Temporal trends in the incidence of kidney stone disease. Kidney Int. 2013;83:146-152. [PMID: 22992468 DOI: 10.1038/ki.2012.320]

Ex Vivo Surgical Removal Versus Conservative Management of Small Asymptomatic Kidney Stones in Living Donors and Long-term Kidney Transplant Outcomes

BACKGROUND

Donors with small asymptomatic kidney stones have been increasingly accepted because of organ shortages and advances in endoscopic urology. This study aims to evaluate and compare long-term living-donor kidney transplant outcomes following ex vivo surgical removal versus conservative management of donors' gifted asymptomatic stones.

METHODS

Between January 2007 and December 2021, 119 kidney transplant recipients received stone-bearing kidneys, divided into the removal group (N = 63) and observation group (N = 56). We evaluated posttransplant stone events, urinary infections, kidney function, delayed graft function, length of hospital stay, and survival outcomes.

RESULTS

After a median follow-up of 75.5 mo, the removal group had a 10.9% lower absolute incidence of stone events (7/56 [12.5%] versus 1/63 [1.6%]; hazard ratio, 0.08; 95% confidence interval, 0.01-0.77) and a 14.3% lower absolute incidence of urinary infections (16/56 [28.6%] versus 9/63 [14.3%]; hazard ratio, 0.42; 95% confidence interval, 0.19-0.95) than the observation group. The removal group also showed superior kidney graft function. The 2 groups had comparable length of hospital stay (11.0 versus 12.0 d; P = 0.297) and exhibited similar delayed graft function incidence (1/56 [1.8%] versus 2/63 [3.2%]; P = 1.000) and urinary stricture incidence (1/56 [1.8%] versus 3/63 [4.8%]; P = 0.621). Graft survival (P = 0.350) and patient survival (P = 0.260) were comparable between 2 groups. Subgroup analyses in recipients who received kidneys with stones <4 mm also reported similar results.

CONCLUSIONS

Ex vivo surgical removal might outperform conservative management for donors' gifted asymptomatic kidney stones, improving long-term transplant outcomes and reducing stone events without increasing perioperative complications, even for stones <4 mm.

Prediction of systemic inflammatory response syndrome and urosepsis after percutaneous nephrolithotomy by urine culture, stone culture, and renal pelvis urine culture: Systematic review and meta-analysis

Background

Percutaneous nephrolithotomy (PCNL) is thought to have an increased risk of infectious complications. This study evaluates the predictability of preoperative midstream urine culture (PMUC), stone culture (SC), and renal pelvis urine culture (RPUC) for post-PCNL systemic inflammatory response syndrome (SIRS) or urosepsis.

Method

After literature search in electronic databases (Embase, PubMed, Ovid, Science Direct, and Springer), studies were selected by following precise eligibility criteria. The quality of included studies was assessed, and meta-analyses of proportions were performed to seek culture positivity rates and incidence rates of post-PCNL SIRS/urosepsis. Meta-analyses of odds ratios (OR) were performed to evaluate the odds of positivity between SC and PMUC or RPUC, and the odds of post-PCNL SIRS/urosepsis with SC versus PMUC or RPUC.

Results

Nineteen studies (4829 patients) were included. Positivity rates of PMUC, SC, and RPUC were 16 % [95 % CI: 12, 20], 21 % [95 % CI: 16, 26] and 10 % [95 % CI: 7, 14] respectively. The odds of positivity were significantly higher for SC compared to PMUC (OR 1.37 [95%CI: 1.02, 1.84]; p = 0.037) or RPUC (OR 1.65 [95%CI: 1.25, 2.18] p < 0.0001). The incidence of post-PCNL SIRS and urosepsis was 21 % [95%CI: 17, 25] and 6 % [95%CI: 3, 10] respectively. The odds of post-PCNL SIRS were significantly higher with SC compared to PMUC (OR 2.45 [95%CI: 1.12, 5.38] p = 0.025) or RPUC (OR 2.10 [95%CI: 1.33, 3.30]; p = 0.001) positivity. The odds of developing urosepsis after PCNL were not significantly different between SC and PMUC positivity (OR 1.874 [95 % CI: 0.943, 3.723]; p = 0.073).

Conclusion

The risk of post-PCNL SIRS is found higher with SC than with PMUC or RPUC positivity. However, the risk of urosepsis may not be different between SC and PMUC.

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.

Causal Effects of Inflammatory Bowel Diseases on the Risk of Kidney Stone Disease

BACKGROUND

Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, have been increasingly associated with kidney stone disease, posing significant health challenges globally.

OBJECTIVE

This research sought to determine the causal relationship between kidney stone disease risk and inflammatory bowel disorders.

METHODOLOGY

This retrospective cohort study included patients with IBDs, such as ulcerative colitis or Crohn's disease, who were diagnosed at least 18 years of age. Information was gathered with an emphasis on patients having comprehensive medical histories and confirmed cases of kidney stone disease from January to December 2022. Medical records were retrospectively evaluated by trained staff to extract treatment information and clinical, radiological, and demographic data. To evaluate relationships, statistical analysis was carried out in SPSS software version 23 using Chi-square tests and descriptive statistics.

RESULTS

The study included 320 patients diagnosed with IBDs, among which 198 (61.87%) had Crohn's disease, and 122 (38.13%) were diagnosed with ulcerative colitis. The cohort consisted of 140 females (43.75%) and 180 men (56.25%), with a mean age of 45.5 years. Regarding smoking, 113 people (35.31%) reported being smokers, whereas 207 people (64.69%) did not smoke. Additionally, 18 (5.62%) of the population had an underweight BMI, 136 (42.50%) had a normal BMI, 119 (37.19%) had an overweight BMI, and 47 (14.69%) had an obese BMI. Of the patients, 86 (26.88%) had a prior history of kidney stone disease, while 194 (60.62%) did not. Aminosalicylates were the most often used therapy modality for IBD in 189 (58.97%) of cases, followed by corticosteroids in 117 (36.56%) and immunomodulators in 93 (28.94%). Radiological examinations showed that renal calculi were present in 60 (18.75%) of patients, and kidney stones occurred in 40 (12.50%) of patients throughout the research period. The smoking status (p=0.006) and prior history of kidney stones (p<0.001) were the corresponding p-values for the significant results.

CONCLUSION

The study highlights an increased risk of kidney stone disease in IBD patients, particularly among smokers and those with a recurrent history of kidney stones. Of the 320 patients, 198 (61.87%) had Crohn's disease and 122 (38.13%) had ulcerative colitis, with a significant relationship found between kidney stones and both smoking (113 patients, 35.31%, p=0.006) and a prior history of kidney stones (86 patients, 26.88%, p<0.001). The findings emphasize the need for targeted preventive measures and close monitoring of these high-risk groups.

The key role of major and trace elements in the formation of five common urinary stones

BACKGROUND

Urolithiasis has emerged as a global affliction, recognized as one of the most excruciating medical issues. The elemental composition of stones provides crucial information, aiding in understanding the causes, mechanisms, and individual variations in stone formation. By understanding the interactions between elements in various types of stones and exploring the key role of elements in stone formation, insights are provided for the prevention and treatment of urinary stone disease.

METHODS

This study collected urinary stone samples from 80 patients in Beijing. The chemical compositions of urinary stones were identified using an infrared spectrometer. The concentrations of major and trace elements in the urinary stones were determined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), respectively. The data were processed using correlation analysis and Principal Component Analysis (PCA) methods.

RESULTS

Urinary stones are categorized into five types: the calcium oxalate (CO) stone, carbonate apatite (CA) stone, uric acid (UA) stone, mixed CO and CA stone, and mixed CO and UA stone. Ca is the predominant element, with an average content ranging from 2.64 to 27.68% across the five stone groups. Based on geochemical analysis, the high-content elements follow this order: Ca > Mg > Na > K > Zn > Sr. Correlation analysis and PCA suggested significant variations in the interactions between elements for different types of urinary stones. Trace elements with charges and ionic structures similar to Ca may substitute for Ca during the process of stone formation, such as Sr and Pb affecting the Ca in most stone types except mixed stone types. Moreover, the Mg, Zn and Ba can substitute for Ca in the mixed stone types, showing element behavior dependents on the stone types.

