The natural history of asymptomatic urolithiasis

The PUrE randomised controlled trial 1: Clinical and cost effectiveness of flexible ureterorenoscopy and extracorporeal shockwave lithotripsy for lower pole stones of ≤10 mm

BACKGROUND AND OBJECTIVE

The European Association of Urology guidelines recommend that extracorporeal shockwave lithotripsy (ESWL) and flexible ureterorenoscopy (FURS) are equally appropriate first-line treatment options for lower pole renal stones (LPSs). We report a pragmatic multicentre, open-label, superiority randomised controlled trial (RCT) comparing FURS versus ESWL for quality of life, and clinical and cost effectiveness for LPSs of ≤10 mm-one of two RCTs that were part of the Percutaneous nephrolithotomy, flexible Ureteroscopy and Extracorporeal shockwave lithotripsy for lower pole kidney stone study (PUrE), with the other PUrE RCT 2 investigating larger stones.

METHODS

In total, 231 and 230 patients were randomised to FURS and ESWL, respectively. The primary outcome was health status area under the curve (AUC) 12 wk after intervention using the EQ-5D-5L questionnaire. The primary economic outcome was the incremental cost per quality-adjusted life-year (QALY) gained at 12 mo after randomisation.

KEY FINDINGS AND LIMITATIONS

The mean health status AUCs over 12 wk were 0.807 (standard deviation [SD] 0.205) for FURS (n = 164) and 0.826 (SD 0.207) for ESWL (n = 188); the between-group difference was 0.024 (95% confidence interval -0.004, 0.053), a small nonsignificant difference in favour of FURS adjusted for an initial baseline imbalance. Complete stone clearance was higher with FURS (72%) than with ESWL (36%). The incremental cost-effectiveness ratio between FURS and ESWL was £65 163, meaning that at a threshold value of £20 000 per QALY, ESWL has a >99% chance of being cost effective.

CONCLUSIONS AND CLINICAL IMPLICATIONS

PUrE RCT 1 found that there was no evidence of a difference in health status between FURS and ESWL for LPSs of ≤10 mm, with FURS leading to a higher stone-free rate. ESWL was more cost effective than FURS.

Brazilian Guidelines on evaluation and clinical management of Nephrolithiasis: Brazilian Society of Nephrology

The prevalence of nephrolithiasis has been increasing in recent years, affecting appro-ximately 10% and 15% of the population. Kidney stone disease is associated with syste-mic comorbidities such as cardiovascular dis-ease, diabetes mellitus, and obesity. The first Nephrolithiasis Guideline by the Brazilian Society of Nephrology was published in 2002, and since then, the accumulation of new clinical studies and guidelines has justified a review of the subject. This updated document, prepared by the Nephrolithiasis Committee of the Brazilian Society of Nephrology, reflects the advances in the management of patients with kidney stones. The guideline aims to provide recommendations for the diagnosis, prevention, and treatment of nephrolithiasis, based on the best available evidence. Topics covered include clinical evaluation, laboratory and imaging tests, as well as dietary and pharmacological interventions, and follow-up strategies.

Evaluating the natural history of incidentally recognized clinically silent nephrolithiasis in healthy adults: an updated systematic review with meta-analysis

The incidental detection of asymptomatic renal stones has risen with increased use of imaging and screening programs. While guidelines exist for treating kidney stones, managing asymptomatic stones remains controversial due to limited understanding of their natural history. A systematic search of the PubMed, Web of Science, Embase, and Scopus databases was conducted on 3rd June 2024 with a distinct search strategy and citation tracking to identify English language publications evaluating the natural history of asymptomatic renal stones in healthy adults. systematic report of the included studies was provided; besides, meta-analysis of proportions and meta regression was conducted to find the pooled estimation of stone-related events and to evaluate factors affecting natural history of these stones. Quality assessment of the included articled was conducted by means of the Newcastle-Ottawa Scale. This study was registered on PROSPERO (CRD42023409454). Out of 4,574 identified publications, twelve studies met inclusion criteria. Reported outcome rates ranged from 28.12% to 32.27% for symptomatic events, 7.1% to 31.88% for requiring intervention, 7.5% to 32.08% for spontaneous passage, 11.11% to 45.9% for stone growth, 31.77% to 77% for stone-related events, and 23% to 68.22% for remaining asymptomatic. Meta-analysis identified the pooled proportion of 30% (95% CI 27% to 33%) for developing symptoms, 22% (95% CI 18% to 27%) for requiring intervention, 25% (95% CI 16% to 36%) for stone growth, 18% (95%CI 13% to 23%) for spontaneous stone passage, 49% (95% CI 39% to 59%) for all stone-related events, 50% (95% CI 48% to 52%) for remaining asymptomatic. Notably, our investigation done by meta-regression did not reveal any specific risk factor for developing symptoms and stone growth. However, multiple and bilateral stones were less likely to pass spontaneously. Moreover, the analyses indicated a positive correlation between multiple stones and requiring intervention and between male sex and all stone-related events, albeit it trended toward significance. The findings offer some guidance for managing asymptomatic renal stones, suggesting that active surveillance could be a potentially viable option. However, further meta-analysis incorporating additional studies with consistent criteria for patient inclusion, standardized stone size categorization, and uniform reporting of effect sizes is needed to validate our findings. Unfortunately, this is not currently feasible due to the limitations outlined above.

Retrograde intrarenal surgery for asymptomatic incidental renal stones: a retrospective, real-world data analysis

OBJECTIVE

To determine surgical outcomes and stone-free rates (SFRs) when offering upfront retrograde intrarenal surgery (RIRS) to patients with asymptomatic incidental renal stones (AIRS), as active surveillance, shockwave lithotripsy or upfront intervention in patients with AIRS is still a debate among urologists.

PATIENTS AND METHODS

This retrospective FLEXible Ureteroscopy Outcomes Registry (FLEXOR), supported by the Team of Worldwide Endourological Researchers (TOWER), examines adult patients who underwent RIRS. We analysed a subset of asymptomatic patients with renal stones on imaging who were treated with RIRS. Data includes patient characteristics, stone specifications, anaesthesia type, perioperative details, complications, and SFR. A multivariable logistic regression analysis was performed to assess factors associated with the SFR.

RESULTS

Among 679 patients with AIRS, 640 met the inclusion criteria. The median age was 55 years, with 33.4% being female. In all, 22.1% had positive urine cultures. The median stone diameter was 12 mm, commonly in lower and interpolar locations. RIRS was preferentially performed under general anaesthesia using a reusable scope in 443 cases. Prophylactic antibiotics were administered to 314 patients. The median operation time was 58 min and the median laser time was 24 min. The SFR was 68.8%. The use of holmium laser (odds ratio [OR] 0.21, 95% confidence interval [CI] 0.06-0.63; P < 0.01) and multiple stones (OR 0.38, 95% CI 0.19-0.76; P < 0.01) were factors associated with lower odds of being stone free. Overall complications were minimal, with sepsis in 1.6% of patients. Re-interventions were performed in 76 cases (11.8%), with RIRS being the most common in 67 cases (10.6%).

CONCLUSION

Our multicentre real-world study is the first of its kind that highlights the pros and cons of offering RIRS to patients with AIRS and demonstrates a favourable SFR with acceptable complications. Pre-emptively discussing potential re-intervention helps patients make informed decisions, particularly in cases involving large and multiple stones.

