Endourologic Management (PCNL, URS, SWL) of Stones in Solitary Kidney: A Systematic Review from European Association of Urologists Young Academic Urologists and Uro-Technology Groups

Safety and Efficacy of Percutaneous Nephrolithotomy in Solitary Functioning Kidneys: A Retrospective Cohort Study in an Asian Population

Objective The aim of the study was to assess the safety of preserved renal function after standard percutaneous nephrolithotomy (PCNL) in patients with a single functional kidney. The main parameters to focus on were serum creatinine levels and any associated complications. Materials and methods This retrospective cohort study was conducted in an Eastern population in a single center from 2016 through 2023 at The Kidney Centre Postgraduate Training Institute, Karachi, Pakistan. Results Out of the total 1,550 PCNL procedures performed on adult patients, 47 patients had a solitary functioning kidney with stones, which were evaluated. The stone clearance rate was 95.74% (45 patients), with a mean operative time of 85.96 minutes. Most patients, i.e., 33 (70.21%), had an infracostal approach, and single tract management was sufficient for 45 (95.74%) patients. The most common complication was transfusion, which was required in five (10.64%) patients. Mean preoperative hemoglobin dropped by 1.43mg/dL postoperatively, and mean serum creatinine decreased from 2.45mg/dL to 1.97mg/dL. Among the 24 (51.06%) analyzed stones, all were calcium oxalate. Conclusion In challenging situations such as a solitary kidney with a large stone, PCNL is the procedure of choice. However, the refined technique is of paramount importance. Overall, the use of PCNL in these unique conditions is safe and rewarding.

Safety and Efficacy of Retrograde Intrarenal Surgery in the Solitary Kidney: A Propensity Score-Matched Analysis of the RIRSearch Study Groups' Results

Background: The aim of this study was to evaluate the efficacy and safety of retrograde intrarenal surgery (RIRS) in patients with renal calculi with solitary kidneys (SKs). Materials and Methods: In this retrospective, multicenter study, a matched case-control study was carried out using the data from 522 RIRS patients treated between 2014 and 2021. Patients' demographic data, stone characteristics, operative outcomes, perioperative and postoperative complications, and surgical success were analyzed. All patients were evaluated with noncontrast-enhanced computed tomography (NCCT) preoperatively and 1 month after the surgery. Surgical success was defined as no evidence of remaining residual fragments of <3 mm in the first-month postoperative NCCT images. The case group of 29 patients with SKs (Group 1) treated with RIRS were matched with 76 control patients (Group 2) with bilateral kidneys, who underwent unilateral RIRS by propensity score-matched (PSM) analysis. Results: After PSM analysis, the demographic and clinical data did not differ significantly between the groups. The stone burden was similar between the groups: 733.6 mm3 (range: 50.4-7565.9) versus 991.1 mm3 (range: 201.2-4380.6) (P = .09), respectively. The perioperative complication rates were 13.8% (n = 4) in Group 1 and 11.8% (n = 9) in Group 2 (P = .78). There was no statistically significant difference between the groups for postoperative complication rates (minor complications, classified as Clavien 1 or 2), (6.9% [n = 2] versus 13.2% [n = 10; P = .34]), respectively. Surgical success was 82.8% (n = 24) in Group 1 and 83.6% in Group 2 (P = .92). There was no significant difference between preoperative and postoperative glomerular filtration rate and creatinine values (P = .005). Conclusions: Our results support that RIRS is a safe and effective treatment method in SK patients with similar complication and stone-free rates compared to patients who had bilateral functional kidneys and underwent unilateral RIRS.

Effect of preoperative ureteral stenting on the surgical outcomes of patients with 1-2 cm renal stones managed by retrograde intrarenal surgery using a ureteral access sheath

OBJECTIVE

To assess the surgical results of patients who underwent retrograde intrarenal surgery (RIRS) using a ureteral access sheath (UAS) for management of renal stones sized 1-2 cm compared between patients who did and did not undergo preoperative ureteral stenting.

