Risk Factors of Infectious Complications after Ureteroscopy: A Systematic Review and Meta-Analysis Based on Adjusted Effect Estimate

Risk Factors for Adverse Outcomes Following Ureteroscopy for Stone Management in US Medicare Patients

OBJECTIVE

To evaluate the proportion of US Medicare patients undergoing ureteroscopy (URS) for kidney stone management at risk for adverse outcomes and analyze the association between risk factors and adverse events.

METHODS

Data from Medicare patients aged ≥65 who underwent URS between 2019 and 2023 were analyzed. Nine risk factors were examined for their prevalence and association with sepsis and intensive care unit (ICU) admission within 30 days, extended length of stay (LOS) during the index procedure, and death within 90 days.

RESULTS

Among 290,610 Medicare patients who underwent URS, 94.4% had ≥1 (n = 274,396) and 76.3% had ≥2 risk factors. The proportion of patients with each risk factor was: age over 70 (64.6%), preoperative stent (59.4%), female (46.4%), urinary tract infection within 3 months (39.1%), diabetes (33.0%), history of sepsis (17.3%), multiple urinary tract infections within 6 months (13.1%), Charlson Comorbidity Index score of ≥7 (10.2%), and ischemic heart disease (2.9%). Patients with risk factors experienced a higher incidence of adverse outcomes. Notably, among patients with sepsis history, the incidence of sepsis, ICU admission within 30 days, and death within 90 days were 30.3%, 2.5%, and 0.86%, respectively, versus, 2.2%, 0.80%, and 0.18% without sepsis history (all P <.001). Median LOS was 5 days among patients with sepsis history versus 3 days without (P <.001).

CONCLUSION

Most URS Medicare patients had risk factors. Those with risk factors were more likely to experience sepsis, ICU admission, prolonged hospital LOS, and death. These findings underscore the need for targeted prevention and careful management for high-risk URS patients.

Infection Risk in Patients with Mixed Flora in Urine Cultures Prior to Ureteroscopy

Purpose: Urine cultures are routinely used to inform preoperative antibiotic choice and duration prior to endourologic surgery. The presence of mixed flora in preoperative urine cultures holds unclear clinical significance. This study examines infectious outcomes after ureteroscopy in patients with preoperative mixed flora urine cultures. Materials and Methods: A retrospective cohort study was conducted on adult patients who underwent ureteroscopy with laser lithotripsy between January 2014 and June 2024 who had urine cultures performed within 60 days preoperatively. Patients were categorized into cohorts based on their preoperative urine culture: mixed flora, negative, or positive. Postoperative urinary tract infection rates within 30 days were compared between cohorts, and logistic regression was performed adjusting for demographic and clinical variables. Results: We identified 5166 patients who underwent ureteroscopy with laser lithotripsy (2139 mixed flora, 1525 negative, 1502 positive). Preoperative antibiotics were used more often in the mixed flora cohort (29%) than in the negative cohort (24%, p = 0.007) but less frequently than in the positive cohort (57%, p < 0.001). Postoperative infections were visualized in 165 patients (8%) in the mixed flora cohort, compared with 88 (6%) in the negative cohort (p = 0.067) and 237 (16%) in the positive cohort (p < 0.001). Multivariable logistic regression demonstrated that positive cultures were associated with an increased risk of infection (odds ratio [OR] = 1.95, 95% confidence interval [CI] = 1.49-2.55, p < 0.001), but negative cultures had a similar risk of infection compared with mixed flora (OR = 0.79, 95% CI = 0.56-1.11, p = 0.177). Within the mixed flora cohort, preoperative antibiotic treatment was not associated with decreased postoperative infection (OR = 0.99, 95% CI = 0.66-1.47, p = 0.964). Conclusions: While patients with preoperative mixed flora urine cultures received preoperative antibiotics more often than patients with negative urine cultures, they were not at higher risk for postoperative infection. Routine preoperative antibiotic use in patients with mixed flora cultures may not be effective in reducing infectious complications after ureteroscopy.