CONCLUSION

This study primarily reveals distinct elemental features associated with five types of urinary stones. Additionally, the analysis of these elements indicates that substitutions of trace elements with charges and ion structures similar to Ca (such as Sr and Pb) impact most stone types. This suggests a dependence of stone composition on elemental behavior. The findings of this study will enhance our ability to address the challenges posed by urinary stones to global health and improve the precision of interventions for individuals with different stone compositions.

Predictive ability of novel and traditional anthropometric measurement indices for kidney stone disease: a cross-sectional study

BACKGROUND

The aim of our research was to examine the association of novel anthropometric indices (a body shape index (ABSI), waist-to-height ratio (WtHR), conicity index (CI) and body roundness index (BRI)) and traditional anthropometric indices (body mass index (BMI), and waist (WC)) with prevalence of kidney stone disease (KSD) in the general population of United States (U.S.).

METHODS

In this study, we conducted a cross-sectional analysis among the participants in the National Health and Nutrition Examination Survey between the years 2007 and 2020. Weighted multivariable logistic regression analysis, restricted cubic spline (RCS), receiver operating characteristic (ROC) curves, and subgroup analysis were performed to analyze the association of ABSI, BRI, WtHR, CI, BMI and WC with prevalence of KSD.

RESULTS

In total, 11,891 individuals were included in our study. The RCS plot shown that the linear positive association was found between ABSI, BRI, WtHR, CI, BMI and WC and KSD risk. Additionally, the ROC curve demonstrated that the area under the curve of ABSI, BRI, WtHR, and CI was significantly higher than traditional anthropometric indices, including BMI and WC.

CONCLUSIONS

Our study found that the discriminant ability of ABSI, BRI, WtHR, and CI for KSD was higher than BMI and WC. Consequently, ABSI, BRI, WtHR, and CI have the potential to become new indicators for the detection of KSD risk in clinical practice.

Illumination matters Part II: advanced comparative analysis of flexible ureteroscopes in a kidney model by PEARLS

PURPOSE

The aim of the study was to evaluate illumination properties in an in-vitro kidney calyx model in saline.

DESIGN AND METHODS

We evaluated a series of contemporary flexible ureteroscopes including the Storz Flex-Xc and Flex-X2s, Olympus V3 and P7, Pusen 7.5F and 9.2F, as well as OTU WiScope using a 3D-printed closed pink kidney calyx model, submerged in saline. A spectrometer was used for illuminance and color temperature measurements at different openings located at center (direct light), 45° (direct and indirect light) and 90°(indirect light) to the axis of the scope.

RESULTS

Maximum illuminance was at the center opening for all scopes (range: 284 to 12,058 lx at 50% brightness and 454 to 11,871 lx at 100% brightness settings). The scope with the highest center illuminance (Flex-Xc) was 26 times superior to the scope with the lowest illuminance (Pusen 7.5Fr) at 100% brightness setting. For each scope, there was a peripheral illuminance drop ranging from - 43 to - 92% at 50% brightness and - 43% to - 88% at 100% brightness settings, respectively (all p < 0.01). Highest drop was for the P7 and the Pusen 9.2F. All scopes had illuminance skew, except the V3. All scopes had a warm color temperature.

CONCLUSION

Illumination properties vary between ureteroscopes in an enclosed cavity in saline, and differs at center vs 45° and 90° positions within scopes. Peripheral illuminance drop can be as high as - 92%, which is undesirable. This may affect the choice of ureteroscope and light brightness settings used in surgery by urologists.

High Self-Reported Prevalence of Kidney Stones in Trinidad and Tobago: Results of a Cross-Sectional Online Survey

Introduction No data exist on the prevalence of kidney stone disease in Trinidad and Tobago. Local clinicians have noted that the disease is very common, and this study represents the first attempt to investigate the prevalence of urolithiasis in these islands. Objectives The objective is to estimate the prevalence of kidney stone disease in Trinidad and Tobago and to investigate the epidemiology of the disease. Methods An online survey using the online tool Survey Monkey was distributed among members of the public via instant messaging and social media. The survey captured data relating to the stone status and demographics of respondents. Results 1225 patients completed the survey of whom 46.5% were males and 53.5% were females. Respondents were equally distributed throughout the country. 16.74% of those surveyed indicated that they were currently affected by stones confirmed by imaging. Kidney stones were more common among Trinidadians of East Indian ancestry (20.6% vs 10.6%). Positive correlations were established between kidney stones and the presence of hypertension, diabetes, and gout. Persons with kidney stones were more likely to have a family member with the disease - 45.6% vs 31.4% among those without kidney stones. Conclusion This study demonstrates a high self-reported prevalence of kidney stones in Trinidad and Tobago.

Impact of ureteric access sheath use during flexible ureteroscopy: A comparative study on efficacy and safety

OBJECTIVES

This study evaluates the impact of using an access sheath (AS) during flexible ureteroscopy (fURS) for urolithiasis treatment, focusing on outcomes such as stone-free rate, operation time, and complications.

METHODS

This prospective, randomized study was carried out at Badr Hospital, Helwan University, and Ain Shams University hospitals from August 2021 to August 2022. Patients were systematically randomized into two groups (fURS with AS: 33 patients and without AS: 31 patients) and underwent preoperative and postoperative assessments, including lab tests and imaging. Possible procedure-associated risks, such as failed stone access, pain, bleeding, and sepsis, were monitored.

RESULTS

The two groups were found to be comparable in terms of demographic characteristics or preoperative stone findings (p > 0.05 for all). However, operation duration was shorter in the No Sheath group (79.4 ± 15.3 min vs. 90.4 ± 16.7 min in the Sheath group, p = 0.008). Intraoperative complication rates, including failed access, operation termination, ureteric injury, and bleeding, were comparable in both groups (p > 0.05). Postoperative stone-free rates (78.8% vs. 71.0%, p = 0.305) and mean residual stone size (2.7 ± 3.5 mm vs. 3.1 ± 3.1 mm, p = 0.687) showed no significant differences.

CONCLUSIONS

The present study suggests that fURS without an access sheath may offer an efficient and equally effective option for managing upper ureteric and renal stones. However, more studies with larger sample sizes and longer follow-up periods are required to validate these findings and to establish more precise indications for this approach.

Is ureteroscopy and active stone treatment safe and effective in octogenarians? A review of current literature

Background

With the aging of our patient population, and the increasing incidence of kidney stone disease in the elderly, active stone treatment is becoming more common. In this review of current literature, we aim to assess safety and efficacy of ureteroscopy (URS) as primary treatment for urolithiasis in the octogenarians.

Materials and methods

A scoping review of literature according to the PRISMA guidelines was performed, using the relevant search terms. Original articles were screened and included. A narrative review of the studies is provided, with emphasis on outcomes of URS in the elderly.

Results

10 studies were included in the analysis. URS performed in the elderly population showed a good safety and efficacy, with stone-free rates (SFR) comparable to the general population. URS specific complication rates seems to be comparable to the other age groups, with postoperative events mostly related to anaesthesia and pre-existing medical conditions. The overall complication rate was still low, with a slightly prolonged hospital stay. Predictors for SFR were age, severe comorbidities and stone burden.

Conclusion

URS for stone treatment in the elderly population is safe and effective, with comparable surgical outcomes to that of the general population. As comorbidities play an important role in the fitness for surgery and overall survival, risks and benefit of active stone treatment should be carefully balanced in this group.