Assessment of Factors Responsible for Stone-Free Status After Retrograde Intrarenal Surgery

Aim The study aimed to evaluate the predictive factors that determined stone-free rate (SFR) after retrograde intrarenal surgery (RIRS). Materials and methods This prospective study was conducted on 183 patients undergoing RIRS for renal stones. Patients were categorized into two groups, depending on stone-free status one month following the procedure. SFR was defined as the complete absence of stones or stones <4 mm. The parameters studied included patient demographics, presence of hydronephrosis, presence of preoperative double J-stent, abnormal renal anatomy, and stone characteristics (stone burden, stone number, stone density, stone location, lower pole infundibulopelvic angle, and lower pole renal infundibular length (RIL)). Univariate and multivariate analyses were performed to identify risk factors for residual stones. We assessed the predictive ability of the RIRS score and Resorlu-Unsal stone score (RUSS) for evaluating SFR utilizing receiver operating characteristic (ROC) analysis. Results 183 patients were included in the study with a median age of 51 years. 131 (71.6%) patients were declared stone-free after the procedure. The mean stone size and density were 16.9 SD±7.5 mm and 1038 SD±342 Hounsfield units (HU) respectively. Stone-free patients had lower stone size (14.3 mm vs. 23.6 mm, p<0.01) and stone density (970 HU vs. 1211 HU, p<0.01) compared to non-stone-free patients. Patients with residual stones had steeper lower pole renal infundibulopelvic angle (RIPA) (31.3° vs. 40.7°, p<0.01) and longer RIL (26.6 mm vs. 21.1 mm, p<0.01). Stone multiplicity (p<0.01), lower pole stone location (p<0.01), and renal malformations (p<0.01) were significant influencing factors for residual renal stones after RIRS. Multivariate analysis revealed stone size, stone density (HU), and stone location as independent predictors for SFR after RIRS. Among the scoring systems, the RIRS score had the highest diagnostic accuracy for SFR (area under the curve (AUC): -0.882, 95% CI-0.828-0.936). Conclusion Stone size, stone density (HU), and stone number are important predictors of SFR after RIRS. Lower pole stone location and abnormal renal anatomy play a substantial role in determining SFR after RIRS. In lower pole stones, a long RIL and acute RIPA negatively influence SFR. Additionally, the RIRS score was found to be a better predictor for SFR than the RUSS score.

Flexible ureteroscopy in Chinese air force pilots with renal calculi: a cohort study at a single medical centre

INTRODUCTION

Renal calculi are the predominant urological ailment in air force pilots. Flexible ureteroscopy (FURS) constitutes a valuable approach for renal calculi treatment. This study presents a decade-long exploration of using FURS for renal calculi treatment in air force pilots. Additionally, it investigates the safety and feasibility of granting waiver flights to pilots with renal parenchyma calcification.

METHODS

From December 2009 to December 2019, a retrospective review was conducted on Chinese air force pilots undergoing treatment for renal calculi. Among the pilots assessed, a total of 71 individuals underwent FURS. Endoscopic methodology involved the insertion of a flexible ureteroscope into the ureter and renal pelvis, guided by a safety wire. Stone fragmentation was achieved using a holmium laser fibre, followed by extraction using a soft stone basket. Postoperative non-enhanced CT (NECT) scans was used to confirm stone clearance. Furthermore, clinical diagnoses were classified based on endoscopic findings and postoperative NECT results. All data were presented as mean (SD) or median (minimum-maximum) for continuous variables and frequency counts and percentages for categorical variables.

RESULTS

FURS identified free kidney stones in 60 cases among all patients. The remaining 11 cases, without free stones detected during ureteroscopy, exhibited persistent high-density spots on postoperative NECT. Of the 60 cases with stones, renal calculi were successfully cleared in 30 pilots, while the remaining 30 exhibited persistent high-density spots on NECT postsurgery. Pilots with completely cleared free stones were deemed fit for flight. Pilots with diagnosed renal parenchyma calcification were granted permission to fly under waivers following a meticulous evaluation.

CONCLUSIONS

FURS could not only effectively eliminate renal calculi but also accurately diagnose renal parenchyma calcification, facilitating a prompt return to flight for pilots. A protocol for managing pilot renal calculi, informed by FURS and our experience, is proposed.

Longitudinal follow-up of incidental renal calculi on computed tomography

RATIONALE AND OBJECTIVES

Measuring small kidney stones on CT is a time-consuming task often neglected. Volumetric assessment provides a better measure of size than linear dimensions. Our objective is to analyze the growth rate and prognosis of incidental kidney stones in asymptomatic patients on CT.

MATERIALS AND METHODS

This retrospective study included 4266 scans from 2030 asymptomatic patients who underwent two or more nonenhanced CT scans for colorectal screening between 2004 and 2016. The DL software identified and measured the volume, location, and attenuation of 883 stones. The corresponding scans were manually evaluated, and patients without follow-up were excluded. At each follow-up, the stones were categorized as new, growing, persistent, or resolved. Stone size (volume and diameter), attenuation, and location were correlated with the outcome and growth rates of the stones.

RESULTS

The stone cohort comprised 407 scans from 189 (M: 124, F: 65, median age: 55.4 years) patients. The median number of stones per scan was 1 (IQR: [1, 2]). The median stone volume was 17.1 mm3 (IQR: [7.4, 43.6]) and the median peak attenuation was 308 HU (IQR: [204, 532]. The 189 initial scans contained 291stones; 91 (31.3%) resolved, 142 (48.8%) grew, and 58 (19.9) remained persistent at the first follow-up. At the second follow-up (for 27 patients with 2 follow-ups), 14/44 (31.8%) stones had resolved, 19/44 (43.2%) grew and 11/44 (25%) were persistent. The median growth rate of growing stones was 3.3 mm3/year, IQR: [1.4,7.4]. Size and attenuation had a moderate correlation (Spearman rho 0.53, P < .001 for volume, and 0.50 P < .001 for peak attenuation) with the growth rate. Growing and persistent stones had significantly greater maximum axial diameter (2.7 vs 2.3 mm, P =.047) and peak attenuation (300 vs 258 HU, P =.031) CONCLUSION: We report a 12.7% prevalence of incidental kidney stones in asymptomatic adults, of which about half grew during follow-up with a median growth rate of about 3.3 mm3/year.

The efficacy of retrograde intra-renal surgery (RIRS) for lower pole stones: results from 2946 patients

PURPOSE

To evaluate the perioperative outcomes of retrograde intra-renal surgery (RIRS) for lower pole stones (LPS) and factors affecting stone-free rate (SFR).

METHODS

Data from 20 centers were retrospectively reviewed. Inclusion criteria were adult patients, normal renal anatomy, and LPS. Exclusion criteria were bilateral surgery, concomitant surgery for ureteral stones. SFR was defined as a single residual fragment (RF) ≤ 2 mm and evaluated 3-months after surgery. A multivariable logistic regression analysis was performed to assess factors associated with RF. Statistical significance was set at p value < 0.05.

RESULTS

2946 patients were included. Mean age and stone size were 49.9 years 10.19 mm, with multiple LPS in 61.1% of cases. Total operation and laser time were 63.89 ± 37.65 and 17.34 ± 18.39 min, respectively. Mean hospital stay was 3.55 days. Hematuria requiring blood transfusion and fever/urinary infections requiring prolonged antibiotics occurred in 6.1% and 169 5.7% of cases, while sepsis with intensive-care admission in 1.1% of patients. On multivariate analysis, Multiple stones (OR 1.380), stone size (OR 1.865), and reusable ureteroscopes (OR 1.414) were significantly associated with RF, while Thulium fiber laser (TFL) (OR 0.341) and pre-stenting (OR 0.750) were less likely associated with RF.

