Preoperative double-J stent placement can improve the stone-free rate for patients undergoing ureteroscopic lithotripsy: a systematic review and meta-analysis

The effect of preoperative ureteral stenting on the outcomes and complications of pediatric ureteroscopy: A systematic review and meta-analysis

INTRODUCTION

Small ureteral caliber may prohibit safe primary ureteroscopy (URS), particularly in children. Pre-stenting was proposed to passively dilate the ureter for later safer ureteral access. This meta-analysis aims to analyze outcomes of both primary and deferred ureteroscopy after a period of pre-stenting.

METHODS

PubMed, Scopus, Cochrane Library, and Web of Science were searched for studies comparing outcomes of primary and deferred ureteroscopy in children younger than 18 years with ureteral and/or renal stones. Outcomes of interest were stone free rate (SFR), complication rates, ureteral injury, urinary tract infection (UTI), operative time, stone migration, postoperative stenting use and ureteral access sheath use.

RESULTS

Four studies encompassing 826 patients were included. When attempted, primary ureteroscopic access was successful in 69-83 % of patients. SFR was higher in the pre-stenting group (OR 0.87, 95 % CI [0.81-0.94], P = 0.0005). No significant difference was found between the two groups in terms of the overall complications rate (RR 1.66, 95 % CI [0.93-2.96], P = 0.09), ureteral injury (RR 3.67, 95 % CI [0.43-31.66], P = 0.24) febrile UTI (RR 0.62 (95 % CI [0.15 to 2.5], P = 0.5), use of postoperative stent (OR 0.86, 95 % CI [0.52-1.44], P = 0.58), use of ureteral access sheath (RR 0.94 (95 % CI [0.73 to 1.22], P = 0.65), or stone migration (RR 2.28 (95 % CI [0.48 to 10.80], P = 0.30).

CONCLUSION

Although pre-stenting is associated with a relatively higher SFR, primary URS is successful in most pediatric patients without increased complication risk. We advocate primary URS whenever possible to allow stone treatment under a single anesthetic and minimize healthcare costs.

A Machine Learning Predictive Model for Ureteroscopy Lasertripsy Outcomes in a Pediatric Population-Results from a Large Endourology Tertiary Center

Introduction: We aimed to develop machine learning (ML) algorithms for the automated prediction of postoperative ureteroscopy outcomes for pediatric kidney stones based on preoperative characteristics. Materials and Methods: Data from pediatric patients who underwent ureteroscopy for stone treatment by a single experienced surgeon, between 2010 and 2023 in Southampton General Hospital, were retrospectively collected. Fifteen ML classification algorithms were used to investigate correlations between preoperative characteristics and postoperative outcomes: primary stone-free status (SFS, defined as stone fragments <2 mm at the end of the procedure confirmed endoscopically and no evidence of stone fragments >2 mm at Xray kidney-ureters-bladder (XR KUB) or ultrasound kidney-ureters-bladder (US KUB) at 3 months follow-up) and complications. For the task of complication and stone status, an ensemble model was made out of Bagging classifier, Extra Trees classifier, and linear discriminant analysis. Also, a multitask neural network was constructed for the simultaneous prediction of all postoperative characteristics. Finally, explainable artificial intelligence techniques were used to explain the prediction made by the best models. Results: The ensemble model produced the highest accuracy (90%) in predicting SFS, finding correlation with overall stone size (-0.205), presence of multiple stones (-0.127), and preoperative stenting (-0.102). Complications were predicted by Synthetic Minority Oversampling Technique (SMOTE) oversampled dataset (93.3% accuracy) with relation to preoperative positive urine culture (-0.060) a1nd SFS (0.003). Training ML for the multitask model, accuracies of 83.3% and 80% were respectively reached. Conclusion: ML has a great potential of assisting health care research, with possibilities to investigate dataset at a higher level. With the aid of this intelligent tool, urologists can implement their practice and develop new strategies for outcome prediction and patient counseling and informed shared decision-making. Our model reached an excellent accuracy in predicting SFS and complications in the pediatric population, leading the way to the validation of patient-specific predictive tools.