Assessment of Pre-operative Factors Associated With Blood Loss in Patients Undergoing Percutaneous Nephrolithotomy: A Prospective Study

Background One of the main risks associated with percutaneous nephrolithotomy (PCNL) is bleeding. In the present study, efforts are made to evaluate the pre-operative predictive factors contributing to bleeding due to the procedure of PCNL. Materials and methods From December 2019 to November 2021, data were collected prospectively from 193 patients undergoing PCNL procedures at Indira Gandhi Institute of Medical Sciences, Patna, India. Following PCNL, to check for hematuria and the extent of blood loss, the urethral catheter's and nephrostomy tube's outputs were evaluated. Multivariate regression analysis was used to evaluate the relationship between blood loss and a variety of patient-related demographic and clinical characteristics. Results Included in the study were 193 patients who underwent PCNL. Male patients made up the majority. The average age of study participants was 33.5 years. No statistically significant difference was reported in the mean hemoglobin level drop in the age groups of up to 25 years (2.211 ± 1.540 g/dL), 26-50 years (2.023 ± 1.882 g/dL), and > 50 years (1.855 ± 0.986 g/dL) with P = 0.64. The mean hemoglobin level drop in patients with stone burden > 30 mm2 was reported to be higher, 2.359 ± 1.822 g/dL, compared to 1.859 ± 1.540 g/dL in patients with lower stone burden, reaching a statistically significant difference (P =0.0408). By univariate regression analysis, the presence of a horseshoe-shaped kidney (odds ratio = -0.158, 95% confidence interval (CI): -0.911, -0.059; P = 0.026) was associated with a higher risk for a drop in mean hemoglobin level. By multivariate regression analysis, the presence of a horseshoe-shaped kidney (odds ratio = 0.071, 95% CI: 0.006, 0.839; P = 0.036) remained significantly and independently associated with a higher risk of a drop in mean hemoglobin level. Conclusion In conclusion, the patients' burden of stones and the presence of a horseshoe-shaped kidney may be associated with a higher risk of bleeding following PCNL.

The association between C-reactive protein levels and the risk of kidney stones: a population-based study

OBJECTIVES

The relationship between C-reactive protein (CRP) and the risk of developing kidney stones is unclear, and we aimed to assess the association between CRP and kidney stones in US adults.

METHODS

We used data from NHANES 2007-2010, and we excluded participants who were under 18 years of age and lacked data on CRP and kidney stones. Finally, we included a total of 11,033 participants and performed weighted multivariate regression analysis and subgroup analysis to assess the independent relationship between CRP and kidney stones.

RESULTS

The mean prevalence of kidney stones among the participants was 9.8%. Notably, as CRP levels increased, the prevalence of kidney stones exhibited a corresponding rise across quartiles (Kidney stones: Quartile 1: 7.59%; Quartile 2: 8.77%; Quartile 3: 9.64%; Quartile 4: 10.89%). CRP was positively associated with the risk of kidney stones (Model 1: OR = 1.09, 95% CI: 1.01-1.18, p = 0.03; Model 2: OR = 1.09, 95% CI: 1.00-1.18, p = 0.03, Model 3: OR = 1.14, 95%CI: 1.02-1.26, p = 0.04). Participants in the highest CRP quartile experienced a 69% increased risk of kidney stones compared to those in the lowest quartile (OR = 1.64, 95% CI: 1.04-2.59, p = 0.03). Notably, interaction tests revealed that gender, BMI, diabetes, hypertension, CKD and smoking or alcohol consumption status did not significantly influence the association between CRP and kidney stones.

CONCLUSIONS

Our findings reveal a significant association between higher CRP levels and an increased risk of kidney stones. In clinical practice, heightened awareness of CRP as a potential biomarker could aid in risk assessment and management strategies for kidney stone patients.

Analysis of Dietary Patterns Associated with Kidney Stone Disease Based on Data-Driven Approaches: A Case-Control Study in Shanghai

The main objective of this study was to analyze dietary patterns using data-driven approaches and to explore preventive or risk dietary factors for kidney stone disease (KSD). A case-control matching study was conducted in adults (n = 6396) from a suburb of Shanghai. A food frequency questionnaire was used to assess the consumption of various types of food, and B-ultrasound was used to identify kidney stones. Principal component analysis and regression were used to generate dietary patterns and further explore the relationship between dietary patterns and KSD. LASSO regression and post-selection inference were used to identify food groups most associated with KSD. Among males, the "balanced but no-sugary-beverages pattern" (OR = 0.78, p < 0.05) and the "nuts and pickles pattern" (OR = 0.84, p < 0.05) were protective dietary patterns. Among females, "high vegetables and low-sugary-beverages pattern" (OR = 0.83, p < 0.05) and "high-crustaceans and low-vegetables pattern" (OR = 0.79, p < 0.05) were protective dietary patterns, while the "comprehensive pattern with a preference for meat" (OR = 1.06, p < 0.05) and "sugary beverages pattern" (OR = 1.16, p < 0.05) were risk dietary patterns. We further inferred that sugary beverages (p < 0.05) were risk factors and pickles (p < 0.05) and crustaceans (p < 0.05) were protective factors.

StoneNet: An Efficient Lightweight Model Based on Depthwise Separable Convolutions for Kidney Stone Detection from CT Images

Kidney stone disease is one of the most common and serious health problems in much of the world, leading to many hospitalizations with severe pain. Detecting small stones is difficult and time-consuming, so an early diagnosis of kidney disease is needed to prevent the loss of kidney failure. Recent advances in artificial intelligence (AI) found to be very successful in the diagnosis of various diseases in the biomedical field. However, existing models using deep networks have several problems, such as high computational cost, long training time, and huge parameters. Providing a low-cost solution for diagnosing kidney stones in a medical decision support system is of paramount importance. Therefore, in this study, we propose "StoneNet", a lightweight and high-performance model for the detection of kidney stones based on MobileNet using depthwise separable convolution. The proposed model includes a combination of global average pooling (GAP), batch normalization, dropout layer, and dense layers. Our study shows that using GAP instead of flattening layers greatly improves the robustness of the model by significantly reducing the parameters. The developed model is benchmarked against four pre-trained models as well as the state-of-the-art heavy model. The results show that the proposed model can achieve the highest accuracy of 97.98%, and only requires training and testing time of 996.88 s and 14.62 s. Several parameters, such as different batch sizes and optimizers, were considered to validate the proposed model. The proposed model is computationally faster and provides optimal performance than other considered models. Experiments on a large kidney dataset of 1799 CT images show that StoneNet has superior performance in terms of higher accuracy and lower complexity. The proposed model can assist the radiologist in faster diagnosis of kidney stones and has great potential for deployment in real-time applications.

Comparison of immediate versus post-stenting ureteroscopy for ureteral stones treatment

Ureteroscopy is a highly effective treatment for ureteral stones, characterized by a high stone-free rate and a low need for re-treatment. Ureteral stent placement can improve the insertion of the ureteral access sheath and ureteroscope but may be associated with higher morbidity prior to and after ureteroscopy. The study aimed to compare immediate versus post-stenting ureteroscopy for ureteral stone treatment in terms of operative time, intra- and post-operative complications, length of hospital stay, and stone-free rate. This prospective study involved 126 patients with ureteral stones divided into two groups: the post-stenting ureteroscopy group (PS-URS), who underwent primary ureteral stenting by double J followed by delayed ureteroscopy, and the immediate ureteroscopy group (I-URS), who underwent immediate ureteroscopy without previous stenting. Sixty-six patients were included in the PS-URS group and 60 patients in the I-URS group. Results were comparable, with no significant differences between both groups. The mean operative time was 33.77±3.51 minutes for the PS-URS group and 34.60±2.01 minutes for the I-URS group. The average length of hospital stay was 0.84±2.55 days for PS-URS and 0.92±1.96 days for I-URS patients. The stone-free rate was 97% in the PS-URS group and 95% in the I-URS group. The overall complication rate was 4.5% versus 5% in the PS-URS and I-URS groups, respectively, with all complications being minor and managed effectively. Immediate ureteroscopy is a safe and relevant operative approach for ureteral stones, with comparative results for post-stenting delayed ureteroscopy.

Rare variants in the sodium-dependent phosphate transporter gene SLC34A3 explain missing heritability of urinary stone disease

Urinary stone disease (USD) is a major health burden affecting over 10% of the United Kingdom population. While stone disease is associated with lifestyle, genetic factors also strongly contribute. Common genetic variants at multiple loci from genome-wide association studies account for 5% of the estimated 45% heritability of the disorder. Here, we investigated the extent to which rare genetic variation contributes to the unexplained heritability of USD. Among participants of the United Kingdom 100,000-genome project, 374 unrelated individuals were identified and assigned diagnostic codes indicative of USD. Whole genome gene-based rare variant testing and polygenic risk scoring against a control population of 24,930 ancestry-matched controls was performed. We observed (and replicated in an independent dataset) exome-wide significant enrichment of monoallelic rare, predicted damaging variants in the SLC34A3 gene for a sodium-dependent phosphate transporter that were present in 5% cases compared with 1.6% of controls. This gene was previously associated with autosomal recessive disease. The effect on USD risk of having a qualifying SLC34A3 variant was greater than that of a standard deviation increase in polygenic risk derived from GWAS. Addition of the rare qualifying variants in SLC34A3 to a linear model including polygenic score increased the liability-adjusted heritability from 5.1% to 14.2% in the discovery cohort. We conclude that rare variants in SLC34A3 represent an important genetic risk factor for USD, with effect size intermediate between the fully penetrant rare variants linked with Mendelian disorders and common variants associated with USD. Thus, our findings explain some of the heritability unexplained by prior common variant genome-wide association studies.

