Retrograde intrarenal surgery for renal stones - Part 2

Efficacy and intrarenal pressure analysis of flexible and navigable suction ureteral access sheaths with flexible ureteroscopy in modified surgical positions for 2-6 cm upper urinary tract stones: a multicenter retrospective study

This multicenter retrospective study aimed to assess the efficacy, intrarenal pressure (IRP), and complications of retrograde intrarenal surgery (RIRS) using a flexible and navigable suction ureteral access sheaths (FANS-UAS) in the reverse Trendelenburg lithotomy position (RTLP) for treating kidney and upper ureteral stones measuring 2-6 cm. Conducted at six medical centers in Fujian Province from 2022 to 2024, the study included 231 patients with a median stone size of 26 mm. The immediate stone-free rate (ISFR) was 90.48%, while the SFR at postoperative day 30 was 95.67%. Only two patients developed postoperative fever, two patients had ureteral laceration and most experienced mild pain. Although surgical time increased with stone size, factors such as sex, infundibulopelvic angle (IPA), and stone density had little effect on duration, and there was no significant difference between ISFR and 30-day SFR. Importantly, all IRP measurements remained within normal limits. These findings suggest that RIRS with FANS-UAS in RTLP is a safe and effective approach for managing upper urinary tract stones of 2-6 cm, especially in 2-4 cm stones.

Assessment of Factors Responsible for Stone-Free Status After Retrograde Intrarenal Surgery

Aim The study aimed to evaluate the predictive factors that determined stone-free rate (SFR) after retrograde intrarenal surgery (RIRS). Materials and methods This prospective study was conducted on 183 patients undergoing RIRS for renal stones. Patients were categorized into two groups, depending on stone-free status one month following the procedure. SFR was defined as the complete absence of stones or stones <4 mm. The parameters studied included patient demographics, presence of hydronephrosis, presence of preoperative double J-stent, abnormal renal anatomy, and stone characteristics (stone burden, stone number, stone density, stone location, lower pole infundibulopelvic angle, and lower pole renal infundibular length (RIL)). Univariate and multivariate analyses were performed to identify risk factors for residual stones. We assessed the predictive ability of the RIRS score and Resorlu-Unsal stone score (RUSS) for evaluating SFR utilizing receiver operating characteristic (ROC) analysis. Results 183 patients were included in the study with a median age of 51 years. 131 (71.6%) patients were declared stone-free after the procedure. The mean stone size and density were 16.9 SD±7.5 mm and 1038 SD±342 Hounsfield units (HU) respectively. Stone-free patients had lower stone size (14.3 mm vs. 23.6 mm, p<0.01) and stone density (970 HU vs. 1211 HU, p<0.01) compared to non-stone-free patients. Patients with residual stones had steeper lower pole renal infundibulopelvic angle (RIPA) (31.3° vs. 40.7°, p<0.01) and longer RIL (26.6 mm vs. 21.1 mm, p<0.01). Stone multiplicity (p<0.01), lower pole stone location (p<0.01), and renal malformations (p<0.01) were significant influencing factors for residual renal stones after RIRS. Multivariate analysis revealed stone size, stone density (HU), and stone location as independent predictors for SFR after RIRS. Among the scoring systems, the RIRS score had the highest diagnostic accuracy for SFR (area under the curve (AUC): -0.882, 95% CI-0.828-0.936). Conclusion Stone size, stone density (HU), and stone number are important predictors of SFR after RIRS. Lower pole stone location and abnormal renal anatomy play a substantial role in determining SFR after RIRS. In lower pole stones, a long RIL and acute RIPA negatively influence SFR. Additionally, the RIRS score was found to be a better predictor for SFR than the RUSS score.

Dynamic renal scans as a modality for follow-up of flexible ureteroscopy

OBJECTIVE

To determine whether dynamic renal scans - DTPA or MAG3 - routinely performed after flexible ureteroscopies (f-URS) could detect the development of an obstruction and thus promote prompt early intervention for kidney preservation.

