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

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.

[The 1-cm lower calyx calculus: SWT, URS or Mini-PCNL? Guidelines vs. reality.]

Urinary stones of the upper urinary tract can be considered a widespread public health concern due to their high incidence and prevalence and their health policy-related and financial implications. A significant proportion of newly diagnosed kidney stones are lower-pole stones, i.e., stones affecting the lower calyx group of the renal pelvicalyceal system. These are often diagnosed by chance, i.e., as incidental findings during ultrasound or CT scans performed for other reasons, or as "secondary stones" detected during the diagnostic work-up of symptomatic urinary stones in other locations. Residual disintegrates after extracorporeal shock-wave lithotripsy (ESWL) or endoscopic stone therapy constitute a further, quantitatively significant group. These incidentally discovered lower-pole stones are often characterised by their small size and lack of symptoms. It stands to reason that some of these small, asymptomatic lower-pole stones do not always remain small and asymptomatic, and that treatment tends to become more complex with increasing size. There has been an astonishing lack of published studies with a high level of evidence over the last 20 years to provide a conclusive and reproducible answer to the question posed in this review. Small, asymptomatic stones can be monitored. Symptomatic and rapidly growing stones should be treated. There is a lack of valid risk factors allowing an identification of subgroups that should be treated prophylactically at the asymptomatic stage. In active therapy, a 10-to-20-year-old principle still holds true today: a high stone-free rate in one therapy session is offset by an increased complication rate, with increasing miniaturisation in endourology (retrograde and percutaneous) and increasingly effective laser disintegration shifting this basic principle more and more in favour of flexible URS and (mini, micro) PCNL. The range of indications for ESWL is undoubtedly becoming smaller, and this also applies to lower-pole stones. The results of an ongoing prospective randomised study comparing the different treatment modalities, albeit with recruitment difficulties, are still pending.

The relationship between stone-free and patient position in retrograde intrarenal surgery: a randomized prospective study

PURPOSE

Residual fragments not removed with urinary stone surgery may become symptomatic. In this context, this study was carried out to investigate the effect of performing retrograde intrarenal surgery, which is conventionally performed in the lithotomy position, in the modified lithotomy position (Trend-side) on stone-free rates following the surgery.

METHODS

This prospective study consisted of 100 patients with a single kidney stone smaller than 2 cm between 2021 and 2023. These patients were randomized into two groups of 50 patients each to be operated on in the conventional lithotomy and Trend-side positions. Variables were compared using independent t test for continuous variables and chi-square test for categorical variables.

RESULTS

There was no significant difference between the lithotomy and Trend-side position groups in terms of preoperative size, density, location of the stone, and hydronephrosis degree. Stone-free rate was 72% (n = 36) in the lithotomy group and 92% (n = 46) in the Trend-side group. Hence, there was a significant difference between the groups in the stone-free rate in favor of the Trend-side group (p = 0.009). Fragmentation time was statistically significantly shorter in the Trend-side group than in the lithotomy group (34 ± 17 min vs. 43 ± 14 min; p = 0.006). There was no significant difference between the groups in postoperative complication rates.

CONCLUSION

Performing retrograde intrarenal surgery in the Trend-side position shortened the duration of fragmentation compared to the lithotomy position and was associated with higher stone-free rates. In conclusion, the Trend-side position can be safely preferred in patients undergoing retrograde intrarenal surgery due to kidney stones.

Determining the Stone Free Rate of Retrograde Intrarenal Surgery. Which Radiological Technique? RIRSearch Study Group

OBJECTIVE

To evaluate the sensitivity and specificity of ultrasonography (USG) and kidney ureter bladder radiography (KUB) for the determination of stone-free status of retrograde intrarenal surgery (RIRS) according to different stone-free status definitions.

MATERIALS AND METHODS

The patients who underwent RIRS between September 2021 and September 2022 were prospectively included in the study. All patients underwent a KUB radiography, urinary system USG and noncontrast abdominal tomography at the postoperative first month of the surgery. The sensitivity, specificity, negative predictive factor, and positive predictive factor of USG and KUB on evaluating the stone-free rate were analyzed according to different stone-free status definitions.