CONCLUSIONS

RIRS showed safety and efficacy for LPS with a mean diameter of 10 mm. This procedure can achieve a satisfactory SFR in pre-stented patients with a single and smaller stone, particularly with TFL use.

A comparison between asymptomatic and symptomatic ureteral stones

To investigate the characteristics and impact of asymptomatic (silent) ureteral stones on renal function and compare them with those of symptomatic stones. We retrospectively reviewed the medical records of 677 patients who underwent ureteroscopic lithotripsy or laparoscopic ureterolithotomy for ureteral stones between 2016 and 2020. Patients were divided into two groups according to the presence of recognizable symptoms. We investigated the characteristics and impact of silent stones on post-treatment renal function recovery and compared them with those of symptomatic stones. Among the 677 patients, 43 (6.4%) had asymptomatic ureteral stones, and 634 (93.6%) had symptomatic ureteral stones. Compared to symptomatic stones, asymptomatic stones were larger (11.4 mm vs. 9.6 mm, p = 0.003), more commonly present in the upper ureter (62.7% vs. 48.0%, p = 0.04), and more commonly associated with high-grade hydronephrosis (32.8% vs. 12.3%, p < 0.001); however, no difference in metabolite composition was observed between the two group of stone. In the asymptomatic stone group, the mean preoperative estimated glomerular filtration rate (eGFR) was 77.37 ± 23.54 mL/min/1.73 m², and the mean postoperative eGFR indicated no significant improvement at 1 day, 7 days, 3 months, and 12 months (76.66 ± 21.45, 77.89 ± 20.87, 77.29 ± 22.22, and 76.71 ± 24.21 mL/min/1.73 m², respectively; p = 0.567, p = 0.613, p = 0.924, and p = 0.202, respectively). In the symptomatic stone group, the mean preoperative eGFR was 78.17 ± 28.25 mL/min/1.73 m²; the mean postoperative eGFRs at 1 day, 7 days, 3 months, and 12 months were 81.24 ± 26.38, 86.16 ± 25.61, 89.11 ± 25.43, and 89.50 ± 26.01 mL/min/1.73 m², respectively and demonstrated significant improvement (p = 0.002, p < 0.001, p < 0.001, and p < 0.001, respectively). Silent stones irreversibly impaired renal function, even after proper management. Therefore, active treatment strategies are required for all patients who are hesitant to receive treatment for silent stones because of their asymptomatic status to prevent permanent renal impairment.

Duration of Follow-up and Timing of Discharge from Imaging Follow-up, in Adult Patients with Urolithiasis After Surgical or Medical Intervention: A Systematic Review and Meta-analysis from the European Association of Urology Guideline Panel on Urolithiasis

CONTEXT

No algorithm exists for structured follow-up of urolithiasis patients.

OBJECTIVE

To provide a discharge time point during follow-up of urolithiasis patients after treatment.

EVIDENCE ACQUISITION

We performed a systematic review of PubMed/Medline, EMBASE, Cochrane Library, clinicaltrials.gov, and reference lists according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Fifty studies were eligible.

EVIDENCE SYNTHESIS

From a pooled analysis of 5467 stone-free patients, we estimated that for a safety margin of 80% for remaining stone free, patients should be followed up using imaging, for at least 2 yr (radiopaque stones) or 3 yr (radiolucent stones) before being discharged. Patients should be discharged after 5 yr of no recurrence with a safety margin of 90%. Regarding residual disease, patients with fragments ≤4 mm could be offered surveillance up to 4 yr since intervention rates range between 17% and 29%, disease progression between 9% and 34%, and spontaneous passage between 21% and 34% at 49 mo. Patients with larger residual fragments should be offered further definitive intervention since intervention rates are high (24-100%). Insufficient data exist for high-risk patients, but the current literature dictates that patients who are adherent to targeted medical treatment seem to experience less stone growth or regrowth of residual fragments, and may be discharged after 36-48 mo of nonprogressive disease on imaging.

CONCLUSIONS

This systematic review and meta-analysis indicates that stone-free patients with radiopaque or radiolucent stones should be followed up to 2 or 3 yr, respectively. In patients with residual fragments ≤4 mm, surveillance or intervention can be advised according to patient preferences and characteristics, while for those with larger residual fragments, reintervention should be scheduled.

PATIENT SUMMARY

Here, we review the literature regarding follow-up of urolithiasis patients. Patients who have no stones after treatment should be seen up to 2-3 yr, those with large fragments should be reoperated, and those with small fragments could be offered surveillance with imaging.

Risk factors for kidney stone disease recurrence: a comprehensive meta-analysis

Background

Kidney stone disease (KSD) is a common illness that causes an economic burden globally. It is easy for patients to relapse once they have suffered from this disease. The reported recurrence rate of KSD ranged from 6.1% to 66.9%. We performed this meta-analysis to identify various potential risk factors for the recurrence of KSD.

Methods

The PubMed, Embase and Web of Science databases were searched using suitable keywords from inception to Mar 2022. A total of 2,663 records were collected initially. After screening the literature according to the inclusion and exclusion criteria, 53 articles (40 retrospective studies; 13 prospective studies) including 488,130 patients were enrolled. The study protocol was registered with PROSPERO (No. CRD42020171771).

Results

The pooled results indicated that 12 risk factors including younger age (n = 18), higher BMI (n = 16), family history of kidney stones (n = 12), personal history of kidney stones (n = 11), hypertension (n = 5), uric acid stone (n = 4), race of Caucasian (n = 3), suspected kidney stone episode before the first confirmed stone episode (n = 3), surgery (n = 3), any concurrent asymptomatic (nonobstructing) stone (n = 2), pelvic or lower pole kidney stone (n = 2), and 24 h urine test completion (n = 2) were identified to be associated with KSD recurrence. In the subgroup analysis, patients with higher BMI (OR = 1.062), personal history of nephrolithiasis (OR = 1.402), or surgery (OR = 3.178) had a higher risk of radiographic KSD recurrence.

Conclusions

We identified 12 risk factors related to the recurrence of KSD. The results of this analysis could serve to construct recurrence prediction models. It could also supply a basis for preventing the recurrence of KSD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01017-4.

Predictors of stone related events in asymptomatic untreated intra-renal calculi

Purpose There is a lack of data on the natural history of asymptomatic intra-renal calculi. In this study we investigate stone related events (SREs) in patients with untreated intra-renal calculi. We also investigate predictive factors for SREs. Materials and Methods All patients diagnosed with an asymptomatic intra-renal calculus on CT KUB managed conservatively with interval imaging for ≥6 months were included. Patients were evaluated for any stone related event. The rate of event according to calculus size, location and number of calculi was also analysed. Multivariate logistic regression analysis was performed to determine significant predictors for SREs. Results In total, 266 renal units from 177 patients met inclusion criteria. The mean stone size was 4.44mm (range of 1-25mm). Duration of follow-up was 43.78 ± 26.86 months (range 6-106 months). The overall rate of SRE's including intervention (n=80) and spontaneous stone passage following ureteric colic (n= 40) was 45.1% (n=120/266). Stones >5mm were more likely to lead to an event compared to stones ≤5mm (OR: 2.94; p=0.01). Inter-polar stones and stones located in multiple calyces were more likely to cause a SRE than lower pole stones (OR: 2.05; p=0.05 and OR:2.29; p=0.03 respectively). Conclusion In this large series of patients with asymptomatic intra-renal calculi, the incidence of a spontaneous SRE was 45.1% after 41 months. Stone size and stone location were significant predictors for stone related event. Information from this study will enable urologists to accurately risk stratify patients with asymptomatic renal stones.