PATIENTS AND METHODS

In this retrospective study, with all the data recorded prospectively between April 2010 and October 2023, 250 renal units in 242 patients with upper urinary tract stones (UUTS) who underwent ureterorenoscopy by one surgeon in the same medical center were evaluated. Stone-free rate (SFR) was defined as no residual fragments at all using an intraoperative "triple test". The following characteristics were examined: gender, BMI, age, Hounsfield unit, stone diameter, laterality, renal/ureteral stones, stone-free rate, and auxiliary procedures per renal unit. The Clavien-Dindo classification was used to report complications. Renal units with residual stones were scheduled for a 2nd f-URS. Post- flexible ureteroscopy ureteral obstruction and renal function were detected using renal scan DTPA or MAG-3. The primary outcome was renal/ ureteral obstruction.

RESULTS

The mean patient age was 53 years. The mean stone size was 12.3 mm. Stones in renal pelvis, upper, middle and lower calyces were treated in 9.2% (23), 27.6% (69), and 30.8% (77) of cases, respectively; 44% (110) ureteral stones were also treated. The single- and second-session SFRs were 94.8% and 99.7%, respectively. A third auxiliary procedure was needed in one renal unit (0.4%). The mean number of procedures per renal unit was 1.06 (264/250). Ureteral double-J stents were inserted in 53.6% (134) of the cases. In 37 (14.8%) cases, a stent was placed before surgery. Post-operative complications were minor, with readmission and pain control needed in only two patients (0.8%). No avulsion or perforation of the ureters was observed. In six patients with t1/2 between 10-20 minutes, a second renal scan revealed spontaneous improvement and no obstruction in five patients. One patient with large stones and a history of prior ureteroscopy developed a ureteral stricture (0.4%) and needed treatment with laser endoureterotomy.

CONCLUSIONS

Post-flexible ureteroscopy obstruction due to ureteral stricture is very rare. A routine renal scan post-operatively may be used in potentially high-risk patients.

Comparison of the effectiveness of two adjustable negative pressure ureteral access sheaths combined with flex ureteroscopy for ≤ 2 cm renal stones

To compare the safety and effectiveness of the combination of intelligent intrarenal pressure control platforms (IPCP) and flexible ureteral access sheath (FUAS) combined with retrograde intrarenal surgery (RIRS) for the treatment of renal stones less than 2 cm. We retrospectively collected 383 patients with renal stones who underwent RIRS in our department from June 2022 to October 2023. Inclusion criteria: stone length or the sum of multiple stone lengths ≤ 2 cm. Finally, 99 cases were included and divided into an IPCP group (n = 40) and FUAS group (n = 59) based on surgical methods. The main endpoint was the stone-free rate (SFR) at third months after surgery, with no residual stones or stone fragments less than 2 mm defined as stone clearance. The secondary endpoints were surgical time and perioperative complications, including fever, sepsis, septic shock, and perirenal hematoma. There was no statistically significant difference in general information between the two groups, including age, gender, body mass index, comorbidities, stone side, stone location, stone length, urine bacterial culture, and hydronephrosis. The operation time for IPCP group and FUAS group was 56.83 ± 21.33 vs 55.47 ± 19.69 min (p = 0.747). The SFR of IPCP group and FUAS group on the first postoperative day was 75.00% vs 91.50% (p = 0.024). The SFR was 90.00% vs 94.90% in the third month (p = 0.349).In IPCP group, there were 11 cases with stones located in the lower renal calyces and 17 cases in FUAS group. The SFR of the two groups on the first day and third months after surgery were 45.50% vs 88.20% (p = 0.014) and 63.60% vs 94.10% (p = 0.040), respectively, with statistical differences. For kidney stones ≤ 2 cm, there was no difference in SFR and the incidence of infection-related complications between IPCP and FUAS combined with RIRS, both of which were superior to T-RIRS. For lower renal caliceal stones, FUAS has a higher SFR compared to IPCP.

Does displacement of lower pole stones during retrograde intrarenal surgery improves stone-free status? A systematic review and meta-analysis

PURPOSE

Kidney stones are one of the most common urological diseases worldwide. The size and location of the stone are the most important factors in determining the most suitable treatment options. The aim of this review was to evaluate the displacement of lower pole stones.