RESULTS

A total of 178 patients were included in the study. The stone-free rates according to stone-free definitions as; residual stone <4 mm, <2 mm and no residual stone were 79.2%, 64.0%, and 56.7%, respectively. According to its definition as a residual stone <4 mm, the sensitivity and specificity of USG were 64.9% and 84.3%, respectively. The sensitivity of USG was 57.1% and 52.5% as the definitions were residual stone <2 mm and no residual stone, respectively. Addition of KUB to USG slightly increased the sensitivity but did not change the specificity.

CONCLUSION

USG had high specificity but low sensitivity for evaluating stone-free status after RIRS and addition of KUB did not increase the diagnostic efficacy. Although USG may be used in daily practice, it may overestimate the stone-free status and noncontrast abdominal tomography must be used during the clinical trials to document the exact stone-free rates of RIRS.

Application of the direct in-scope suction technique in antegrade flexible ureteroscopic lithotripsy for the removal of a large ureteric calculus in a kidney transplant recipient: A case report

The occurrence of a large ureteric calculus in a transplanted kidney, originating from a donor, is a rare but significant complication. It poses risks such as urinary obstruction, septicemia, and potential loss of allograft function. In this case, we report our first use of the direct in-scope suction technique during antegrade flexible ureteroscopy lithotripsy. This method successfully removed a donor-derived ureteric calculus in a kidney transplant recipient. The procedure resulted in complete stone removal, and the patient experienced a favorable postoperative recovery without additional adverse events.

Urological Guidelines for Kidney Stones: Overview and Comprehensive Update

BACKGROUND

Evidence-based guidelines are published by urological organisations for various conditions, including urolithiasis. In this paper, we provide guidance on the management of kidney stone disease (KSD) and compare the American Urological Association (AUA) and European Association of Urologists (EAU) guidelines.

METHODS

We evaluate and appraise the evidence and grade of recommendation provided by the AUA and EAU guidelines on urolithiasis (both surgical and medical management).

RESULTS

Both the AUA and EAU guidelines provide guidance on the type of imaging, treatment options, and medical therapies and advice on specific patient groups, such as in paediatrics and pregnancy. While the guidelines are generally aligned and based on evidence, some subtle differences exist in the recommendations, but both are generally unanimous for the majority of the principles of management.

CONCLUSIONS

We recommend that the guidelines should undergo regular updates based on recently published material, and while these guidelines provide a framework, treatment plans should still be personalised, respecting patient preferences, surgical expertise, and various other individual factors, to offer the best outcome for kidney stone patients.

Is traditional stone clinic the optimal use of NHS resources?

There is no clear guidance on the efficacy of stone follow-up. NICE have been unable to make recommendations with current published evidence. The aim of this study was to understand the patient journey resulting in surgical intervention, and whether traditional stone follow-up is effective. A retrospective review of patients undergoing ureteroscopy (URS) or percutaneous nephrolithotomy (PCNL) over a 3 year period identified 471 patients who underwent these procedures to treat stone disease. Records were interrogated for the following: symptoms, mechanism of booking, reason for intervention, stone size, stone location, risk factors and previous follow-up. Of 471 patients who underwent intervention, 168 were booked from stone clinic follow-up (36%). Of these, 96% were symptomatic and 4% were asymptomatic. When risk factors were removed, this figure was reduced to 1%. Sepsis rate for emergency admissions differs between those followed up (13%) versus new presentations (19)%. There was no statistically significant difference in the outpatient imaging frequency between patients booked from an emergency admission (80% having imaging every 6 months) and those from the clinic (82%). Our Hospital provides on average 650 stone clinic appointments a year with a cost of £93,000. Given the low rate of intervention in patients with asymptomatic renal stones, a symptomatic, direct-access emergency stone clinic could be a better model of care and use of NHS resources. Urgent research is required in this area to further assess if this is the case.