Natural history of small asymptomatic kidney and residual stones over a long-term follow-up: systematic review over 25 years

OBJECTIVE

To systematically review the natural history of small asymptomatic kidney and residual stones, as the incidental identification of small, asymptomatic renal calculi has risen with increasing use of high-resolution imaging.

MATERIALS AND METHODS

We reviewed the natural history of small asymptomatic kidney and residual stones using the Cochrane and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. We searched MEDLINE, Scopus, EMBASE, EBSCO, Cochrane library and Clinicaltrials.gov using themes of 'asymptomatic', 'nephrolithiasis', 'observation', 'symptoms', 'admission', 'intervention' and similar allied terms for all English language articles from 1996 to 2020 (25 years). Inclusion criteria were studies with ≥50 patients, stones ≤10 mm, and a mean follow-up of ≥24 months. Primary outcomes were occurrence of symptoms, emergency admission, and interventions.

RESULTS

Our literature search returned 2247 results of which 10 papers were included in the final review. Risk of symptomatic episodes ranged from 0% to 59.4%. Meta-analysis did not identify any significant difference in the likelihood of developing symptoms when comparing stones <5 mm to those >5 mm, nor those <10 mm to those >10 mm. Risk of admission varied from 14% to 19% and the risk of intervention from 12% to 35%. Meta-analysis showed a significantly decreased likelihood of intervention for stones <5 vs >5 mm and <10 vs >10 mm. Studies had variable risk of bias due to heterogeneous reporting of outcome measures with significant likelihood that observed differences in results were compatible with chance alone (Symptoms: I² =0%, Cochran's Q = 3.09, P = 0.69; Intervention: I² =0%, Cochran's Q = 1.76, P = 0.88).

CONCLUSIONS

The present systematic review indicates that stone size is not a reliable predictor of symptoms; however, risk of intervention is greater for stones >5mm vs <5 mm and >10 vs <10 mm. This review will inform urologists as they discuss management strategies with patients who have asymptomatic renal stones and offer insight to committees during the development of evidence-based guidelines.

Role of conservative management of stones

Urinary tract stone disease is one of the most common pathologies of the modern era with a rising prevalence owing to incidentally detected renal stones from imaging for other reasons. Although there is consensus on active management of symptomatic and asymptomatic stones in high-risk patient groups, conservative management of stones is still controversial. We have reviewed the literature pertaining to conservative management of 3 groups of stones-asymptomatic calyceal stones, staghorn stones, and ureteric stones-and summarized the findings to provide guidance in the conservative management of stones. In the calyceal stone group, our review showed an average spontaneous stone passage rate of 18% (range, 8%-32%) and an average requirement for surgical intervention of 20% (range, 7%-40%), with 62% of patients remaining safely on surveillance over a mean time of 4 years. In the staghorn group, overall disease-specific mortality was noted to be 16% (range, 0%-30%) and chance of renal deterioration was 21% (range, 0%-34.5%), with a mean incidence of infection of 22%. In case of conservatively managed ureteric stones, the rate of spontaneous passage for stones smaller than 5 mm was 75%, compared with 62% for those larger than 5 mm. Based on the position in the ureter, spontaneous passage rates were 49%, 58%, and 68% for proximal, middle, and distal thirds, respectively. Conservative management may be recommended for asymptomatic patients and those who are deemed unfit for any procedures. However, careful patient selection and thorough counseling about the risks of conservative management could make it a suitable option for an appropriate subset of patients.

The Prevalence of Incidentally Detected Urolithiasis in Subjects Undergoing Computerized Tomography

Background and objective

Urolithiasis is defined as the presence of calculi in the urinary tract. Multiple studies have shown that urinary tract stones are one of the most common incidental findings in medical imaging. These stones are potentially dangerous and can cause severe impairment to renal function if they remain undiagnosed for a long time. The objective of this study was to determine the prevalence of incidentally detected urolithiasis in patients undergoing abdominopelvic CT scans.

Materials and methods

A retrospective cross-sectional study was conducted, which involved 721 patients selected by consecutive non-randomized sampling. The study population included patients who underwent an abdominopelvic CT scan in the radiology department of a tertiary care hospital in Pakistan. Patients aged below 10 years and those above 90 years were excluded from the study. Patients undergoing kidney, ureter, and bladder (KUB) scan for urolithiasis-associated symptoms and those with already known urolithiasis were also excluded. The data were recorded in a predesigned pro forma and analyzed with SPSS Statistics version 20.00 (IBM, Armonk, NY).

Results

A total of 721 patients underwent an abdominopelvic CT scan during the six months from July to December in the radiology department of the hospital. Out of these, 336 (46.6%) were males, and 385 (53.4%) were females. Incidental stones were found in 20 of these patients. Among these 20 stone formers, 11 were males, and nine were females. Out of them, six had stones in the right kidney, eight in the left kidney, and four patients had bilateral stones. The remaining two patients had stones in their ureters. In most cases, stones were found in lower poles as compared to the mid pole and upper pole of the kidneys.

Conclusion

The prevalence of incidentally detected urolithiasis was found to be 2.8% in this study. Its frequency was much higher in males (3.27%) compared to females (2.33%). Most of the stones were found in the kidneys whereas no stone was detected in the urinary bladder.

Lessons Learnt (Clinical Outcomes and Cost Savings) from Virtual Stone Clinic and Their Application in the Era Post-COVID-19: Prospective Outcomes over a 6-Year Period from a University Teaching Hospital

Introduction: We introduced a nurse-led telephone-based virtual stone clinic (VSC) follow-up for the surveillance of patients with asymptomatic renal calculi or those at a high risk of recurrent kidney stone disease (KSD). The aim of this study was to look at the outcomes of VSC and its role in the post-COVID era. Methods: Prospective outcomes audit was done for all patients referred to the VSC for a 6-year period (March 2014-April 2020). VSC is led by specialist stone nurses for on-going surveillance of KSD patients. Results: A total of 290 patients were seen (468 individual appointments; 1.6 ± 1.0 per patient), with a mean age of 57.0 ± 15.8 years (range: 17-92) and a men-women ratio of 3:2. The referral was for surveillance of asymptomatic small renal stones (230, 79.3%); history of recurrent stone disease (45, 15.5%); solitary kidneys (5, 1.7%); cystine stones; young age; and other conditions (10, 3.4%). The mean stone size was 5.0 ± 2.7 mm, followed up with kidney, ureter, and bladder radiograph (225, 77.6%) and ultrasound scan (USS) (65, 22.4%), for median duration of 12 months (range: 3-24 months). At the end, 132 patients (45.6%) remained in VSC, 106 (36.6%) were discharged, 47 (16.2%) returned to face-to-face clinic or treatment, and 5 (1.7%) had emergency admissions. Of 47 patients who returned, 23 (48.9%) developed new symptoms, 21 (44.6%) had stone growth, and 3 defaulted to face-to-face appointment. Thirty-five patients needed surgical intervention (URS-21, SWL-13, and PCNL-1) and 10 were managed conservatively. VSC reduced the cost per clinic appointment from £27.9 to £2 per patient (93% reduction), equating to a total saving of £12,006 for the study period. Conclusion: Nurse-led VSC not only provided a safe follow-up but also allowed to substantially reduce the cost of treatment by allowing patients to be either discharged or return to a face-to-face clinic or surgical intervention if needed. Post-COVID, this model using telemedicine will have a much wider uptake and further help to optimize health care resources.