Longitudinal trend of urolithiasis incidence rates among world countries during past decades

INTRODUCTION

This study explores the trend of urolithiasis in various countries and categorizes the countries in terms of how their urolithiasis incidence rate has changed over time.

METHODS

The incidence rate of urolithiasis in 204 countries from 1990 to 2019, extracted from the Global Burden of Disease study, has been analyzed.

RESULTS

According to the results, all regions had experienced an increasing trend in urolithiasis rate, except for Eastern Europe, Central Europe, and Southeast Asia regions (decreasing rates of -71.4, -56.2, and -9.2 per 100000, respectively). Moreover, the Caribbean region had the highest increasing trend of urolithiasis rates, and Central Asia was in the next rank (increasing rate of 48.3 and 34.3 per 100,000, respectively, p-value < .05). Also, African regions revealed significant increasing trends over time (p-value < 0.05). The outstanding findings in cluster analysis showed that Afghanistan, Andorra, and Comoros had the most decreasing trend in urolithiasis rates over time (decreasing rate of -128.2 per 100000, p-value < .001). Cuba, Cyprus, Czechia, the Democratic People's Republic of Korea, Denmark, and Djibouti were in the next rank in terms of decreasing rate (decreasing rate of -92.3 per 100000, p-value < .001). In addition, urolithiasis rates in Congo, Eswatini, Gabon, and Grenada have the most increasing trend (increasing rate of 116.1 per 100000, p-value < .001).

CONCLUSION

The trend of urolithiasis rates was significantly increased in most countries, and Congo, Eswatini, Gabon, and Grenada had the highest trend among others. Also, Afghanistan, Andorra, and Comoros revealed the most decreasing rates, and the trend has dropped remarkably in several other countries.

Vitamins as regulators of calcium-containing kidney stones - new perspectives on the role of the gut microbiome

Calcium-based kidney stone disease is a highly prevalent and morbid condition, with an often complicated and multifactorial aetiology. An abundance of research on the role of specific vitamins (B6, C and D) in stone formation exists, but no consensus has been reached on how these vitamins influence stone disease. As a consequence of emerging research on the role of the gut microbiota in urolithiasis, previous notions on the contribution of these vitamins to urolithiasis are being reconsidered in the field, and investigation into previously overlooked vitamins (A, E and K) was expanded. Understanding how the microbiota influences host vitamin regulation could help to determine the role of vitamins in stone disease.

Pulsed thulium:YAG laser-ready to dust all urinary stone composition types? Results from a PEARLS analysis

PURPOSE

To evaluate whether stone dust can be obtained from all prevailing stone composition types using the novel pulsed thulium:YAG (p-Tm:YAG), including analysis of stone particle size after lithotripsy.

METHODS

Human urinary stones of 7 different compositions were subjected to in vitro lithotripsy using a p-Tm:YAG laser with 270 µm silica core fibers (Thulio®, Dornier MedTech GmbH®, Wessling, Germany). A cumulative energy of 1000 J was applied to each stone using one of three laser settings: 0.1 J × 100 Hz, 0.4 J × 25 Hz and 2.0 J × 5 Hz (average power 10 W). After lithotripsy, larger remnant fragments were separated from stone dust using a previously described method depending on the floating ability of dust particles. Fragments and dust samples were then passed through laboratory sieves to evaluate stone particle count according to a semiquantitative analysis relying on a previous definition of stone dust (i.e., stone particles ≤ 250 µm).

RESULTS

The p-Tm:YAG laser was able to produce stone dust from lithotripsy up to measured smallest mesh size of 63 µm in all seven stone composition types. Notably, all dust samples from all seven stone types and with all three laser settings had high counts of particles in the size range agreeing with the definition stone dust, i.e., ≤ 250 µm.

CONCLUSION

This is the first study in the literature proving the p-Tm:YAG laser capable of dusting all prevailing human urinary stone compositions, with production of dust particles ≤ 250 µm. These findings are pivotal for the broader future implementation of the p-Tm:YAG in clinical routine.

Urine pH and Citrate as Predictors of Calcium Phosphate Stone Formation

Key Points

The occurrence of calcium phosphate stones has increased over the past five decades, and this is most notable in female stone formers. High urine pH and hypocitraturia are the most discriminatory urine parameters between calcium phosphate and calcium oxalate stone formers. High urine pH in calcium phosphate stone formers is independent of the effect of dietary alkali and acid.

Background

Urinary parameters, including urine pH and citrate, are recognized as critical in the pathophysiology of calcium-based stones. The factors contributing to variation in these parameters between calcium oxalate (CaOx) and calcium phosphate (CaP) stone formers (SFs) are, however, not well-understood. In this study, using readily available laboratory data, we explore these differences to delineate the odds of forming CaP versus CaOx stones.

Methods

In this single-center retrospective study, we compared serum and urinary parameters between adult CaP SFs, CaOx SFs, and non–stone formers.

Results

Urine pH was higher and urine citrate lower in CaP SFs compared with same-sex CaOx SFs and non–stone formers. In CaP SFs, higher urine pH and lower citrate were independent of markers of dietary acid intake and gastrointestinal alkali absorption, suggesting abnormal renal citrate handling and urinary alkali excretion. In a multivariable model, urine pH and urine citrate were most discriminatory between CaP SFs and CaOx SFs (receiver-operating characteristic area under the curve of 0.73 and 0.65, respectively). An increase in urine pH by 0.35, a decrease in urine citrate by 220 mg/d, a doubling of urine calcium, and female sex all independently doubled the risk of CaP stone formation compared with CaOx stones.

Conclusions

High urine pH and hypocitraturia are two clinical parameters that distinguish the urine phenotype of CaP SFs from CaOx SFs. Alkalinuria is due to intrinsic differences in the kidney independent of intestinal alkali absorption and is accentuated in the female sex.

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.

Epidemiology of Kidney Stones

In the past two decades, major breakthroughs that improve our understanding of the pathophysiology and therapy of kidney stones (KS) have been lacking. The disease continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of kidney stones. Our expanding knowledge of the epidemiology of kidney stones is of paramount importance and largely upgrades the modern management of the disease. In this paper, we review the variables affecting prevalence and incidence, including age, gender, race, ethnicity, occupation, climate, geography, systemic diseases, diabetes, vascular disease, chronic kidney disease, and dietary risk factors relevant to kidney stones.

Safety and efficacy of ureteroscopy for urolithiasis in octogenarians

OBJECTIVE

To examine the safety and efficacy of ureteroscopy (URS) for urolithiasis in octogenarians, and identify preoperative risk factors for the incidence of postoperative complications.

METHODS

The patients who underwent URS for urolithiasis were divided into octogenarians and younger patients (age: <80 years), and the groups were compared regarding their clinical characteristics, intraoperative and postoperative complications, and stone-free rate. The predictors of postoperative complications were evaluated using logistic regression models.

RESULTS

A total of 1207 patients were included, 166 in the octogenarian patient group and 1041 in the younger patient group. The proportion of female patients (p < 0.001), American Society of Anesthesiologists (ASA) score (p < 0.001), rate of preoperative pyelonephritis (p < 0.001), and diabetes mellitus (p = 0.003) were higher in the octogenarian group. No statistically significant differences were found between the two groups regarding stone size, location, and intraoperative complications. Postoperative complications, which reached a significant difference, were observed in 34 (20.5%) octogenarians and 117 (11.2%) younger patients (p = 0.002). However, age itself was not significantly associated with postoperative fever, the most frequent postoperative complication, in multivariate analysis. Female sex, ASA score of ≥3, history of diabetes mellitus, and prolonged operative time (≥120 min) were the significant predictors of fever. The stone-free rate in the octogenarian group was superior to that in the younger patient group (80.1% vs. 70.6%, respectively; p = 0.035).

CONCLUSION

Our results suggest that URS for urolithiasis can be safely and effectively applied to octogenarians in selected cases.

