A Machine Learning Approach to Predict the Outcome of Urinary Calculi Treatment Using Shock Wave Lithotripsy: Model Development and Validation Study.

BACKGROUND: Shock wave lithotripsy (SWL), ureteroscopy, and percutaneous nephrolithotomy are established treatments for renal stones. Historically, SWL has been a predominant and commonly used procedure for treating upper tract renal stones smaller than 20 mm in diameter due to its noninvasive nature. However, the reported failure rate of SWL after one treatment session ranges from 30% to 89%. The failure rate can be reduced by identifying candidates likely to benefit from SWL and manage patients who are likely to fail SWL with other treatment modalities. This would enhance and optimize treatment results for SWL candidates. OBJECTIVE: We proposed to develop a machine learning model that can predict SWL outcomes to assist practitioners in the decision-making process when considering patients for stone treatment. METHODS: A data set including 58,349 SWL procedures performed during 31,569 patient visits for SWL to a single hospital between 1990 and 2016 was used to construct and validate the predictive model. The AdaBoost algorithm was applied to a data set with 17 predictive attributes related to patient demographics and stone characteristics, with success or failure as an outcome. The AdaBoost algorithm was also applied to a training data set. The generated model's performance was compared to that of 5 other machine learning algorithms, namely C4.5 decision tree, naïve Bayes, Bayesian network, K-nearest neighbors, and multilayer perceptron. RESULTS: The developed model was validated with a testing data set and performed significantly better than the models generated by the other 5 predictive algorithms. The sensitivity and specificity of the model were 0.875 and 0.653, respectively, while its positive predictive value was 0.7159 and negative predictive value was 0.839. The C-statistics of the receiver operating characteristic (ROC) analysis was 0.843, which reflects an excellent test. CONCLUSIONS:  We have developed a rigorous machine learning model to assist physicians and decision-makers to choose patients with renal stones who are most likely to have successful SWL treatment based on their demographics and stone characteristics. The proposed machine learning model can assist physicians and decision-makers in planning for SWL treatment and allow for more effective use of limited health care resources and improve patient prognoses.

Clips Can be Safely Used for Vascular Control of the Renal Vessels During Laparoscopic Donor Nephrectomy.

OBJECTIVE: To review our experience using clips to control the renal vessels during laparoscopic donor nephrectomy (LDN) and determine the safety of this practice. METHODS: We performed a retrospective review of patients who underwent LDN at our centre January 1, 2007-September 17, 2019. The primary outcome was the rate of complication associated with vascular control of the renal vessels, which included (1) conversion to open to manage bleeding, (2) additional procedures for bleeding, and (3) major bleeding requiring blood transfusion. Secondary outcomes included the rate of renal artery/vein clip dislodgement or crossing, change in hemoglobin, warm ischemia time and the incidence of intra-operative complications and postoperative in-hospital complications. RESULTS: We included 503 patients who underwent LDN, of which 497 were left sided. The main renal artery was controlled with 3 titanium clips in 489 (97%) cases. The main renal vein was controlled with 2 polymer-locking clips in 478 (95%) cases. For our primary outcome, there were no conversions to open to manage bleeding, no secondary procedures due to bleeding and no major bleeding requiring blood transfusion. Additionally, there were no donor deaths. Regarding our secondary outcomes, there were 5 intraoperative events related to the titanium clips being placed on the renal artery and 1 intraoperative event related to the polymer-locking clips on the renal vein, none of which resulted in any morbidity. CONCLUSION: Using 3 titanium clips on the renal artery and 2 polymer-locking clips on the renal vein during left LDN is safe and provides excellent vascular control.

Assessing the Necessity of Routine Crossmatching for Blood Transfusion in Renal Transplantation.