Can Machine Learning Correctly Predict Outcomes of Flexible Ureteroscopy with Laser Lithotripsy for Kidney Stone Disease? Results from a Large Endourology University Centre

Background and objective

The integration of machine learning (ML) in health care has garnered significant attention because of its unprecedented opportunities to enhance patient care and outcomes. In this study, we trained ML algorithms for automated prediction of outcomes of ureteroscopic laser lithotripsy (URSL) on the basis of preoperative characteristics.

Methods

Data were retrieved for patients treated with ureteroscopy for urolithiasis by a single experienced surgeon over a 7-yr period. Sixteen ML classification algorithms were trained to investigate correlation between preoperative characteristics and postoperative outcomes. The outcomes assessed were primary stone-free status (SFS, defined as the presence of only stone fragments <2 mm on endoscopic visualisation and at 3-mo imaging) and postoperative complications. An ensemble model was constructed from the best-performing algorithms for prediction of complications and for prediction of SFS. Simultaneous prediction of postoperative characteristics was then investigated using a multitask neural network, and explainable artificial intelligence (AI) was used to demonstrate the predictive power of the best models.

Key findings and limitations

An ensemble ML model achieved accuracy of 93% and precision of 87% for prediction of SFS. Complications were mainly associated with a preoperative positive urine culture (1.44). Logistic regression revealed that SFS was impacted by the total stone burden (0.34), the presence of a preoperative stent (0.106), a positive preoperative urine culture (0.14), and stone location (0.09). Explainable AI results emphasised the key features and their contributions to the output.

Conclusions and clinical implications

Technological advances are helping urologists to overcome the classic limits of ureteroscopy, namely stone size and the risk of complications. ML represents an excellent aid for correct prediction of outcomes after training on pre-existing data sets. Our ML model achieved accuracy of >90% for prediction of SFS and complications, and represents a basis for the development of an accessible predictive model for endourologists and patients in the URSL setting.

Patient summary

We tested the ability of artificial intelligence to predict treatment outcomes for patients with kidney stones. We trained 16 different machine learning tools with data before surgery, such as patient age and the stone characteristics. Our final model was >90% accurate in predicting stone-free status after surgery and the occurrence of complications.

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.

Primary Ureteroscopy without Pre-Stenting for Proximal Ureteral Stones-Is It Feasible?

BACKGROUND

Primary ureteroscopy with laser lithotripsy is the treatment of choice for distal ureteral stones. However, in cases of proximal ureteral stones, some urologists recommend the preliminary insertion of a ureteral stent and deferred ureteroscopy. We aimed to evaluate the necessity of preliminary ureteral stent insertion in the management of proximal ureteral stones by comparing the surgical outcomes of patients undergoing primary ureteroscopy with laser lithotripsy for proximal vs. distal ureteral stones.

METHODS

Medical records of patients who underwent ureteroscopy between 2016 and 2017 in our institution were retrospectively reviewed. Data collected included demographic data, stone size, renal function, intra- and post-operative complications, and stone-free rate (SFR). Patients were divided into two groups: proximal ureteral stones and distal ureteral stones.

RESULTS

The cohort included 241 patients who underwent ureteroscopy. Among them, 106 had a proximal ureteral stone. The median age was 51 (IQR 41-65) years. Patients who underwent ureteroscopy for proximal ureteral stones were significantly older (p = 0.007). The median stone's maximal diameter was 7 (5-10) mm. The complication rate and stone-free rate (SFR) were similar in both groups (p = 0.657 and p = 1, respectively). The prevalence of post-procedural ureteral stent insertion was higher among patients who underwent ureteroscopy for proximal ureteral stones: 92.5% vs. 79.3% (p = 0.004).

CONCLUSIONS

Our study concludes that primary ureteroscopy with laser lithotripsy for proximal ureteral stones is a valid and feasible treatment with a similar surgical outcome compared to distal ureteral stones. Preliminary ureteral stent insertion seems to be unnecessary.

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.