The relationship between ethylene oxide levels in hemoglobin and the prevalence of kidney stones in US adults: an exposure-response analysis from NHANES 2013-2016

Exposure to ethylene oxide may cause a number of diseases. The purpose of this study was to investigate whether there is an association between hemoglobin ethylene oxide (HbEO) and the risk of developing kidney stones in US adults. We analyzed 3348 patients from the National Health and Nutrition Survey (NHANES) 2013-2016 and conducted a cross-sectional study. Dose-response analysis curves of restricted cubic spline function, multiple logistic regression, and subgroup analysis were used to investigate the association between HbEO and the risk of kidney stones. Logistic regression models were used to analyze the correlation between HbEO and kidney stones. Among the 3348 participants, 3016 people self-reported having a kidney stone. After adjusting for age, sex, race, marital status, education level, diabetes, vigorous recreational activity, moderate recreational activity, body mass index, blood urea nitrogen, creatinine, eGFR, and uric acid, we found a positive association between HbEO and the risk of kidney stones. We divided patients into four groups based on quartiles of HbEO levels and performed multifactorial logistic regression after adjusting for confounders, which showed that the incidence of kidney stones increased with increasing HbEO concentrations compared with Q1 (Q2, OR = 0.922, 95% CI, 0. 657-1.295, P = 0.639; Q3, OR = 1.004, 95% CI, 0.713-1.414, P = 0.983; Q4, OR = 1.535, 95% CI, 1.114-2.114, P = 0.009). High levels of HbEO were positively correlated with the risk of kidney stone development and could be used as an indicator of kidney stone prevention.

Top Ten Tips Palliative Care Clinicians Should Know About Urological Care

Patients receiving palliative care (PC) can present with or develop a host of urological needs or complications. These needs can include attention to sexual health, urinary incontinence, genitourinary bleeding, and urinary tract obstruction by benign, malignant, or urinary stone diseases. These varied conditions require that PC clinicians understand invasive and noninvasive medical, surgical, and radiation options for treatment. This article, written by a team of urologists, geriatricians, and PC specialists, offers information and guidance to PC teams in an accessible "Top Ten Tips" format to increase comfort with and skills around assessment, evaluation, and specialist referral for urological conditions common in the PC setting.

Design and kinematics of a tube-shaped multidirectional bending robotic device using slackened SMA wires for transurethral ureterolithotripsy

PURPOSE

The complex and elaborate structure of the urinary system presents surgeons with difficulty in using a ureteroscope with a fixed optical fiber to reach the targeted calculus. To address this challenge, a robotic device is required to control the direction of laser irradiation position independently in ureteroscopes.

METHOD

A continuum robotic device was designed and fabricated. The device is constructed with three slackened shape memory alloy (SMA) wires to control the laser irradiation position of the optical fiber combined with the view of the camera on the tip of the ureteroscope. Kinematics analysis and experimental evaluation reveal the capability of the device.

RESULTS

The structure of the device is the same as a single-joint continuum robot. This device is unique because of the tiny diameter of 1.1 mm which can be used inside the ureteroscope through a Ø1.2 mm inner channel into the kidney for transurethral ureterolithotripsy. Kinematic analysis revealed the relationship among space coordinates, angles of bending, and direction and SMA wires length. The maximum bending angle was around 25° when the current value was 350 mA on a single SMA wire. The device could achieve multi-directional bending by allocating the values of current on SMA wires, separately.

CONCLUSION

This device offers a major advancement in small size and dexterity in medical robotics. Combined with a proper control system, this device could simplify the operation and improve the efficiency of the transurethral ureterolithotripsy.

Prevalence and risk factors of kidney stone disease in population aged 40-70 years old in Kharameh cohort study: a cross-sectional population-based study in southern Iran

BACKGROUND

Kidney stone is the major cause of morbidity, and its prevalence is increasing in the world. This study aimed to assess the prevalence and risk factors of kidney stone in the adult population of southern Iran based on the data of the Kharameh Cohort Study.

METHODS

This cross-sectional study was conducted on 10,663 individuals aged 40-70 years old, using the baseline data of Kharamah cohort study, which started in 2014. Among all participants, 2251 individuals had a history of kidney stone. The participants' demographic characteristics, behavioral habits, and the history of underlying diseases were investigated. The crude and Age Standardized Prevalence Rate of kidney stones was calculated. Also, logistic regression was used to identify the predictors of kidney stone. To check the goodness of fit index of the model, we used the Hosmer-Lemeshow test. All analyses were performed in STATA software.

RESULTS

The prevalence of kidney stone was estimated 21.11%. Also, the Age Standardized Prevalence Rate in men and women was calculated 24.3% and 18.7%, respectively. The mean age of the participants was 52.15 years. Higher prevalence of kidney stone was seen in women aged 40-50 years (40.47%, p = 0.0001) and moderate level of social economic status (31.47%, p = 0.03), men with overweight (44.69%, p < 0.0001) and those in a very high level of social economic status (35.75%, p = 0.001). The results of multiple logistic regression showed that the chance of having kidney stone was 1.17 times higher in diabetic individuals, 1.43 times higher in hypertensive individuals, 2.21 times higher in individuals with fatty liver, and 1.35 times higher in individuals with overweight. The level of socio economic status, male sex, and age were the other factors related to kidney stone.

CONCLUSION

In this study, underlying diseases such as fatty liver, diabetes, and hypertension as well as age, male sex, overweight, and high social economic status were identified as important risk factors for kidney stone. Therefore, identifying individuals at risk of kidney stone and providing the necessary training can greatly help to reduce this disease. However, health policymakers should prepare preventive strategies to reduce the occurrence of kidney stone.

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

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

The association between caffeine intake and risk of kidney stones: A population-based study

Background

Although many studies have proven the beneficial effects of caffeine on human health, the association between caffeine intake and the risk of kidney stones is limited in large epidemiologic studies.

Objectives

We aimed to investigate the association between caffeine intake and the risk of kidney stones.

Methods

A total of 30,716 participants (with weight numbers of 204, 189, and 886) with a history of kidney stone were included in this analysis. All data were survey-weighted, and corresponding logistic regression models were performed to examine the associations between caffeine intake and the risk of kidney stones.

Results

In a fully adjusted model, a per-quartile increase in caffeine intake was associated with a 5.32% decreased risk of kidney stones. In the subgroup analysis, the multivariate-adjusted odds ratios (95% confidence intervals) of the risk of kidney stones for per-quartile increments in caffeine intake were 0.9650 (0.9643, 0.9656) for men, 0.9320 (0.9313, 0.9327) for women, 0.9384 (0.9378, 0.9389) for white race individuals, 1.0281 (1.0270, 1.0292) for nonwhite race individuals, 0.9460 (0.9455, 0.9465) for overweight/obese individuals, and 0.9314 (0.9303, 0.9324) for non-overweight individuals, 0.9100 (0.9094, 0.9105) for caffeine from coffee, and 1.0021 (1.0013, 1.0029) for caffeine from non-coffee sources.

Conclusion

Caffeine intake was negatively associated with the risk of kidney stones. In subgroup analyses, the negative association of caffeine with kidney stone risk was only found in white individuals. In addition, the decreased risk was found higher in women and non-overweight individuals. Especially for women, white individuals and non-overweight individuals. The protective effect of caffeine intake from coffee on stone formation was more significant than that of caffeine from non-coffee sources.

Hybrid flexible ureteroscopy strategy in the management of renal stones - a narrative review

The introduction of single-use flexible ureteroscopes (suFURSs) in daily practice tends to overcome the main limitations of reusable ureteroscopes (reFURSs), in terms of high acquisition costs, maintenance, breakages and repairing costs, reprocessing and sterilization, as retrograde intrarenal surgery (RIRS) is promoted as first-line treatment of renal stones in most cases. A hybrid strategy implies having both instruments in the armamentarium of endourology and choosing the best strategy for cost-efficiency and protecting expensive reusable instruments in selected high-risk for breakage cases such as large stones of the inferior calyx, a steep infundibulopelvic angle or narrow infundibulum, or abnormal anatomy as in horseshoe and ectopic kidney. In terms of safety and efficiency, data present suFURSs as a safe alternative considering operating time, stone-free, and complication rates. An important aspect is highlighted by several authors about reusable instrument disinfection as various pathogens are still detected after proper sterilization. This comprehensive narrative review aims to analyze available data comparing suFURSs and reFURSs, considering economic, technical, and operative aspects of the two types of instruments, as well as the strategy of adopting a hybrid approach to selecting the most appropriate flexible ureteroscope in each case.