Appropriate antimicrobial prescribing for bacteriuria before urological procedures: A room for improvement

In the presence of a positive preoperative urine culture, the prescription of a preoperative antibiotic therapy is recommended. The choice of antibiotic therapy and prescription are usually made by the urologist or the general practitioner (GP). The objective of the treatment is urinary sterilization rather than parenchymal treatment, and the treatment choice is key to reduce selective pressure and antimicrobial resistance. The objective of this study was to evaluate prescription patterns made by urologists and GPs, then to compare the antibiotics chosen by urologists or GPs to the "ideal" treatment defined by infectious diseases specialists. We retrospectively reviewed all positive preoperative urine cultures obtained between November 2022 and July 2023. Data pertaining to antibiotic prescriptions, including the duration of treatment, antibiotic class, and prescriber were collected. An infectious disease specialist conducted a blind review of each urine culture, providing recommendations for the most appropriate antibiotic based on their assessment. In cases of disagreement, a second infectious disease specialist conducted a similar evaluation. Out of 196 preoperative antibiotic prescriptions, 40 (20%) differed from the recommendations provided by the infectious disease specialist, with 39 involving the use of overly broad-spectrum antibiotics. Both infectious disease specialists yielded congruent recommendations in all cases. Notably, in 50% of these instances, the preoperative antibiotic treatment duration unduly exceeded 48hours. A statistically significant increase (4.84days vs. 2.99days) in preoperative treatment duration was observed when a GP was the prescriber (P<0.001). There is room for improvement of urologists' antibiotic prescription practices to reduce the ecological impact on the patient's microbiota and on a global scale. The delegation to GPs resulted in unjustified longer treatment durations and should be avoided without dedicated training. LEVEL OF EVIDENCE: 4.

Management of urinary stones: state of the art and future perspectives by experts in stone disease

AIM

To present state of the art on the management of urinary stones from a panel of globally recognized urolithiasis experts who met during the Experts in Stone Disease Congress in Valencia in January 2024. Options of treatment: The surgical treatment modalities of renal and ureteral stones are well defined by the guidelines of international societies, although for some index cases more alternative options are possible. For 1.5 cm renal stones, both m-PCNL and RIRS have proven to be valid treatment alternatives with comparable stone-free rates. The m-PCNL has proven to be more cost effective and requires a shorter operative time, while the RIRS has demonstrated lower morbidity in terms of blood loss and shorter recovery times. SWL has proven to be less effective at least for lower calyceal stones but has the highest safety profile. For a 6mm obstructing stone of the pelviureteric junction (PUJ) stone, SWL should be the first choice for a stone less than 1 cm, due to less invasiveness and lower risk of complications although it has a lower stone free-rate. RIRS has advantages in certain conditions such as anticoagulant treatment, obesity, or body deformity. Technical issues of the surgical procedures for stone removal: In patients receiving antithrombotic therapy, SWL, PCN and open surgery are at elevated risk of hemorrhage or perinephric hematoma. URS, is associated with less morbidity in these cases. An individualized combined evaluation of risks of bleeding and thromboembolism should determine the perioperative thromboprophylactic strategy. Pre-interventional urine culture and antibiotic therapy are mandatory although UTI treatment is becoming more challenging due to increasing resistance to routinely applied antibiotics. The use of an intrarenal urine culture and stone culture is recommended to adapt antibiotic therapy in case of postoperative infectious complications. Measurements of temperature and pressure during RIRS are vital for ensuring patient safety and optimizing surgical outcomes although techniques of measurements and methods for data analysis are still to be refined. Ureteral stents were improved by the development of new biomaterials, new coatings, and new stent designs. Topics of current research are the development of drug eluting and bioresorbable stents. Complications of endoscopic treatment: PCNL is considered the most invasive surgical option. Fever and sepsis were observed in 11 and 0.5% and need for transfusion and embolization for bleeding in 7 and 0.4%. Major complications, as colonic, splenic, liver, gall bladder and bowel injuries are quite rare but are associated with significant morbidity. Ureteroscopy causes less complications, although some of them can be severe. They depend on high pressure in the urinary tract (sepsis or renal bleeding) or application of excessive force to the urinary tract (ureteral avulsion or stricture). Diagnostic work up:  Genetic testing consents the diagnosis of monogenetic conditions causing stones. It should be carried out in children and in selected adults. In adults, monogenetic diseases can be diagnosed by systematic genetic testing in no more than 4%, when cystinuria, APRT deficiency, and xanthinuria are excluded. A reliable stone analysis by infrared spectroscopy or X-ray diffraction is mandatory and should be associated to examination of the stone under a stereomicroscope. The analysis of digital images of stones by deep convolutional neural networks in dry laboratory or during endoscopic examination could allow the classification of stones based on their color and texture. Scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) is another fundamental research tool for the study of kidney stones. The combination of metagenomic analysis using Next Generation Sequencing (NGS) techniques and the enhanced quantitative urine culture (EQUC) protocol can be used to evaluate the urobiome of renal stone formers. Twenty-four hour urine analysis has a place during patient evaluation together with repeated measurements of urinary pH with a digital pH meter. Urinary supersaturation is the most comprehensive physicochemical risk factor employed in urolithiasis research. Urinary macromolecules can act as both promoters or inhibitors of stone formation depending on the chemical composition of urine in which they are operating. At the moment, there are no clinical applications of macromolecules in stone management or prophylaxis. Patients should be evaluated for the association with systemic pathologies.