METHODS

Three studies assessing the efficacy of translocating kidney stones from the lower pole of the kidney to other locations during retrograde intrarenal surgery published in the last 20 years were included. A systematic search was conducted in the PubMed, Embase, Latin American and Caribbean Health Sciences Literature (LILACS), and Web of Science databases using the following search terms: "Lower pole," "Lithotripsy." Meta-analysis was performed using Review Manager version 5.4.

RESULTS

Stone-free rates were improved through displacement (odds ratio - OR = -0.15; 95% confidence interval-95%CI -0.24--0.05; p = 0.002; I2 = 21%), but at the cost of increased surgical duration (mean difference = -12.50; 95%CI -24.06--0.95; p = 0.03; I2 = 94%). Although this represents a potentially negative outcome, the improvement in clearance rates justifies the additional investment of time and effort.

CONCLUSIONS

Displacement of lower pole kidney stones for subsequent lithotripsy brings significant benefits in terms of stone-free rate, with no difference in laser energy usage. However, it results in increased surgical time. Despite these factors, the benefits to patients undergoing the procedure are substantial.

The outcomes of flexible ureteroscopy for renal calculi of 2 cm or more with and without the use of ureteral access sheath: A retrospective study

INTRODUCTION

The rate of success of retrograde intrarenal surgery (RIRS) for treating urinary tract stones is high, and the procedure is growing in popularity. The routine use of ureteral access sheath (UAS) remains somewhat controversial. The aim of this study was to assess the efficacy and safety of employing UAS during flexible ureteroscopy for treating renal stones ≥ 2 cm.

METHODS

This retrospective study was accomplished from January 2021 to February 2023. From 495 consecutives flexible ureteroscopies, 112 patients had renal stones ≥ 2 cm (60 patients with the use of UAS and 52 patients without). The stone-free status was verified after 8 weeks of operation.

RESULTS

The average diameter of the renal stones in non-UAS or UAS treated groups was 22.5 mm and 22.6, respectively. None of the groups differed significantly in terms of stone side, stone size, stone position, or Hounsfield unite but there was significant difference (p < 0.001) among two groups as regard pre-operative stenting (cases with UAS had 23.3% pre-operative stenting).

CONCLUSIONS

It is not always necessary to use UAS in conjunction with flexible ureteroscopy and laser lithotripsy to treat renal calculi bigger than or equal two cm. Without the assistance of UAS, the surgery may be carried out successfully and safely.

Flexible Ureteroscopy Without Radiation Exposure

Introduction:Renal stones are a common pathology in daily practice with a continuously increasing incidence. Using flexible ureteroscopy (fURS), urologists can treat difficult renal stones through the natural orifice and maintain a satisfactory stone-free rate. Even though advancing technologies offer the opportunity for minimally invasive surgery, the surgeon is still exposed to a considerable amount of ionizing radiation during several procedures. In this study, the aim is to determine the efficacy of flexible ureteroscopy without fluoroscopy in terms of stone-free rates and complications. Materials and methods:In the Urology Department of Saint John Clinical Emergency Hospital in Bucharest, Romania, a retrospective study was conducted on 98 patients diagnosed with renal calculi between September 2020 and December 2021. Using two different groups, the demographic characteristics of patients, characteristics of stones (size, number, location), the use of fluoroscopy, the operative time (in minutes) and postoperative complications, and the stone-free rate were compared. In one of the groups, fluoroscopy was used during fURS (Group I), while in the second group (Group II), no ionizing radiation was used during fURS. Results:Twenty-four males and 23 females were enrolled in Group I, whereas 31 males and 20 females were enrolled in Group II. The mean age of subjects was 63.2 years old in the fluoroscopy group and 61.6 years old in the group without fluoroscopy. While the stone characteristics revealed some variations in stone location between the compared groups, there were no statistical differences in mean stone diameter (1.489 mm - Group I vs. 1.588 mm - Group II). Stone-free rates and complications classified using Clavien-Dindo modified system for urological surgeries were used to analyze the main results. Group II had a slightly higher stone-free rate, but statistical studies found no significant differences; therefore, both methods are deemed equal in this field. Identified complications were classified as Clavien I and II and were successfully treated for both groups. Conclusion:This study reveals that by adhering to additional intraoperative measurements for guiding the access sheath, fURS without fluoroscopy can be performed safely and with a high success rate.