Vascular Calcification Is Associated with Fetuin-A and Cortical Bone Porosity in Stone Formers

Background: Nephrolithiasis has been associated with bone loss and vascular calcification (VC), reflecting abnormal extraosseous calcium deposition. Fetuin-A (Fet-A) acts as a potent inhibitor of ectopic mineralization. The aim of the present study was to evaluate the prevalence of VC in stone formers (SF) and non-stone formers (NSF) and to investigate potential determinants of VC among SF, including circulating levels of Fet-A and bone microarchitecture parameters. Methods: Abdominal aortic calcification (AAC) was assessed using available computed tomography in SF and in age-, sex-, and BMI-matched NSF (potential living kidney donors). Serum Fet-A was measured in stored blood samples from SF. Bone microarchitecture parameters were obtained as a post hoc analysis of a cross-sectional cohort from young SF evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Results: A total of 62 SF (38.0 [28.0−45.3] years old) and 80 NSF (40.0 [37.0−45.8] years old) were included. There was no significant difference in AAC scores between SF and NSF. However, when dividing SF according to mean AAC score, below <5.8% (n = 33) or above ≥5.8% (n = 29), SF with higher AAC presented significantly higher BMI and tibial cortical porosity (Ct.Po) and significantly lower serum HDL, klotho, Fet-A, and eGFR. Urinary calcium did not differ between groups, but fractional excretion of phosphate was higher in the former. Upon multivariate regression, BMI, serum Fet-A, and tibial Ct.Po remained independently associated with AAC. Conclusions: This study suggests an association between reduced circulating Fet-A levels and increased bone Ct.Po with VC in SF.

Advances in Assistive Electronic Device Solutions for Urology

Recent technology advances have led urology to become one of the leading specialities to utilise novel electronic systems to manage urological ailments. Contemporary bladder management strategies such as urinary catheters can provide a solution but leave the user mentally and physically debilitated. The unique properties of modern electronic devices, i.e., flexibility, stretchability, and biocompatibility, have allowed a plethora of new technologies to emerge. Many novel electronic device solutions in urology have been developed for treating impaired bladder disorders. These disorders include overactive bladder (OAB), underactive bladder (UAB) and other-urinary-affecting disorders (OUAD). This paper reviews common causes and conservative treatment strategies for OAB, UAB and OUAD, discussing the challenges and drawbacks of such treatments. Subsequently, this paper gives insight into clinically approved and research-based electronic advances in urology. Advances in this area cover bladder-stimulation and -monitoring devices, robot-assistive surgery, and bladder and sphincter prosthesis. This study aims to introduce the latest advances in electronic solutions for urology, comparing their advantages and disadvantages, and concluding with open problems for future urological device solutions.

Comparative Study of Laparoscopic and Open Pyelolithotomy in the Management of Large Renal Pelvic Stones

Background Large renal pelvic stones can be effectively managed with laparoscopic pyelolithotomy. The aim of this study was to compare the surgical outcomes of laparoscopic pyelolithotomy versus open surgery for the treatment of large renal pelvic stones.

Materials and Methods This prospective comparative study was performed at the Sher-i-Kashmir Institute of Medical Sciences Medical College and Hospital over a period of 8 years. Using computer-generated random numbers, the patients were randomized into two groups: group A received laparoscopic pyelolithotomy, while group B had open pyelolithotomy. The data was collected and analyzed using SPSS software 22.

Results Among 74 patients who met the inclusion criteria, the mean age was 39.18 years with 66.21% being males and a male:female ratio of 1.96. Forty-one (55.41%) patients had open surgery and 33 (44.59%) had laparoscopic pyelolithotomy. The difference in mean operative time of laparoscopy (117.66 minutes) and open (78.13 minutes) surgery was statistically significant (p = 0.05). The mean blood loss was significantly lower in the laparoscopic pyelolithotomy group (62.12 mL) than in the open group (92.07 mL) (p = 0.009). The difference in mean hospital stay between the open and laparoscopic groups was significant (p = 0.02). In both laparoscopy and open surgery, we observed a 100% stone-free rate at the end of 1 month. None of our patients expired during the study period.

Conclusion Laparoscopic pyelolithotomy is a promising alternative to traditional open and other endourological techniques, with encouraging results. Despite its technical difficulty, it yields high stone-free rates and low postoperative morbidity.

Should we support prophylactic intervention for asymptomatic kidney stones? A retrospective cohort study with long-term follow-up

The purpose of this study was to evaluate the long-term outcomes of patients undergoing prophylactic intervention or active surveillance for asymptomatic kidney stones and identify factors influencing the outcomes. In this retrospective cohort study, we reviewed the medical records of patients with asymptomatic kidney stones in two institutes between November 2014 and November 2019. Standardized questions were asked via phone calls to supplement the outcomes. Pain, hydronephrosis, stone growth, serious infection, gross hematuria, and spontaneous passage were defined as stone-related events. Future intervention was also recorded to evaluate management. A total of 101 patients with 120 kidney units were enrolled in this study. The median follow-up time was 63 months. The patients were classified into the control group (79 cases) or exposure group (41 cases) according to whether they underwent prophylactic intervention before any stone-related events. Generally, the rates of stone-related events and future intervention were significantly different between the two groups (57.0 vs. 12.2%, p < 0.001; and 31.6 vs. 4.9%, p = 0.002, respectively). After applying stabilized inverse probability of treatment weighted, Cox regression suggested that patients who underwent prophylactic intervention were less likely to experience stone-related events and future intervention (HR = 0.175, and HR = 0.028, respectively). In conclusion, patients who underwent prophylactic intervention had a lower risk of stone-related events and future intervention, although they had some slight complications.

Urolithiasis in Germany: Trends from the National DRG Database

INTRODUCTION

Urolithiasis is a common disease leading to a high socioeconomic burden due to treatment costs and sickness leave. The aim of this study was to evaluate recent trends in the incidence of urolithiasis in Germany and in the use of therapeutic interventions.

METHODS

Treatment data for all in-patient hospital episodes for urolithiasis between 2005 and 2016 were extracted from the national DRG statistics at DESTATIS and analysed with regard to the corresponding procedures according to the OPS code.

RESULTS

Incidence for urolithiasis was stable at around 120,000 cases per year during the observation period with a male:female ratio of 2:1. Rising numbers were noted for patients >80 years. Nevertheless, the number of coded procedures rose significantly with a marked disproportionate transition from extracorporeal shock wave lithotripsy towards ureterorenoscopy. Percutaneous nephrolithotomy was performed more frequently on a smaller scale.

DISCUSSION/CONCLUSION

While the global incidence of urolithiasis is still rising, Germany, as other Western countries, has reached a plateau. There is a remarkable trend towards invasive treatment of even asymptomatic kidney stones. Besides the effects on individual patients with increased risk for complications, this results in a higher monetary burden to the health care system and society.

Correlation between Ion Composition of Oligomineral Water and Calcium Oxalate Crystal Formation

The ion content of drinking water might be associated with urinary stone formation, representing a keystone of conservative nephrolithiasis management. However, the effects of specific ions on calcium oxalate crystal formation and their mechanism of action are still highly controversial. We report an investigation of the effects of oligomineral waters with similar total salt amount but different ion composition on calcium oxalate (CaOx) precipitation in vitro, combining gravimetric and microscopic assays. The results suggest that the “collective” physicochemical properties of the aqueous medium, deriving from the ion combination rather than from a single ionic species, are of importance. Particularly, the ability of ions to strengthen/weaken the aqueous medium structure determines an increase/decrease in the interfacial energy, modulating the formation and growth of CaOx crystals.

Doppler-Assessed Ureteric Jet Frequency: A Valuable Predictor of Ureteric Obstruction

Objectives: To compare ureterovesical jet frequency in non-obstructed versus obstructed ureter secondary to ureteric stone using ultrasonography in patients presenting with ureteral stones.

Study design: Cross-sectional prospective study.

Place of study and duration: Urology Department, The Kidney Centre Post Graduate Training Institute from May 16 to November 15, 2019.