PROPHYLAXIS

Personalized medicine and public health interventions are complementary to prevent stone recurrence. Personalized medicine addresses a small part of stone patients with a high risk of recurrence and systemic complications requiring specific dietary and pharmacological treatment to prevent stone recurrence and complications of associated systemic diseases. The more numerous subjects who form one or a few stones during their entire lifespan should be treated by modifications of diet and lifestyle. Primary prevention by public health interventions is advisable to reduce prevalence of stones in the general population. Renal stone formers at "high-risk" for recurrence need early diagnosis to start specific treatment. Stone analysis allows the identification of most "high-risk" patients forming non-calcium stones: infection stones (struvite), uric acid and urates, cystine and other rare stones (dihydroxyadenine, xanthine). Patients at "high-risk" forming calcium stones require a more difficult diagnosis by clinical and laboratory evaluation. Particularly, patients with cystinuria and primary hyperoxaluria should be actively searched.

FUTURE RESEARCH

Application of Artificial Intelligence are promising for automated identification of ureteral stones on CT imaging, prediction of stone composition and 24-hour urinary risk factors by demographics and clinical parameters, assessment of stone composition by evaluation of endoscopic images and prediction of outcomes of stone treatments. The synergy between urologists, nephrologists, and scientists in basic kidney stone research will enhance the depth and breadth of investigations, leading to a more comprehensive understanding of kidney stone formation.

Urinary tract infection after flexible ureterorenoscopy for urolithiasis in patients with positive treated preoperative urinalysis