Does Relocation of Lower Pole Stone During Retrograde Intrarenal Surgery Improve Stone-Free Rate? A Prospective Randomized Study

Purpose: The aim of this study was to compare the stone-free rate (SFR) of in situ treatment vs relocation and lithotripsy for lower pole stones of less than 2 cm following retrograde intrarenal surgery (RIRS). Methods: This prospective randomized study was undertaken from June 2019 to May 2020 in patients undergoing RIRS for lower pole renal stones less than 2 cm in diameter. Patients were randomized into two groups: in situ lithotripsy group and relocation lithotripsy group. The in situ lithotripsy group underwent laser lithotripsy for lower pole stones without relocation of the calculus, and the relocation lithotripsy group had their stones relocated to a favorable location using a tipless Nitinol basket, followed by laser lithotripsy. Laser lithotripsy was achieved using the holmium:YAG (Ho:YAG) laser (120 W) with a 200-μm laser fiber. A Double-J stent was placed in all patients at the end of the procedure. Patient demographics, stone characteristics, operative outcomes, and complications were evaluated. The SFR was determined at 1 month postoperatively with a kidney, ureter, and bladder radiograph (KUB) and ultrasound KUB. Results: Sixty-eight patients were included in the study: in situ group (n = 35) and relocation group (n = 33). The mean stone size and stone density were similar between the groups. The total operative duration, lasing duration, and total energy used were similar between the groups. At the 1-month follow-up, the complete SFR was 85.7% and 91% in the in situ lithotripsy and relocation lithotripsy groups, respectively (p = 0.506). Conclusions: Relocation followed by subsequent laser lithotripsy was associated with similar SFRs as with in situ laser lithotripsy for lower pole renal calculi less than 2 cm in diameter following RIRS using the Ho:YAG laser.

The effects of stone density on surgical outcomes of retrograde intrarenal stone surgery

OBJECTIVE

Several pre-operative parameters have been studied to estimate stone-free rate (SFR) following retrograde intrarenal surgery (RIRS) procedures. The objective of this study was to evaluate the effects of stone density on surgical outcomes of RIRS.

METHODS

This retrospective study included 30 stone-free patients (Group SF) and 30 patients with residual fragments (Group RF). Patients' age and gender, laterality, non-contrast CT findings, including size and density of the kidney stones, infundibular pelvic angle (IPA), operational time, and post-operative pain were recorded and compared between the two groups. The stone density was measured by free hand region of interest (ROI) determination coincident with the stone borders and expressed as Hounsfield units (HUs).

RESULTS

The rate of single stones was significantly higher in Group SF compared to Group RF (p < 0.001). The mean stone size was found as 11.93 ± 7.81 mm in Group SF and 16.27 ± 7.29 mm in Group RF with the difference being statistically significant (p < 0.001). The mean IPA was 53.87 degrees in Group SF and 50.33 degrees in Group RF. The mean density was measured as 748.17 ± 318.14 HU in Group SF and 945.90 ± 345.30 HU in Group RF. The mean stone density was statistically significantly higher in patients with residual fragments compared to the stone-free patients (p < 0.001).

CONCLUSION

This study revealed that stone density as measured as HU affects the treatment outcomes with RIRS procedure and the mean density is significantly higher in patients with residual stone fragments.

ADVANCES IN KNOWLEDGE

Studies about the effects of HUs on stone-free rate are limited in the literature. Stone density affects the treatment outcomes with RIRS procedure and the mean density is significantly higher in patients with residual stone fragments.

Sheathed flexible retrograde intrarenal surgery without safety guide wire for upper urinary tract stones

OBJECTIVES

To assess the success rate and intraoperative complications of flexible ureterorenoscopy (f-URS) in patients with upper urinary tract (UUT) stones using a ureteral access sheath (UAS) without a safety guide wire (SGW).