MATERIALS AND METHODS

This prospective study included 83 patients (aged ≥ 20 years) who underwent RIRS from July 2021 to January 2023. All patients had renal calculi (stone size: 1-2 cm) located within the pelvicalyceal system. 43 and 40 patients were allocated to the non-prestent (group A) and prestent (group B), respectively. Patient baseline characteristics, renal stone details, operative data, stone-free rate (SFR) at 4 weeks and 6 months, and perioperative complications were compared between groups.

RESULTS

The baseline characteristics of all patients were comparable across the groups. Four weeks after surgery, the overall stone-free rate (SFR) stood at 62.65%. In the non-prestent and prestent groups, the SFRs were 58.12% and 67.5%, respectively (p = 0.89). By the sixth month post-surgery, the overall SFR rose to 80.72%. In the non-prestent and prestent groups, the SFRs were 76.74% and 85%, respectively (p = 0.081). No notable differences emerged in other variables, including perioperative complications, between the two groups.

CONCLUSIONS

The SFR showed no significant difference between the prestenting and non-prestenting groups at the 4-week and 6-month postoperative marks. Additionally, there were no substantial differences in complications during surgery and recovery between the groups. Notably, the SFR increased from 4 weeks to 6 months without any additional procedures in either group.

2022 Recommendations of the AFU Lithiasis Committee: Specific cases - chronic kidney disease, bilateral stones, and solitary kidney

Chronic kidney disease, diabetes and hypertension are risk factors of kidney function impairment. The relative risk of kidney failure is 1.52 in patients with urinary stone disease. The various techniques used to remove upper urinary tract stones generally do not alter kidney function in patients with normal kidney function and may sometimes improve kidney function or slow its deterioration in patients with kidney disease. Compared to the asynchronous treatment of bilateral renal and ureteral stones, concomitant treatment is associated with higher risk of anuria and the need of additional interventions, in the absence of postoperative stenting. For the treatment of solitary kidney stones, the absence of postoperative stenting increases the risk of postoperative anuria. Moreover, the multiplication of percutaneous nephrolithotomy access tracts increases the risk of bleeding and that of kidney function impairment. METHODOLOGY: These recommendations were developed according to two methods: the Clinical Practice Recommendations (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU Guidelines on urolithiasis. 2022] and their adaptability to the French context.

A multicenter study on the application of artificial intelligence radiological characteristics to predict prognosis after percutaneous nephrolithotomy

Background

A model to predict preoperative outcomes after percutaneous nephrolithotomy (PCNL) with renal staghorn stones is developed to be an essential preoperative consultation tool.

Objective

In this study, we constructed a predictive model for one-time stone clearance after PCNL for renal staghorn calculi, so as to predict the stone clearance rate of patients in one operation, and provide a reference direction for patients and clinicians.

Methods

According to the 175 patients with renal staghorn stones undergoing PCNL at two centers, preoperative/postoperative variables were collected. After identifying characteristic variables using PCA analysis to avoid overfitting. A predictive model was developed for preoperative outcomes after PCNL in patients with renal staghorn stones. In addition, we repeatedly cross-validated their model's predictive efficacy and clinical application using data from two different centers.

Results

The study included 175 patients from two centers treated with PCNL. We used a training set and an external validation set. Radionics characteristics, deep migration learning, clinical characteristics, and DTL+Rad-signature were successfully constructed using machine learning based on patients' pre/postoperative imaging characteristics and clinical variables using minimum absolute shrinkage and selection operator algorithms. In this study, DTL-Rad signal was found to be the outstanding predictor of stone clearance in patients with renal deer antler-like stones treated by PCNL. The DTL+Rad signature showed good discriminatory ability in both the training and external validation groups with AUC values of 0.871 (95% CI, 0.800-0.942) and 0.744 (95% CI, 0.617-0.871). The decision curve demonstrated the radiographic model's clinical utility and illustrated specificities of 0.935 and 0.806, respectively.

Conclusion

We found a prediction model combining imaging characteristics, neural networks, and clinical characteristics can be used as an effective preoperative prediction method.

