Impact of retrograde flexible ureteroscopy and intracorporeal lithotripsy on kidney functional outcomes

Ultrathin semirigid retrograde ureteroscopy versus antegrade flexible ureteroscopy in treating proximal ureteric stones 1-2 cm, a prospective randomized multicenter study

To compare the outcomes of using Ultrathin semirigid retrograde ureteroscopy and antegrade flexible ureteroscopy to treat proximal ureteric stones of sizes 1-2 cm. A prospective randomized multicenter study included patients who had proximal ureteric stones 1-2 cm, amenable for ureteroscopy and laser lithotripsy between August 2023 and February 2024. Two hundred thirty patients were divided evenly into two treatment groups. Group I included patients treated with antegrade flexible ureteroscopy and holmium laser stone fragmentation, and Group II included patients treated with retrograde ultrathin semirigid ureteroscopy. The study groups were compared in terms of patient demographics, stone access success, operation time, reoperation rates, peri-operative complications, and stone-free status. Group I included 114 patients, while Group II included 111. The mean age of the patients was 33.92 ± 10.37 years, and the size of the stones was 15.88 ± 3 mm. The study groups had comparable demographics and stone characteristics. The mean operative time was significantly longer in group I than in group II (102.55 ± 72.46 min vs. 60.98 ± 14.84 min, respectively, P < 0.001). Most reported complications were MCCS grades I and II, with no significant difference between the study groups. The stone-free rate after four weeks was 92.1% and 81.1% for groups I and II, respectively, which increased to 94.7% and 85.6% after eight weeks (P > 0.05). Antegrade flexible ureteroscopy is equivalent to retrograde ultrathin semirigid ureteroscopy in treating proximal ureteric stones regarding stone-free status and procedure-related morbidity. However, the antegrade approach has a longer operative time, greater fluoroscopy exposure, and longer hospital stays.

Play it safe: renal function after bilateral flexible ureteroscopy for kidney stones

PURPOSE

We searched for perioperative renal function deterioration risk factors in patients that underwent bilateral flexible ureteroscopy (fURS) for kidney stones.

METHODS

From August 2016 to February 2020, symptomatic patients > 18 years old with bilateral kidney stones up to 20 mm in each side were prospectively studied. Serum creatinine samples were collected on admission to surgery, immediate postoperative (IPO), on POD 3, 10, and 30. Estimated glomerular filtration rate (eGFR) was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) without a race coefficient.

RESULTS

Thirty patients underwent bilateral fURS. Comparing to preoperative eGFR, median IPO and POD3 eGFR (p < 0.001) were significantly lower, and POD10 (p = 0.092) and POD30 (p = 0.648) were similar to preoperative eGFR. During follow-up, 22/30 (73.3%), 14/30 (46.7%), and 7/30 (23.3%) of the patients presented a decrease > 10% eGFR, > 20% eGFR, and > 30% eGFR, respectively. Multivariate analysis demonstrated that lower preoperative eGFR is a risk factor for eGFR < 60 mL/min/1.73 m2, p = 0.019 [1.021-1.263; 1.136]; ASA > 1 is a risk factor for decrease of eGFR > 10%, p = 0.028 [1.25-51.13; 8.00]; longer operative time is a risk factor for decrease of eGFR > 20%, p = 0.042 [1.00-1.05; 1.028]; and operative time ≥ 120 min is a risk factor for decrease of eGFR > 30%, p = 0.026 [0.016-0.773; 0.113].

CONCLUSIONS

Renal function suffers a reversible decrease after bilateral fURS. Our study suggests that adequate selection of patients and maintaining operative time < 120 min are relevant factors in preventing acute renal function deterioration following bilateral fURS.

Is There Any Effect of Retrograde Intrarenal Stone Surgery on Renal Functions in Childhood?

Purpose In this study, we aimed to demonstrate whether retrograde intrarenal stone surgery (RIRS) performed due to renal stones during the childhood period has any detrimental impact on renal functions. Materials and methods We retrospectively analyzed 121 patients aged 2 to 16 years who underwent RIRS for renal stones between March 2018 and February 2023. Data were available for 41 patients. The estimated glomerular filtration rate (eGFR) was computed using the modification of diet in renal disease (MDRD) formula on the day preceding the surgery and the third month after the surgery. We employed the National Kidney Foundation's chronic kidney disease (CKD) classification to categorize the glomerular filtration rate (GFR) into five groups. Preoperative and postoperative eGFR values of pediatric patients were compared by analyzing changes in CKD groups. Results Of the patients included in the study, 21 (51.2%) were male, while 20 (48.8%) were female children. No significant difference was found between the preoperative median eGFR and the postoperative median eGFR values (p=0.958). In the 3rd month after surgery, it was observed that 5 (12.1%) patients showed an improvement in their CKD stage, while deterioration was noted in 1 (2.4%) patient. Although a negative correlation was observed between the median eGFR change and both the operation time and the stone volume in Pearson correlation analysis, it was determined that this change did not create a significant difference (p=0.213 and p=0.295, respectively). Conclusion Stone surgery conducted with RIRS appears to yield positive outcomes on kidney function in the pediatric population. Nevertheless, being particularly attentive to patients with prolonged operation times and larger stone volumes is essential.