Retrograde Intrarenal Surgery in Children: Evolution, Current Status, and Future Trends

Introduction: Incidence of urolithiasis in children has increased in recent years and with technological advancements and miniaturization of surgical instruments, pediatric urologists have acquired an impressive arsenal for their treatment. Retrograde intrarenal surgery (RIRS) has gained widespread popularity as it is a natural extension of semirigid ureteroscopy and can be done through natural orifice minimizing the morbidity of percutaneous access. The aim of this narrative review is to describe how RIRS has evolved over the decades in children and if the age-related anatomical difference impacts reported outcomes especially stone-free rate (SFR) and complications. Materials and Methods: An electronic literature search from inception to October 15, 2021 was performed using Medical Subject Heading terms in several combinations on PubMed, EMBASE, and Web of Science without language restrictions. A total of 2022 articles were founded and 165 articles were full-text screening. Finally, 2 pediatric urologists included 51 articles that summarize the available literature regarding the development and use of RIRS in children. Results: RIRS as of today is well established as a superior modality for all stones in all locations compared with extracorporeal shockwave lithotripsy both in children and adults. The passive dilation has decreased the need of active ureteral dilation, but the need to perform prestenting is not defined yet. Regarding the use of the ureteral access sheath, the literature tends to lean toward its placement in most cases, but we do not know its long-term effects over the growth of children. Finally, the SFR has increased as the experience of pediatric urologists increases, as well as the number of complications has decreased. Conclusion: RIRS in pediatrics has crossed many milestones, yet many areas need further research and larger data are required to make RIRS the procedure of choice for renal stone management in children across all age groups.

Development of a novel predictive model for a successful stone removal after flexible ureteroscopic lithotripsy based on ipsilateral renal function: a single-centre, retrospective cohort study in China

OBJECTIVES

The aims of this study were to investigate the effect of preoperative ipsilateral renal function on the success of kidney stone removal with flexible ureteroscopic lithotripsy and to develop a predictive model based on the results.

DESIGN

Retrospective cohort study.

SETTING

Data from the 2001-2012 period were collected from the electronic records of West China Hospital, Sichuan University.

PARTICIPANTS

576 patients who underwent flexible ureteroscopic lithotripsy were included in the study.

PRIMARY OUTCOME

Stone-free rate (SFR) after the procedures.

RESULTS

In patients with suspected impaired kidney function, the overall SFR was 70.1%. Stone volume (OR 1.46; 95% CI 1.18 to 1.80), lower calyx stones (OR 1.80; 95% CI 1.22 to 2.65), age (OR 1.02; 95% CI 1.00 to 1.04), body mass index (OR 1.10; 95% CI 1.04 to 1.17) and estimated glomerular filtration rate of the affected kidney (OR 0.95; 95% CI 0.94 to 0.97) were identified as independent predictors of SFR. Lasso regression selected the same five predictors as those identified by univariate and multivariate logistic regression analyses, thus verifying our model. The mean area under the curve, based on 1000 iterations and 10-fold validation, was 0.715 (95% CI 0.714 to 0.716). The Hodges-Lehmann test and calibration curve analysis revealed no significant mismatch between the prediction model and the retrospective cohort.

CONCLUSION

Ipsilateral renal function may be a novel independent risk factor for kidney stone removal with flexible ureteroscopic lithotripsy. A novel nomogram for predicting SFR that uses stone volume, lower calyx stones, age, body mass index and estimated glomerular filtration rate was developed, but remains to be externally validated.

Effectiveness and Safety of Ureteroscopic Lithotripsy in Young, Old-Old, and Oldest Old Patients

Objectives: To investigate the efficacy and safety of ureteroscopic lithotripsy (URSL) in young, old-old, and oldest old patients. Materials and Methods: We enrolled 157 patients who underwent URSL. We divided the patients into young (<65 years), old-old (65-84 years), and oldest old (≥85 years) groups and compared the safety of surgery between young vs old-old and young vs oldest old, separately. Results: In the <65 group, 65 to 85 group, and ≥85 group, respectively, the mean stone diameters were 8.9 ± 4.9, 10.8 ± 7.7, and 11.4 ± 6.3 mm; mean operative time was 76.6 ± 33.1, 86.7 ± 44.7, and 84.0 ± 44.5 min; the stone-free rates were 95.9%, 94.4%, and 96.3%; and the complication rates were 8.2%, 9.8%, and 3.7%. Conclusions: In this study, we showed the feasibility and safety of URSL for elderly people. Although oldest old (≥85 years) people had multiple comorbidities with low performance status, URSL could be performed with acceptable complication rates. Clinical Trial Registration Number: 1809-1.