PATIENTS AND METHODS

Between April 2010 and March 2022, 464 renal units in patients with renal stones with and without concomitant ureteral stones (UUT), underwent ureterorenoscopy by one surgeon, and UAS was used in all of them. The primary endpoint was the stone-free rate (SFR). SFR was defined as no residual fragments at all. The following characteristics were examined: age, sex, laterality, renal/ureteral stones, stone diameter, SFR, Hounsfield unit, auxiliary procedures, double-J stent insertion, and intraoperative complications. This study was retrospective, with all the data recorded prospectively. Patients with residual stones were scheduled for the 2nd RIRS. The Clavien-Dindo classification was used to report complications.

RESULTS

The mean patient age was 52.9 years. The mean stone size was 13.1 mm. Lower pole, upper and middle calyces, renal pelvis and ureteral stones were found in 51.5% (239), 34.9% (162), 18.3% (85) and 46.9% (218) of cases, respectively. The mean diameter was 8.1 mm, 8 mm, 12.5 mm and 8.1 mm for the lower pole, upper and middle calyces, renal pelvis and ureteral stones, respectively. The single- and second-session SFRs were 90% and 100%, respectively. The mean number of procedures per renal unit was 1.1. Ureteral double-J stents were inserted in 45.7% (212) of patients. In 96 cases, a stent was placed before surgery. Postoperative complications were minor, with no avulsion or perforation of the ureters; readmission and insertion of a DJ stent occurred in one patient. Ureteral stricture developed in one patient (0.2%) and needed treatment with laser ureterotomy.

CONCLUSIONS

f-URS is a safe and effective mode of surgical management of renal and simultaneous renal and ureteral calculi using the ureteral access sheath without a safety guide wire. A guide wire should not be routinely used in these cases.

Super-mini percutaneous nephrolithotomy (SMP) vs retrograde intrarenal surgery (RIRS) in the management of renal calculi ≤ 2 cm: a propensity matched study

OBJECTIVE

To compare the effectiveness and safety of Super-Mini PCNL (SMP) and Retrograde Intrarenal Surgery (RIRS) in the management of renal calculi ≤ 2 cm.

PATIENTS AND METHODS

A prospective, inter-institutional, observational study of patients presenting with renal calculi ≤ 2 cm. Patients underwent either SMP (Group 1) or RIRS (Group 2) and were performed by 2 experienced high-volume surgeons.

RESULTS

Between September 2018 and April 2019, 593 patients underwent PCNL and 239 patients had RIRS in two tertiary centers. Among them, 149 patients were included for the final analysis after propensity-score matching out of which 75 patients underwent SMP in one center and 74 patients underwent RIRS in the other. The stone-free rate (SFR) was statistically significantly higher in Group 1 on POD-1 (98.66% vs. 89.19%; p = 0.015), and was still higher in Group 1 on POD-30 (98.66% vs. 93.24%, p = 0.092) SFR on both POD-1 and POD-30 for lower pole calculi was higher in Group 1 (100 vs. 82.61%, p = 0.047 and 100 vs 92.61% p = 0.171). The mean (SD) operative time was significantly shorter in Group 1 at 36.43 min (14.07) vs 51.15 (17.95) mins (p < 0.0001). The mean hemoglobin drop was significantly less in Group 1 (0.31 vs 0.53 gm%; p = 0.020). There were more Clavien-Dindo complications in Group 2 (p = 0.021). The mean VAS pain score was significantly less in Group 2 at 6 and 12 h postoperatively (2.52 vs 3.67, 1.85 vs 2.40, respectively: p < 0.0001), whereas the mean VAS pain score was significantly less in Group 1 at 24 h postoperatively (0.31 vs 1.01, p < 0.0001). The mean hospital stay was significantly shorter in Group 1 (28.37 vs 45.70 h; p < 0.0001).

CONCLUSION

SMP has significantly lower operative times, complication rates, shorter hospital stay, with higher stone-free rates compared to RIRS. SMP is associated with more early post-operative pain though.