Influencing factors of acute kidney injury following retrograde intrarenal surgery

PURPOSE

To investigate the influencing factors of acute kidney injury (AKI) following retrograde intrarenal surgery (RIRS).

METHODS

The data of patients who underwent RIRS for kidney stones between January 2018 and June 2022 at two tertiary centers were retrospectively analyzed. Demographic data of patients were obtained. According to kidney disease: Improving Global Outcomes (KDIGO) criteria, those with and without AKI were divided into two groups. Preoperative, intraoperative, and postoperative predictive factors of patients were investigated between the groups. In addition, the influencing factors of AKI were examined by multivariate analysis.

RESULTS

This study included 295 (35.7%) women and 532 (64.3%) men. The mean age was 50.03 ± 15.4 years (range 18-89), and mean stone size was 15.5 ± 6.1 mm (range 6-47). Overall, 672 of patients (81.3%) were stone-free after the initial treatment. According to KDIGO, 110 of patients (13.3%) had AKI during the postoperative period. Univariate analysis showed that stone size (P = .003), previous stone surgery (P = .010), renal malformations (P = .017), high operative time (P =  < .001), high preoperative creatinine value (P = .036), intraoperative complications (P = .018), and postoperative urinary tract infection (P = .003) had significant influence on the AKI after RIRS. Multivariate analysis excluded previous stone surgery, high preoperative creatinine value, renal malformations, and intraoperative complications from the logistic regression model, whereas other factors maintained their statistically significant effect on AKI, indicating that they were independent predictors.

CONCLUSIONS

Stone size, operative time, postoperative urinary tract infection, and diabetes mellitus are significant predictors of AKI. During RIRS, urologists should consider the factors that increase the risk of AKI and evaluate the treatment outcomes based on these factors.

Stone disease in low-middle income countries. Could augmented reality have a role in its management?

Urolithiasis is a global phenomenon. Cystolithiasis is common in parts of Africa due to low protein intake and dehydration from endemic diarrhoeal illnesses. Nephrolithiasis is less prevalent than in high income countries, probably due to a variety of lifestyle issues, such as a more elemental diet, higher physical activity and less obesity. Although renal stones are less common in low-middle income countries (LMICs), the social and economic impacts of nephrolithiasis are still considerable; many stones present late or with complications such as upper urinary tract obstruction or urosepsis. These may lead to the development of chronic kidney disease, or end-stage renal failure in a small proportion of cases, conditions for which there is very poor provision in most LMICs. Early treatment of nephrolithiasis by the least invasive method possible can, however, reduce the functional consequences of urinary stone disease. Although ESWL is uncommon, and endoscopic interventions for stone are not widespread in most of Africa, percutaneous nephrolithomy and ureteroscopic renal surgery are viable techniques in those regional centres with infrastructure to support them. Longitudinal mentoring has been shown to be a key step in the adoption of these minimally invasive procedures by local surgeons, something that has been difficult during the COVID-19 pandemic due to travel restriction. Augmented reality (AR) technology is an alternative means of providing remote mentoring, something that has been trialled by Urolink, the MediTech Trust and other global non-governmental organisations during this period. Our preliminary experience suggests that this is a viable technique for promulgating skills in LMICs where appropriate connectivity exists to support remote communication. AR may also have long term promise for decreasing the reliance upon short-term surgical visits to consolidate competence, thereby reducing the carbon footprint of global surgical education.

Changes of renal function after retrograde intrarenal surgery using flexible ureteroscope in renal stone patients

Background

Retrograde intrarenal surgery (RIRS) is widely performed for renal stones. Theoretically, removing renal stones could prevent the deterioration of renal function. However, two studies reported that not all patients would see an increase in renal function after RIRS. The aim of our study was to evaluate the change of renal function of the operative site, and to identify predictors of improvement or deterioration of renal function after RIRS.

Methods

We retrospectively reviewed renal stones patients who received RIRS and single-photon emission computed tomography (SPECT) before and after surgery. Improved renal function was defined as the change of glomerular filtration rate (GFR) >10% postoperatively, and that <−10% was regarded as deteriorated renal function. Logistic and least absolute shrinkage and selection operator regression analyses were used to identify predictors for the improvement or deterioration of renal function, and predictive nomogram models were built.