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Effective deep learning classification for kidney stone using axial computed tomography (CT) images

INTRODUCTION

Stone formation in the kidneys is a common disease, and the high rate of recurrence and morbidity of the disease worries all patients with kidney stones. There are many imaging options for diagnosing and managing kidney stone disease, and CT imaging is the preferred method.

OBJECTIVES

Radiologists need to manually analyse large numbers of CT slices to diagnose kidney stones, and this process is laborious and time-consuming. This study used deep automated learning (DL) algorithms to analyse kidney stones. The primary purpose of this study is to classify kidney stones accurately from CT scans using deep learning algorithms.

METHODS

The Inception-V3 model was selected as a reference in this study. Pre-trained with other CNN architectures were applied to a recorded dataset of abdominal CT scans of patients with kidney stones labelled by a radiologist. The minibatch size has been modified to 7, and the initial learning rate was 0.0085.

RESULTS

The performance of the eight models has been analysed with 8209 CT images recorded at the hospital for the first time. The training and test phases were processed with limited authentic recorded CT images. The outcome result of the test shows that the Inception-V3 model has a test accuracy of 98.52 % using CT images in detecting kidney stones.

CONCLUSIONS

The observation is that the Inception-V3 model is successful in detecting kidney stones of small size. The performance of the Inception-V3 Model is at a high level and can be used for clinical applications. The research helps the radiologist identify kidney stones with less computational cost and disregards the need for many experts for such applications.

Effect of external physical vibration lithecbole in obese patients with lower pole stones <15 mm after ESWL: a single-centre, randomized, open label clinical trial

Objective

To investigate the efficacy and safety of external physical vibration lithecbole (EPVL) in obese patients with <15 mm lower pole stones following extracorporeal shock wave lithotripsy (ESWL).

Methods

Two hundred and ninety-nine obese patients with BMI greater than 30 kg/m2 and lower pole stones smaller than 15 mm were prospectively randomized into two groups. While ESWL was the only option in the control group, patients in the treatment group accepted EPVL after receiving ESWL. Imaging tests were used to compare the stone expulsion status on day 1 and the stone-free rates (SFR) on the first, second, and fourth weekends.

Results

All 299 obese patients were randomly divided into two groups, with 152 patients assigned to the treatment group and 147 assigned to the control group. EPVL was effective in facilitating the expulsion of stone fragments. The treatment group's stone expulsion rate on the first day following EPVL was significantly greater than the control group's (66.4% vs. 51.7%, p = 0.009). Stone clearance rates in the treatment and control groups were 63.2 and 55.1% at 1 week (p = 0.041), 84.9 and 70.7% at 2 weeks (p = 0.011), and 90.8 and 79.6% at 4 weeks (p = 0.017), respectively. The complications (hematuria, lumbago, and fever) between the groups did not show any significance (p > 0.05). Patients in the treatment group received an average of 5.2 sessions.

Conclusion

EPVL is an efficient and secure procedure that facilitates lower pole stone discharge in obese patients following ESWL treatment. To support the aforementioned conclusions, additional large-scale multi-center prospective studies are required.

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.

Technique, Feasibility, Utility, Limitations, and Future Perspectives of a New Technique of Applying Direct In-Scope Suction to Improve Outcomes of Retrograde Intrarenal Surgery for Stones