Effects of Delayed Surgical Intervention Following Emergency Department Presentation on Stone Surgery Complexity

Introduction and Objective: Prior literature had demonstrated increased stone burden and higher rates of staged surgery in individuals of lower socioeconomic status (SES). Low SES individuals are more likely to experience delays in definitive stone surgery after initial presentation to the emergency department (ED) for kidney stones. This study aims to investigate the relationship between delays in definitive kidney stone surgery and the subsequent need for percutaneous nephrolithotomy (PNL) and/or staged surgical procedures using a statewide data set. Methods: This retrospective cohort study gathered longitudinal data from 2009 to 2018 using the California Department of Health Care Access and Information data set. Patient demographic characteristics, comorbidities, diagnosis/procedure codes, and distance were analyzed. Complex stone surgery was defined as initial PNL and/or undergoing more than one procedure within 365 days of initial intervention. Results: A total of 1,816,093 billing encounters from 947,798 patients were screened, resulting in 44,835 patients with ED visits for kidney stones followed by a urologic stone procedure. Multivariable analysis revealed that relative to patients who underwent surgery within 1 month of initial ED visit for stone disease, patients were at increased odds of undergoing complex surgery if waiting ≥6 months (odds ratio [OR] 1.18, p = 0.022), ≥1 year (OR 1.29, p < 0.001), and ≥3 years (OR 1.43, p < 0.001). Conclusions: Delays in definitive stone surgery after initial ED encounter for stone disease were associated with increased likelihood of undergoing a complex stone treatment.

Surgical outcomes of patients who underwent retrograde intrarenal surgery using a ureteral access sheath to manage kidney stones sized 1-2 cm compared between patients who did and did not undergo preoperative ureteral stenting

Objective

To investigate the surgical outcomes of patients who underwent retrograde intrarenal surgery (RIRS) using a ureteral access sheath (UAS) to manage kidney stones sized 1-2 cm compared between patients who did and did not undergo preoperative ureteral prestenting.

Materials and methods

This retrospective cohort study included 166 patients (aged ≥18 years) who underwent RIRS at Siriraj Hospital (Bangkok, Thailand) during February 2015-February 2020. All patients had renal calculi (stone size: 1-2 cm) located within the pelvicalyceal system. 80 and 86 patients were allocated to the prestent and non-prestent groups, respectively. Patient baseline characteristics, renal stone details, operative equipment, stone-free rate (SFR) at 2 weeks and 6 months, and perioperative complications were compared between groups.

Results

All patient baseline characteristics were similar between groups. At 2 weeks after surgery, the overall SFR was 65.1%, and the SFRs in the prestent and non-prestent groups were 73.4% and 59.5%, respectively (p = 0.09). At 6 months after surgery, the overall SFR was 80.1%, and the SFRs in the prestent and non-prestent groups were 90.7% and 79.3%, respectively (p = 0.08). The incidence of perioperative complications was not significantly different between groups.

Conclusions

There was no significant difference in the SFR between the presenting and non-prestenting groups at both the 2-week and 6-month postoperative time points. There was also no significant difference in intraoperative and postoperative complications between groups. The SFR was higher at 6 months than at 2 weeks in both groups with no additional procedure.

A modified triangular Double-J stent for retrograde intrarenal surgery improvement of free-stone rate, and quality of life: a randomized controlled, multiple centers, perspective trial

PURPOSE

The goal of this study is to evaluate the efficacy and safety of modified triangular double-J (DJ) stent in 1-2 cm renal or ureter calculi after retrograde intrarenal surgery (RIRS) via a randomized, controlled clinical study.

METHODS

A total of 196 patients with 1-2 cm renal or ureter calculi who were performed RIRS and received 7Fr modified triangular DJ stents (100 cases) or 6Fr normal DJ stents (96 cases). All operations were performed by experienced surgeons. The clinical characteristics and outcomes were analyzed.

RESULTS

There were no significant differences between two groups in terms of age, gender, BMI, location, hydronephrosis, urea WBC, urea RBC, BUN, Cr, laser emission time, operation time, Hb loss, postoperative BUN, postoperative Cr. Patients who received modified triangular DJ stents were shown to have higher stone-free rate (p = 0.038), but lower general health (p = 0.004).

CONCLUSION

The modified triangular 7Fr DJ stents were more efficient for patients underwent RIRS than 6Fr normal DJ stents.