Results

A total of 120 renal stone patients were included. Twenty-one (17.5%), 79 (65.8%) and 20 (16.7%) patients had improved, stable and deteriorated renal function of operative site after surgery, respectively. Lower alkaline phosphatase, lower low-density lipoprotein, lower GFR of the operative site, thicker renal parenchyma, higher serum creatinine, and extracorporeal shock wave lithotripsy (SWL) history were associated with the improved renal function. The predictive accuracy of the model for the improved renal function was 0.800. Additionally, older age, longer flexible ureteroscopic time, thinner renal parenchyma and existence of ureteral stones were risk factors for deteriorated renal function. The predictive accuracy of the model for the deteriorated renal function was 0.725.

Conclusions

The renal function of most renal stone patients did not decrease after RIRS. For patients with potential deterioration of renal function postoperatively, urologists could shorten flexible ureteroscopic time to prevent the occurrence of this outcome.

Effect of Endoscopic Ureteral Stone Treatment on Kidney Function

INTRODUCTION

Ureteral stones may have an influence on kidney functions due to postrenal obstruction or urinary infections. Urgent decompression or stone removal is necessary and recommended to prevent further complications in case of severe conditions such as anuria and urosepsis. Although it is believed that ureteral stone removal would result in renal function improvement, there are still unclear points on whether ureteroscopy (URS) can provide benefit as expected and has some adverse effects. In this study, we aimed to evaluate the alteration of kidney functions of patients who undergo rigid or flexible URS for ureteral stones and find if there are any influencing factors on kidney function alteration.

MATERIALS AND METHOD

We analyzed 126 patients who underwent retrograde intrarenal surgery (RIRS) for renal stones between May 2018 and February 2020 prospectively. The estimated glomerular filtration rate (eGFR) was calculated on the day before the surgery, by modification of diet in renal disease (MDRD) formula. The calculation was repeated and saved three times during follow-up for the same patient; on the day after the operation, on the postoperative 30th day, and the postoperative 90th day. Then, we evaluated the renal function by comparing eGFR and assessed the predicting factors affecting the kidney function.

RESULTS

Preoperative mean eGFR was 82.28 ± 25.20 mL/min/1.73 m2 for the study group. Mean eGFR was calculated 90.92 ± 22.97 mL/min/1.73 m2 on the first postoperative day, and 94.54 ± 21.95 mL/min/1.73 m2 on the third-month follow-up. The mean change in eGFR was 8.63 ± 16.68 mL/min/1.73 m2 in the early period and 12.26 ± 21.09 mL/min/1.73 m2 in the long-term follow-up period. Fifty-one patients improved on chronic kidney disease (CKD) stage, and 13 deteriorated in three months follow-up.

CONCLUSION

Removing the stone and relieving the obstruction by ureteroscopic treatment have an alteration on eGFR. Although eGFR improves in the short-term follow-up, amelioration is evident in long-term follow-up, especially in female patients. The other predictive factors for eGFR improvement after URS are the presence of ureteral obstruction and high preoperative serum creatinine levels.

Are endourological procedures for nephrolithiasis treatment associated with renal injury? A review of potential mechanisms and novel diagnostic indexes

Nephrolithiasis is one of the most common urological conditions with a huge socio-economic impact. About 50% of recurrent stone-formers have just one lifetime recurrence and >10% of patients present with a high recurrent disease requiring subsequent and sometimes multiple surgical interventions. The advent of new technology has made endourological procedures the pinnacle of stone treatment, including procedures like percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery and miniaturized PCNL procedures. Researchers have primarily focused on comparisons with respect to stone-free rates, procedure parameters and post-operative complications. However, the effect of these three procedures on renal function or indexes of renal injury has not been sufficiently examined. This was only reported in a few studies as a secondary objective with the use of common and not the appropriate and detailed renal parameters. This review presents current literature regarding the use of novel and highly predictive biomarkers for diagnosing acute kidney injury, discusses potential mechanisms through which endourological procedures for renal stone treatment may affect renal function and proposes areas with open questions where future research efforts in the field should focus.

Role of Endourological Procedures (PCNL and URS) on Renal Function: a Systematic Review

PURPOSE OF REVIEW

To present the latest evidence related to the impact of ureteroscopy (URS) and percutaneous nephrolithotomy (PCNL) on the renal function.

RECENT FINDINGS

Our review suggests that the overall renal function is not detrimentally affected by endourological interventions (URS, PCNL). This is however influenced by the preoperative renal function, presence of comorbidities such as diabetes and hypertension. For PCNL procedures, tract multiplicity, preoperative UTI, and postoperative bleeding also contribute to a decline in renal function. This review suggests that endourological interventions do not adversely affect renal function and tend to improve it in patients who do not have a poor renal function prior to the procedure. Several factors including poor preoperative renal function, diabetes, hypertension, and multiple percutaneous tracts appear to predispose patients to declining renal function after procedure, and these patients should be counseled for and followed up appropriately.