Noninvasive acoustic manipulation of objects in a living body

In certain medical applications, transmitting an ultrasound beam through the skin to manipulate a solid object within the human body would be beneficial. Such applications include, for example, controlling an ingestible camera or expelling a kidney stone. In this paper, ultrasound beams of specific shapes were designed by numerical modeling and produced using a phased array. These beams were shown to levitate and electronically steer solid objects (3-mm-diameter glass spheres), along preprogrammed paths, in a water bath, and in the urinary bladders of live pigs. Deviation from the intended path was on average <10%. No injury was found on the bladder wall or intervening tissue.

The clinical and cost effectiveness of surgical interventions for stones in the lower pole of the kidney: the percutaneous nephrolithotomy, flexible ureterorenoscopy and extracorporeal shockwave lithotripsy for lower pole kidney stones randomised controlled trial (PUrE RCT) protocol

INTRODUCTION

Renal stones are common, with a lifetime prevalence of 10% in adults. Global incidence is increasing due to increases in obesity and diabetes, with these patient populations being more likely to suffer renal stone disease. Flank pain from stones (renal colic) is the most common cause of emergency admission to UK urology departments. Stones most commonly develop in the lower pole of the kidney (in ~35% of cases) and here are least likely to pass without intervention. Currently there are three technologies available within the UK National Health Service to remove lower pole kidney stones: extracorporeal shockwave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL) and flexible ureterorenoscopy (FURS) with laser lithotripsy. Current evidence indicates there is uncertainty regarding the management of lower pole stones, and each treatment has advantages and disadvantages. The aim of this trial is to determine the clinical and cost effectiveness of FURS compared with ESWL or PCNL in the treatment of lower pole kidney stones.

METHODS

The PUrE (PCNL, FURS and ESWL for lower pole kidney stones) trial is a multi-centre, randomised controlled trial (RCT) evaluating FURS versus ESWL or PCNL for lower pole kidney stones. Patients aged ≥16 years with a stone(s) in the lower pole of either kidney confirmed by non-contrast computed tomography of the kidney, ureter and bladder (CTKUB) and requiring treatment for a stone ≤10 mm will be randomised to receive FURS or ESWL (RCT1), and those requiring treatment for a stone >10 mm to ≤25 mm will be randomised to receive FURS or PCNL (RCT2). Participants will undergo follow-up by questionnaires every week up to 12 weeks post-intervention and at 12 months post-randomisation. The primary clinical outcome is health status measured by the area under the curve calculated from multiple measurements of the EuroQol five dimensions five-level version (EQ-5D-5L) questionnaire up to 12 weeks post-intervention. The primary economic outcome is the incremental cost per quality-adjusted life year gained at 12 months post-randomisation.

DISCUSSION

The PUrE trial aims to provide robust evidence on health status, quality of life, clinical outcomes and resource use to directly inform choice and National Health Service provision of the three treatment options.

TRIAL REGISTRATION

ISRCTN: ISRCTN98970319. Registered on 11 November 2015.

Safety and efficacy of an herbal formulation in patients with renal calculi - A 28 week, randomized, double-blind, placebo-controlled, parallel group study

BACKGROUND

Urolithiasis is a growing problem worldwide. Many a times, asymptomatic stones are kept under observation. Many herbal preparations are available for the same, but they lack proper scientific documentation.

OBJECTIVE

To study the anti-urolithiatic effect of an herbal preparation, Subap Plus (IP) capsules in patients with asymptomatic renal calculi of size ranging from 4 to 9 mm.

MATERIAL AND METHODS

This was a prospective, randomized, double-blind, placebo-controlled clinical trial conducted in a tertiary care hospital in Pune, India. Patients with asymptomatic renal calculi of 4-9 mm size were randomized (1:1, block randomization) to one of the group Subap Plus (treatment group) or placebo (placebo group). The study outcome included change in visual analog scale (VAS), change in the surface area and density of calculi and their expulsion. Statistical analysis was performed using student's t-test and Chi-square test.

RESULTS

A total of 120 patients were screened and 84 were enrolled who met the eligibility criteria, of which 65 patients completed the trial (treatment, n = 34; placebo, n = 31). The VAS score significantly decreased in the treatment group (6.9-1.8) than placebo group (7.2-6.8) (p < 0.001). The surface area and density were decreased by 47.58% (p < 0.008) and 43.01% (p < 0.001), respectively, in the treatment group than the placebo group. The expulsion of calculi was significantly higher in the treatment group than placebo group (20.59 vs. 3.23%, p < 0.03).

CONCLUSION

Patients treated with herbal formulation showed better expulsion rate and reduction in surface area and density than the placebo group.

The rs1256328 (ALPL) and rs12654812 (RGS14) Polymorphisms are Associated with Susceptibility to Calcium Nephrolithiasis in a Taiwanese population

Nephrolithiasis is a common disease affecting almost all populations, with an increasing prevalence over the past decades. Previous studies revealed several functional polymorphisms associated with the pathogenesis of nephrolithiasis. However, data on Asian populations are limited. In this study, three candidate polymorphisms were selected from previous studies to investigate the correlations with nephrolithiasis in a Taiwanese population. In total, 454 nephrolithiasis patients were recruited from Kaohsiung Medical University Hospital, with SNP frequency for 1513 subjects of general population from the Taiwan Biobank (TWB) as a genotypic reference. Results revealed that subjects with minor TT genotype at rs1256328 (alkaline phosphatase, liver/bone/kidney (ALPL)) have higher susceptibility to nephrolithiasis (odds ratio (OR) = 2.03, p = 0.0013). In addition, subjects carrying the minor AA genotype at rs12654812 (regulator of G protein signaling 14 (RGS14)) have higher susceptibility to nephrolithiasis (OR = 1.91, p = 0.0017). Among nephrolithiasis patients, subjects with GG at rs7627468 (calcium-sensing receptor (CASR)) have lower pH level in urine (p = 0.0088). Importantly, rs7627468 is associated with the expressions of IQCB1 and EAF2. rs12654812 could influence the expression of RGS14 itself, MXD3, and FGFR4. In summary, this study successfully validated the genetic roles of rs1256328 and rs12654812 in human nephrolithiasis.

The Urological Association of Asia clinical guideline for urinary stone disease

The Urological Association of Asia, consisting of 25 member associations and one affiliated member since its foundation in 1990, has planned to develop Asian guidelines for all urological fields. The field of stone diseases is the third of its guideline projects. Because of the different climates, and social, economic and ethnic environments, the clinical practice for urinary stone diseases widely varies among the Asian countries. The committee members of the Urological Association of Asia on the clinical guidelines for urinary stone disease carried out a surveillance study to better understand the diversity of the treatment strategy among different regions and subsequent systematic literature review through PubMed and MEDLINE database between 1966 and 2017. Levels of evidence and grades of recommendation for each management were decided according to the relevant strategy. Each clinical question and answer were thoroughly reviewed and discussed by all committee members and their colleagues, with suggestions from expert representatives of the American Urological Association and European Association of Urology. However, we focused on the pragmatic care of patients and our own evidence throughout Asia, which included recent surgical trends, such as miniaturized percutaneous nephrolithotomy and endoscopic combined intrarenal surgery. This guideline covers all fields of stone diseases, from etiology to recurrence prevention. Here, we present a short summary of the first version of the guideline - consisting 43 clinical questions - and overview its key practical issues.

