Guideline of the guidelines: urolithiasis

Gut microbiota modulation via fecal microbiota transplantation mitigates hyperoxaluria and calcium oxalate crystal depositions induced by high oxalate diet

Hyperoxaluria, including primary and secondary hyperoxaluria, is a disorder characterized by increased urinary oxalate excretion and could lead to recurrent calcium oxalate kidney stones, nephrocalcinosis and eventually end stage renal disease. For secondary hyperoxaluria, high dietary oxalate (HDOx) or its precursors intake is a key reason. Recently, accumulated studies highlight the important role of gut microbiota in the regulation of oxalate homeostasis. However, the underlying mechanisms involving gut microbiota and metabolite disruptions in secondary hyperoxaluria remain poorly understood. Here, we investigated the therapeutic efficacy of fecal microbiota transplantation (FMT) sourced from healthy rats fed with standard pellet diet against urinary oxalate excretion, renal damage and calcium oxalate (CaOx) crystal depositions via using hyperoxaluria rat models. We observed dose-dependent increases in urinary oxalate excretion and CaOx crystal depositions due to hyperoxaluria, accompanied by significant reductions in gut microbiota diversity characterized by shifts in Ruminococcaceae_UCG-014 and Parasutterella composition. Metabolomic analysis validated these findings, revealing substantial decreases in key metabolites associated with these microbial groups. Transplanting microbes from healthy rats effectively reduced HDOx-induced urinary oxalate excretion and CaOx crystal depositions meanwhile restoring Ruminococcaceae_UCG-014 and Parasutterella populations and their associated metabolites. Furthermore, FMT treatment could significantly decrease the urinary oxalate excretion and CaOx crystal depositions in rat kidneys via, at least in part, upregulating the expressions of intestinal barrier proteins and oxalate transporters in the intestine. In conclusion, our study emphasizes the effectiveness of FMT in countering HDOx-induced hyperoxaluria by restoring gut microbiota and related metabolites. These findings provide insights on the complex connection between secondary hyperoxaluria caused by high dietary oxalate and disruptions in gut microbiota, offering promising avenues for targeted therapeutic strategies.

Radiomics-driven spectral profiling of six kidney stone types with monoenergetic CT reconstructions in photon-counting CT

OBJECTIVES

Urolithiasis, a common and painful urological condition, is influenced by factors such as lifestyle, genetics, and medication. Differentiating between different types of kidney stones is crucial for personalized therapy. The purpose of this study is to investigate the use of photon-counting computed tomography (PCCT) in combination with radiomics and machine learning to develop a method for automated and detailed characterization of kidney stones. This approach aims to enhance the accuracy and detail of stone classification beyond what is achievable with conventional computed tomography (CT) and dual-energy CT (DECT).

MATERIALS AND METHODS

In this ex vivo study, 135 kidney stones were first classified using infrared spectroscopy. All stones were then scanned in a PCCT embedded in a phantom. Various monoenergetic reconstructions were generated, and radiomics features were extracted. Statistical analysis was performed using Random Forest (RF) classifiers for both individual reconstructions and a combined model.

RESULTS

The combined model, using radiomics features from all monoenergetic reconstructions, significantly outperformed individual reconstructions and SPP parameters, with an AUC of 0.95 and test accuracy of 0.81 for differentiating all six stone types. Feature importance analysis identified key parameters, including NGTDM_Strength and wavelet-LLH_firstorder_Variance.

CONCLUSION

This ex vivo study demonstrates that radiomics-driven PCCT analysis can improve differentiation between kidney stone subtypes. The combined model outperformed individual monoenergetic levels, highlighting the potential of spectral profiling in PCCT to optimize treatment through image-based strategies.

KEY POINTS

Question How can photon-counting computed tomography (PCCT) combined with radiomics improve the differentiation of kidney stone types beyond conventional CT and dual-energy CT, enhancing personalized therapy? Findings Our ex vivo study demonstrates that a combined spectral-driven radiomics model achieved 95% AUC and 81% test accuracy in differentiating six kidney stone types. Clinical relevance Implementing PCCT-based spectral-driven radiomics allows for precise non-invasive differentiation of kidney stone types, leading to improved diagnostic accuracy and more personalized, effective treatment strategies, potentially reducing the need for invasive procedures and recurrence.

Efficacy and Safety of Semirigid Ureteroscopy Combined with Holmium:yttrium-aluminum-garnet Laser Lithotripsy for the Treatment of Proximal Ureteral Calculi: A Single-arm Meta-analysis

Background and objective

Ureteral stones are currently treated with holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy using rigid and flexible ureteroscopes. This study aims to evaluate the efficacy and safety of semirigid ureteroscopy combined with Ho:YAG laser lithotripsy for treating proximal ureteral stones in real-world studies.

Methods

The PubMed, Embase, and Web of Science databases were searched systematically to retrieve all relevant studies up to April 2024. A meta-analysis of the retrieved studies was performed using Stata 14.0 software and expressed as rate, mean difference, and 95% confidence interval (CI). The main outcomes of this meta-analysis were stone-free rate (SFR) and perioperative outcomes including operation time, hospital stay, postoperative ureteral stent placement, auxiliary procedures, and intra- or postoperative complications.

Key findings and limitations

A total of 24 studies were included in this study, including 2058 patients with proximal ureteral stones. According to the results of the combined analysis, the SFR of semirigid ureteroscopy combined with Ho:YAG laser lithotripsy for the treatment of proximal ureteral stones was 78% (95% CI [75%, 82%]), operation time was 51.03 min (95% CI [43.5, 58.56]), hospital stay was 1.62 d (95% CI [1.54, 1.70]), auxiliary procedure rate was 20% (95% CI [15%, 25%]), and postoperative complication rate was 16% (95% CI [12%, 22%]).

Conclusions and clinical implications

The results of this study show that semirigid ureteroscopic Ho:YAG laser lithotripsy is a commonly used treatment for proximal ureteral calculi, but its efficacy and safety need to be improved further, and its efficacy is not related to the diameter of the endoscope.

Patient summary

This study showed that Ho:YAG laser lithotripsy with semirigid ureteroscopes is commonly used for treating ureteral stones. However, its efficacy and safety need to be improved further, and future research should focus on these.

Is flexible and navigable suction ureteral access sheath (FANS-UAS) the next best development for retrograde intrarenal surgery in children? Results of a prospective multicentre study

PURPOSE

To assess retrograde intrarenal surgery (RIRS) outcomes in children using ClearPetra, a flexible and navigable suction ureteral access sheath (FANS-UAS).

METHODS

Children with kidney stone(s) only undergoing RIRS in 8 centers were prospectively included (September 2023-May 2024).

EXCLUSION CRITERIA

ureteral stone, bilateral procedures, anomalous kidneys, surgery for residual fragments. Lithotripsy was performed using either a Holmium or Thulium fiber laser. Postoperative pain was assessed within 24 h using a 10-point visual analogue score. The use of FANS-UAS was graded by surgeons after each case using a 5-point likert scale. Low-dose non-contrast CT scan was performed before and within 30 days of RIRS to assess residual fragments (RFs). Stone-free status was defined as no RF or single RF up to 2 mm.

RESULTS

50 children were included. 66% were male. Mean age was 6.6 (± 3.38) years. 88% stones were < 2 cm. one-third of the patients had a stone volume > 1500mm3. 10-12 Fr FANS-UAS was used in 98% of the procedure. The mean operative time was 46.02 (± 20.72) minutes. 2 patients had Traxer grade1 distal ureter and 2 forniceal injuries on sheath placement. Mean pain score was 2.18 (± 1.34). Mean likert scale was 1.16 (± 0.47) for ease of suction, 1.24 (± 0.52) for manipulation, 1.02 (± 0.32) for visibility. 4 patients had post-operative fever lasting less than 24 h. No sepsis occurred. Stone-free rate was 100%.