The safety of continued low dose aspirin therapy during Complete Supine Percutaneous Nephrolithotomy (csPCNL)

OBJECTIVE

Using anticoagulants and antiplatelet drugs in patients with cardiovascular and medical comorbidities is prevalent. Because of hyper vascular nature of kidney, physicians tend to stop using aspirin before percutaneous nephrolithotomy (PCNL). We have shown the effects of remaining on low dose aspirin in complete supine PCNL (csPCNL).

MATERIAL AND METHODS

The records of 643 patients who underwent csPCNL between 2012 and 2018 were analyzed. Surgical outcomes and complications of patients who were on aspirin therapy and continued it daily (group A) were compared with those not taking aspirin (group B).

RESULTS

Of the 643 csPCNLs, 40 (6%) were performed in patients of group A and the rest of 603 (94%) cases were in group B. The differences between the mean age of groups were statistically significant (60.08±9.45, group A and 48.66±12.32, group B) (P<0.001). Thirty-nine (97.5%) of patients in group A and 548 (90.9%) of group B were stone free by the end of the study which was not statistically significant (P=0.118). The mean operative time between groups A and B (43.20±21.37 and 44.83±16.83, respectively) was not considered significant (P=0.561). There was also no significant difference between 2 groups in any types of complications. Multivariate analysis showed that, perioperative aspirin use was not a significant predictor of transfusion, Hb drop, operative time and other complications.

CONCLUSIONS

Remaining on aspirin does not increase the risk of bleeding, transfusionand other complications. Consequently, continuing aspirin prioperatively in csPCNL appears safe. There is no fear for continuing aspirin in csPCNL.

LEVEL OF EVIDENCE

3.

External validation and comparison of current scoring systems in retrograde intrarenal surgery: Multi-institutional study with 949 patients

OBJECTIVES

To externally validate and compare Resorlu-Unsal stone score (RUSS), modified Seoul National University Renal Stone Complexity Score(S-ReSC), Ito's nomogram, and Retrograde Intra-Renal Surgery (R.I.R.S.) scoring systems for predicting capabilities of both the stone-free status and complications in a multi-institutional study.

MATERIALS AND METHODS

We performed a retrospective analysis of 949 patients who underwent flexible ureterorenoscopy (f-URS) and laser lithotripsy for renal stones in two institutions between March-2015 and June-2020. The RUSS, modified S-ReSC, Ito's nomogram, and R.I.R.S. scores were calculated for each patient by the same surgeon on imaging methods. Results were compared for their predictive capability of stone-free status and complications.

RESULTS

Of 949 patients 603 were male and 346 were female with a mean age of 47.2 ± 14.3 (range 2-84 years). Mean stone burden was 102.6 ± 42.2 (48-270 mm² ). All nomograms predicted stone-free status (Area Under Curve (AUC) were 0.689, 0.657, 0.303, and 0.690, respectively). All four scoring systems predicted complications with AUC values of 0.689, 0.646, 0.286, and 0.664 for RUSS, modified S-ReSC, Ito's nomogram, and R.I.R.S., respectively. Although all scoring systems were able to predict complications only Ito's nomogram was able to predict Clavien ≥2 complications.

CONCLUSION

All four scoring systems (RUSS, modified S-ReSC, Ito's nomogram, and R.I.R.S.) could predict stone-free status after f-URS, however, the AUC values are not satisfactory in our large patient cohort. Although these scoring systems were not developed for predicting post-operative complications, they were associated with complications in our study. However, these four scoring systems have some significant limitations. The ideal scoring system is yet to be developed.

Visual-electromagnetic system: A novel fusion-based monocular localization, reconstruction, and measurement for flexible ureteroscopy

BACKGROUND

During flexible ureteroscopy (FURS), surgeons may lose orientation due to intrarenal structural similarities and complex shape of the pyelocaliceal cavity. Decision-making required after initially misjudging stone size will also increase the operative time and risk of severe complications.

METHODS

A intraoperative navigation system based on electromagnetic tracking (EMT) and simultaneous localization and mapping (SLAM) was proposed to track the tip of the ureteroscope and reconstruct a dense intrarenal three-dimensional (3D) map. Furthermore, the contour lines of stones were segmented to measure the size.