Composition and spatial distribution of elements and isotopes of a giant human bladder stone and environmental implications

The composition and spatial distribution of minerals, trace elements, as well as carbon and nitrogen isotopes from the outer crust to inner nucleus of a 20-year old giant human bladder stone comprising thirteen layers were intensively investigated. Calcium oxalate monohydrate (COM) was found to concentrate in the inner and middle layers, struvite was concentrated in middle and outer layers, and fluorapatite occurred in almost all layers. The spatial distribution of minerals has the potential to provide preliminary knowledge regarding the long-term urine composition, or even the physiological condition of the patient. The stable carbon isotope ratio (δ¹³C) and stable nitrogen isotope ratio (δ¹⁵N) were measured in each layer and significant correlation was found between δ¹³C with calcium oxalate monohydrate content and between δ¹⁵N and struvite content. Nearly constant values of -23.2‰ and 7.1‰ for δ¹³C and δ¹⁵N, respectively, were found in the organic components of the stone. Both isotope ratios indicate a long-term fixed diet consisting mainly of C3 plants, such as rice and wheat, for the 20-year time period of the stone formation. In addition, eighteen elements (Ca, P, Mg, K, Na, Al, Fe, Zn, Pb, Cu, Sr, Ba, Ti, V, Cr, Ni, Mn and Co) were measured in all the layers. The trace elements Al, Fe, Cu, Zn, Pb, Sr, Ba and Ti showed a similar spatial distribution pattern from the outer crust to the inner core. Although there were complex correlations between elements and minerals, Factor Analysis suggests that the occurrence of these elements in stones may be mainly the result of environmental exposure to metals during the formation of the stone, indicating that urinary stones may serve as potential long-term biomonitors. In particular, Ni and Cr showed a distinct distribution pattern in the stone, which may relate to human metabolic activities.

Incidental Finding of Urethral Diverticulum in a Woman with History of Recurrent Urinary Tract Infections

We present an incidental finding and management of a urethral diverticulum containing mixed composition of struvite and ammonium urate stones. Status post sleeve gastrectomy, patient presented to our bariatric clinic with epigastric pain associated with nausea and vomiting. A computed tomography scan was performed to rule out any complications of the procedure in which urethral stones were reported contained within a diverticulum. This finding, in retrospect, correlated with patient's past history of recurrent urinary tract infections. Over all, urethral diverticulum with struvite stones is a rare entity with few reported cases in literature thus a high index of suspicion is needed in patients with related symptoms. Here a case presentation and treatment rationale are described along with a brief review of existing literature.

Long term follow up of kidney donors with asymptomatic renal stones

Patients with asymptomatic kidney stones have a high rate of progression to becoming symptomatic kidney stones when followed for several years. Small kidney stones are often found incidentally on imaging when evaluating patients for kidney donation, and there is a concern that after nephrectomy, the donor may become symptomatic and incur damage to the remaining kidney. We reviewed kidney donors at our institution with asymptomatic stones and surveyed them several years after donation to see if the stones became clinically active.

Chinese herbal medicine to treat urolithiasis in a patient with right flank pain and hematuria: A case report

OBJECTIVE

Urolithiasis is a common medical condition affecting the urinary tract. Typical symptoms reported by patients include colic pain and hematuria. Some patients may undergo surgical intervention or lithotripsy to remove the stones. In this case, we demonstrated that Chinese herbal medicine (CHM) was an effective modality to remove stones in a patient with urolithiasis.

CLINICAL FEATURES AND OUTCOME

A 47-year-old man suffered from right flank pain and hematuria for three months and was diagnosed with an upper third ureteral stone obstruction with right hydronephrosis. He had received extracorporeal shock wave lithotripsy (ESWL) three times before his first CHM visit, but it was unsuccessful. Therefore, he sought CHM for further intervention. His symptoms subsided, and the image study showed complete removal of the ureteral stone after regular therapy with Zhi Bai Di Huang Wan () combined with Lygodii spora (), Curcumae radix (), Endothelium Corneum Gigeriae Galli (), Lysimachiae herba (), Orthosiphon stamineus () for approximately four months. Neither complications nor side-effects were noted during the CHM treatment.

CONCLUSIONS

In this case, we concluded that CHM may be an effective alternative therapy for the treatment of ureteral stones, and furthermore, may also be applied as an option to salvage failed ESWL procedures.

The efficacy of a shared-care surveillance protocol for asymptomatic renal calculi

Objective:

Patients at our institution with asymptomatic calyceal stones (<11 mm) are discharged to their GPs with a request for 12- and 24-month X-ray KUBs with specific re-referral criteria. We aimed to assess the effectiveness of this shared care protocol as well as to investigate long-term outcomes.

Patients and methods:

All patients satisfying the above criteria discharged during October 2009–June 2011 were reviewed for protocol compliance, symptomatic events and/or surgical intervention up to July 2015.

Results:

A total of 134 patients were identified. Out of 115 patients eligible for their first X-ray, and 100 patients eligible for their second X-ray, 43% and 26% respectively were performed. Of these, 75% demonstrated no progression. No patients were treated surgically solely on the basis of radiographic progression. Over a mean five-year follow-up, patients had a 39% chance of experiencing a symptomatic event and a 24% chance of requiring surgical intervention (ESWL, ureteroscopy and/or PCNL). Risk factors included a previous stone history and having a total stone size >10 mm.

Conclusion:

There was poor adherence to this protocol. Despite this, only symptomatic patients were treated surgically, challenging the value of indefinite surveillance of asymptomatic patients. Longitudinal studies are needed to determine a cost-effective manner in which these patients can be safely followed up.

What happens to asymptomatic lower pole kidney stones smaller than 10 mm in children during watchful waiting?

BACKGROUND

The optimal management of lower pole kidney (LPK) stones in children is controversial. The aim of this study was to determine the outcomes of children with asymptomatic isolated LPK stones smaller than 10 mm during follow-up.

METHODS

A total of 242 patients with 284 stones presenting at our institution between June 2004 and December 2014 with an asymptomatic, single LPK stone with a diameter of <10 mm were enrolled in the study. All children were assigned to receive first-line therapy and then categorized according to the need for medical intervention. Age, gender, stone laterality, stone size and type, associated urinary tract problems, and uncontrolled metabolic status were assessed as predictive factors of medical treatment for small (<10 mm) asymptomatic LPK stones. Stone-free rates were compared between interventions.

RESULTS

The mean age and mean stone size were 9.4 ± 1.9 years and 7.4 ± 0.6 mm at admission, respectively. Stone progression rate was 61.2%, and the mean time for intervention was 19.2 ± 4.6 months. Flexible ureterorenoscopy (n = 68) or micro-percutaneous nephrolithotomy (n = 4) were performed for 72 stones (25.4%; group 1), and extracorporeal shock wave lithotripsy was performed for 102 stones (35.9%; group 2). The stone-free rates were 81.8 and 79.3% in group 1 and 2, respectively (p > 0.05). The remaining asymptomatic stones (110, 38.8%; group 3) were managed by continued observation, and at the end of the observation time (mean 40.8 ± 20.8 months) the spontaneous passage rate was 9.1% in this group. In the multivariate analysis, stone size of >7 mm, concurrent renal anomalies, and stones composed of magnesium ammonium phosphate (struvite) and cystine were statistically significant predictors of the need for intervention.

CONCLUSIONS

Children with stones larger than 7 mm, renal anomalies, or stones composed of metabolically active cystine or struvite are more likely to require intervention, and those with asymptomatic LPK stones smaller than 10 mm can be managed by continued observation.