The impact of preoperative percutaneous nephrostomy as a treatment strategy before flexible ureteroscopy for impacted upper ureteral stones with hydronephrosis

Background

The treatment of impacted upper ureteral stones with hydronephrosis remains a challenge for urologists. The current study aimed to evaluate the impact of preoperative percutaneous nephrostomy (PNS) as a treatment strategy before flexible ureteroscopy (f-URS) of asymptomatic impacted upper ureteral stones with hydronephrosis.

Methods

This multicenter retrospective study included patients who underwent PNS (group A, n=61) and those who did not (group B, n=75) before f-URS for asymptomatic impacted upper ureteral stones with hydronephrosis. Impacted ureteral stones are defined as those that remain in one position for >2 months. Operative outcomes, including stone-free rate, operation time, postoperative hospital days, and complication rate, were evaluated.

Results

There were no significant differences in age, sex, and stone size between the two groups except in the grade of hydronephrosis, with group A having more cases of advanced hydronephrosis than group B. The stone-free rate was significantly higher in group A than in group B [95% vs. 77% (P=0.004)]. However, there were no significant differences between the groups in operation time [55 vs. 55 min (P=0.84)], postoperative fever [5% vs. 5% (P=1.00)], and postoperative hospital days [2 vs. 2 days (P=0.44)]. In group A, preoperative PNS placement was performed 4 days before f-URS, and the PNS was removed postoperatively on the same day of the f-URS. Additionally, subgroup analysis was performed in cases of grade 2 and 3 hydronephrosis. A total of 110 patients, 60 who underwent f-URS with PNS and 50 who underwent f-URS without PNS, were included. The stone-free rate was significantly higher in f-URS with PNS than in f-URS without PNS [95% vs. 76% (P=0.005)]. However, no significant differences were found between the groups in operation time, ureteral injury, postoperative fever, and postoperative hospital days.

Conclusions

At grade 2 or 3 hydronephrosis, preoperative PNS as a treatment strategy for a few days prior to f-URS for impacted upper ureteral stones improved the stone-free rate without increasing the operation time and postoperative length of hospital stay.

The Outcomes of Pre-Stenting on Renal and Ureteral Stones: A Meta-Analysis

BACKGROUND

Pre-stenting (PS) on the outcomes of semirigid and flexible ureteroscopic lithotripsy for a different upper urinary urolithiasis remains controversial. We performed a meta-analysis comparing the outcomes of ureteroscopic lithotripsy between PS and non-PS.

MATERIALS AND METHODS

Randomized, controlled trials and observational studies comparing PS and non-PS were identified from electronic databases. Stone-free rate (SFR), operative time, and complications were compared by qualitative and quantitative syntheses (meta-analyses).

RESULTS

Eleven articles were included in this study. Nearly, all of recently published studies exhibited relatively moderate or high quality during quality assessment. PS was more likely to achieve good SFR compared with non-PS (p < 0.00001). The subgroup results indicated that PS improved the SFR for renal stones and the stones dealt by flexible ureteroscopy (p = 0.0002; p < 0.0001, respectively; some ureteral stones were dealt by flexible ureteroscopy). Ureteral stones and the stones dealt by semirigid ureteroscopy were not influenced by PS (p = 0.62; p = 0.90, respectively). PS is equal as non-PS in terms of operative time for renal stones and the renal and ureteral stones dealt by flexible ureteroscopy (p = 0.47; p = 0.05). No significant difference was found in major complications between the 2 groups for total or for the subgroup of renal stones (p = 0.3; p = 0.69).

CONCLUSIONS

For ureteral stones or the stones dealt by semirigid ureteroscopy, PS does not show any benefits. For renal stones or the stones dealt by flexible ureteroscopy, PS improves the SFR and may be as safe as non-PS.

Does ureteral access sheath affect the outcomes of retrograde intrarenal surgery: a prospective study

OBJECTIVES

To evaluate whether or not using a ureteral access sheath (UAS) affects the perioperative outcomes after retrograde intrarenal surgery (RIRS) performed in patients with renal stones.