INTRODUCTION: Routine crossmatch of packed red blood cells (pRBCs) is completed preoperatively at many centers despite conflicting evidence on the incidence of blood transfusions with renal transplantation. In the current economic climate, resource adjudication should be judicious and medically appropriate. The objective of this study was to determine the incidence, timing, and predictors of early postoperative pRBC transfusion in patients undergoing renal transplantation. METHODS: A retrospective review of all patients undergoing renal transplantation at our institution from January 2013 to May 2016 was performed. Demographic, biochemical, and clinical parameters were recorded. The primary outcome was early postoperative transfusion, defined as an intraoperative transfusion or within 2 days of surgery. Multivariable logistic regression was performed to identify associations with early postoperative transfusion. RESULTS: We identified 428 patients during the study period (average age 55 years, 60% male, 30% obese, 67% deceased donor, and 43% preoperative antithrombotic use). Forty (9.3%) patients required early postoperative transfusion (mean: 2.8 pRBCs/transfusion) and most did not require blood urgently. Only 20 (4.7%) patients required a transfusion intraoperatively or on the same day of surgery. Lower preoperative hemoglobin (per g/L unit: odds ratio [OR]: 0.943), female gender (OR: 2.752), and preoperative antithrombotic use (OR 2.369) were associated with a need for early postoperative transfusion. CONCLUSION: Transfusion in the early postoperative period following renal transplantation was less than 10%, suggesting that routine crossmatch may not be necessary for all patients. Preoperative hemoglobin, female gender, and preoperative antithrombotic use were associated with increased risk and may be useful to risk-stratify patients who require crossmatch.

Are Routine Laboratory Investigations Necessary Following Percutaneous Nephrolithotomy?

OBJECTIVE: To determine how effective routine postoperative blood work is in identifying complications after percutaneous nephrolithotomy (PCNL), the gold standard treatment for large volume stone disease. Although major complication rates are low, hemorrhagic and sepsis-related complications are serious and can occur. Routine post-PCNL complete blood count is routinely performed by most endourologists but may be a low-value practice. METHODS: A retrospective review was performed of all PCNL procedures at our center over a 3-year period. Patient demographic, stone characteristics and postoperative data were collected and analyzed. RESULTS: Three hundred and eighty-five patients (196 female and 189 males) underwent PCNL for the treatment of urolithiasis. Mean age was 55.8 years and mean length of stay in hospital was 1.74 days. Most patients (82.9%) had neither ureteric stent nor percutaneous tube prior to PCNL. Postoperatively, 4 patients (1.0%) required a blood transfusion and 14 patients (3.6%) developed urosepsis. Patients who required either a transfusion or developed urosepsis demonstrated abnormal vital signs (tachycardia, hypotension, or fever) postoperatively. Sixteen patients (4.2%) had normal vital signs but had an extended hospital stay only to monitor abnormal blood work results. None these patients required a transfusion nor developed urosepsis but had a length of stay that was a mean of 1.5 days longer patients with normal postoperative vital signs and blood work. CONCLUSION: Abnormal vital signs alone identified all patients that required transfusion or treatment for urosepsis after PCNL. Routine complete blood count testing postoperatively may not improve detection of infectious or bleeding complications and may prolong hospital admission unnecessarily.

Photoacoustic imaging of kidney fibrosis for assessing pretransplant organ quality.

Roughly 10% of the world's population has chronic kidney disease (CKD). In its advanced stages, CKD greatly increases the risk of hospitalization and death. Although kidney transplantation has revolutionized the care of advanced CKD, clinicians have limited ways of assessing donor kidney quality. Thus, optimal donor kidney-recipient matching cannot be performed, meaning that some patients receive damaged kidneys that function poorly. Fibrosis is a form of chronic damage often present in donor kidneys, and it is an important predictor of future renal function. Currently, no safe, easy-to-perform technique exists that accurately quantifies renal fibrosis. We describe a potentially novel photoacoustic (PA) imaging technique that directly images collagen, the principal component of fibrotic tissue. PA imaging noninvasively quantifies whole kidney fibrotic burden in mice, and cortical fibrosis in pig and human kidneys, with outstanding accuracy and speed. Remarkably, 3-dimensional PA imaging exhibited sufficiently high resolution to capture intrarenal variations in collagen content. We further show that PA imaging can be performed in a setting that mimics human kidney transplantation, suggesting the potential for rapid clinical translation. Taken together, our data suggest that PA collagen imaging is a major advance in fibrosis quantification that could have widespread preclinical and clinical impact.