Retrograde intrarenal surgery (RIRS) is accepted as a primary modality for the management of renal stones up to 2 cm. The limitations of RIRS in larger volume stones include limited visualization due to the snow-globe effect and persistence of fragments that cannot be removed. We describe a new, simple, cost-effective modification that can be attached to any flexible ureteroscope which allows simultaneous/alternating suction and aspiration during/after laser lithotripsy using the scope as a conduit to remove the fragments or dust from the pelvicalyceal system called direct in-scope suction (DISS) technique. Between September 2020 and September 2021, 30 patients with kidney stones underwent RIRS with the DISS technique. They were compared with 28 patients who underwent RIRS with a 11Fr/13Fr suction ureteral access sheaths (SUASs) in the same period. RIRS and laser lithotripsy were carried out traditionally with a Holmium laser for the SUAS group or a thulium fiber laser for the DISS group. There was no difference in age, gender, and history of renal lithiasis between the two groups. Ten (40%) patients had multiple stones in the DISS groups, whilst there were no patients with multiple stones in the SUAS group. Median stone size was significantly higher in the DISS group [22.0 (18.0−28.8) vs. 13.0 (11.8−15.0) millimeters, p < 0.001]. Median surgical time was significantly longer in the DISS group [80.0 (60.0−100) minutes] as compared to the SUAS group [47.5 (41.5−60.3) minutes, p < 0.001]. Hospital stay was significantly shorter in the DISS group [1.00 (0.667−1.00) vs. 1.00 (1.00−2.00) days, p = 0.02]. Postoperative complications were minor, and there was no significant difference between the two groups. The incidence of residual fragments did not significantly differ between the two groups [10 (33.3%) in the DISS group vs. 10 (35.7%) in the SUAS group, p = 0.99] but 10 (33.3%) patients required a further RIRS for residual fragments in the DISS group, whilst only one (3.6%) patient in the SUAS group required a subsequent shock wave lithotripsy treatment. Our audit study highlighted that RIRS with DISS technique was feasible with an acceptable rate of retreatment as compared to RIRS with SUAS.

Optimal Delivery of Follow-Up Care for the Prevention of Stone Recurrence in Urolithiasis Patients: Improving Outcomes

Urolithiasis is a common clinical condition with frequent recurrences. Advances in knowledge of pathophysiological mechanisms permit the categorization of patients to low and high risk for recurrence, with specific metabolic abnormalities diagnosed in the second category. Follow-up is essential for patients with urolithiasis and consists of both imaging and metabolic follow-up with urine studies. No formal guidelines or solid evidence currently exists regarding frequency and type of follow-up studies to be performed in each category. This review aims to summarize existing evidence regarding follow-up, in order to guide clinicians on how and when to follow-up urolithiasis patients according to existing clinical scenario.

Global Trends in Incidence and Burden of Urolithiasis from 1990 to 2019: An Analysis of Global Burden of Disease Study Data

Background

Urolithiasis is among the most common urologic diagnoses globally, with substantial burden and cost on healthcare systems worldwide. Increasing evidence links urolithiasis with an array of risk factors, including diet and lifestyle trends, noncommunicable diseases such as diabetes and obesity, and global warming.

Objective

To examine geographic, temporal, and sociodemographic patterns to better understand global disease burden of urolithiasis.

Design, setting, and participants

We extracted data on age-standardized incidence rate (ASIR), deaths, and disability-adjusted life years (DALYs) attributed to urolithiasis for 21 regions, including 204 countries, for 1990–2019 from the Global Burden of Disease (GBD) study.

Outcome measurements and statistical analysis

Data were analyzed at the global, regional, and country levels, as well as stratified by the Socio-Demographic Index. The average annual percentage change (AAPC) was calculated to measure temporal trends across groups.

Results and limitations

Globally, total cases, DALYs, and deaths attributed to urolithiasis increased over the study period, while the age-standardized rates of these measures decreased. The age-standardized incidence of urolithiasis decreased from 1696.2 (95% confidence interval [CI] 1358.1–2078.1) cases per 100 000 population in 1990 to 1394.0 (95% CI, 1126.4–1688.2) cases per 100 000 population in 2019, with an AAPC of −0.7 (95% CI [−0.8, −0.6]). Of the GBD regions, Eastern Europe demonstrated a consistently higher ASIR of urolithiasis than all other regions, while the Caribbean had the highest AAPC. This study is limited by the available national and regional data, as described in the original GBD study.

Conclusions

Worldwide, total cases, DALYs, and deaths attributed to urolithiasis have increased since 1990, while age-standardized rates have decreased, with demonstrated regional and sociodemographic variation. Multifaceted strategies to address urolithiasis prevention and treatment are necessary.