MATERIAL AND METHODS

An observational study was carried out using data of 60 patients who underwent RIRS with the diagnosis of renal stones <2 cm between February 2017 and November 2017 at our institution. The data of the 60 patients were registered prospectively during the study period. Patients were divided into two groups based on whether a UAS was used (Group 1-30 patients) or not (Group 2-30 patients) during RIRS. Perioperative outcomes and complications were collected and analyzed.

RESULTS

The stone burdens of the patients in Group 1 and in Group 2 were 76.59 mm² and 62.19 mm², respectively (p = .160). There was no statistically significant difference in SFR (p = 1.000), complication rates (p = .418), and operation time (p = .411) between both groups, except for the fact that postoperative pain intensity levels using the VAS were slightly higher in Group 2 (4.13 ± 2.37 vs. 5.33 ± 1.89, p = .064).

CONCLUSIONS

In the present study, we showed that similar success and acceptable complication rates can be achieved without using UAS compared to using UAS during RIRS. However, using UAS may provide an advantage in reducing postoperative pain after RIRS.

Optimal timing of ureteroscopic lithotripsy after the initial drainage treatment and risk factors for postoperative febrile urinary tract infection in patients with obstructive pyelonephritis: a retrospective study

Background

A history of preoperative obstructive pyelonephritis has been reported as a risk factor for febrile urinary tract infection (fUTI) after ureteroscopic lithotripsy (URSL). But there is no clear evidence of risk factors for developing fUTI including the optimal timing of URSL after obstructive pyelonephritis treatment.

Methods

Of the 1361 patients, who underwent URSL at our hospital from January 2011 to December 2017, 239 patients had a history of pre-URSL obstructive pyelonephritis. The risk factors were analyzed by comparing the patients’ backgrounds with the presence or absence of fUTI after URSL. The factors examined were age, gender, body mass index, comorbidity, presence or absence of preoperative ureteral stent, stone position, stone laterality, stone size, Hounsfield unit (HU) value on computed tomography scan, history of sepsis during obstructive pyelonephritis, period from antipyresis to URSL, ureteral stenting period, operation time, and presence or absence of access sheath at URSL. In addition, the stone components and renal pelvic urinary culture bacterial species during pre-URSL pyelonephritis were also examined.

Results

Post-URSL fUTI developed in 32 of 239 patients (13.4%), and 11 of these 32 cases led to sepsis (34.4%). Univariate analysis showed that stone position, stone maximum HU value, presence of sepsis during obstructive pyelonephritis, period from antipyresis to URSL, pre-URSL ureteral stent placement, operation time were risk factors of fUTI. Stone components and urinary cultures during pyelonephritis were not associated with risk of fUTI. Multivariate analysis showed that renal stone position, pre-URSL ureteral stent placement > 21 days, and operation time > 75 min were independent risk factors of fUTI following the URSL.

Conclusions

F-UTI following the URSL could be avoided by ureteral stent placement period 21 days or less and operation time 75 min or less in patients with obstructive pyelonephritis.

Preoperative positive urine nitrite and albumin-globulin ratio are independent risk factors for predicting postoperative fever after retrograde Intrarenal surgery based on a retrospective cohort

Background

To determine risk factors for postoperative fever (POF) after retrograding intrarenal surgery (RIRS) and a nomogram for prediction of POF in patients undertaking RIRS has been developed based on the risk factors found.

Methods

This is a retrospective designed-study. A continuous cohort from a single-center database that consisted of 1095 cases undertaking RIRS with complete preoperative medical records from January 2009 to December 2018 was obtained. Independent risk factors were identified according to the multi-variate logistics regression and a further nomogram was developed. The performance of the nomogram was evaluated through three aspects including net clinical benefit, calibration, and discrimination.

Results

A total of 31(2.8%) cases had POF after the RIRS. Risk factors included time in RIRS ≥30mins (only the flexible scope use period) (OR: 2.16, 95%CI; 1.01–4.62, P = 0.047), preoperative positive urine culture (OR: 2.55, 95%CI; 1.01–6.42, P = 0.047), preoperative positive urine nitrite (OR: 9.09, 95%CI; 2.99–27.64, P < 0.001), Albumin/globulin ratio (AGR) (OR: 0.14, 95%CI; 0.03–0.74, P = 0.020) were further included in the nomogram to predict the POF probability for individuals. The Hosmer-Lemeshow test showed a goodness-of-fit. The calibration curve demonstrated good agreement between observation and prediction. Decision curve analysis (DCA) demonstrated it was clinical use in RIRS.