Preoperative Alpha-Blockers for Ureteroscopy for Ureteral Stones: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Introduction: Preoperative alpha-blockers have been proposed to improve intraoperative outcomes and patient stone-free status after ureteroscopy for ureteral stones. Materials and Methods: We searched six databases, including Medline, Embase, and Web of Science, for randomized controlled trials (RCTs) evaluating alpha-blocker use before planned ureteroscopy for the management of ureteral calculi. Meta-analysis was performed using DerSimonian and Laird method with inverse variance weighting. Quality of evidence was summarized using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. Results: Of 3338 records, 26 were screened as full text and 12 RCTs were included totaling 1352 patients. Meta-analysis demonstrated a 61% risk reduction in need for intraoperative ureteral dilatation in patients administered preoperative alpha-blockers (relative risk [RR]: 0.39 [95% confidence interval, CI: 0.31-0.48], p < 0.00001), as well as increased stone-free status for patients at 4 weeks postoperatively (RR: 1.17 [95% CI: 1.08-1.26], p < 0.0001), and at final follow-up (RR: 1.18 [95% CI: 1.11-1.24], p < 0.00001; median final follow-up 4 weeks [range: 2-8 weeks]). Urologists were more likely to reach the stone with the ureteroscope in patients administered alpha-blockers (RR: 1.16 [95% CI: 1.10-1.23], p < 0.00001). A statistically significant reduction in operative time (mean difference [MD]: -6.05 [95% CI: -10.17 to -1.93] minutes, p = 0.004) and length of hospital stay (weighted MD: -0.34 [95% CI: -0.55 to -0.13] days, p = 0.001) was also demonstrated. Main reported side effects of treatments were abnormal ejaculation, postural hypotension, and dizziness. Outcomes were robust to sensitivity analyses. Results were rated moderate quality evidence using the GRADE framework. Conclusions: Among patients scheduled for semirigid ureteroscopy of ureteral stones, use of preoperative alpha-blockers demonstrated a significant reduction in the need for ureteral orifice dilation and an increase in patient stone-free status at follow-up, and facilitates higher rate of ureteroscopic access to stones, although reducing operative time. An adequately powered trial is needed to definitively address the safety and efficacy of preoperative alpha-blockers for ureteroscopy of ureteral stones.

Celebrating 75 years.

INTRODUCTION: Following the introduction of shock wave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL), the subspecialty of endourology was born in the late 1970s. The purpose of this study was to report milestones in Canadian endourology, highlighting Canada's contributions to the field. METHODS: A review of the literature was performed from the late 1970s to the present. The literature review included bibliographic and digital resources. Additionally, records and recollections by various individuals were used, including some who were directly involved. RESULTS: Endourology was born in Canada when SWL, URS, and PCNL emerged as minimally invasive treatment options for stones in the early to mid-1980s. According to our research, the first PCNL was performed at the University of Toronto in 1981. Dr. Joachim Burhenne, a Harvard-trained radiologist from Germany, first used extracorporeal SWL in Canada at the University of British Columbia (UBC) for the treatment of biliary stones. Treatment for urinary tract stones followed at UBC and Dalhousie University. The first worldwide use of the holmium laser for lithotripsy of urinary tract calculi took place at the University of Western Ontario. Other endourology milestones in Canada include the formation of the Canadian Endourology Group and the emergence of the Endourological Society-accredited fellowship programs at the University of Toronto and Western University in the 1990s. Canada hosted the 21st and 35th World Congress of Endourology and Shock Wave Lithotripsy annual meeting in Montreal and Vancouver, respectively. CONCLUSIONS: Canadian urologists have led many advances in SWL, URS, and PCNL over the past four decades and, for a relatively small community, have made significant contributions to the field. Through the training of the next generation of endourologists at Canadian institutions, the future of endourology in Canada is bright.