Methods: This study included 97 patients having presented in the emergency department with acute renal colic and were diagnosed as having ureteral stones on a non-contrast-enhanced computed tomography (NCCT). The ureteric jet frequency was measured by Doppler ultrasonography by our radiologist with the Hitachi Aloka F-37 ultrasound machine after they underwent CT. Patients were asked to drink 750-1000 ml of liquids 15-20 minutes before their ultrasonographic examination of both kidneys, ureters, and urinary bladder. The kidney size (length and width) and presence/absence of hydronephrosis were evaluated by grayscale ultrasound. Then, with the help of color Doppler ultrasonography, the frequency of the ureteric jet was recorded.

Results: The patient's mean age was 46.66 ± 3.21 years ranging from 37 to 56 years. There were 58 (59.8%) male and 39 (40.2%) female cases. The mean cumulative stone size was 9.77 ± 2.65 mm. According to stone location, 44 (45.4%) cases had upper ureteric, 24 (24.7%) cases had mid ureteric, and 29 (29.9%) cases had lower ureteric stone. The mean obstructive side jet frequency was 0.70/min ± 0.49, and the non-obstructive side jet frequency was 2.89/min ± 1.29 (P < 0.05).

Conclusions: The mean obstructive side jet frequency was 0.70 ± 0.49/min, which, if we compare to the non-obstructed normal ureter, is significantly less. Hence, color Doppler ultrasonography can be helpful to patients who were previously diagnosed with ureteral stones on NCCT to see if their stone has passed. This can be a very cost-effective modality especially in resource-poor countries where repeat CT can be very expensive. The results from this study can also be used in a specific population (i.e., pregnancy) where the use of imaging modalities that involve ionizing radiation is prohibited.

Prevention and control of urinary tract stones using a smartphone-based self-care application: design and evaluation

BACKGROUND

Self-care and participation of patients in improving health and increasing awareness about the risk factors that affect the development of disease in patients with urinary tract stones are influential factors in controlling and improving the quality of life in these patients. In this regard, the availability and capability of smartphones increase patients' self-care ability. The present study aimed to develop and evaluate a self-care application based on smartphones for patients with urinary tract stones.

METHODS

The present study is a developmental and applied study that was conducted in three phases. First, the information needs and functionalities of the self-care application were determined by surveying 101 patients, 32 urologists and nephrologists, 11 nurses, and six other specialists. In the second phase, the initial sample of the smartphone-based application was created, and in the third phase, the designed application was evaluated by 15 experts using the standard Post-Study System Usability Questionnaire (PSSUQ 18.3) and Nielsen's Attributes of Usability (NAU) questionnaire. Results of the questionnaires were entered into SPSS-23 software for analysis using descriptive statistics.

RESULTS

In the first phase, 21 information elements and nine critical functionalities for the self-care application were identified, and then this application was designed by Java programming language. The evaluation of experts showed that two aspects of the quality of system user interface from the user's point of view and the overall performance of the application together obtained the highest score (6.43 from 7), which was equal to 91.85%. Then according to the experts, aspects of the degree of convenience and user-friendliness of the application received the highest score (6.10 from 7), which was equal to 87.14%, and also all aspects of the application were evaluated at an acceptable level. In general, results of the evaluation of application's usability by experts showed that the usability of the application for patients with urinary tract stones was at an acceptable level.

CONCLUSION

According to the results obtained from evaluating the smartphone-based application for patients with urinary tract stones, this self-care application can be used to prevent and control urinary tract stones and facilitate self-care and active patient participation in care.

Effect of Vitamin B2-Deficient Diet on Hydroxyproline- or Obesity-Induced Hyperoxaluria in Mice

SCOPE

Hyperoxaluria is a major cause of kidney stone disease. Around half of the oxalate in mammals is supplied from the diet and the other half is endogenously synthesized from glyoxylate. Reduction of hepatic glycolate oxidase (GO) activity is one approach to reduce endogenous production of oxalate. However, there are currently few effective dietary approaches to reduce hepatic GO activity.

METHODS AND RESULTS

In the present study, it is investigated whether restriction of dietary vitamin B2 (VB2) can reduce hepatic GO activity and oxalate excretion in mice with hyperoxaluria induce by hydroxyproline (Hyp) or obesity. It is found that VB2 restriction significantly reduces hepatic GO activity in both the Hyp- and obesity-induced model of hyperoxaluria in mice. However, VB2 restriction reduces urinary oxalate excretion only in the Hyp-treated mice and not the obese mice. This difference could be due to the contribution of endogenous oxalate production that manifests as increased hepatic GO activity in Hyp-treated mice but not obese mice.

CONCLUSION

Together these results suggest that VB2 restriction could be a new dietary approach to improve hyperoxaluria when endogenous production of oxalate is increased.

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.

Evaluations of the curative efficacy of G. fruticosus solvent extracts in experimentally induced nephrolithiatic Wistar male rats

BACKGROUND

In Ethiopian folk medicine, there is a claim that medicinal plants can treat urolithiasis although there is insufficient scientific evidence. The objective of this study was to evaluate the curative efficacy of Gomphocarpus fruticosus extracts in experimentally induced nephrolithiatic rats.

METHODS

Urolithiasis was induced in male Wistar rats by feeding ethylene glycol in drinking water for 28 days. The curative effects were evaluated after oral administrations of 200 mg/kg of the extracts from 15 to 28 days. Urine samples were collected 1 day before sacrificing the rats. Blood, liver and kidney samples were gathered under anaesthetic condition at day 28. Crystals in the urine were also analyzed by light microscopy.

RESULTS

G. fruticosus EtOAc extract reduced significantly the level of sodium (P < 0.001), whereas it was significantly elevated the levels of magnesium and citrate (P < 0.01) compared to lithiatic control. G. fruticosus BuOH extract lowered the levels of potassium (P < 0.01), calcium and phosphate in urolithiatic rats. It was also observed that G. fruticosus EtOAc extract decreased the level of oxalate in the urine (P < 0.001), whereas it was increased the levels of magnesium (P < 0.05) and citrate (P < 0.01) in serum analysis after exposure to BuOH extract. In the kidneys, CaOx crystal deposits were reduced significantly by G. fruticosus EtOAc extract (P < 0.01).

CONCLUSION

It has been noted that G. fruticosus EtOAc extract was potent in treating urolithiasis. However, further study is required to assess the efficacy of the active compounds against urolithiasis.

Maternal and fetal outcomes of urolithiasis: A retrospective cohort study

OBJECTIVES

Although urolithiasis is relatively common in the general population, there is limited information on this condition available in the pregnant population. The objectives of this study are to identify the incidence of urolithiasis in pregnancy, as well as to compare maternal and fetal outcomes associated with urolithiasis in pregnancy.

METHODS

Using the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample database from the United States, a population-based retrospective cohort study consisting of pregnant women who delivered between 1999 and 2015 was conducted. ICD-9-CM code 592.X was used to identify pregnant women with urolithiasis within the cohort, with pregnant women without urolithiasis forming the comparison group. Unconditional logistic regression models were used to estimate the associations between urolithiasis in pregnancy and maternal and neonatal outcomes, while adjusting for baseline maternal characteristics.

RESULTS

A cohort of 13,792,544 pregnant women was identified, of which 11,528 had a urolithiasis-related admission during pregnancy, for an overall incidence of 8.3 per 10,000 pregnancies. Women with urolithiasis had a greater risk of developing preeclampsia/eclampsia, OR 1.35(95% CI 1.24-1.47), gestational diabetes, 1.29(1.20-1.30), abruptio placenta, 1.41(1.22-1.64), placenta previa, 1.55(1.27-1.90), pyelonephritis, 88.87(81.69-96.69), venous thromboembolism, 1.65(1.23-2.22), and more likely to deliver by cesarean, 1.20(1.15-1.25). As well, maternal death was more common among these women, 2.85(1.07-7.60). Congenital anomalies, 2.84(2.43-3.31) and prematurity, 1.92(1.82-2.03) were more commonly found among babies born to women with urolithiasis.

CONCLUSION

Although the mechanism is unclear, women with urolithiasis in pregnancy have an increased risk of adverse pregnancy and newborn outcomes.

