The purpose of the study was to introduce a novel surgical approach of combining laparoscopic pyelotomy with ultrasonic lithotripsy via a nephroscope for the treatment of complex renal stones. Between May 2021 and April 2023, 32 patients underwent laparoscopic pyelotomy combined with ultrasonic lithotripsy via a nephroscope and their perioperative variables were retrospectively collected and outcomes were assessed. Dissection and incision of the anterior renal pelvis wall was performed via a laparoscope. A 19.5 F nephroscope was introduced into the renal pelvis through a laparoscopic trocar from the incision. Stones were fragmented and sucked out using a 3.3 mm ultrasonic probe placed through the nephroscope. All operations were completed successfully and the stone-free rate at 3 days after operation was 87.5% (28/32). Four (12.5%, 4/32) patients with staghorn stones had a small residual stone in the lower calyx after operation and did not require reintervention. No patient required perioperative transfusion and four (12.5%, 4/32) patients with struvite stones developed postoperative fever, which was successfully treated with intravenous antibiotics. The mean follow-up time was 14.0 ± 7.2 months, with no patient developing long-term complications. This approach offers a safe and effective treatment option for complex renal stones, as the method exhibits a high clearance rate with few complications.

OBJECTIVE: To compare the efficiency and safety of a novel flexible ureteral access sheath (f-UAS) and traditional ureteral access sheath (UAS) during retrograde intrarenal surgery (RIRS).
METHODS: Between January 2022 and September 2022, a total of 152 consecutive cases with renal stones underwent RIRS with the f-UAS. Their outcomes were compared with those of another 152 consecutive cases undergoing RIRS with traditional UAS using a 1:1 scenario matched-pair analysis, with matching parameters including age and stone size. The f-UAS is a novel UAS with a 10-cm-long tube at the tip that can follow the bends of flexible ureteroscope (f-URS).
RESULTS: Baseline characteristics were found to be similar between the two groups. The f-UAS group demonstrated significantly higher SFR (76.3% vs. 7.2%; P < 0.001) at 1 day postoperatively and a higher clearance rate of stone volume (98.11% vs. 91.78%; P < 0.001). The f-UAS group also had lower total complications rate (9.9% vs. 22.4%; P = 0.003), lower incidence of fever (5.9% vs 11.9%; P = 0.001), shorter operative times (56.5 min vs. 59.9 min; P = 0.047), and lower usage rate of baskets (17.1% vs. 100%; P < 0.001). There was no significant difference in SFR at 1 month postoperatively (P = 0.627) and in the length of postoperative hospital stay between the two groups (P = 0.225).
CONCLUSIONS: Compared to the traditional UAS during RIRS, the f-UAS showed several advantages, including higher SFR at 1 day postoperatively, shorter operative times, lower incidence of complications, and less use of basket.

OBJECTIVE: To assess and compare the effectiveness and safety of flexible ureteroscopy (f-URS) with a novel flexible ureteral access sheath (f-UAS) versus mini-percutaneous nephrolithotripsy (mini-PCNL) in treating 2-3 cm renal stones.
METHODS: Retrospectively analyzed consecutive cases that underwent f-URS with f-UAS (12/14 Fr) from January 29, 2022, to November 30, 2022. Consecutive cases that underwent mini-PCNL (18 Fr) from June 5, 2021, to January 26, 2022, were selected as controls. The f-UAS is a novel device with a 10 cm anterior tip that passively bends along with the f-URS to enter the renal calyx. We analyzed demographic characteristics, stone parameters, operative time, stone-free rates (SFR), hospitalization time, and complication.
RESULTS: A total of 96 consecutive cases that underwent f-URS with f-UAS and 96 consecutive cases that underwent mini-PCNL were included in the study. There were no significant differences between the two groups in terms of operative time (p = 0.06), stone volume clearance (p = 0.533) and complete SFR (p = 0.266) on the first postoperative day or residual Stone after 1 month (p = 0.407). We observed a significantly shorter postoperative hospital stay (1.4 days vs. 2.1 days; p < 0.001) and a lower decrease in hemoglobin levels (0.39 g/dL vs. 0.68 g/dL; p < 0.001) in the f-UAS group. The mini-PCNL group had a significantly higher overall complication rate (13.5%) compared with the f-UAS group (5.2%; p = 0.048).
CONCLUSIONS: In the treatment of 2-3 cm renal stones, f-URS with a novel f-UAS may provide a superior alternative to mini-PCNL, potentially challenging its established status.