Prevalence of kidney stones is increasing worldwide, flexible ureterorenoscopy (f-URS) is the most common surgical treatment. Postoperative urinary tract infection (PUTI) is the primary complication. Some risk factors are classically associated with PUTI, especially preoperative positive urinalysis (POPU). We aimed to identify risk factors for PUTI after f-URS for urolithiasis in patients with treated POPU, and to identify the different pre and postoperative pathogens. Retrospective, single-center study of all f-URS for urolithiasis between January 2004 and December 2020. Procedures with treated POPU were categorized as PUTI or no PUTI (NPUTI). We examined demographics, preoperative, perioperative and postoperative characteristics in each group. Among 1934 procedures analyzed, 401 (20.7%) had POPU; these were categorized into NPUTI (n = 352, 87.8%) and PUTI (n = 49, 12.2%). By univariate analysis, only preoperative stenting duration (76.3 in NPUTI group vs 107.7 days in PUTI group, p = 0.001) was significantly associated with a higher risk of PUTI in univariate analysis. Germ distribution was similar in both groups. We compared pre- and postoperative microbiological data for interventions with PUTI, and found that only 8.7% of pathogens were identical between pre and postoperative urinalysis. Our study shows that the rate of PUTI is higher for patients with a POPU and that preoperative stent duration is the sole risk factor in patients with POPU. The low concordance rate (8.7%) between POPU and post-operative pathogens highlights the need for further research on obtaining sterile preoperative urinalysis, or performing intraoperative culture (urines, stent or stone), to treat PUTI early with an adapted antibiotic therapy.

Predicting urine culture results in candidates for lithotripsy

Background

Urological guidelines assert that "urine culture should be obtained" before surgical management of ureteral or kidney stones. Thus, many surgeries are delayed by 1-3 days until the results of urine culture are available. During this time, the patient frequently experience pain and possible kidney damage. We investigated the hypothesis that it is possible to predict the results of urine culture in candidates for surgical intervention using parameters that are accessible immediately upon admission.

Materials and methods

A database of 1000 patients who underwent either percutaneous nephrolithotomy (PCNL) or ureteroscopy/retrograde intrarenal surgery was analyzed. Eleven parameters potentially related to urinary infections and accessible to the clinician at the emergency department were correlated with the preoperative urine culture results.

Results

Of the patients, 234 (23.4 %) had positive cultures. On multivariate analysis, only sex, hydronephrosis grade, and history of previous nephrolithotomy were significantly associated with a positive preoperative urine culture. The risk of a positive culture can be easily determined from a simple table or an Excel-based calculator. This risk could be as low as 0.45% for a man without a history of PCNL and no hydronephrosis (4% in a woman with similar parameters) or as high as 79.5% in a man with a history of PCNL and hydronephrosis (85% in a woman with similar parameters).

Conclusions

The risk of preoperative positive urine culture can be predicted using 3 parameters that are accessible upon admission. In low-risk cases, prompt surgical treatment can be provided, eliminating the anticipation time for urine culture results.

Comparison of the efficacy and safety of holmium laser with the Moses technology and regular mode for stone treatment: a systematic review and meta-analysis

BACKGROUND

As a new pulse modality of holmium laser in retrograde intrarenal stone surgery, the MOSES technique can reduce the possibility of stone drifting and help to powder kidney stones in vitro and in animal experiments. However, there remains controversy about whether the MOSES mode needs to be used instead of the regular mode in clinical practice. This meta-review was conducted to evaluate the clinical efficacy and safety of MOSES technology for stone disease.

METHODS

PubMed, Embase, Web of Science, Cochrane Library, and CNKI were searched for relevant studies until September 2022, with 1 RCT and 6 nonrandomized studies included. We pulled data on adverse events, success rates and operative time to analyze based on the random effect model.

RESULTS

We found that using MOSES mode could shorten the operative time (standard mean difference [SMD] - 0.43; 95% confidence interval [CI] - 0.79 to  - 0.08; P = 0.016) than regular mode especially in a small sample study or in the Asian area. When the number of women is smaller than the number of men, the reduction of the duration was also significant. Stone-free rates of the two modes had no difference (relative risk [RR] 1.06; 95% CI 0.99-1.12; P = 0.30), and there was no publication bias. In terms of safety, no significant difference in complications was detected between the two approaches (RR 0.85; 95% CI 0.48-1.53; P = 0.81) without significant heterogeneity.

CONCLUSION

MOSES mode holmium laser was superior to the regular mode laser in terms of procedure time. There was no large disparity in stone-free rates or complications between the two modes. However, our conclusions should be confirmed in prospective studies with high evidence.

