 26 patients (17%). A history of intensive care unit (ICU) follow-up and a stone size > 5 mm at time of diagnosis were defined as independent risk factors for stone growth (p = 0.005, < 0.001, respectively). The surgical intervention rate was higher in stones > 5 mm and stones with pelvic localization (p = 0.018, 0.021, respectively). Stone resolution was higher in patients with stone size ≤ 5 mm (p = 0.018).

CONCLUSION

A stone size > 5 mm at the time of diagnosis and a history of ICU follow-up are independent risk factors for stone growth. Pelvic localization of stones and stones > 5 mm are associated with an increased risk of surgical intervention.

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.

Nephrolithiasis: Approach to Diagnosis and Management

Although kidney stones are less common in children than in adults, incidence in children is rising. Kidney stones may lead to significant morbidity in addition to escalating medical costs. Clinical presentation is variable. Bilateral kidney stones in a younger child should prompt work-up for primary hyperoxaluria. Metabolic abnormalities are more frequent in children and can result in frequent stone recurrence. Whole exome sequencing data shows genetic defects in about 30% of stone formers. 24 h urine collection should be conducted when patient receives his usual diet and fluid intake with normal activity. Infrared spectroscopy and X-ray diffraction are used for stone analysis. Urine studies should be delayed by 4-6 wk after stone fragmentation or treatment of any stone related complications. The goal of evaluation is to identify modifiable risk factors for which targeted therapy may be instituted. Primary indications for surgical intervention include pain, infection and obstruction. Extracorporeal shockwave lithotripsy (ESWL), ureteroscopy, and percutaneous nephrolithotomy (PCNL) are most commonly used, and selection is based on stone size, anatomy, composition and anatomy. Advances in technology have allowed a shift to minimally invasive surgeries. Comprehensive management requires multidisciplinary team. Children with kidney stones require long term follow-up with periodic assessment of stone forming activity and ascertaining stone burden. High index of suspicion should be there to diagnose diseases like primary hyperoxaluria, Dent's disease, renal tubular acidosis (RTA) etc. as these diseases have ramifications on kidney function and growth.

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.

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.

Experience of a Tertiary-Level Urology Center in the Clinical Urological Events of Rare and Very Rare Incidence. VI. Unusual Events in Urolithiasis: 1. Long-Standing Urethral Stones without Underlying Anatomical Abnormalities in Male Children

OBJECTIVES

The study aimed to present our center's experience with long-standing urethral stones in male children with normal urethra.

MATERIALS AND METHODS

Retrospective search of our center data was done for the cases of long-standing urethral stones with normal urethra in male children during the period July 2001 - June 2016. Demographic and clinical data were studied.

RESULTS

Of more than 54,000 urolithiasis procedures, 17 male children (0.031%) were operated for long-standing urethral stones with normal urethra. In 14 cases (82.4%), residence was rural and parental education levels were low or none. All children were regularly prompted voiding with a history of difficulty or dysuria. All the stones lodged in the posterior urethra with an approximate mean duration of 2 months. The mean stone size of 11.29 ± 3.88 mm and rough surfaces in 88.2% of cases represented the main predisposing factors. Major complications included rectal prolapse in 1 case and vesicoureteral reflux in 3 cases. Endoscopic push-back was followed by disintegration in 76.5% or cystolithotomy in 17.7%, while it failed in 1 case that was treated by cystolithotomy.

CONCLUSIONS

Long-standing urethral stones in male children with normal urethra are very rare misdiagnoses. Stone topography and sociocultural factors predisposed to their lodgments and negligence. Endoscopic treatment is the best approach.

Infant nephrolithiasis and nephrocalcinosis: Natural history and predictors of surgical intervention

INTRODUCTION

Renal stone disease diagnosed in the first year of life is relatively uncommon. While risk factors such as low birth weight, furosemide exposure, and metabolic disorders are well established, there exists little information regarding resolution rates and need for surgical intervention. Our study objective was to evaluate urolithiasis and renal calcification resolution rates, time to resolution, and need for surgical intervention in children diagnosed in their first year of life.

MATERIAL AND METHODS

REB approved retrospective chart review of children younger than 12 months of age (corrected for prematurity) diagnosed with nephrolithiasis and/or nephrocalcinosis in a tertiary pediatric hospital between April 2000 and August 2015 with a minimum 1-year follow-up period. Exact logistic regression was performed to assess the relationship between size of the largest stone (on either side) and the need for surgical intervention. Kaplan-Meier curves were constructed to examine time to stone resolution among those not requiring surgical intervention.

RESULTS

62 patients (61% male) were diagnosed with stones or nephrocalcinosis by ultrasound at a median age of 2.9 months. Of these, 37% had been admitted to the NICU because of prematurity, low birth weight or comorbidities. A total of 45 patients were found to have stones (Table); 35 of these had a stone at initial ultrasound and 10 initially diagnosed as nephrocalcinosis were later confirmed to have a stone. 67% of all stones were asymptomatic on presentation. Metabolic anomalies were present in 56% (35/62), and 16% (10/62) required medical treatment. Seven patients ultimately required surgical intervention. Stone size was found to predict the eventual need for surgical intervention (OR 3.52, 95% CI 1.47-12.78) for each 0.1 mm increase in diameter). Among patients not requiring surgical intervention (n = 38), the estimated median time to spontaneous resolution of urolithiasis was 1.1 years (95% CI 0.89-1.53, range 2 months-6 years) and 1.2 years for nephrocalcinosis (95% CI 0.59-2.13).

CONCLUSIONS

Spontaneous resolution was a common outcome for newborns and infants diagnosed with urolithiasis in the first year of life, but high variability in time-to-resolution was observed. Only a small proportion who had confirmed stones on ultrasound required surgical intervention (15%), and large stone size was a predictive factor for surgery.

Pediatric Nephrolithiasis: A Review

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

Clinical effectiveness in the diagnosis and acute management of pediatric nephrolithiasis

The incidence of pediatric nephrolithiasis has risen over the past few decades leading to a growing public health burden. Children and adolescents represent a unique patient population secondary to their higher risks from radiation exposure as compared to adults, high risk of recurrence, and longer follow up time given their longer life expectancies. Ultrasound imaging is the first-line modality for diagnosing suspected nephrolithiasis in children. Although data is limited, the best evidence based medicine supports the use of alpha-blockers as first-line MET in children, especially when stones are small and in a more distal ureteral location. Surgical management of pediatric nephrolithiasis is similar to that in adults with ESWL and URS first-line for smaller stones and PCNL reserved for larger renal stone burden. Clinical effectiveness in minimizing risks in children and adolescents with nephrolithiasis centers around ED pathways that limit CT imaging, strict guidance to ALARA principles or use of US during surgical procedures, and education of both patients and families on the risks of repeat ionizing radiation exposures during follow up and acute colic events.