CONCLUSIONS

Our study shows that the use of FANS-UAS in paediatric RIRS is feasible and safe with a low rate of complications and excellent stone-free rate.

A novel infrared spectroscopy marker for assessing the postoperative infection risk in patients with upper urinary tract calculus

The aim of this study is to evaluate the ability of infrared wavenumber of calculus to predict postoperative infection in patients with upper urinary tract calculus (UUTC), and to establish a predictive model based on this. From March 2018 to March 2023, 480 UUTC patients from Fujian Provincial Hospital were included in this study. The infrared-wavenumbers related infection score (IR-infection score) was constructed by univariate analysis, multicollinearity screening, and Lasso analysis to predict postoperative infection. Continually, the Delong test was used to compare the predictive power between the IR-infection score and traditional indicators. Afterward, we performed urine metagene sequencing and stone culture to prove the correlation between calculus toxicity and IR-infection score. Finally, logistic regression was used to build a nomogram. IR-infection score composed of four independent wavenumbers could precisely predict postoperative infection (AUCvalidation cohort = 0.707) and sepsis (AUCvalidation cohort = 0.824). IR-infection score had better predictive ability than commonly used clinical indicators. Moreover, metagenomics sequencing and calculus culture confirmed the correlation between IR-infection score and calculus toxicity (all P < 0.05). The nomogram based on the IR-infection score had high predictive power (all AUCs > 0.803). Our study first developed a novel infrared spectroscopy marker and nomogram, which can help urologists better predict postoperative infection in UUTC patients.

Optimizing the outcome of non-pre-stented flexible ureteroscopic lithotripsy regarding the quality of life, when to remove the stent?

OBJECTIVES

To investigate the safety of short-term stenting following flexible ureteroscopic lithotripsy (fURL) for patients without preoperative stents. Retaining double-J stent for 1-2 weeks after fURL is a common practice. At present, data on short-term stenting after non-pre-stented fURL is still lacking.

METHODS

182 patients who met inclusion criteria were retrospectively divided into the 2-days group (2-day removal, 76 cases) and the 1-week group (1-week removal, 106 cases). The study endpoint was stent-associated adverse symptoms assessed by follow-up and completed validated questionnaires on postoperative days (POD) 7 and 12. A postoperative imaging review was performed 1 month after the surgery.

RESULTS

No statistical differences were found in the patients' demographic and stone-related characteristics. The 2-days group showed fewer urinary tract symptoms and lower scores on the ureteral stent symptom questionnaire on POD 7: less backache during urination (p = 0.004), less hematuria (p = 0.031), less frequent urination (p = 0.004), lower urinary symptoms index (p < 0.001), lower general health index (p < 0.001), and lower performance index (p < 0.001). There were no significant differences in fever (p = 0.372), visual analogue scale score (p = 0.760), and painkiller requirements (p = 0.160) on POD 7. The average general health score and work performance score remained significantly higher in the 1-week group patients at 5 days after removal compared to the 2-days group patients at 5 days after removal. (p < 0.001, p = 0.005). Five patients in the 2-days group and 15 patients in the 1-week group returned to the emergency department for additional treatments. No patient required rehospitalization. Stone-free rates were 85.5% in the 2-days group and 80.2% in the 1-week group (p = 0.499), respectively, and none of the patients got aggravating hydronephrosis.

CONCLUSIONS

Compared to the common 1-week stent removal option, short-term stenting after non-pre-stented fURL is safe, which can enhance the patient's quality of life.

Impact of previously failed extracorporeal shock wave lithotripsy on ureterorenoscopy outcomes in upper urinary tract stones: a prospective comparative study

OBJECTIVE

We sought to prospectively evaluate the impact of previously failed SWL on subsequent URS outcomes in the treatment of upper urinary tract stones.

MATERIALS AND METHODS

Between May 2021 and May 2023, one hundred thirty-six patients with proximal ureteral stones < 1.5 cm and renal stones < 2.5 cm who were candidates for URS were prospectively assigned to a non-SWL group, which included patients without a history of failed SWL before URS, and a post-SWL group, which included patients with a history of failed SWL before URS. The success rate was the primary outcome. The perioperative data of the two groups were compared.

RESULTS

The stone-free rate was 83.3% in the post-SWL group versus 81.3% in the non-SWL group, and 8.3% in the post-SWL group versus 9.4% in the non-SWL group had clinically insignificant residual fragments. There was no significant difference in the stone-free rate or success rate between the groups. No significant differences in intraoperative fluoroscopy time, operative time, intraoperative stone appearance, perioperative complications, or the presence of embedded fragments in the ureteral mucosa were detected between the two groups.

CONCLUSION

Compared with patients who underwent primary URS, patients who underwent salvage URS for upper urinary tract stones had similar stone-free rates, success rates, operative times, fluoroscopy times, and complication rates without any significant differences.

Simultaneous determination of plasma protein binding of five C-glycosylflavones from TFDS by rapid equilibrium dialysis

The total flavonoids of Desmodium styracifolium (TFDS) are flavonoid-rich extracts obtained from Desmodii Styracifolii Herba, which is approved for the treatment of urolithiasis in China. C-glycosylflavones including schaftoside, vicenin-1, vicenin-2, vicenin-3, and isovitexin are the main active constituents. In this study, the plasma protein binding of these compounds was determined for the first time in rat and human plasma by rapid equilibrium dialysis combined with HPLC-MS/MS method. The developed method was validated in terms of specificity, linearity, accuracy, precision, extraction effect, matrix effect, and stability. Schaftoside, vicenin-1, vicenin-2, and vicenin-3 exhibited moderate plasma protein binding, ranging from 56.6% to 61.5% in rat plasma and 55.0%-62.9% in human plasma. In comparison, isovitexin demonstrated a higher plasma protein binding in the range of 92.3-93.1% and 95.1-96.2% in rat and human plasma, respectively. Furthermore, the potential interactions mediated via plasma protein binding between isovitexin and nonsteroidal anti-inflammatory drugs (NSAIDs) were investigated by rapid equilibrium dialysis. No significant changes were observed, indicating a lower likelihood of interaction between TFDS and NSAIDs due to plasma protein binding in the treatment of urinary system disorders.

The anti-urolithiasis activity and safety of strangury-relieving herbs: A comparative study based on fruit fly kidney stone model

ETHNOPHARMACOLOGICAL RELEVANCE

Urolithiasis is one of the oldest and most widespread urological diseases suffered globally. In the long history of Traditional Chinese Medicine, there're numerous herbs documented with strangury-relieving properties playing crucial roles in treating various urological disorders, including dysuria, hematuria, and renal colic, etc., which may be caused by urolithiasis. Exploring these herbs may reveal safer, more effective, and cost-efficient drugs and therapies for urolithiasis.

AIM OF THE STUDY

This study aims to assess the anti-urolithiasis efficacy and safety of 46 Chinese traditional and folk herbal drugs using the fruit fly (Drosophila melanogaster) kidney stone model, in order to identify the most valuable ethnomedicinal materials.

MATERIALS AND METHODS

Water extract and 50% ethanol extract of each herb were prepared respectively. 0.2% (w/w) sodium oxalate was chosen as appropriate lithogenic agent through fruit fly life span study. Male fruit-flies within three days of emergence were aged for an additional three days, then were randomly divided into experimental groups, model group and control groups (n = 20). The flies in blank control group, model group and positive control group were fed with standard food, standard food containing 0.2% sodium oxalate, standard food containing 0.2% sodium oxalate and 3% (w/w) Garcinia cambogia extract, respectively. Meanwhile, flies in the experimental groups were raised on standard food containing 0.2% sodium oxalate and 3% (w/w) herbal extract. The anti-urolithiasis capability of the extracts was evaluated using stone area ratio (the stone area divided by the area of the Malpighian tubule) and stone-clearing rate. Additionally, the 7-day mortality rate was employed as an indicator of safety.