Randomized comparison of effect of standard antibiotic prophylaxis versus enhanced prophylactic measures on rate of urinary tract infection after flexible ureteroscopy

PURPOSE

To compare the rate of post-flexible ureteroscopy urinary tract infection (UTI) in patients subjected to the standard antibiotic prophylaxis alone versus enhanced prophylactic measures.

METHODS

A prospective randomized controlled study included 256 patients subjected to flexible ureteroscopy (FURS) for ureteral or renal stones from March 2018 to July 2022. Treatment groups included the standard antibiotic prophylaxis group (group 1, n=128) and the enhanced prophylaxis group (group 2, n=128). Patients in group 1 were injected with intravenous fluoroquinolone one hour preoperatively, and oral antibiotics were used for 24 h postoperatively. Patients in group 2 had urine culture ten days before the procedure; antibiotic-culture based was given for positive asymptomatic cases, while the procedure was deferred for active UTI.

RESULTS

The study groups were comparable regarding patient demographics, stone characteristics, operative time, and intraoperative complications. The overall hospitalization time was 1.68 ± 0.81 days. Postoperative, and overall complications were significantly higher in group 1 (15.6% vs. 6.3%, p = 0.04 and 26.6% vs. 17.2%, p = 0.047), respectively. Twenty patients (15.6 %) in the standard prophylaxis group were diagnosed with UTI in comparison to 8 patients (6.3 %) in the enhanced prophylaxis group (p = 0.047).

CONCLUSIONS

Urinary tract infection after FURS could be reduced significantly by utilizing the suggested enhanced prophylactic approach.

Development and validation of a predictive model for major complications after extracorporeal shockwave lithotripsy in patients with ureteral stones: based on a large prospective cohort

The risk factors of complications after SWL are not well characterized. Therefore, based on a large prospective cohort, we aimed to develop and validate a nomogram for predicting major complications after extracorporeal shockwave lithotripsy (SWL) in patients with ureteral stones. The development cohort included 1522 patients with ureteral stones who underwent SWL between June 2020 and August 2021 in our hospital. Five hundred and fifty-three patients with ureteral stones participated in the validation cohort from September 2020 to April 2022. The data were prospectively recorded. Backward stepwise selection was applied using the likelihood ratio test with Akaike's information criterion as the stopping rule. The efficacy of this predictive model was assessed concerning its clinical usefulness, calibration, and discrimination. Finally, 7.2% (110/1522) of patients in the development cohort and 8.7% (48/553) of those in the validation cohort suffered from major complications. We identified five predictive factors for major complications: age, gender, stone size, Hounsfield unit of stone, and hydronephrosis. This model showed good discrimination with an area under the receiver operating characteristic curves of 0.885 (0.872-0.940) and good calibration (P = 0.139). The decision curve analysis showed that the model was clinically valuable. In this large prospective cohort, we found that older age, female gender, higher Hounsfield unit, size, and grade of hydronephrosis were risk predictors of major complications after SWL. This nomogram will be helpful in preoperative risk stratification to provide individualized treatment recommendations for each patient. Furthermore, early identification and appropriate management of high-risk patients may decrease postoperative morbidity.

Safety and efficacy of ureteroscopy for urolithiasis in octogenarians

OBJECTIVE

To examine the safety and efficacy of ureteroscopy (URS) for urolithiasis in octogenarians, and identify preoperative risk factors for the incidence of postoperative complications.

METHODS

The patients who underwent URS for urolithiasis were divided into octogenarians and younger patients (age: <80 years), and the groups were compared regarding their clinical characteristics, intraoperative and postoperative complications, and stone-free rate. The predictors of postoperative complications were evaluated using logistic regression models.