Low-dose dual-energy CT for stone characterization: a systematic comparison of two generations of split-filter single-source and dual-source dual-energy CT

PURPOSE

To compare noise texture and accuracy to differentiate uric acid from non-uric acid urinary stones among four different single-source and dual-source DECT approaches in an ex vivo phantom study.

METHODS

Thirty-two urinary stones embedded in gelatin were mounted on a Styrofoam disk and placed into a water-filled phantom. The phantom was imaged using four different DECT approaches: (A) dual-source DECT (DS-DE); (B) 1st generation split-filter single-source DECT (SF1-TB); (C) 2nd generation split-filter single-source DECT (SF2-TB) and (D) 2nd generation split-filter single-source DECT using serial acquisitions (SF2-TS). Two different radiation doses (3 mGy and 6 mGy) were used. Noise texture was compared by assessing the average spatial frequency (f_av) of the normalized noise power spectrum (nNPS). ROC curves for stone classification were computed and the accuracy for different dual-energy ratio cutoffs was derived.

RESULTS

NNPS demonstrated comparable noise texture among A, C, and D (f_av-range 0.18-0.19) but finer noise texture for B (f_av = 0.27). Stone classification showed an accuracy of 96.9%, 96.9%, 93.8%, 93.8% for A, B, C, D for low-dose, respectively, and 100%, 96.9%, 96.9%, 100% for routine dose. The vendor-specified cutoff for the dual-energy ratio was optimal except for the low-dose scan in D for which the accuracy was improved from 93.8 to 100% using an optimized cutoff.

CONCLUSION

Accuracy to differentiate uric acid from non-uric acid stones was high among four single-source and dual-source DECT approaches for low- and routine dose DECT scans. Noise texture differed only slightly for the first-generation split-filter approach.

Nephroprotective and antilithiatic activities of Costus spicatus (Jacq.) Sw.: Ethnopharmacological investigation of a species from the Dourados region, Mato Grosso do Sul State, Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

Costus spicatus (Jacq.) Sw., also known as "cana-do-brejo," is a species that is widely used in Brazilian traditional medicine for the treatment of kidney diseases. However, no studies have evaluated its nephroprotective and antilithiatic effects.

AIM

To investigate nephroprotective and antilithiatic effects of C. spicatus in a preclinical model of acute kidney injury (AKI) and in vitro nephrolithiasis.

MATERIALS AND METHODS

C. spicatus leaves were collected directly from the natural environment in the Dourados region, Mato Grosso do Sul State, Brazil. The ethanol-soluble fraction of C. spicatus (ESCS) was obtained by infusion. Phytochemical characterization was performed by liquid chromatography coupled to diode array detector and mass spectrometer (LC-DAD-MS). We assessed whether ESCS has acute or prolonged diuretic activity. The nephroprotective effects of ESCS were evaluated in a model of AKI that was induced by glycerol (10 ml/kg, intramuscularly) in Wistar rats. Different doses of ESCS (30, 100, and 300 mg/kg) were administered orally for 5 days before the induction of AKI. Urinary parameters were measured on days 1, 3, 5, and 7. Twenty-four hours after the last urine collection, blood samples were obtained for the biochemical analysis. Blood pressure levels, renal vascular reactivity, renal tissue redox status, and histopathological changes were measured. Antilithiatic effects were evaluated by in vitro crystallization. Calcium oxalate precipitation was induced by sodium oxalate in urine samples with ESCS at 0.05, 0.5, and 5 mg/ml.

RESULTS

From LC-DAD-MS analyses, flavonoids, saponins and other phenolic compounds were determined in the composition of ESCS. Significant reductions of the excretion of urinary total protein, creatinine, sodium, and potassium were observed in the AKI group, with significant histopathological damage (swelling, vacuolization, necrosis, and inflammatory infiltration) in the proximal convoluted tubule. Treatment with ESCS exerted a significant nephroprotective effect by increasing the urinary excretion of total protein, urea, creatinine, sodium, potassium, calcium, and chloride. All of the groups that were treated with ESCS exhibited a reduction of histopathological lesions and significant modulation of the tissue redox state. We also observed a concentration-dependent effect of ESCS on the crystallization of urinary crystals, with reductions of the size and proportion of monohydrated crystals.

CONCLUSION

The data suggest that C. spicatus has nephroprotective and antilithiatic effects, suggesting possible effectiveness in its traditional use.

Incidence of kidney stones in pregnancy and associations with adverse obstetrical outcomes: a systematic review and meta-analysis of 4.7 million pregnancies

BACKGROUND

Renal stones are a common cause of non-obstetrical abdominal pain in pregnant women. Though the management of renal stones in pregnancy is challenging, it remains unclear how the incidence of kidney stones may affect the course of pregnancy and delivery.

OBJECTIVE

To determine the incidence of renal stones in pregnancy and its impact on adverse obstetrical outcomes.

DATA SOURCES

We conducted a systematic literature search of three databases: Ovid MEDLINE, Ovid EMBASE, and EBSCO CINAHL Plus. After the selection of articles, an additional hand-search of their citations was completed to maximize sensitivity. Databases were examined from the last four decades (19 March 1970) up to the search date (19 March 2020).

STUDY ELIGIBILITY CRITERIA

Articles were excluded if they were not relevant to kidney stones or did not report outcomes related to pregnancy. Case reports, animal studies, and cadaveric studies were excluded. Conference abstracts, gray literature, and unpublished data were not eligible.

STUDY APPRAISAL AND SYNTHESIS METHODS

All screening, extraction, and synthesis were completed in duplicate with two independent reviewers. All outcomes reported in the included studies were systematically evaluated to determine suitability for meta-analysis. Random-effects models and sensitivity analyses were used to account for interstudy variation. Renal stone incidence rates were pooled to generate summary proportions. Risk of bias assessment was completed using the Risk of Bias Assessment tool for Non-randomized Studies.

RESULTS

Twenty-one studies were included through systematic review and approximately 4.7 million pregnancies across nine studies were included for meta-analysis. There are three major findings of this review regarding renal stone incidence in pregnancy and maternal, child, and birth-related outcomes associated with renal stones. First, we found pooled incidence of renal stones was 0.49%, or one case for every 204 pregnancies. Second, renal stones during pregnancy were significantly associated with the development of preeclampsia and urinary tract infection, as well as increased likelihood of low birth weight, preterm labor, and C-section deliveries. However, renal stones were not significantly associated with premature rupture of membranes or infant mortality. Third, there were limited obstetrical complications reported with either medical or surgical therapies although comparative outcomes were not provided in the majority of studies, precluding formal meta-analysis.

CONCLUSIONS

Although renal stones in pregnancy are relatively rare, there may be an associated risk of serious adverse obstetrical outcomes. However, further research is required to understand whether these obstetrical outcomes are causal or due to other confounders. Interdisciplinary care and pregnancy-specific counseling should be advised for pregnant women with kidney stones.

Polyfluoroalkyl chemicals and the risk of kidney stones in US adults: A population-based study

The potential nephrotoxicity of polyfluoroalkyl chemicals (PFCs) have received extensive attention. However, the relationship between PFCs and the risk of kidney stones remain unclear. This study aimed to examine the level of PFCs in the US population and its relationship with the risk of kidney stones. We investigated the serum levels of six PFCs in 8453 adult participants (≥20 years) from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2016, including perfluorodecanoic acid (PFDE), perfluorohexane sulfonic acid (PFHS), 2-(N-methyl-perfluorooctane sulfonamido) acetate (MPAH), perfluorononanoic acid (PFNA), perfluoroundecanoic acid (PFUA), and perfluorododecanoic acid (PFDO). Logistic regression model was used to evaluate the correlation between PFCs and kidney stones. Of the 8453 participants, 787 self-reported a history of kidney stones. After adjusting for gender, age, race, education, marital status, body mass index (BMI), hypertension, diabetes and estimated glomerular filtration rate (eGFR), we found that total PFCs and PFHS were positively correlated with the risk of kidney stones. Compared with the lowest tertile, the odds ratios with 95% confidence intervals (CI) with increasing tertiles were 1.30 (95% CI,1.08-1.59, p = 0.007) and 1.25 (95 CI%,1.00-1.52, p = 0.024) for total PFCs and 1.24 (95 CI%,1.03-1.51, p = 0.032), and 1.35 (95 CI,1.10-1.68, p = 0.005) for PFHS. Our study shows that total PFCs and PFHS were associated with an increased risk of kidney stones.