Can We Identify Patients in Danger of Complications in Retrograde Intrarenal Surgery?-A Retrospective Risk Factors Analysis

Retrograde intrarenal surgery (RIRS) is an innovative and effective method of kidney stones treatment, as it had great influence on the development of endoscopy in urology. The increasing prevalence of urolithiasis together with the rapid development of endourology leads to a rise in the number of procedures related to the disease. Flexible ureteroscopy is constantly being improved, especially regarding the effectiveness and safety of the procedure. The purpose of this study is to evaluate intraoperative and early post-operative complications of RIRS in the treatment of kidney stones. A retrospective analysis of medical records was performed. A series was comprised of 207 consecutive operations performed from 2017 to 2020. Complications occurred in 19.3% (n = 40) of patients. Occurrence according to the Clavien-Dindo scale was: 11.1% for grade I, 5.8% for grade II and 2.4% for grade IV. Infectious complications included SIRS (5.3%, n = 11) and sepsis (2.4%, n = 5). Statistical analysis revealed a correlation between acute post-operative infections and positive midstream urine culture, history of chronic or recurrent urinary tract infections, and increased body mass index (BMI). Furthermore, a significant correlation was observed between pain requiring the use of opioids with BMI over 25. Consequently, history of urinary tract infections, positive pre-operative urine culture, and increased BMI are considered risk factors and require appropriate management.

Efficacy and safety of percutaneous nephrolithotomy in patients with chronic kidney disease: Outcomes from a tertiary care center

BACKGROUND

The management of renal stone disease in the presence of chronic kidney disease is a challenging scenario, both in terms of surgical safety as well as perioperative outcomes. The aim of the present study is to study the efficacy, safety, and outcomes of percutaneous nephrolithotomy in patients with chronic kidney disease.

MATERIALS AND METHODS

A prospective study was conducted including adult patients with renal stone disease and a creatinine clearance of <90ml/min (Stage 2 CKD or more) who underwent percutaneous nephrolithotomy. Pre-operative and post-operative serum creatinine and glomerular filtration rates were compared. Patients were divided into CKD stages 1-5 having creatinine clearance >90ml/min, 60-90ml/min, 30-60ml/min, 15-30ml/min and <15ml/min respectively. Based on up migration or down migration of CKD stages, patients were classified as improved, deteriorated or stable. Peri-operative complications and outcomes were also compared.

RESULTS

A total of 185 patients with CKD stage less than or equal to 2 underwent PCNL. The mean age of the patients was 43.24+/-14.32 years. The mean preoperative estimated glomerular filtration rate was 62.88±23.42mL/min/1.73m2. Pre-operative CKD stage distribution was as follows: stage 2-121(65.4%), stage 3-34(18.4%), stage 4-24(13%) and stage 5-6(3.2%). On last follow-up of patients, the mean creatinine was 1.07±0.65 mg/dL and the mean eGFR was 82.75±31.22 mL/min/1.73m2. The median change in creatinine and mean change in GFR was 0.23 (0.16-0.27) g/dL and 19.87 ± 19.77 mL/min/1.73 m2 respectively. Improvement in kidney function with a stage down migration was seen in 115 cases(62.2%), slight improvement with no change in stage in 69 cases(37.3%) and deterioration of CKD stage was present in one case(0.5%).

CONCLUSION

Percutaneous nephrolithotomy is associated with favourable functional outcomes in chronic kidney disease patients including severe CKD(stage IV and V). Improvement or stabilization of CKD stage was seen in 99.5% patients post PCNL.

Calcium Oxalate Crystallization: Influence of pH, Energy Input, and Supersaturation Ratio on the Synthesis of Artificial Kidney Stones

The removal of kidney stones can lead to small residual fragments remaining in the human body. Residual stone fragments can act as seeds for kidney stone crystallization and may necessitate another intervention. Therefore, it is important to create a consistent model with a particle size comparable to the range of kidney stone fragments. Thus, the size-determining parameters such as supersaturation ratio, energy input, and pH value are examined. The batch crystallizations were performed with supersaturation ratios between 5.07 and 6.12. The compositions of the dried samples were analyzed with Raman spectroscopy, infrared spectroscopy, and X-ray diffraction (XRD). The samples were identified as calcium oxalate monohydrate with spectroscopic analysis, while calcium oxalate dihydrate being the most prominent crystalline species at all supersaturation ratios for the investigated conditions. The aggregate size, obtained with analytical centrifugation, varied between 2.9 and 4.3 μm, while the crystallite domain size, obtained from XRD, varied from 40 to 61 nm. Our results indicate that particle sizes increase with increasing supersaturation, energy input, and pH. All syntheses yield a high particle heterogeneity and represent an ideal basis for reference materials of small kidney stone fragments. These results will help better understand and control the crystallization of calcium oxalate and the aggregation of such pseudopolymorphs.