BACKGROUND: There has been a consistent increase in the last decades in prevalence of renal stones in elderly.
OBJECTIVE: To evaluate outcomes of retrograde intrarenal surgery (RIRS) for renal stones in elderly and factors associated with postoperative complications and residual fragments (RFs).
METHODS: Data from 12 centers were retrospectively reviewed.
METHODS:  ≥ 75 years, renal stones only, normal renal anatomy. Patients were divided into three groups; Group 1: patients aged 75-79 years; Group 2: age 80-84 years; Group 3: age ≥ 85 years. Multivariable logistic regression analyses were performed to assess factors associated with perioperative complications, sepsis, and RFs.
RESULTS: 366 patients were included. There were 189 patients in Group 1, 113 in Group 2, and 64 in Group 3. There was no difference between groups regarding stone features and total surgical time. Median length of stay was significantly longer in Group 3 (6.0 days, vs 2.0 days in Group 2 vs 2.5 days in Group 1, p = 0.043). There was no significant difference in postoperative complications and RFs between the groups. At multivariable logistic regression analysis, female gender (OR 2.82) and maximum stone diameter (OR 1.14) were associated with higher odds of sepsis, while surgical time (OR 1.12) and the use of a reusable ureteroscope (OR 6.51) with overall complications. Stone size (OR 1.23) was associated with higher odds of RFs.
CONCLUSIONS: RIRS showed safety and efficacy for kidney stones in elderly patients. Surgical time should be kept as short as possible to avoid higher odds of postoperative complications, particularly in females.

UNASSIGNED: Several reports in recent years have found an association between gut microbiota and upper urinary urolithiasis. However, the causal relationship between them remains to be clarified.
UNASSIGNED: Genetic variation is used as a tool in Mendelian randomization for inference of whether exposure factors have a causal effect on disease outcomes. We selected summary statistics from a large genome-wide association study of the gut microbiome published by the MiBioGen consortium with a sample size of 18,340 as an exposure factor and upper urinary urolithiasis data from FinnGen GWAS with 4,969 calculi cases and 213,445 controls as a disease outcome. Then, a two-sample Mendelian randomization analysis was performed by applying inverse variance-weighted, MR-Egger, maximum likelihood, and weighted median. In addition, heterogeneity and horizontal pleiotropy were excluded by sensitivity analysis.
UNASSIGNED: IVW results confirmed that class Deltaproteobacteria (OR = 0.814, 95% CI: 0.666-0.995, P = 0.045), order NB1n (OR = 0.833, 95% CI: 0.737-0.940, P = 3.15 × 10-3), family Clostridiaceae1 (OR = 0.729, 95% CI: 0.581-0.916, P = 6.61 × 10-3), genus Barnesiella (OR = 0.695, 95% CI: 0.551-0.877, P = 2.20 × 10-3), genus Clostridium sensu_stricto_1 (OR = 0.777, 95% CI: 0.612-0.986, P = 0.0380), genus Flavonifractor (OR = 0.711, 95% CI: 0.536-0.944, P = 0.0181), genus Hungatella (OR = 0.829, 95% CI: 0.690-0.995, P = 0.0444), and genus Oscillospira (OR = 0.758, 95% CI: 0.577-0.996, P = 0.0464) had a protective effect on upper urinary urolithiasis, while Eubacterium xylanophilum (OR =1.26, 95% CI: 1.010-1.566, P = 0.0423) had the opposite effect. Sensitivity analysis did not find outlier SNPs.
UNASSIGNED: In summary, a causal relationship was found between several genera and upper urinary urolithiasis. However, we still need further randomized controlled trials to validate.

Objectives: To compare the outcomes of using low-power (up to 30 W) vs high-power (up to 120 W) holmium lasers in retrograde intrarenal surgery (RIRS) in children and to analyze if lasering techniques and the use of access sheath have any influence on the outcomes. Methods: We retrospectively reviewed data from 9 centers of children who underwent RIRS with holmium laser for the treatment of kidney stones between January 2015 and December 2020. Patients were divided into two groups: high-power and low-power holmium laser. Clinical, perioperative variables and complications were analyzed. Outcomes were compared between groups using Student\'s t-test for continuous variables, and Chi-square and Fisher\'s exact test for categorical variables. A multivariable logistic regression analysis model was also performed. Results: A total of 314 patients were included. A high-power and low-power holmium laser was used in 97 and 217 patients, respectively. Clinical and demographic variables were comparable between both groups, except for stone size where the low-power group treated larger stones (mean 11.11 vs 9.70 mm, p = 0.018). In the high-power laser group, a reduction in surgical time was found (mean 64.29 vs 75.27 minutes, p = 0.018) with a significantly higher stone-free rate (SFR) (mean 81.4% vs 59%, p < 0.001). We found no statistical differences in complication rates. The multivariate logistic regression model showed lower SFR in the low-power holmium group, especially with larger (p = 0.011) and multiple stones (p < 0.001). Conclusion: Our real-world pediatric multicenter study favors high-power holmium laser and establishes its safety and efficacy in children.