Peritoneal dialysis catheter removal at the time of renal transplantation: Choosing the optimal candidate.

INTRODUCTION: Concurrent peritoneal dialysis (PD) catheter removal during renal transplantation is controversial, with limited evidence supporting this practice. Our objective was to determine the rate of delayed graft function (DGF) in patients on preoperative PD. Additionally, we sought to identify which patients can safely have their PD catheter removed during transplantation due to a low risk of DGF. METHODS: We conducted a retrospective observational study between June 2011 and December 2015. The primary outcome was the diagnosis of DGF, defined as the need for dialysis within the first week of transplantation. Clinical and transplant factors, including graft type and donor criteria, were assessed for association with the primary outcome. Catheter-related complication rates were also compared between post-transplant PD and hemodialysis (HD). RESULTS: Of our cohort of 567 patients, 145 patients (25.6%) developed DGF. Obesity (odds ratio [OR] 1.06; 95% confidence interval [CI] 1.00-1.11; p=0.04) and increased perioperative blood loss (OR 1.002; 95% CI 1.000-1.003; p=0.03) were predictors of DGF. Protective factors included living donor (LD) grafts (OR 0.15; 95% CI 0.05-0.49; p=0.002) and intraoperative graft urine production (OR 0.39; 95% CI 0.23-0.65; p<0.001). In our PD cohort, only LD grafts demonstrated lower DGF rates (0 LD vs. 20.8% deceased donor; p=0.003). In terms of post-transplant renal replacement therapy, patients on PD and HD had similar duration of temporary dialysis (one day PD vs. two days HD; p=0.48) and catheter-related complication rates (4.5% PD vs. 2.6% HD; p=0.30). CONCLUSIONS: Carefully selected patients, such as those receiving LD grafts, may benefit from concurrent PD catheter removal.

The New/Novel Oral Anticoagulants and Their Impact on Patients Being Considered for Shockwave Lithotripsy: The Findings of an International Survey of the Endourological Society.

INTRODUCTION: Although general guidelines exist directing the management of new/novel oral anticoagulants (NOACs) in the perioperative period for open/endoscopic procedures, no consensus exists for those patients being considered for shockwave lithotripsy (SWL). To gauge current practice, we administered a survey to the international endourologic community. METHODS: A web-based survey was sent to current Endourological Society members. Respondents were asked whether they would consider SWL in patients receiving NOACs, and if they used SWL how these agents were managed perioperatively. Respondents were also asked which physicians in the patients' circle of care managed the discontinuation and reinstitution of the drugs. RESULTS: There were 165 respondents from 27 countries. Approximately 92.7% of urologists had access to SWL but only 53.4% indicated they would offer SWL to patients receiving NOACs. Among these urologists, 63.3% relied on internal medicine/hematology/cardiology colleagues to counsel patients on the discontinuation of NOACs pretreatment, whereas the majority (64%) handled the resumption guidance themselves. There was wide variability in the management of NOACs before lithotripsy, with discontinuation varying from 2 to 7 days. Resumption was more consistent, ranging from 1 to 2 days or when hematuria resolved. None of the respondents reported knowledge of adverse effects such as perinephric hematomas or cardiovascular morbidity. CONCLUSIONS: A large percentage of globally surveyed endourologists do not offer SWL to patients who are taking NOACs. Among those that do offer SWL, there seems to be a absence of consensus on optimal duration of discontinuation, suggesting a need to establish evidence-based guidance to optimize patient outcomes.