Can the introduction of single-use flexible ureteroscopes increase the longevity of reusable flexible ureteroscopes at a high volume centre?

OBJECTIVES

To assess whether the introduction of single use flexibles ureteroscopes (su-fURS) at our high-volume centre had an advantageous impact on the turn-over and breakage rates of reusable fURS (re-fURS).

METHODS

We analysed re-fURS number of usages and breakages at our centre between February 2015 and December 2018. We recorded the number of usages for analysed scope between the first usage until a breakage requiring reconditioning. Usage count was restarted following each reconditioning episode. Since su-fURS (Lithovue, Boston Scientific, USA) were introduced at our center in September 2016, we had the chance to compare different re-fURS life cycles according to both su-fURS availability and usage intensity (i.e., number of su-fURS used during each re-fURS life cycle). We then explored the relationship between su-fURS usage intensity and reusable scope survival (i.e., number of utilizations before any breakage requiring reconditioning) using locally weighted scatterplot smoothing (LOWESS) approach.

RESULTS

Five different re-fURSs were employed at our centre, for a total of 1820 usages and 40 breakages requiring reconditioning. The overall mean (SD) number of usages before breaking was 40 (22). After su-fURS introduction, mean (SD) re-fURS number of usages increased from 35 (22) to 49 (20), (+ 40%, p = 0.02). The relationship between su-fURS usage intensity and reusable scopes survival showed a linear survival increase after 10 or more su-fURS scopes were used per life cycle.

CONCLUSIONS

The life cycle of re-fURS increased by 40% after the introduction of su-fURS. Ten or more used su-fURS per life cycle were associated with increased re-fURS survival.

Retrograde intrarenal surgery for a staghorn renal calculus in a patient with solitary kidney and urinary tract deformity: a case report

Staghorn renal calculi are large, branched stones in the kidney that partially or completely fill the renal pelvis and renal calyces. Percutaneous nephrolithotomy (PCNL) is the gold standard treatment for staghorn calculi. However, we report a retrograde intrarenal surgery (RIRS) performed to treat a staghorn calculus in a patient with a solitary kidney and a deformed urinary tract. The 37-year-old male patient presented with right-sided lumbar pain. The computed tomography (CT) scan found a solitary kidney on the right side with an opaque 4.5 cm × 2.4 cm renal stone and grade I hydronephrosis. Additionally, a urinary tract deformity was observed, and it was secondary to the deformity of the pelvis caused by a previous pubis fracture, which significantly increased the risk and the difficulty of intrarenal surgery. A total number of 3 sessions of RIRS were conducted, and the patient was discharged 3 days after each session on average. The postoperative X-ray exam of the third session revealed that the renal stone was completely removed. The patient recovered well without any complications. This case demonstrates that RIRS is a safe and effective treatment of staghorn calculi with the presence of urinary tract deformation. This suggests RIRS may be of particular interest in minimizing the procedure-related damage of a solitary kidney.

The Long-Term Follow-Up of Patients with Cystine Stones: A Single-Center Experience for 13 Years

Introduction: Cystine stone development is relatively uncommon among patients with urolithiasis, and most studies have reported only on small sample sizes and short follow-up periods. We evaluated clinical courses and treatment outcomes of patients with cystine stones with long-term follow-up at our center. Methods: We retrospectively analyzed 22 patients diagnosed with cystine stones between January 1989 and May 2019. Results: The median follow-up was 160 (range 6–340) months, and the median patient age at diagnosis was 46 (range 12–82) years. All patients underwent surgical interventions at the first visit (4 extracorporeal shockwave lithotripsy, 5 ureteroscopy, and 13 percutaneous nephrolithotripsy). The median number of stone events and surgical interventions per year was 0.45 (range 0–2.6) and 0.19 (range 0–1.3) after initial surgical intervention. The median time to stone events and surgical intervention was 2 years and 3.25 years, respectively. There was a significant difference in time to stone events and second surgical intervention when patients were divided at 50 years of age at diagnosis (p = 0.02, 0.04, respectively). Conclusions: Only age at a diagnosis under 50 was significantly associated with recurrent stone events and intervention. Adequate follow-up and treatment are needed to manage patients with cystine stones safely.