RESULTS

Out of the 46 herbs, 24 exhibited significant anti-urolithiasis effects in their water extracts. Among them, Herba Nephrolepidis, Herba Humuli, Herba Desmodii Styracifolii, Cortex Plumeriae Rubrae, and Herba Mimosae Pudicae showed us a low 7-day mortality rate of fruit-flies as well. However, only a limited number of herbal extracts (8 out of 46) showed obvious anti-urolithiasis activity in their 50% ethanol extracts.

CONCLUSION

Highly potential anti-urolithiasis candidates were discovered from strangury-relieving herbs recorded in classical Traditional Chinese Medicine works, highlighting the significant value of traditional and folk ethnopharmacological knowledge.

Scoping Review of Experimental and Clinical Evidence and Its Influence on Development of the Suction Ureteral Access Sheath

The ureteral access sheath (UAS) has been a boon and a bane in flexible ureteroscopy (FURS), with its merits and demerits well established. Its design and dimensions were instrumental in reshaping the way flexible scopes were used and were key adjuncts to establishing retrograde intrarenal surgery (RIRS) as a standard of care in the endourological management of renal stones. With the ever-changing landscape of RIRS over the decades shaped by technological advancements in lasers and flexible scopes, the UAS has also continuously evolved. The utility of suction in endourology has recently changed the way RIRS is performed and is a game changer for FURS outcomes. With strong clinical and experimental evidence to support its use, the UAS has undergone a transformative change in the recent past, with its ability to monitor intrarenal pressure and provide a superior vacuum-cleaner effect that improves the trifecta of RIRS, namely an improved single-stage stone-free rate (SFR), minimise complications, and reduce reinterventions. Our comprehensive review outlines the key clinical and experimental evidence and traces the developments that were key to modifying the traditional UAS into a flexible and navigable suction ureteric access sheath (FANS) and highlights how the design and modifications, in turn, influence the ability to push the boundaries of RIRS.

Ureteral wall thickness as a predictor for non-invasive treatment success for steinstrasse. Can we save time?

PURPOSE

We aimed to define factors affecting the non-invasive overall treatment success (medical expulsive therapy (MET) ± shock wave lithotripsy (SWL)) for uncomplicated ureteral steinstrasse (SS) clearance.

METHODS

We retrospectively evaluated consecutive patients who underwent SWL for renal stones between 2017 and 2021. Patients with uncomplicated SS were included. All patient's demographic and radiological data, e.g., age, gender, pre-SWL stenting, SS site, type, leading stone size in widest diameter (< 10 mm and ≥ 10 mm), ureteral wall thickness (UWT) in mm against the leading stone were collected. If SS was diagnosed, medical treatment was given for 4 weeks. In case of MET failure, either SWL for the leading stones + MET or direct URS was done. Non-invasive treatment success (SFR) was considered if complete clearance of SS occurred with no complications or the need for invasive intervention.

RESULTS

A total of 145 patients were included with mean age of 45.9 ± 12.4 years. SFR in case of MET only occurred in 27.9%. Complications happened in 26 patients (17.9%). Non-invasive treatment SFR was achieved in 78 patients (53.8%) totally where SS type I, leading stone size ≤ 10 mm type and decreased UWT around the leading stone increased treatment success.

CONCLUSION

Ureteral wall thickness is an important factor predicting SS management success. Besides the decreased UWT, non-invasive management should be offered for type I SS with leading stone ≤ 10 mm.

Predicting stone composition via machine-learning models trained on intra-operative endoscopic digital images

OBJECTIVES

The aim of this study was to use deep learning (DL) of intraoperative images of urinary stones to predict the composition of urinary stones. In this way, the laser frequency and intensity can be adjusted in real time to reduce operation time and surgical trauma.

MATERIALS AND METHODS

A total of 490 patients who underwent holmium laser surgery during the two-year period from March 2021 to March 2023 and had stone analysis results were collected by the stone laboratory. A total of 1658 intraoperative stone images were obtained. The eight stone categories with the highest number of stones were selected by sorting. Single component stones include calcium oxalate monohydrate (W1), calcium oxalate dihydrate (W2), magnesium ammonium phosphate hexahydrate, apatite carbonate (CH) and anhydrous uric acid (U). Mixed stones include W2 + U, W1 + W2 and W1 + CH. All stones have intraoperative videos. More than 20 intraoperative high-resolution images of the stones, including the surface and core of the stones, were available for each patient via FFmpeg command screenshots. The deep convolutional neural network (CNN) ResNet-101 (ResNet, Microsoft) was applied to each image as a multiclass classification model.

RESULTS

The composition prediction rates for each component were as follows: calcium oxalate monohydrate 99% (n = 142), calcium oxalate dihydrate 100% (n = 29), apatite carbonate 100% (n = 131), anhydrous uric acid 98% (n = 57), W1 + W2 100% (n = 82), W1 + CH 100% ( n = 20) and W2 + U 100% (n = 24). The overall weighted recall of the cellular neural network component analysis for the entire cohort was 99%.

CONCLUSION

This preliminary study suggests that DL is a promising method for identifying urinary stone components from intraoperative endoscopic images. Compared to intraoperative identification of stone components by the human eye, DL can discriminate single and mixed stone components more accurately and quickly. At the same time, based on the training of stone images in vitro, it is closer to the clinical application of stone images in vivo. This technology can be used to identify the composition of stones in real time and to adjust the frequency and energy intensity of the holmium laser in time. The prediction of stone composition can significantly shorten the operation time, improve the efficiency of stone surgery and prevent the risk of postoperative infection.

Tight junction and kidney stone disease

Defects of tight junction (TJ) are involved in many diseases related to epithelial cell functions, including kidney stone disease (KSD), which is a common disease affecting humans for over a thousand years. This review provides brief overviews of KSD and TJ, and summarizes the knowledge on crystal-induced defects of TJ in renal tubular epithelial cells (RTECs) in KSD. Calcium oxalate (CaOx) crystals, particularly COM, disrupt TJ via p38 MAPK and ROS/Akt/p38 MAPK signaling pathways, filamentous actin (F-actin) reorganization and α-tubulin relocalization. Stabilizing p38 MAPK signaling, reactive oxygen species (ROS) production, F-actin and α-tubulin by using SB239063, N-acetyl-L-cysteine (NAC), phalloidin and docetaxel, respectively, successfully prevent the COM-induced TJ disruption and malfunction. Additionally, genetic disorders of renal TJ, including mutations and single nucleotide polymorphisms (SNPs) of CLDN2, CLDN10b, CLDN14, CLDN16 and CLDN19, also affect KSD. Finally, the role of TJ as a potential target for KSD therapeutics and prevention is also discussed.

The value of dual-energy computed tomography (DECT) in the diagnosis of urinary calculi: a systematic review and meta-analysis of retrospective studies

Objective

Dual-energy computed tomography (DECT) imaging technology opens a new idea and method for analyzing stone composition, which can obtain several quantitative parameters reflecting tissue-related information and energy images different from traditional images. However, the application of DECT in diagnosing urinary calculi remains unknown. This study aims to evaluate the value of DECT in diagnosing urinary calculi by meta-analysis.

Methods

PubMed, EMBASE, Web of Science, and the Cochrane Library were searched to articles published from the establishment of the databases to April 18, 2023. We reviewed the articles on the diagnosis of urinary calculi detected by DECT, established standards, screened the articles, and extracted data. Two researchers carried out data extraction and the Cohen's unweighted kappa was estimated for inter-investigator reliability. The quality of the literature was evaluated by the diagnostic test accuracy quality evaluation tool (QUADAS-2). The heterogeneity and threshold effects were analyzed by Meta-Disc 1.4 software, and the combined sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic ratio were calculated. The combined receiver-operating characteristic (ROC) curve was drawn, and the value of DECT in the diagnosis of urinary calculi was evaluated by the area under the curve (AUC). The meta-analysis was registered at PROSPERO (CRD42023418204).