DEVELOPING COMPLETE ULTRASONIC MANAGEMENT OF KIDNEY STONES FOR SPACEFLIGHT

Bone demineralization, dehydration, and stasis put astronauts at an increased risk of forming kidney stones in space. The incidence of kidney stones and the potential for a mission-critical event are expected to rise as expeditions become longer and immediate transport to Earth becomes more problematic. At the University of Washington, we are developing an ultrasound-based stone management system to detect stones with S-mode™ ultrasound imaging, break stones with burst wave lithotripsy (BWL™), and reposition stones with ultrasonic propulsion (UP™) on Earth and in space. This review discusses the development and current state of these technologies, as well as integration on the flexible ultrasound system sponsored by NASA and the National Space Biomedical Research Institute.

Irreversible Renal Function Impairment Due to Silent Ureteral Stones

OBJECTIVE

To evaluate if renal function loss and hydronephrosis due to a silent ureteral stone might be reversed.

MATERIALS AND METHODS

We prospectively selected patients with silent ureteral stones between January 2006 and January 2014. A silent case was considered if there were no specific or subjective symptoms related to the ureteral stone. Patient, stone, and kidney characteristics were evaluated preoperatively, 3 and 12 months postoperatively. Renal function was accessed in the same intervals with serum creatinine (SCr), glomerular filtration rate (GFR), and (99m)Tc-dimercaptosuccinic acid. Patients without complete pre- and postoperative evaluation were excluded. Primary end point was midterm progress of global and ipsilateral renal function. Secondary end points included the evaluation of renal and collecting system anatomy from diagnosis to 12 months after treatment. Analysis of variance with repeated measures and marginal homogeneity test were used to evaluate renal function and hydronephrosis progression.

RESULTS

Twenty-six patients met our inclusion criteria. Mean preoperative SCr and GFR were 1.24 mg/dL and 72.5 mL/min, respectively. At initial scintigraphy, mean renal function was 33.4%. Laser ureterolithotripsy was performed in 84.6% of cases and all patients were rendered stone free. Two patients (8%) developed ureteral stenosis. There was no difference regarding SCr (P = .89), GFR (P = .48), and renal function at scintigraphy (P = .19) during follow-up. Hydronephrosis significantly improved from preoperatively to 3 months postoperatively (P < .0001), but not from 3 to 12 months (P = .065).

CONCLUSION

Patients with silent ureteral stones present with significant impairment of ipsilateral renal function and hydronephrosis at diagnosis. On midterm follow-up evaluation, renal function of the affected unit remains stable whereas hydronephrosis improves after treatment.

Urinary stones as a novel matrix for human biomonitoring of toxic and essential elements

Monitoring of body burden of toxic elements is usually based on analysis of concentration of particular elements in blood, urine and/or hair. Analysis of these matrices, however, predominantly reflects short- or medium-term exposure to trace elements or pollutants. In this work, urinary stones were investigated as a matrix for monitoring long-term exposure to toxic and essential elements. A total of 431 samples of urinary calculi were subjected to mineralogical and elemental analysis by infrared spectroscopy and inductively coupled plasma mass spectrometry. The effect of mineralogical composition of the stones and other parameters such as sex, age and geographical location on contents of trace and minor elements is presented. Our results demonstrate the applicability of such approach and confirm that the analysis of urinary calculi can be helpful in providing complementary information on human exposure to trace metals and their excretion. Analysis of whewellite stones (calcium oxalate monohydrate) with content of phosphorus <0.6 % has been proved to be a promising tool for biomonitoring of trace and minor elements.

Management behaviors of the urology practitioners to the small lower calyceal stones: the results of a web-based survey

Lower pole calyceal stones (LPS) represent lower spontaneous passage rates and, therefore, require several interventional treatment approaches. The aim of this survey study was to investigate the attitudes of the urology practitioners and the factors affecting their decision making in the management of small asymptomatic LPS. A total of 149 urologists participated to the study via email through the internet-based website. Participating urologists were asked to complete a 29-question survey including personal and academic data, level of surgical experience, available equipment for interventional approaches, which treatment do they prefer for small LPS (≥5 mm and <1 cm), and factors affecting their treatment decision. All data were analyzed to make inferences related with treatment decision and factors affecting decision-making. Mean participant age was 41.57 (26-62) years. The most preferred approach was observation/medical treatment option (52.3 %), subsequently SWL (25.5 %), RIRS (16.1 %), miniPNL (5.4 %) and standard PNL (0.7 %) were chosen by the participants. On the other side, SWL and medical treatment were at the forefront (52 and 16.1 %) among children. In the multivariate analysis of participants' age, academic status, surgical experience and institution, none was significantly associated with treatment decision-making (p > 0.05). The most important factors associated with decision making were calyceal dilatation (85.9 %) and patient preferences (81.2 %). The other factors effecting treatment decision were reported to be recurrent disease (70.5 %), the duration of the stone (74.5 %), patient age (95.3 %), current guidelines (87.9 %), stone density (50.3 %), body mass index (BMI) (73.8 %) and other morbid diseases (91.9 %). Our surveys' greatest value is in demonstrating the preferred treatment options and factors effecting decision-making in the treatment of LPS. The most preferred option in our population was follow-up and medical treatment. The most influencing factors on decision-making were age, patients' preferences, presence of calyceal dilatation, body mass index, comorbid conditions, available options for stone treatment and the surgeon's experience on the existing opportunities.

First in Human Clinical Trial of Ultrasonic Propulsion of Kidney Stones

PURPOSE

Ultrasonic propulsion is a new technology using focused ultrasound energy applied transcutaneously to reposition kidney stones. We report what are to our knowledge the findings from the first human investigational trial of ultrasonic propulsion toward the applications of expelling small stones and dislodging large obstructing stones.

MATERIALS AND METHODS

Subjects underwent ultrasonic propulsion while awake without sedation in clinic, or during ureteroscopy while anesthetized. Ultrasound and a pain questionnaire were completed before, during and after propulsion. The primary outcome was to reposition stones in the collecting system. Secondary outcomes included safety, controllable movement of stones and movement of stones less than 5 mm and 5 mm or greater. Adverse events were assessed weekly for 3 weeks.

RESULTS

Kidney stones were repositioned in 14 of 15 subjects. Of the 43 targets 28 (65%) showed some level of movement while 13 (30%) were displaced greater than 3 mm to a new location. Discomfort during the procedure was rare, mild, brief and self-limited. Stones were moved in a controlled direction with more than 30 fragments passed by 4 of the 6 subjects who had previously undergone a lithotripsy procedure. The largest stone moved was 10 mm. One patient experienced pain relief during treatment of a large stone at the ureteropelvic junction. In 4 subjects a seemingly large stone was determined to be a cluster of small passable stones after they were moved.

CONCLUSIONS

Ultrasonic propulsion was able to successfully reposition stones and facilitate the passage of fragments in humans. No adverse events were associated with the investigational procedure.

Combined ureterorenoscopy for ureteral and renal calculi is not associated with adverse outcomes

Introduction

We intended to evaluate the feasibility and effectiveness of the simultaneous rigid and flexible ureteroscopic treatment of symptomatic ureteral and ipsilateral small simultaneous calyceal stones. Outcomes of combined therapy were compared with monotherapy alone.

Material and methods

In this retrospective study, group 1 consisted of 45 patients with middle or lower ureteral and ipsilateral small simultaneous calyceal stones treated by combined therapy. Group 2 included 45 patients with middle or lower ureteral stones only and treated by monotherapy. Stone characteristics, operative time, hospital stay, stone free rates, and complications were compared between groups 1 and 2. Stone free status was defined as no fragments and/or the presence of asymptomatic fragments smaller than 4 mm.