Effects of flexible ureteroscopy on kidney: A prospective clinical trial

OBJECTIVE

To investigate the effects of flexible ureteroscopy (F-URS) on the operated side of a kidney by assessing the renal damage markers, urine neutrophil gelatinase-related lipocalin (NGAL) and serum cystatin-C (Cys-C), and overall kidney function with the measurements of standard serum creatinine and urine albumin and protein levels.

MATERIAL AND METHODS

A total of 30 patients who underwent F-URS for treatment of upper urinary stone disease were prospectively evaluated. Preoperative serum urea, creatinine, and Cys-C levels were noted. Levels of urine albumin, protein, creatinine, and NGAL in spot urine samples from the operated side of a kidney obtained through the access sheath preoperatively and through the ureteral catheter 1 and 24 hours postoperatively were also measured. Preoperative and postoperative parameter levels were statistically compared.

RESULTS

The patients' mean age was 46.6±15.9 years. The mean operative and fluoroscopy times were 90.67±32.5 and 3.15±1.43 minutes, respectively. The urine creatinine, albumin, protein, albumin/creatinine, and protein/creatinine levels were similar in preoperative and postoperative periods. Postoperative serum urea, creatinine, and Cys-C levels and urine NGAL and NGAL/creatinine levels were not also found with remarkable changes from the baseline levels.

CONCLUSION

F-URS is a safe therapeutic intervention in the treatment of urolithiasis, especially regarding renal damage, and functional outcomes.

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.

Postoperative renal functional changes assessed by 99mTc-DTPA scintigraphy and predictive factors after miniaturized percutaneous nephrolithotomy and retrograde intrarenal surgery: An observational 1-year follow-up study

Purpose

We evaluated the comparative effect of miniaturized percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS) on perioperative kidney function by use of diethylenetriamine penta-acetic acid (^99mTc-DTPA) scintigraphy and identified significant predictors associated with deterioration or amelioration of renal function after surgery.

Materials and Methods

All 70 patients who underwent mini-PCNL or RIRS between 2012 and 2016 were monitored by ^99mTc-DTPA scintigraphy preoperatively. Patients with abnormal renal function were monitored from 3 to 12 months postoperatively. Logistic regression analyses were conducted to estimate the predictors of aggravated renal dysfunction and improvement.

Results

The difference in preoperative renal function between the contralateral and the operative side was >10% in 57 patients (81.4%). Among those in the group with abnormal renal function, 40 (70.2%), 10 (17.5%), and 7 (12.3%) patients showed stability, deterioration, and improvement in renal function at postoperative year 1, respectively. Functional changes did not differ according to the type of surgery. A high level of serum creatinine preoperatively (p=0.060) and a history of previous stone procedures (p=0.051) showed borderline significance for prediction of deterioration in renal function.

Conclusions

RIRS and mini-PCNL had similar effects and favorable outcomes on renal function during a 1-year follow-up period. High baseline serum creatinine levels and a history of procedures warrant careful attention.

Changes in separate renal function in patients who underwent minimally invasive renal stone surgery according to the preoperative functional deterioration

The significant predictors for the postoperative deterioration of separate renal function after minimally invasive stone surgery were investigated in the present prospective and observational study. A total of 117 consecutive patients who underwent retrograde intrarenal surgery or mini-percutaneous nephrolithotomy for renal calculi >10 mm were included in the present study. Perioperative changes in separate renal function were evaluated with Technetium-99m-Diethylene TriaminePenta acetic acid scan prior to intervention and at postoperative 3 months. Based on the functional differences between bilateral renal units, deterioration of separate renal function was graded into the following three groups: normal deterioration (<10%), moderate deterioration (10–20%), and severe deterioration (>20%). A total of 46 patients had a normal separate renal function, while 71 (60.7%) showed abnormal separate function in the involved side, including 29 (24.8%) moderate and 42 (35.9%) severe deterioration. Postoperatively, 48 patients (41.0%) showed aggravation or no recovery of separate renal function. Of the 46 patients with normal separate function, only 9 patients (19.5%) showed postoperative aggravation. Patients with moderate and severe deterioration showed aggravation (n = 7, 24.1%) or no recovery of separate renal function (n = 32, 76.1%, P < 0.001). Preoperative severe deterioration of separate renal function was an independent significant predictor for the postoperative deterioration of renal function (OR: 9.09, 95% CI: 4.007–20.624, P < 0.001). Lower preoperative deterioration of separate renal function showed a high probability of functional recovery. Therefore, it is hypothesized that early intervention might be necessary in cases where the patient exhibits severe aggravation of renal function.