RESULTS

Our system was evaluated on a kidney phantom, achieving an absolute trajectory accuracy root mean square error (RMSE) of 0.6 mm. The median error of the longitudinal and transversal measurements was 0.061 and 0.074 mm, respectively. The in vivo experiment also demonstrated the effectiveness.

CONCLUSION

The proposed system worked effectively in tracking and measurement. Further, this system can be extended to other surgical applications involving cavities, branches and intelligent robotic surgery.

External validation of the R.I.R.S. scoring system to predict stone-free rate after retrograde intrarenal surgery

Background

The R.I.R.S. scoring system is defined as a novel and straightforward scoring system that uses the main parameters (kidney stone density, inferior pole stones, stone burden, and renal infundibular length) to identify most appropriate patients for retrograde intrarenal surgery (RIRS). We strived to evaluate the accuracy of the R.I.R.S. scoring system in predicting the stone-free rate (SFR) after RIRS.

Methods

In our medical center, we retrospectively analyzed charts of patients who had, between September 2018 and December 2019, been treated by RIRS for kidney stones. A total of 147 patients were enrolled in the study. Parameters were measured for each of the four specified variables.

Results

Stone-free status was achieved in 105 patients (71.43%), and 42 patients had one or more residual fragments (28.57%). Differences in stone characteristics, including renal infundibulopelvic angle, renal infundibular length, lower pole stone, kidney stone density, and stone burden were statistically significant in patients whether RIRS achieved stone-free status or not (P < 0.001, P: 0.005, P < 0.001, P < 0.001, P: 0.003, respectively). R.I.R.S. scores were significantly lower in patients treated successfully with RIRS than patients in which RIRS failed (P < 0.001). Binary logistic regression analyses revealed that R.I.R.S. scores were independent factors affecting RIRS success (P = 0.033). The area under the curve of the R.I.R.S. scoring system was 0.737.

Conclusions

Our study retrospectively validates that the R.I.R.S. scoring system is associated with SFR after RIRS in the treatment of renal stones, and can predict accurately.

A Novel Clinical-Radiomics Model Pre-operatively Predicted the Stone-Free Rate of Flexible Ureteroscopy Strategy in Kidney Stone Patients

Purpose: The purpose of the study is to develop and validate a novel clinical-radiomics nomogram model for pre-operatively predicting the stone-free rate of flexible ureteroscopy (fURS) in kidney stone patients. Patients and Methods: Altogether, 2,129 fURS cases with kidney stones were retrospectively analyzed, and 264 patients with a solitary kidney stone were included in a further study. For lower calyx calculi, a radiomics model was generated in a primary cohort of 99 patients who underwent non-contrast-enhanced computed tomography (NCCT). Radiomics feature selection and signature building were conducted by using the least absolute shrinkage and selection operator (LASSO) method. Multivariate logistic regression analysis was employed to build a model incorporating radiomics and potential clinical factors. Model performance was evaluated by its discrimination, calibration, and clinical utility. The model was internally validated in 43 patients. Results: The overall success rate of fURS was 72%, while the stone-free rate (SFR) for lower calyx calculi and non-lower calyx calculi was 56.3 and 90.16%, respectively. On multivariate logistic regression analysis of the primary cohort, independent predictors for SFR were radiomics signature, stone volume, operator experience, and hydronephrosis level, which were all selected into the nomogram. The area under the curve (AUC) of clinical-radiomics model was 0.949 and 0.947 in the primary and validation cohorts, respectively. Moreover, the calibration curve showed a satisfactory predictive accuracy, and the decision curve analysis indicated that the nomogram has superior clinical application value. Conclusion: In this novel clinical-radiomics model, the radiomics scores, stone volume, hydronephrosis level, and operator experience were crucial for the flexible ureteroscopy strategy.

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.