Patient summary

In this study, we looked at trends in the global burden of stone disease using data from 204 countries from 1990 to 2019. We found that the overall burden has increased, but it varies by age, sociodemographic variables, and geographic region. We conclude that we need adaptable policies that suit the specific needs of the country to address this burden.

The Relationship Between Renal Stones and Primary Aldosteronism

INTRODUCTION

The association between primary aldosteronism (PA) and nephrolithiasis is still unclear. The hypercalciuria and hypocitraturia of PA patients might be the reason leading to recurrent calcium nephrolithiasis. This study aimed to evaluate the relationship between PA and renal stones, including stone size and density.

MATERIALS AND METHODS

From February 2010 to March 2021, we retrospectively collected 610 patients who presented to our medical center with hypertension history, and all these patients, suspicious of PA, had PA data survey. In total, 147 patients had kidney stone and were divided into 44 patients with essential hypertension as group 1 and 103 patients with PA as group 2. Pearson χ² test and independent Student's t-test were performed to examine the differences among variables.

RESULTS

The mean age was 54.4 ± 12.0 years in group 1 and 53.0 ± 11.1 years in group 2. The incidence rate of renal stones in the PA group was around 24%. No significant differences between the two groups were found for gender, systolic/diastolic blood pressure, duration of hypertension, diabetes mellitus history, and laterality of kidney stone; however, mean stone size was 4.0 ± 3.3 mm in group 1 and 6.5 ± 7.2 mm in group 2, with a significantly larger renal stone size noted in the PA group than that in the essential hypertension group (p = 0.004). Hounsfield unit (HU) density was higher in the PA group vis-à-vis the essential hypertension cohort, although this did not reach a significant difference (p = 0.204).

CONCLUSIONS

Our study revealed that PA patients had a higher incidence rate of renal stones compared to that of the general population. Besides, the PA-related renal stones also presented as larger and harder than those of the essential hypertension group. Further investigation concerning the association between PA and renal stones is warranted.

Decision-Making, Preference, and Treatment Choice for Asymptomatic Renal Stones-Balancing Benefit and Risk of Observation and Surgical Intervention: A Real-World Survey Using Social Media Platform

Introduction: The burden of kidney stone disease has risen, and several treatment options now exist. We wanted to evaluate the preference and treatment choices based on the information provided for management of hypothetical 8 and 15 mm renal stone, and factors that influenced their decision. Materials and Methods: An online questionnaire to investigate trends in decision-making for two hypothesized scenarios of asymptomatic kidney stones (8 and 15 mm) was formatted online in Microsoft Forms and posted on social media (Facebook) in Europe. The ethical approval was obtained from the University Ethics Committee, and data were collected from general public between September and November 2020. Results: A total of 476 participants of different age and background answered the survey with a male:female ratio of 1:2.7. The age groups were categorized as 18-25 years (n = 149), 26-49 years (n = 192), and 50+ years (n = 135). In the 8 mm scenario, 107 of the 476 participants (22.5%) chose observation, 249 (52.3%) chose extracorporeal shockwave lithotripsy (SWL) and 120 (25.2%) opted for ureteroscopy (URS). In the 15 mm scenario, 194 participants chose SWL treatment (40.8%), 216 (45.4%) URS, and 66 (13.9%) preferred percutaneous nephrolithotomy. The influencing factors were success rate, complication risk and invasiveness of the procedure. On comparison to 8 mm stone, while stent avoidance and activity limitation were considered less important with 15 mm stone (p < 0.001), complication rates were considered more important (p < 0.001). Conclusion: More than one treatment choice for kidney stones often exists and clinicians must take patient choice into account via an informed decision-making process. While some might accept a higher risk of invasiveness and complications for higher stone-free rate, others might have a more conservative approach to this. It is about time that urologists take patient priorities and concerns into account and perhaps use Patient Reported Outcome Measures in addition to clinical outcomes when comparing treatment success.