Comparison of antegrade and retrograde ureterolithotripsy for proximal ureteral stones: a systematic review and meta-analysis

Background

Antegrade percutaneous ureterolithotripsy (URSL) could be a treatment option for large and/or impacted proximal ureteral stones, which are difficult to treat. To review the current approach and treatment outcomes and to compare the efficacy of retrograde and antegrade URSL for large proximal ureteral stones, we evaluated the unique perspectives of both surgical modalities.

Methods

This systematic literature review and meta-analysis was performed in July 2020. Articles on human studies and treatment of ureteral stones with URSL were extracted from the PubMed, MEDLINE, Embase, Cochrane Library, Scopus, and the Japan Medical Abstracts Society databases without any language restrictions. The risks of bias for randomized controlled trials (RCTs) and non-randomized controlled trials (non-RCTs) were assessed using the Cochrane risk of tool and the Risk of Bias in Non-randomized Studies- of Interventions tool, respectively.

Results

A total of 10 studies, including seven RCTs and three non-RCTs, were selected for the analysis; 433 and 420 cases underwent retrograde and antegrade URSL, respectively. The stone-free rate (SFR) was significantly higher in antegrade URSL than in retrograde URSL (SFR ratio: 1.17, 95% CI: 1.12-1.22; P<0.001), while the hospital stay was significantly longer in antegrade URSL than in retrograde URSL (standardized mean difference: 2.56, 95% CI: 0.67-4.46; P=0.008). There were no significant differences in the operation time and the overall complication rate between the two approaches.

Conclusions

Despite the heterogeneity of data and bias limitations, this latest evidence reflects real practice data, which may be useful for decision making.

Ureteroscopy and Laser Stone Fragmentation Is Safe and Tends to Improve Renal Function in Patients with Chronic Kidney Disease: Prospective Outcomes with a Minimum Follow-Up of 6 Months

Introduction: The role and long-term follow-up of ureteroscopy and laser stone treatment (URSL) in patients with chronic kidney disease (CKD) is unclear. Given conflicting results and a lack of robust data, we looked at the results of URSL in patients with CKD. Methods: Over a 6.5-year period (March 2012-July 2018), prospective outcomes were recorded for consecutive patients who underwent URSL for ureteral or renal stones. The inclusion criteria were all patients with CKD II-V. Renal function was checked preoperatively and at a minimum of 6 months postprocedure. Data were collected and analyzed for patient and stone demographics, procedural and postoperative details, and complications. Results: Over the study period, 277 patients with preoperative CKD stage II-V were included with a male:female ratio of 188:89 and a mean age of 66.6 years. The mean preoperative estimated glomerular filtration rate (eGFR) (mL/minute) was 63 (range: 14-89, ±18) with 167 (60.2%) CKD II, 70 (25.2%) CKD IIIa, 27 (9.7%) CKD IIIb, 10 (3.6%) CKD IV, and 3 (1%) CKD V patients. The mean single stone size was 9.6 mm (range: 3-37 mm, ±5.2) and 35.3% had multiple stones. The stone was located in the ureter for 112 patients, kidney for 137 patients, with 28 patients who had stones in both ureter and kidneys. A pre- and postoperative stent was present in 34.3% to 60% and 82.6% to 100% of patients, respectively, with an access sheath used in 103 (37.8%). The mean operative time was 44.5 minutes, with a stone-free rate of 91.6%. Postoperatively the mean eGFR improved to 68 (±20) (p < 0.002). Complications occurred in 22 (7.9%) patients of which 18 were Clavien I/II and 4 were Clavien III/IV complications. Conclusion: URSL is safe and effective in patients with CKD with most patients discharged the same day of surgery. For majority of patients with both ureteral and renal stones, the renal function either stayed stable or improved after ureteroscopy on a long-term follow-up irrespective of their underlying CKD status.