Results

One thousand and twenty-seven stones were detected in 1,223 samples from 10 diagnostic tests. The analyzed kappa alternated between 0.78-0.85 for the document's retrieval and detection procedure. The sensitivity of DECT in the diagnosis of urinary calculi was 0.94 (95% CI [0.92-0.96]). The positive likelihood ratio (PLR) of DECT in the diagnosis of urinary stones was 0.91 (95% CI [0.88-0.94]), and the negative likelihood ratio (NLR) was 0.08 (95% CI [0.05-0.11]). The specificity of DECT for detecting urinary calculi was 0.91 (95% CI [0.88-0.94]). The area under the curve of the summary receiver operator characteristic (SROC) was 0.9875. The sensitivity of dual-energy CT in the diagnosis of urinary calculi diameter <3 mm was 0.94 (95% CI [0.91-0.96]). The PLR of DECT in the diagnosis of urinary stones diameter <3 mm was 10.79 (95% CI [5.25 to 22.17]), and the NLR was 0.08 (95% CI [0.05-0.13]). The specificity of DECT for detecting urinary calculi <3 mm was 0.91 (95% CI [0.87-0.94]). The SROC was 0.9772.

Conclusion

The DECT has noble application value in detecting urinary calculi.

Design and internal validation of S.I.C.K.: a novel nomogram predicting infectious and hemorrhagic events after percutaneous nephrolithotomy

BACKGROUND

Hemorrhagic and infectious events represent severe complications after percutaneous nephrolithotomy (PCNLs). Existing nephrolithometric nomograms have been introduced but their reliability in predicting complications is debated. We present a newly designed nomogram with intention to predict hemorrhagic/infectious events after PCNLs.

METHODS

We conducted a multicentric prospective study on adult patients undergoing standard (24 Fr) or mini (18 Fr) PCNL. Dataset was derived from previous RCT, where patients have been assigned to mini-PCNL or standard-PCNL to treat renal stones up to 40 mm. Aim of the study was to identify preoperative risk factors for early postoperative infectious/hemorrhagic complications including fever, septic shock, transfusion or angioembolization.

RESULTS

A total of 1980 patients were finally included. 992 patients (50.1%) received mini-PCNL and 848 standard PCNL (49.9%). The overall SFR was 86.1% with a mean maximum stone diameter of 29 mm (SD 25.0-35.0). 178 patients (8.9%) had fever,14 (0.7%) urosepsis, 24 patients (1.2%) required transfusion and 18 (0.9%) angioembolization. The overall complication was (11.7%). After multivariable analysis, the included elements in the nomogram were age (P=0.041), BMI (P=0.018), maximum stone diameter (P<0.001), preoperative hemoglobin (P=0.005), type 1/2 diabetes (P=0.05), eGFR<30 (P=0.0032), hypertension (>135/85 mmHg, P=0.001), previous PCNL or pyelo/nephrolithotomy (P=0.0018), severe hydronephrosis (P=0.002). After internal validation, the AUC of the model was 0.73.

CONCLUSIONS

This is the first nomogram predicting infections and bleedings after PCNLs, it shows a good accuracy and can support clinicians in their patients' peri-operative workout and management.

Development and external validation of a machine learning-based model to classify uric acid stones in patients with kidney stones of Hounsfield units < 800

The correct diagnosis of uric acid (UA) stones has important clinical implications since patients with a high risk of perioperative morbidity may be spared surgical intervention and be offered alkalization therapy. We developed and validated a machine learning (ML)-based model to identify stones on computed tomography (CT) images and simultaneously classify UA stones from non-UA stones. An international, multicenter study was performed on 202 patients who received percutaneous nephrolithotomy for kidney stones with HU < 800. Data from 156 (77.2%) patients were used for model development, while data from 46 (22.8%) patients from a multinational institution were used for external validation. A total of 21,074 kidney and stone contour-annotated CT images were trained with the ResNet-18 Mask R-convolutional neural network algorithm. Finally, this model was concatenated with demographic and clinical data as a fully connected layer for stone classification. Our model was 100% sensitive in detecting kidney stones in each patient, and the delineation of kidney and stone contours was precise within clinically acceptable ranges. The development model provided an accuracy of 99.9%, with 100.0% sensitivity and 98.9% specificity, in distinguishing UA from non-UA stones. On external validation, the model performed with an accuracy of 97.1%, with 89.4% sensitivity and 98.6% specificity. SHAP plots revealed stone density, diabetes mellitus, and urinary pH as the most important features for classification. Our ML-based model accurately identified and delineated kidney stones and classified UA stones from non-UA stones with the highest predictive accuracy reported to date. Our model can be reliably used to select candidates for an earlier-directed alkalization therapy.

Influence of pre-stenting on RIRS outcomes. Inferences from patients of the Global Multicentre Flexible Ureteroscopy Outcome Registry (FLEXOR)

BACKGROUND

Retrograde Intrarenal Surgery (RIRS) is recommended as an alternative to percutaneous nephrolithotomy for stones up to 2 cm. Pre-stenting before RIRS remains controversial with various studies differing in outcomes and recommendations. We aim to understand how pre-stenting influences surgical outcomes.

METHODS

A number of 6579 patients from the TOWER group registry were divided into pre-stented (group 1) and non-pre-stented groups (group 2). Patients aged ≥18 years old, with normal calyceal anatomy were enrolled. Patients with ureteric stones, anomalous kidneys, bilateral stones, planned for ECIRS were excluded.

RESULTS

Patients are homogeneously distributed in both groups (3112 vs. 3467). The predominant indication for pre-stenting was symptom relief. Overall stone size was comparable, whilst group 1 had a significantly more multiple (1419 vs. 1283, P<0.001) and lower-pole (LP) stones (1503 vs. 1411, P<0.001). The mean operative time for group 2 was significantly longer (68.17 vs. 58.92, P<0.001). Stone size, LP stones, age, recurrence and multiple stones are contributing factors for residual fragments at the multivariable analysis. The incidence of postoperative day 1 fever and sepsis was significantly higher in group 2, indicating that pre-stenting is associated with a lower risk of post-RIRS infection and a lower overall complications rate (13.62% vs. 15.89%) (P<0.001).

CONCLUSIONS

RIRS without pre-stenting can be considered safe without significant morbidity. Multiple, lower-pole and large stone is a significant contributor towards residual fragments. Patients who were not pre-stented had significantly higher but low-grade complications, especially for lower pole and large volume stones. While we do not advocate routine pre-stenting, a tailored approach for these patients should include proper counselling regarding pre-stenting.

Effects of lithotomy and prone positions on hemodynamic parameters, respiratory mechanics, and arterial oxygenation in percutaneous nephrolithotomy performed under general anesthesia

AIM

The position of the body during surgery may affect the patient's body functions, especially the hemodynamic parameters. We aimed to comparatively analyze the effects of lithotomy and prone position on respiratory mechanics, arterial oxygenation, and hemodynamic parameters in patients who underwent percutaneous nephrolithotomy (PNL).

Prospective Comparison of Thulium and Holmium Laser Lithotripsy for the Treatment of Upper Urinary Tract Lithiasis

Background

Lithotripsy with holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the current gold standard for treating stones of the upper urinary tract (UUT). The recently introduced thulium fiber laser (TFL) has the potential to be more efficient and as safe as Ho:YAG.

Objective

To compare the performance and complications between Ho:YAG and TFL for UUT lithotripsy.

Design setting and participants

This was a prospective single-center study of 182 patients treated between February 2021 and February 2022. In a consecutive approach, laser lithotripsy was performed via ureteroscopy with Ho:YAG for 5 mo, and then with TFL for 5 mo.

Outcome measurements and statistical analysis

Our primary outcome was stone-free (SF) status at 3 mo after ureteroscopy with Ho:YAG versus TFL lithotripsy. Secondary outcomes were complication rates and results regarding the cumulative stone size. Patients were followed at 3 mo with abdominal imaging (ultrasound or computed tomography).