The management of children with concomitant ureteropelvic junction (UPJ) obstruction and calyceal stones remains challenging. The various treatment options available for pediatric nephrolithiasis may require multiple sessions, and the techniques by themselves are not designed for simultaneous correction of UPJ obstruction. Recently, success in combining robot-assisted laparoscopic pyeloplasty (RALP) and flexible endoscopy has been reported by multi-institutional studies to treat children with concomitant UPJ obstruction and renal stones. Given the paucity of technical details of this novel approach in the existing literature, we herein report our techniques to treat two girls aged 6 and 10 years who had concomitant UPJ obstruction and multiple stones in mid- and lower poles calyces. Three robotic ports were used without any assistant ports. A flexible endoscope, either a cystoscope or a single-use ureteroscope, was introduced via the undocked epigastric port to perform nephroscopy and stones removal after the renal pelvis was opened. The rest of the RALP was completed in the usual manner. Technical modifications were employed to facilitate the flexible endoscope to examine the entire calyceal system. Both patients underwent successful surgical procedures by the combined approach without any intra- or post-operative complications. Three and 14 stones were removed from each of the patients respectively. Postoperative investigations demonstrated successful correction of UPJ obstruction and complete stone clearance in both patients. A combined approach of RALP and flexible endoscopy is a safe and effective technique to treat concurrent UPJ obstruction and calyceal stones in children.

Polyunsaturated fatty acids (PUFAs) can decrease the risk of calcium oxalate stone formation, which accounts for 80% of all renal stones. This study aimed to investigate the protective mechanisms of PUFAs against renal stones.
Urine samples of patients with renal stones and biopsy tissue samples from patients with nephrocalcinosis were tested for miR-93-5p expression. A renal stone mouse model was established with intraperitoneal injection of glyoxylic acid, during which mice were treated with PUFAs and/or an miR-93-5p inhibitor adenovirus. Periodic acid-Schiff staining, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling staining, oil red O staining, triacylglycerol assay, and colorimetry testing were performed to assess glycogen deposition, apoptosis, lipid accumulation, blood urea nitrogen, and serum creatinine levels, respectively. Renal proximal tubular epithelial cells (human kidney 2 [HK-2]) were subjected to gain- and loss-of-function assays before calcium-oxalate monohydrate (COM) induction and PUFA treatment. Cell counting kit 8, flow cytometry, and lactate dehydrogenase activity assays were used to examine cell viability, apoptosis, and damage. A luciferase reporter gene assay verified the interaction between miR-93-5p and Pknox1, and miR-93-5p and Pknox1 levels were assessed using a reverse transcription-quantitative polymerase chain reaction and Western blot analysis.
miR-93-5p was downregulated in clinical samples with renal stones and negatively targeted Pknox1. PUFAs increased miR-93-5p expression and reduced apoptosis, glycogen deposition, and lipid accumulation in mice with renal stones, which were annulled by miR-93-5p downregulation. PUFAs increased proliferation and diminished apoptosis, lipid accumulation, and lactate dehydrogenase activity in COM-induced HK-2 cells, which were negated by miR-93-5p inhibition. Pknox1 overexpression reversed the effect of miR-93-5p upregulation on COM-induced HK-2 cells.
PUFAs repressed renal stone-induced renal tubular damage via the miR-93-5p/Pknox1 axis.

Retrograde intrarenal surgery (RIRS) is accepted as a primary modality for the management of renal stones up to 2 cm. The limitations of RIRS in larger volume stones include limited visualization due to the snow-globe effect and persistence of fragments that cannot be removed. We describe a new, simple, cost-effective modification that can be attached to any flexible ureteroscope which allows simultaneous/alternating suction and aspiration during/after laser lithotripsy using the scope as a conduit to remove the fragments or dust from the pelvicalyceal system called direct in-scope suction (DISS) technique. Between September 2020 and September 2021, 30 patients with kidney stones underwent RIRS with the DISS technique. They were compared with 28 patients who underwent RIRS with a 11Fr/13Fr suction ureteral access sheaths (SUASs) in the same period. RIRS and laser lithotripsy were carried out traditionally with a Holmium laser for the SUAS group or a thulium fiber laser for the DISS group. There was no difference in age, gender, and history of renal lithiasis between the two groups. Ten (40%) patients had multiple stones in the DISS groups, whilst there were no patients with multiple stones in the SUAS group. Median stone size was significantly higher in the DISS group [22.0 (18.0−28.8) vs. 13.0 (11.8−15.0) millimeters, p < 0.001]. Median surgical time was significantly longer in the DISS group [80.0 (60.0−100) minutes] as compared to the SUAS group [47.5 (41.5−60.3) minutes, p < 0.001]. Hospital stay was significantly shorter in the DISS group [1.00 (0.667−1.00) vs. 1.00 (1.00−2.00) days, p = 0.02]. Postoperative complications were minor, and there was no significant difference between the two groups. The incidence of residual fragments did not significantly differ between the two groups [10 (33.3%) in the DISS group vs. 10 (35.7%) in the SUAS group, p = 0.99] but 10 (33.3%) patients required a further RIRS for residual fragments in the DISS group, whilst only one (3.6%) patient in the SUAS group required a subsequent shock wave lithotripsy treatment. Our audit study highlighted that RIRS with DISS technique was feasible with an acceptable rate of retreatment as compared to RIRS with SUAS.

The introduction of robotics has revolutionized surgery. Robotic platforms have also recently been introduced in clinical practice specifically for flexible ureteroscopy. In this paper, we look at the robotic platforms currently available for flexible ureteroscopy, describing their advantages and limitations. The following robotic platforms are discussed: Roboflex Avicenna®, EasyUretero®, and ILY® robot. Finally, potential future advancements in this field are presented.