Conclusions

The preoperative urine nitrite, AGR, RIRS time, and preoperative urine culture are found to be independent risk factors associated with POF after RIRS. Then we have developed a nomogram taking these factors into account that accurately predicted POF after RIRS.

The role of preoperative ureteral stenting in retrograde intrarenal surgery in renal stone patients: a propensity score-matched study

Background

The purpose of this study was to investigate the effect of preoperative ureteral stenting on retrograde intrarenal surgery (RIRS).

Methods

We retrospectively analyzed RIRS cases from October 2014 to June 2017. Patients were divided into two groups according to preoperative ureteral stent insertion. The characteristics of the patients [age, body mass index (BMI), sex, previous disease history, hemoglobin, creatinine, estimated glomerular filtration rate (eGFR)], characters of stone (size, number, density, location), ureteral access sheath (UAS) success rate, perioperative complication, operative time, hospitalization time, period with stent, postoperative urinary tract infection (UTI) rate, stone free rate (SFR), and additional treatment rate were analyzed.

Results

RIRS was performed for 122 patients. Seventy-three patients had preoperative ureteral stents before RIRS, while 49 patients did not have preoperative ureteral stents. The median size of the stone was 14.5 mm. Overall SFR was 87.7%. Preoperative eGFR was relatively high in patients who underwent preoperative stenting (68.18 vs. 79.01 mL/min/1.73 m², P=0.042). Preoperative stenting led to improvement in the success rate of UAS insertion (97.3% vs. 87.8%, P=0.038) during surgery. Before and after propensity score matching revealed a significant difference in operation time when the diameter of the stone was smaller than 1 cm (P=0.019 and P=0.004). However, there was no significant difference in operation time, postoperative UTI rate, additional treatment rate, or SFR.

Conclusions

Preoperative ureteral stenting can facilitate UAS insertion, and reduce operation time in RIRS for stones with a diameter less than 1 cm.

Ureteroscopy: a population based study of clinical complications and possible risk factors for stone surgery

Introduction

The aim of this study was to describe the complications of ureteroscopy (URS) and to investigate whether performing URS outside normal working hours leads to increased risk for clinically significant complications.

Material and methods

A cohort of 486 consecutive patients treated with URS, with a total of 567 sessions between 2009 and 2015 at Helsingborg/Ängelholm Hospital, Sweden, was analyzed. Outcome was complications within 14 days after URS treatment.

Results

We found no increased risk of complications related to URS performed outside normal working hours. Stone-free rate (SFR) in the distal third of the ureter was 95.2% (315/331), in the middle ureter 92.8% (90/97), in the proximal ureter 84.0% (63/75) and 69.0% (40/58) in renal pelvis. The overall complication rate was 10.6% (n = 60). None of the potential risk factors for complications showed any significance when adjusted for age and gender. We found an inverse relationship between stenting and SFR (p = 0.002). The most common preoperatively cultured bacteria was Escherichia coli. With adequate antibiotics, there was no increased risk of complications. There was an increased risk of complications after URS related to age, but not with gender.

Conclusions

URS in modern setting provides excellent results with adequate SFR and low morbidity. Time of day, the presence of urological specialized operating nurses did not affect the risk of complications and we found no other significant risk factors for complications. Escherichia coli was the most commonly found bacteria in preoperative cultures. The risk of complications increases with age. For patients >65 years old, this should be considered in preoperative counseling.

Ureteral stents in urolithiasis

Ever since the ureteral stent design was fitted with a curl on both sides to prevent it from migrating up or down the ureter some 40 years ago, its use has gained tremendous momentum, aiding in the rise and evolution of endourology and has confidently kept its place in modern time urology. Over the past four decades, several designs, coating and biomaterials have been developed, trying to reduce infection, encrustation and other stent related symptoms. As the ideal stent has not yet been discovered, different ways of helping patients with their complaints have been researched. This review will cover these aspects of stent use in urolithiasis.