Results and limitations

The study cohort comprised 76 patients treated with Ho:YAG laser and 100 patients treated with TFL. Cumulative stone size was significantly higher in the TFL than in the Ho:YAG group (20.4 vs 14.8 mm; p = 0.01). SF status was similar in both groups (68.4% vs 72%; p = 0.06). Complication rates were comparable. In subgroup analysis, the SF rate was significantly higher (81.6% vs 62.5%; p = 0.04) and the operative time was shorter for stones measuring 1-2 cm, whereas the results were similar for stones <1 cm and >2 cm. The lack of randomization and single-center design are the main limitations of the study.

Conclusions

TFL and Ho:YAG lithotripsy are comparable in terms of the SF rate and safety for the treatment of UUT lithiasis. According to our study, for a cumulative stone size of 1-2 cm, TFL is more effective than Ho:YAG.

Patient summary

We compared the efficiency and safety of two laser types for the treatment of stones in the upper urinary tract. We found that stone-free status at 3 months did not significantly differ between the holmium and thulium lasers.

Stone attenuation on computer tomography helps surgeons make decisions between miniaturized percutaneous nephrolithotomy or retrograde intrarenal surgery for lower pole stones: a retrospective study

A retrospective study was performed on 200 patients who underwent miniaturized percutaneous nephrolithotomy (mini-PCNL) or retrograde intrarenal surgery (RIRS) for 10-20 mm sized lower pole renal calculi to investigate the relationship between computed tomography (CT) attenuation of calculi and surgical outcomes. CT was used to examine the location, size, and CT attenuation values of the calculi. Additionally, the operation time, hospital stay, hemoglobin (Hb) reduction, stone-free rate (SFR), and complication rate were also meticulously documented and subjected to comparative analysis. Complications were assessed using the Clavien-Dindo grading system. We observed no significant differences in hospitalization data and follow-up outcomes, except for a longer hospital stay and higher Hb drops in patients receiving mini-PCNL. Statistical analysis revealed an association between CT attenuation and operation time. Compared with mini-PCNL, RIRS could reduce bleeding, hospital stay, surgery time, and complications for 10-20 mm sized lower pole kidney stones with CT values < 1000 HU. RIRS resulted in longer operation time and lower stone-free rates despite shorter hospital stays and less bleeding than mini-PCNL for stones with CT values > 1000 HU. Therefore, selecting an appropriate surgical method based on CT attenuation might improve outcomes. For patients with stone attenuation values < 1000 HU, RIRS is the recommended option. When stone attenuation values > 1000 HU, the surgical method should be chosen based on the patient's individual situation.

Metabolic stone workup abnormalities are not as important as stone culture in patients with recurrent stones undergoing percutaneous nephrolithotomy

To investigate the association between metabolic urinary abnormalities and urinary tract infection (UTI) and the stone recurrence status in patients undergoing percutaneous nephrolithotomy (PCNL). A prospective evaluation was performed for patients who underwent PCNL between November 2019 and November 2021 and met the inclusion criteria. Patients with previous stone interventions were classified as recurrent stone formers. Before PCNL, a 24 h metabolic stone workup and midstream urine culture (MSU-C) were done. Renal pelvis (RP-C) and stones (S-C) cultures were collected during the procedure. The association between the metabolic workup and UTI results with stone recurrence was evaluated using univariate and multivariate analyses. The study included 210 patients. UTI factors that showed significant association with stone recurrence included positive S-C [51 (60.7%) vs 23 (18.2%), p < 0.001], positive MSU-C [37 (44.1%) vs 30 (23.8%), p = 0.002], and positive RP-C [17 (20.2%) vs 12 (9.5%), p = 0.03]. Other factors were mean ± SD GFR (ml/min) (65 ± 13.1 vs 59.5 ± 13.1, p = 0.003), calcium-containing stones [47 (55.9%) vs 48 (38.1%), p = 0.01], median (IQR) urinary citrate levels (mg/day) [333 (123-512.5) vs 221.5 (120.3-412), p = 0.04], and mean ± SD urinary pH (6.1 ± 1 vs 5.6 ± 0.7, p < 0.001). On multivariate analysis, only positive S-C was the significant predictor of stone recurrence (odds ratio: 9.9, 95% confidence interval [CI] (3.8-28.6), p < 0.001). Positive S-C, and not metabolic abnormalities, was the only independent factor associated with stone recurrence. A focus on preventing UTI might prevent further stone recurrence.

Fifty years of basic and clinical renal stone research: have we achieved major breakthroughs? A debate

PURPOSE OF REVIEW

After 50 years of basic and clinical renal stone research, it is appropriate to evaluate whether breakthroughs have been achieved and if so, how they may be harnessed to combat stone disease therapeutically and prophylactically.

RECENT FINDINGS

Regarding stone therapeutics and prophylaxis, recent innovative studies are sparse. Researchers have resorted to publishing articles derived from data mining. Stone incidence and prevalence have increased during the past 50 years, suggesting the absence of any major breakthroughs. However, new sciences and technologies have created fresh opportunities. Information technology stores huge epidemiological databases leading to identification of new risk factors. Genetic coding has prompted identification of monogenic diseases associated with urolithiasis. Genome-wide association studies in combination with epigenomics, transcriptomics, proteomics, and metabolomics are providing new insights. High-throughput and culture-independent techniques promise to define the impact of microbiome on stone formation while artificial intelligent techniques contribute to diagnosis and prediction of treatment outcomes. These technologies, as well as those which are advancing surgical treatment of stones represent major breakthroughs in stone research.

SUMMARY

Although efforts to cure stones have not yielded major breakthroughs, technological advances have improved surgical management of this disease and represent significant headway in applied stone research.

The study of double-J stent free mode of flexible ureteroscopy and laser lithotripsy: a single centre experience

OBJECTIVE

To evaluate the effectiveness and safety of flexible ureteroscopy in the treatment of kidney and upper ureteral calculi under double-J stent free mode.

METHODS

Data from patients who underwent flexible ureteroscopy and laser lithotripsy between February 2018 and September 2021 were retrospectively and analysed. Cases were grouped according to pre- or postoperative use of the double-J stent (6 Fr): Post-F group (preoperative double-J stent but no postoperative double-J stent); Pre-F group (no preoperative stenting but with postoperative double-J stent); and Routine group (preoperative and postoperative double-J stenting).

RESULTS

A total of 554 patients (390 male and 164 female) were included. The mean operation time was similar between the three groups, with no statistically significant difference. Incidence of grade 0-1 ureteral injury was significantly higher in the Pre-F group versus other groups, but there were no significant between-group differences in other operation-related complications. During follow-up, stent-associated complications were observed in the Pre-F and Routine groups, but not in the Post-F group. Stone clearance rates were similar between all groups at 1, 3 and 6 months following surgery.

CONCLUSIONS

Flexible ureteroscopy using double-J stent free mode was found to be safe, feasible and effective in treating renal and upper ureteral calculi.

Current evidence for suction in endourological procedures: comprehensive review of literature

PURPOSE OF REVIEW

To identify the latest advances on the utilization of suctioning devices in the surgical treatment of urinary stones.

RECENT FINDINGS

Advances are being made to incorporate suction and pressure control capabilities in percutaneous and ureteroscopic lithotripsy. Multiple retrospective studies and few prospective studies have shown that suctioning with minimally invasive percutaneous nephrolithotomy, commonly referred to as Super MiniPerc, can lead to better stone-free rates (SFR) and shorter operative time with lower incidence of infectious complications. Suctioning during retrograde intrarenal surgery (RIRS) has mainly been achieved through suctioning ureteral access sheath. Here as well, the incorporation of suction improved the SFR, but most importantly, reduced the risk of postoperative infectious complications.