Retrograde intrarenal surgery vs miniaturized percutaneous nephrolithotomy to treat lower pole renal stones 1.5-2.5 cm in diameter

AIM

To compare the outcomes of retrograde intrarenal surgery (RIRS) and miniaturized percutaneous nephrolithotomy (mini-PCNL) in treating lower pole (LP) renal stones with a diameter of 1.5-2.5 cm.

METHODS

A total of 216 patients who underwent mini-PCNL (n = 103) or RIRS n = 113) for LP stones with a diameter of 1.5-2.5 cm were enrolled between December 2015 and April 2017 at the Urology Department of Ningbo Urology and Nephrology Hospital.

RESULTS

Significant differences were found in the hospital stay (9.39 ± 4.01 vs 14.08 ± 5.26, P < 0.0001) and hospitalization costs (2624.5 ± 513.36 vs 3255.2 ± 976.5, P < 0.0001) between the RIRS and mini-PCNL groups. The mean operation time was not significantly different between the RIRS group (56.48 ± 24.77) and the mini-PCNL group (60.04 ± 30.38, P = 0.345). The stone-free rates at the first postoperative day (RIRS vs mini-PCNL: 90.2% vs 93.2%, P = 0.822) and the second month postoperatively (RIRS vs mini-PCNL: 93.8% vs 95.1%, P = 0.986) were not significantly different.

CONCLUSION

RIRS and mini-PCNL are both safe and effective methods for treating LP stones with a diameter of 1.5-2.5 cm. RIRS can be considered as an alternative to PCNL for the treatment for LP stones of 1.5-2.5 cm.

Factors affecting infectious complications following flexible ureterorenoscopy

In the present study, we aimed to clarify predictive factors that may cause postoperative infectious complications after flexible ureterorenoscopy (f-URS). In a 4-year prospective study, charts of patients who underwent f-URS between January 2014 and January 2018 for renal stone(s) in a tertiary academic center were reviewed. A standardized f-URS procedure was performed for all patients. Post-operative infectious complications including fever, sepsis and septic shock were categorized into same group. Patients with and without infectious complications were compared in the terms of preoperative, operative and post operative characteristics. In total, 463 patients who did not face infectious complications and 31 patients who faced infectious complications were enrolled into the study. The mean age was significantly lower in patients who did face infectious complications (34.8 vs 44.7 years old, p < 0.001). On the other hand, presence of renal abnormality was significantly more common in patients with infectious complications (12.3% vs 35.5%, p < 0.001). The mean operation time was 65.3 min in patients with infectious complications and significantly longer when compared with patients who did not face infectious complication (47.8 min, p < 0.001). Stone-free rate was significantly higher in patients without infectious complications (85.3% vs 77.5, p = 0.009). Multivariate regression analysis revealed that longer operation time ≥ 60 min, presence of renal abnormality and age ≤ 40 years were predictive factors for infectious complications following f-URS. The present study has demonstrated that operation time ≥ 60 min, presence of renal abnormality and patients with ≤ 40 years were significantly associated with infectious complications following f-URS.

Miniaturised percutaneous nephrolithotomy: Its role in the treatment of urolithiasis and our experience

Miniaturized percutaneous nephrolithotomy (PCNL) procedures have gained increased popularity in recent years. They aim to reduce percutaneous tract size in order to lower complication rates, while maintaining high stone-free rates. Recently, miniaturized PCNL techniques have further expanded, and can currently be classified into mini-PCNL, minimally invasive PCNL (MIP), Chinese mini-PCNL (MPCNL), ultra-mini-PCNL (UMP), micro-PCNL, mini-micro-PCNL, and super-mini-PCNL (SMP). However, despite its minimally-invasive nature, its potential superiority in terms of safety and efficacy when compared to conventional PCNL is still under debate. The aim of this review is to summarise different available modalities of miniaturized PCNL, details of instruments involved, and their corresponding safety and efficacy. In particular, this article highlights the role of the SMP and our experience with this novel technique in management of urolithiasis. Overall, miniaturized PCNL techniques appear to be safe and effective alternatives to conventional PCNL for both adult and pediatric patients. Well-designed, randomized studies are required to further investigate and identify specific roles of miniaturized PCNL techniques before considering them as standard rather than alternative procedures to conventional PCNL.