Results

Mean BMI were 29.3 ±0.9 kg/m² and 27.6 ±0.6 kg/m² in groups 1 and 2, respectively. Mean ureteral stone size (7.6 ±0.4 mm vs. 8.0 ±0.4 mm, p = 0.261) and ureteral stone burden (56.0 ±5.5 mm²vs. 54.8 ±6.1 mm², p = 0.487) were similar between groups. Mean renal stone size and renal stone burden for group 1 were 7.1 ±0.8 mm and 83.7 ±11.3 mm². The mean operative time was significantly longer (for a mean of 32.5±1.2 minutes) for group 1 (p = 0.001). Ureteral stents were left in 38 (84.4%) and 19 (42.2%) patients in group 1 and group 2 (p = 0.001). Hospital stay and complication rates were similar between groups. SFRs were 100% for ureteral stones in both groups and 88.9% for renal stones within group 1.

Conclusions

Simultaneous ureteroscopic treatment of the ureteral and ipsilateral small calyceal stones prolongs operative time and increases use of ureteral stent without leaving any residual renal stones.

Simultaneous retrograde intrarenal surgery for ipsilateral asymptomatic renal stones in patients with ureteroscopic symptomatic ureteral stone removal

Background

Ipsilateral asymptomatic renal stone associated with symptomatic ureteral stone is not a rare event, and the recommended treatment policy was not declared clearly. This study was conducted to compare the outcomes of simultaneous retrograde intrarenal surgery (RIRS) and ureteroscopy to ureteroscopy alone for this clinical event.

Methods

415 patients with symptomatic ureteral stone and ipsilateral asymptomatic renal stones were reviewed to obtain two match groups, who were treating with simultaneous modality (group A, N = 72), or ureteroscopy alone (group B, N = 72). Matching criteria were ureteral and renal stone side, duration and location, the presence of pre-stented. Perioperative and postoperative characteristics were compared between the two groups.

Results

Mean stone burdens were similar between group A and B. Mean operative duration for group A and B were 72.4 ± 21.3 and 36.4 ± 10.2 min, respectively (P < 0.001). Mean hospital duration was 6.4 ± 2.9 and 5.3 ± 2.1 days in group A and B, respectively (P = 0.521). Ureteral SFR was 100% in each group. Renal SFR for RIRS was 86.1%. Complication rates in group A were higher (22.2% vs 13.9%), but the differences were not statistically significant (P = 0.358). In group A, complications were significantly less in pre-stented patients (3/25 vs 5/11, P = 0.04). Auxiliary treatment rate was significant higher in group B (69.4% vs 5.6%, P < 0.001) during follow-up (mean >18 months).

Conclusions

Simultaneous RIRS for ipsilateral asymptomatic renal stones in patients with ureteroscopic symptomatic ureteral stone removal can be performed safely and effectively. It promises a high SFR with lower auxiliary treatment rate, and does not lengthen hospital duration and increase complications.

The natural history of nonobstructing asymptomatic renal stones managed with active surveillance

PURPOSE

We documented the natural history of asymptomatic nonobstructing renal calculi managed with active surveillance and explored factors predicting stone related events to better inform shared decision making.

MATERIALS AND METHODS

Patients with asymptomatic nonobstructing renal calculi electing active surveillance of their stone(s) were retrospectively reviewed. Stone characteristics, patient characteristics, and stone related events were collected. We evaluated the effects of stone size and location on development of symptoms, spontaneous passage, requirement for surgical intervention, and stone growth.

RESULTS

We identified 160 stones with an average size of 7.0 ± 4.2 mm among 110 patients with average followup of 41 ± 19 months. Forty-five (28% of total) stones caused symptoms during followup. Notably 3 stones (3% of asymptomatic subgroup, 2% of total stones) caused painless silent obstruction necessitating intervention after an average of 37 ± 17 months. The only significant predictor of spontaneous passage or symptom development was location. Upper pole/mid renal stones were more likely than lower pole stones to become symptomatic (40.6% vs 24.3%, p = 0.047) and to pass spontaneously (14.5% vs 2.9%, p = 0.016).

CONCLUSIONS

Among asymptomatic nonobstructing renal calculi managed with active surveillance, most remained asymptomatic through an average followup of more than 3 years. Less than 30% caused renal colic, less than 20% were operated on for pain and 7% spontaneously passed. Lower poles stones were significantly less likely to cause symptoms or pass spontaneously. Despite 3 stones causing silent hydronephrosis suggestive of obstruction, regular followup imaging facilitated interventions that prevented renal loss.

Quantification of asymptomatic kidney stone burden by computed tomography for predicting future symptomatic stone events

OBJECTIVE

To find the optimal characterization of asymptomatic radiographic stone burden on computed tomography (CT) scans.

METHODS

A survey was sent to stone formers who underwent a CT scan while asymptomatic during a stone clinic evaluation. Symptomatic stone passage events after CT scan were detected by survey and medical record review. Radiographic stone burden was quantified by number of stones, largest stone diameter, automated total stone volume (TSV), and bilateral stones and then compared as predictors of stone events.

RESULTS

There were 550 stone formers; 43% had a stone event for a median of 4.7 years after the CT scan. Stone burden by quartiles was 0-1, 2-3, 4-6, and ≥7 for number of stones; 0-2, 3-4, 5-7, and ≥8 mm for largest stone diameter; and 0-8, 9-78, 79-280, and ≥281 mm(3) for TSV; 48% had bilateral stones. The hazard ratios (HRs) for symptomatic event was 1.30 (P <.001) for the number of stones per quartile, 1.26 (P <.001) for largest stone diameter per quartile, 1.38 (P <.001) for TSV per quartile, and 1.80 (P <.001) for bilateral stones. On multivariate analysis, only TSV was an independent predictor of symptomatic events (HR, 1.35 per quartile; P = .01). This risk of events with TSV was also independent of demographics, urine chemistries, and stone composition. Among the 53 patients with interim events between CT scans, a rapid increase in TSV between CT scans (>570 mm(3) per year) predicted subsequent events (HR, 2.8; P = .05).

CONCLUSION

Automated TSV is more predictive of symptomatic events than manual methods for quantifying stone burden on CT scan.

The ROKS nomogram for predicting a second symptomatic stone episode

Most patients with first-time kidney stones undergo limited evaluations, and few receive preventive therapy. A prediction tool for the risk of a second kidney stone episode is needed to optimize treatment strategies. We identified adult first-time symptomatic stone formers residing in Olmsted County, Minnesota, from 1984 to 2003 and manually reviewed their linked comprehensive medical records through the Rochester Epidemiology Project. Clinical characteristics in the medical record before or up to 90 days after the first stone episode were evaluated as predictors for symptomatic recurrence. A nomogram was developed from a multivariable model based on these characteristics. There were 2239 first-time adult kidney stone formers with evidence of a passed, obstructing, or infected stone causing pain or gross hematuria. Symptomatic recurrence occurred in 707 of these stone formers through 2012 (recurrence rates at 2, 5, 10, and 15 years were 11%, 20%, 31%, and 39%, respectively). A parsimonious model had the following risk factors for recurrence: younger age, male sex, white race, family history of stones, prior asymptomatic stone on imaging, prior suspected stone episode, gross hematuria, nonobstructing (asymptomatic) stone on imaging, symptomatic renal pelvic or lower-pole stone on imaging, no ureterovesicular junction stone on imaging, and uric acid stone composition. Ten-year recurrence rates varied from 12% to 56% between the first and fifth quintiles of nomogram score. The Recurrence of Kidney Stone nomogram identifies kidney stone formers at greatest risk for a second symptomatic episode. Such individuals may benefit from medical intervention and be good candidates for prevention trials.