SUMMARY

Theoretically suction in endourological procedures could facilitate stone debris removal and could reduce intrarenal pressure at the same time allowing for increased irrigation flow potentially decreasing operation time and infectious complications. These claims are supported in contemporary clinical studies, reporting superior SFR and reduced postoperative infectious complications in both percutaneous nephrolithotomy and RIRS.

The regular use of calcium channel blockers before flexible URS appears to facilitate primary UAS insertion: a retrospective study in a single center

PURPOSE

To evaluate the effect of regular use of CCB before flexible URS for successful primary UAS insertion.

MATERIALS AND METHODS

We retrospectively analyzed 209 patients who underwent flexible ureteroscopy (URS) for upper urinary tract calculi between Jan 2021 and Dec 2021. Patients were divided into two groups based on whether calcium channel blockers (CCB) were used (n = 72) or not (n = 137). The following parameters were collected: age, sex, height and weight, BMI, stone location, stone burden, number of stones, operation time, hospital stay, hospital readmission, post-operative fever, post-operative SIRS rate, Clavien-Dindo grade, hospitalization costs, successful primary UAS insertion. We compared the two groups using Student's t test, Mann-Whitney U test and χ² test for quantitative and categorical variables, respectively. A logistic regression model was used to identify predictive factors of UAS successful primary insertion.

RESULTS

Compared with the non-CCB group, the CCB group had a higher successful primary UAS insertion rate (97.2% vs.85.4%, p = 0.008), and a lower hospital readmission rate (2.8% vs.12.4%, p = 0.021). In multivariate analyses, the regular use of CCB was the only predictive factor of successful primary UAS insertion rate (OR 6.32, 95% CI 1.41-28.29, p = 0.016).

CONCLUSION

The regular use of calcium channel blockers (CCB) before flexible URS appears to facilitate ureteral access sheaths (UAS) primary insertion.

Impact of malnutrition as defined by the GLIM criteria on treatment outcomes in patients with cancer: A systematic review and meta-analysis

BACKGROUND & AIMS

Malnutrition has been reported to lead to poor postoperative outcomes. The Global Leadership Initiative on Malnutrition (GLIM) criteria were published in 2019 as a global consensus on the criteria for diagnosing malnutrition. However, the relationship between GLIM-defined malnutrition and treatment outcomes in patients with cancer has not been fully investigated. Therefore, this study aimed to clarify the impact of GLIM-defined malnutrition on the treatment outcomes of patients with cancer.

METHODS

We searched MEDLINE, the Cochrane Central Register of Controlled Trials, EMBASE, the World Health Organization International Clinical Trials Platform Search Portal, and ClinicalTrials.gov and identified observational studies published from inception to January 17, 2022. We conducted a systematic review and random-effects meta-analysis studies that included patients with cancer aged >18 years who received any kind of treatment and whose nutritional status was assessed using GLIM criteria. We independently assessed the risk of bias and quality of evidence using Quality In Prognosis Studies and Grading of Recommendations, Assessment, Development, and Evaluation approach. The primary outcomes were overall survival (OS) and postoperative complications. Hazard ratios and 95% confidence intervals (CIs) for OS and relative risk ratios and 95% CIs for postoperative complications were pooled. The protocol was published by PROSPERO (CRD42022304004).

RESULTS

Of 67 studies after screening, ten studies (n = 11,700) reported the impact of GLIM-defined malnutrition on postoperative outcomes. Compared with no malnutrition, GLIM-defined malnutrition may worsen OS (hazard ratio, 1.56; 95% CI, 1.38-1.75; I² = 37%) and increase postoperative complications (relative risk ratio, 1.82; 95% CI, 1.28-2.60; I² = 87%). The risk of bias in each study was either moderate or high. The certainty of the evidence was low because of publication bias and a moderate or high risk of bias.

CONCLUSIONS

GLIM-defined malnutrition may worsen OS and increase the risk of postoperative complications in patients with cancer undergoing treatment. Further studies are needed to confirm these findings and mitigate this risk.

Stone-scoring systems for predicting complications in percutaneous nephrolithotomy: A systematic review of the literature

Objective

Percutaneous nephrolithotomy is a treatment of choice for larger stones of the upper urinary tract. Currently, several nephrolithometric nomograms for prediction of post-operative surgical outcomes have been proposed, although uncertainties still exist regarding their roles in the estimation of complications.

Methods

We conducted a systematic review on PubMed and Web of Sciences databases including English studies with at least 100 cases and published between January 2010 and December 2021. We identified original articles evaluating correlations between the Guy's stone score, the stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence or stone density (E) (S.T.O.N.E.), Clinical Research Office of the Endourological Society (CROES), and Seoul National University Renal Stone Complexity (S-ReSC) scores and post-operative complications in adult patients. We also included newly designed nomograms for prediction of specific complications.

Results

After an initial search of 549 abstracts, we finally included a total of 18 papers. Of them, 11 investigated traditional nephrolithometric nomograms, while seven newly designed nomograms were used to predict specific complications. Overall, 7316 patients have been involved. In total, 14 out of 18 papers are derived from retrospective single-center studies. Guy's stone score obtained correlation with complications in five, S.T.O.N.E. nephrolithometry score in four, while CROES score and S-ReSC score in three and two, respectively. None of the studies investigated minimally invasive percutaneous nephrolithotomy (PCNL) and all cases have been conducted in prone position. Considering newly designed nomograms, none of them is currently externally validated; five of them predict post-operative infections; the remaining two have been designed for thromboembolic events and urinary leakage.

Conclusion

This review presents all nomograms currently available in the PCNL field and highlights a certain number of concerns. Published data have appeared contradictory; more recent tools for prediction of post-operative complications are frequently based on small retrospective cohorts and lack external validations. Heterogeneity among studies has also been noticed. More rigorous validations are advisable in the future, involving larger prospective patients' series and with the comparison of different tools.

Virtual reality for pain control during shock wave lithotripsy: a randomized controlled study

PURPOSE

Although external shock wave lithotripsy (SWL) is an outpatient procedure generally not requiring anesthesia or sedation, patients may experience pain during the procedure. The aim of this study is to evaluate whether a virtual reality device is effective in reducing patient-reported pain during the procedure, consequently leading to exposure to higher energy levels and better clinical outcomes.

METHODS

Inclusion criteria for SWL were according to the latest EAU guidelines on urolithiasis. Patients were randomized 1:1 in two groups (SWL with VR and SWL without VR). The primary outcome of this randomized, controlled study (RCT) was an overall difference in pain levels determined by VAS-scores. Secondary outcomes were differences in comfort levels, determined by Likert-scale scores, clinical success and total delivered energy.

RESULTS

Between January 2019 and September 2021, we enrolled 166 patients; 84 were randomized to the control arm and 82 to the VR arm. Patients without VR experienced significantly more pain compared to the VR group (mean VAS-score = 4.94 vs 4.01; p = 0.011). The mean total delivered energy was significantly higher in the VR group compared to the control group (55.2 J vs. 48.8 J; p = 0'037). No significant differences in comfort levels and clinical success were found.

CONCLUSION

This study supports the use of VR as a method of pain relief during shock wave lithotripsy. Higher energy levels can be achieved during the treatment while comfort levels remained equal; this however did not lead to improved clinical success.

REGISTRATION NUMBER AND NAME OF TRIAL REGISTRY

Clinicaltrials.gov: NCT05183269. Virtual reality for pain control during extracorporeal shock wave lithotripsy: prospective, comparative, randomized study at a single institution. https://clinicaltrials.gov/ct2/show/NCT05183269?term=shock+wave+lithotripsy&cond=virtual+reality&cntry=BE&draw=2&rank=1 .

RIRS with disposable or reusable scopes: does it make a difference? Results from the multicenter FLEXOR study

Introduction

With several single-use ureteroscopes now available, our aim was to analyze and compare data obtained globally from high-volume centers using both disposable and reusable flexible ureteroscopes and see if indeed in real-world practice either scope has a distinct advantage.