RESULTS

A total of 1207 patients were included, 166 in the octogenarian patient group and 1041 in the younger patient group. The proportion of female patients (p < 0.001), American Society of Anesthesiologists (ASA) score (p < 0.001), rate of preoperative pyelonephritis (p < 0.001), and diabetes mellitus (p = 0.003) were higher in the octogenarian group. No statistically significant differences were found between the two groups regarding stone size, location, and intraoperative complications. Postoperative complications, which reached a significant difference, were observed in 34 (20.5%) octogenarians and 117 (11.2%) younger patients (p = 0.002). However, age itself was not significantly associated with postoperative fever, the most frequent postoperative complication, in multivariate analysis. Female sex, ASA score of ≥3, history of diabetes mellitus, and prolonged operative time (≥120 min) were the significant predictors of fever. The stone-free rate in the octogenarian group was superior to that in the younger patient group (80.1% vs. 70.6%, respectively; p = 0.035).

CONCLUSION

Our results suggest that URS for urolithiasis can be safely and effectively applied to octogenarians in selected cases.

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.

Risk of Sepsis in Retrograde Intrarenal Surgery: A Systematic Review of the Literature

Context

Objective

Evidence acquisition

Evidence synthesis

Conclusions

Patient summary

The active guidewire technique versus standard technique as different way to approach ureteral endoscopic stone treatment

BACKGROUND

One of the greatest challenges in semi-rigid ureteroscopies, for both stones and tumors, is the control of endoscopic vision and the maintenance of low intracavitary liquid pressure. We present a comparison between two operative techniques: in the first method an ordinary guide wire (diameter 0.032'') is used for the procedure; in the second one a 5 Fr ureteral catheter replaces the guidewire (we called it "Active guidewire") Methods We compared 50 semirigid ureteroscopies (sURS) performed using the active guidewire with another 50 procedures conducted with a classic guidewire. We evaluated the difference in operating times, quality of endoscopic vision, periprocedural infections rate and stone-free rate.

RESULTS

The use of active guidewire has considerably reduced the standardized operating times per unit stone-volume by about 39%. Vision quality has improved considerably thanks to the continuous flow in-and-out. Consequently, periprocedural infections decreased (3% vs 30%) and the stone-free rate rose from 86% to 92%.

DISCUSSION AND CONCLUSIONS

Employing an "active guidewire" instead of the standard guidewire, the risk of complications related to high pressures and operating time is considerably lower, as well as better treatment quality thanks to the cleaner vision. This technique has proven to be safe as well as easy to apply, and in our belief is to be preferred whenever the ureter accepts without forcing, both the presence of the catheter and the semi-rigid 7 F ureteroscope.

The effect of ideal urine culture time on urinary infections after flexible ureteroscopy: A match-pair case-control study

AIMS

To investigate the effect of the ideal period (Δ-day), which is a period between the sterile urine culture and initiation of flexible ureteroscopy (f-URS), on postoperative urinary tract infections (UTI) in our tertiary referral centre.

METHODS

After obtaining the approval of the local ethics committee, retrospective data were collected for all f-URS procedures performed between January 2017 and March 2019. Patients that developed UTI were matched in 1:1 proportion with patients that did not develop UTI based on their demographic and stone characteristics. The group of patients with postoperative UTI was compared with the control group.

RESULTS

A total of 916 f-URS cases that had all required data were analysed. Sixty-eight patients with postoperative UTI were determined and a total of 136 patients were included in the study after match-pair. We found that if the Δ-day is longer than 2 weeks, the possibility of postoperative urinary infection rates increases with statistical significance (P = .006). According to our subgroup analysis, postoperative UTI was more common if the Δ-day >14 days. ROC curve analysis provided a 14.5-day period as a cut-off value of Δ-day for postoperative UTI.

CONCLUSIONS

The present study is the first to examine the impact of the Δ-day for f-URS on postoperative UTIs. In brief, prolonging the Δ-day, especially if Δ-day >14 days, leads to an increase in the rates of postoperative UTI. We conclude that it is preferred to either perform the f-URS in the early period after the urine culture analysis or doing the urine culture analysis shortly before the surgery.