Methods

Retrospective analysis was performed on the FLEXOR registry, which was created as a TOWER group (Team of Worldwide Endourological Researchers, research wing of the Endourological Society) endeavor. Patients who underwent retrograde intrarenal surgery (RIRS) for renal stones from January 2018 to August 2021 were enrolled from 20 centers globally. A total of 6663 patients whose data were available for analysis were divided into Group 1 (Reusable scopes, 4808 patients) versus Group 2 (Disposable scopes, 1855 patients).

Results

The age and gender distribution were similar in both groups. The mean stone size was 11.8 mm and 9.6 mm in Groups 2 and 1, respectively (p < 0.001). Group 2 had more patients with >2 cm stones, lower pole stones and of higher Hounsfield unit. Thulium fiber laser (TFL) was used more in Group 2 (p < 0.001). Patients in Group 2 had a slightly higher stone-free rate (SFR) (78.22%) and a lower number of residual fragments (RFs) compared with Group 1 (p < 0.001). The need for further treatments for RF and overall complications was comparable between groups. On multivariate analysis, overall complications were more likely to occur in elderly patients, larger stone size, lower pole stones, and were also more when using disposable scopes with longer operative time. RFs were significantly higher (p < 0.001) for lower pole, larger, harder, multiple stones and in elderly.

Conclusion

Our real-world practice observations suggest that urologists choose disposable scopes for bigger, lower pole, and harder stones, and it does indeed help in improving the single-stage SFR if used correctly, with the appropriate lasers and lasing techniques in expert hands.

Use of whole-exome sequencing to identify novel monogenic gene mutations and genotype-phenotype correlations in Chinese Han children with urolithiasis

The incidence of urolithiasis (UL) in children has been increasing. Although the pathogenesis of pediatric UL is controversial and remains unclear, multiple monogenic causes of UL have been identified. We aim to investigate the prevalence of inherited UL causes and explore the genotype-phenotype correlation in a Chinese pediatric group. In this study, we analyzed the DNA of 82 pediatric UL patients using exome sequencing (ES). The data of metabolic evaluation and genomic sequencing were subsequently analyzed together. We detected 54 genetic mutations in 12 of 30 UL-related genes. A total of 15 detected variants were described as pathogenic mutations, and 12 mutations were considered likely pathogenic. Molecular diagnoses were made in 21 patients with pathogenic or likely pathogenic variants. Six novel mutations that were not previously reported were identified in this cohort. Calcium oxalate stones were detected in 88.9% cases (8/9) with hyperoxaluria-related mutations, while 80% of individuals (4/5) with cystinuria-causing defects were diagnosed with cystine stones. Our study highlights the significant genetic abnormalities in pediatric UL and demonstrates the diagnostic power of ES for screening patients with UL.

Theranostic roles of machine learning in clinical management of kidney stone disease

Kidney stone disease (KSD) is a common illness caused by deposition of solid minerals formed inside the kidney. The disease prevalence varies, based on sociodemographic, lifestyle, dietary, genetic, gender, age, environmental and climatic factors, but has been continuously increasing worldwide. KSD is a highly recurrent disease, and the recurrence rate is about 11% within two years after the stone removal. Recently, machine learning has been widely used for KSD detection, stone type prediction, determination of appropriate treatment modality and prediction of therapeutic outcome. This review provides a brief overview of KSD and discusses how machine learning can be applied to diagnostics, therapeutics and prognostics in clinical management of KSD for better therapeutic outcome.

An in vitro Comparative Assessment of Single-Use Flexible Ureteroscopes Using a Standardized Ureteroscopy Training Model

INTRODUCTION

Perceived benefits like decreased contamination rates and reduced postoperative incidence of complications after urolithiasis surgery have led to increased adoption of single-use flexible ureteroscopes (su-fURS). Using a validated, standardized simulator model with enhanced "fluoroscopic" capabilities, we performed an in vitro comparative assessment of four commercially available models of su-fURS. Both objective and subjective parameters were assessed in this study.

METHODS

Two standardized tasks, (1) exploration of the model's kidney collecting system and (2) repositioning of a stone fragment from the upper renal to lower renal pole were assigned to participants, who performed these tasks on all four scopes. Four models of su-fURS (Boston LithoVue, PUSEN PU3033A, REDPINE, INNOVEX EU-ScopeTM) were assessed, with task timings as end-points for objective analysis. Cumulative "fluoroscopic" time was also recorded as a novel feature of our enhanced model. Post-task questionnaires evaluating specific components of the scopes were distributed to document subjective ratings.

RESULTS

Both subjective and objective performances (except stone repositioning time) across all four su-fURS demonstrated significant differences. However, objective performance (task timings) did not reflect subjective scope ratings by the participants (Rs < 0.6). Upon Kruskal-Wallis H test with post hoc analyses, REDPINE and INNOVEX EU-ScopeTM were the preferred su-fURS as rated by the participants, with overall scope scores of 9.00/10 and 9.57/10.

CONCLUSIONS

Using a standardized in vitro simulation model with enhanced fluoroscopic capabilities, we demonstrated both objective and subjective differences between models of su-fURS. However, variations in perception of scope features (visibility, image quality, deflection, maneuverability, ease of stone retrieval) did not translate into actual technical performance. Eventually, the optimal choice of su-fURS fundamentally lies in individual surgeon preference, as well as cost-related factors.

European Association of Urology Section of Urolithiasis and International Alliance of Urolithiasis Joint Consensus on Retrograde Intrarenal Surgery for the Management of Renal Stones

BACKGROUND

Retrograde intrarenal surgery (RIRS) has become the preferred treatment modality for nephrolithiasis. However, because of ongoing uncertainties regarding the optimal perioperative management, operative technique, and postoperative follow-up, as well as a lack of standardization for outcome reporting, consensus is needed to achieve more uniform clinical practice worldwide.

OBJECTIVE

To develop recommendations for RIRS on the basis of existing data and expert consensus.

DESIGN, SETTING, AND PARTICIPANTS

A protocol-driven, three-phase study was conducted by the European Association of Urology Section of Urolithiasis (EULIS) and the International Alliance of Urolithiasis (IAU). The process included: (1) a nonsystematic review of the literature to define domains for discussion; (2) a two-round modified Delphi survey involving experts in this field; and (3) an additional group meeting and third-round survey involving 64 senior representative members to formulate the final conclusions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The results from each previous round were returned to the participants for re-evaluation of their decisions during the next round. The agreement threshold was set at 70%.

RESULTS AND LIMITATIONS

The panel included 209 participants who developed 29 consensus statements on the following topics of interest: (1) perioperative infection management; (2) perioperative antithrombotic therapy; (3) fundamentals of the operative technique; and (4) standardized outcome reporting. Although this consensus can be considered as a useful reference for more clinically oriented daily practice, we also acknowledge that a higher level of evidence from further clinical trials is needed.

CONCLUSIONS

The consensus statements aim to guide and standardize clinical practice and research on RIRS and to recommend standardized outcome reporting.

PATIENT SUMMARY

An international consensus on the best practice for minimally invasive surgery for kidney stones was organized and developed by two international societies. It is anticipated that this consensus will provide further guidance to urologists and may help to improve clinical outcomes for patients.

Tissue neutrophil elastase contributes to extracorporeal shock wave lithotripsy-induced kidney damage and the neutrophil elastase inhibitor, sivelestat, attenuates kidney damage with gratifying immunohistopathological and biochemical findings: an experimental study

Although the efficacy of extracorporeal shock wave lithotripsy (ESWL) has been well established within the literature, debate continues on the safety of the procedure while focusing on cellular injury and its long-term consequences. Here, we describe the role of neutrophil elastase (NE) in ESWL-related rat kidney damage and investigate the protective effects of sivelestat, an inhibitor of NE, during the early and late phases. Four groups including control, ESWL alone, ESWL with sivelestat 50 mg/kg and ESWL with treatment of 100 mg/kg, each consisting of ten rats were created. Biochemical parameters of kidney function and damage and immunohistopathological findings were compared in the early (72 h after ESWL) and late (1 week after ESWL) periods between the groups. During the early period, serum and urine creatinine levels and urine kidney injury molecule-1 (KIM-1) levels and the KIM-1/creatinine ratio increased in rats treated with ESWL compared to the control group. Furthermore, increased tissue inflammation, ductal dilatation and hemorrhage, and glomerular, tubular, and interstitial damage with increased NE staining were also detected in the ESWL treatment group. During the late phase, although urine KIM-1 levels remained stable at high levels, other parameters showed significant improvements. On the other hand, the administration of sivelestat 50 mg/kg decreased serum creatinine and urine KIM-1 and KIM-1/creatinine levels significantly in rats treated with ESWL, during the early and late periods. Significant decreases in tissue inflammation, tubular, and interstitial tissue damage were also observed during the early period. In conclusion, ESWL-related kidney tissue damage occurs primarily during the early period, and NE is involved in this process. On the other hand, the NE inhibitor sivelestat attenuated this ESWL-induced kidney damage.

Meta-Analysis of the Safety and Efficacy of α-Adrenergic Blockers for Pediatric Urolithiasis in the Distal Ureter

OBJECTIVE

Pediatric urolithiasis is a common condition, and medical expulsive therapy has grown to be accepted by many parents. We carried out a meta-analysis to identify the efficacy and safety of α-adrenergic blockers for the treatment of pediatric urolithiasis.

METHODS

We identified related articles from the PubMed, Embase, and Cochrane Library databases. All published randomized controlled trials (RCTs) describing the use of α-adrenergic blockers and placebo treatment for pediatric distal urolithiasis were involved. The outcomes included stone expulsion rate, stone expulsion time, pain episodes, need for analgesia, adverse events, and related subgroup analyses.

RESULTS

A total of nine RCTs were involved in our study, including 586 patients. We found that α-adrenergic blockers could significantly increase the rate of stone expulsion [odds ratio (OR), 3.49; 95% confidence interval (CI), 2.38-5.12; p < 0.00001], reduce the stone expulsion time [mean difference (MD), -5.15; 95% CI, -8.51 to -1.80; p = 0.003], and decrease pain episodes (MD, -1.02; 95% CI, -1.33 to -0.72; p < 0.00001) and analgesia demand (MD, -0.92; 95% CI, -1.32 to -0.53; p < 0.00001) but had a higher incidence of side effects (MD, 2.83; 95% CI, 1.55 to 5.15; p = 0.0007). During subgroup analyses, different medications (tamsulosin, doxazosin, and silodosin) also exhibited better efficiencies than placebo, except for doxazosin, which showed no difference in expulsion time (MD, -1.23; 95% CI, -2.98 to 0.51; p = 0.17). The three kinds of α-adrenergic blockers also appeared to be better tolerated, except for tamsulosin with its greater number of adverse events (MD, 2.85; 95% CI, 1.34 to 6.03; p = 0.006). Silodosin led to a better expulsion rate than tamsulosin (OR, 0.42; 95% CI, 0.20 to 0.92; p = 0.03). In addition, α-adrenergic blockers increased the stone expulsion rate regardless of stone size and decreased the expulsion time of stones measuring <5 mm (MD, -1.71; 95% CI, -2.91 to -0.52; p = 0.005), which was not the case for stones measuring >5 mm in expulsion time (MD, -3.61; 95% CI, -10.17 to 2.96; p = 0.28).

CONCLUSION

Our review suggests that α-adrenergic blockers are well-tolerated and efficient for treating pediatric distal urolithiasis. We also conclude that silodosin is the best choice of drug, offering a better expulsion rate, but it remains to be evaluated further by future studies.

Comparison of Vacuum Suction Sheath and Non-Vacuum Suction Sheath in Minimally Invasive Percutaneous Nephrolithotomy: A Meta-Analysis

Objective To evaluate the clinical efficacy of minimally invasive percutaneous nephrolithotomy (mPCNL) with vacuum suction sheath in the treatment of renal calculi. Methods: We collected relevant studies of vacuum suction sheath and non-vacuum sheath mPCNL from PubMed, Embase, and Cochrane databases for a meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Results: 7 studies were included (4 randomized controlled studies, 3 retrospective studies involving 1803 patients). The final meta-analysis results showed that the operative time (Standardised Mean Difference [SMD] = -0.84, 95% CI [-1.20; -0.48], P < 0.001), auxiliary procedures (Odds Ratio [OR] = 0.61, 95% CI [0.46; 0.81], P < 0.001) and complications in the vacuum suction sheath group were significantly lower than those in the non-vacuum sheath group. The immediate and final stone-free rates (OR = 1.69, 95% CI [1.30; 2.18], P < 0.001; OR = 1.44, 95% CI [0.98; 2.13], P = 0.039) were also significantly lower in the vacuum suction sheath group. Conclusion: This study indicates that the application of vacuum suction sheath in mPCNL can significantly shorten the operative time and patient hospitalization, reduce auxiliary procedures and complications (especially fever, urinary tract infection, and pain).

Development of prediction models of spontaneous ureteral stone passage through machine learning: Comparison with conventional statistical analysis

Objectives

To develop a prediction model of spontaneous ureteral stone passage (SSP) using machine learning and logistic regression and compare the performance of the two models. Indications for management of ureteral stones are unclear, and the clinician determines whether to wait for SSP or perform active treatment, especially in well-controlled patients, to avoid unwanted complications. Therefore, suggesting the possibility of SSP would help make a clinical decision regarding ureteral stones.

Methods

Patients diagnosed with unilateral ureteral stones at our emergency department between August 2014 and September 2018 were included and underwent non-contrast-enhanced computed tomography 4 weeks from the first stone episode. Predictors of SSP were applied to build and validate the prediction model using multilayer perceptron (MLP) with the Keras framework.

Results

Of 833 patients, SSP was observed in 606 (72.7%). SSP rates were 68.2% and 75.6% for stone sizes 5–10 mm and <5 mm, respectively. Stone opacity, location, and whether it was the first ureteral stone episode were significant predictors of SSP. Areas under the curve (AUCs) for receiver operating characteristic (ROC) curves for MLP, and logistic regression were 0.859 and 0.847, respectively, for stones <5 mm, and 0.881 and 0.817, respectively, for 5–10 mm stones.

Conclusion

SSP prediction models were developed in patients with well-controlled unilateral ureteral stones; the performance of the models was good, especially in identifying SSP for 5–10-mm ureteral stones without definite treatment guidelines. To further improve the performance of these models, future studies should focus on using machine learning techniques in image analysis.

Kidney stone proteomics: an update and perspectives

INTRODUCTION

Main problems of kidney stone disease are its increasing prevalence and high recurrence rate after calculi removal in almost all areas around the globe. Despite enormous efforts in the past, its pathogenic mechanisms remain unclear and need further elucidations. Proteomics has thus become an essential tool to unravel such sophisticated disease mechanisms at cellular, subcellular, molecular, tissue, and whole organism levels.

AREAS COVERED

This review provides abrief overview of kidney stone disease followed by updates on proteomics for investigating urinary stone modulators, matrix proteins, cellular responses to different types/doses of calcium oxalate (CaOx) crystals, sex hormones and other stimuli, crystal-cell interactions, crystal receptors, secretome, and extracellular vesicles (EVs), all of which lead to better understanding of the disease mechanisms. Finally, the future challenges and translation of these obtained data to the clinic are discussed.

EXPERT OPINION

Knowledge from urinary proteomics for exploring the important stone modulators (either inhibitors or promoters) will be helpful for early detection of asymptomatic cases for prompt prevention of symptoms, complications, and new stone formation. Moreover, these modulators may serve as the new therapeutic targets in the future for successful treatment and prevention of kidney stone disease by medications or other means of intervention.