Routine Preoperative Electrocardiograms in Patients at Low Risk for Cardiac Complications During Shockwave Lithotripsy: Are They Useful?

INTRODUCTION: Routine preoperative electrocardiogram (ECG) before shockwave lithotripsy (SWL) is frequently performed despite recommendations against its use in asymptomatic patients undergoing low-risk surgical procedures. This study assesses whether routine preoperative ECG before SWL is useful in patients at low risk for cardiac complications. MATERIALS AND METHODS: A retrospective study of SWL at our center (2003-2013) reviewed all cardiac-related preoperative cancellations, intraoperative complications, postoperative admissions, and emergency department presentations in patients at low risk for cardiac complications. Patients received SWL with sedation and continuous five-lead ECG monitoring. RESULTS: Of 30,892 referrals, preoperative ECG triggered 13 (0.04%) cancelations in low-risk patients (1 with new atrial fibrillation and 12 with ischemia/previous infarction). Of these patients, 1 had a subsequent abnormal cardiac work-up and 11 underwent uncomplicated SWL without cardiac intervention (2 had unknown history). Of 27,722 treatments, 5 (0.02%) were stopped prematurely in low-risk patients because of arrhythmia (3 had normal preoperative ECG, 1 had abnormal ECG, and 1 did not complete ECG). Three patients developed an arrhythmia with sedation and 2 patients were admitted postoperatively because of cardiac complications (1 for atrial fibrillation and 1 for hypertension), of whom all had normal preoperative ECG. No patients presented to our emergency department with cardiac complications after SWL. CONCLUSIONS: In patients at low risk for cardiac complications, preoperative ECG triggered very few cancellations and did not predict early termination of treatment or cardiac complications after SWL. These findings suggest that in low-risk patients, routine preoperative ECG has little effect on treatment or complication rate and should be omitted.

Evaluation of Optimal Timing of Expert Feedback in a Simulated Flexible Ureteroscopy Course.

Introduction: Simulation-based training (SBT) has become an increasingly popular modality to train novice surgical residents in the face of rapidly increasing innovative surgical techniques across all surgical disciplines. Recent studies have already demonstrated SBT to be effective in helping overcome the learning curve associated with new surgical techniques, especially in junior residents and endoscopic procedures. In addition, it is known that trainees benefit significantly from expert feedback; however, there is a paucity of data looking into the optimal timing of this feedback during SBT. To address this knowledge deficit, an SBT curriculum was developed for junior urology residents to assess optimal timing of feedback during SBT for flexible ureteroscopy (fURS). Materials and Methods: The SBT course consisted of a pretraining assessment, three independent practice sessions, and a post-training assessment, with residents receiving expert feedback right after their pretraining assessment (early feedback [EF]) or after their final independent training session (late feedback [LF]). Results: Fifteen trainees with similar baseline fURS experience and precourse fURS task performance score participated in the study. There was a significant difference between the pre- and post-task completion times overall (15.2 minutes vs 9.1 minutes, p < 0.001), with no difference between the early or LF groups (p = 0.884). The mean performance scores improved for both groups (18.2 vs 24.2, p < 0.001) with the EF group having a more statistically significant improvement in performance scores than the LF group (p = 0.05), and most (73%) of residents preferred EF. Conclusions: This study demonstrates that an SBT curriculum for fURS is effective for technical skills development among junior trainees, and that EF resulted in marginally better overall scores and was preferred by residents.

Is extracorporeal shockwave lithotripsy a risk factor for the development of diabetes mellitus? A population-based study.

OBJECTIVE: To determine if patients treated with extracorporeal shockwave lithotripsy (ESWL) are at a greater risk of developing diabetes mellitus (DM) than those treated with ureteroscopy (URS). PATIENTS AND METHODS: A retrospective population-based cohort study was performed of all ESWL and URS stone treatments done in Ontario between January 1994 and March 2014, utilising linked encoded healthcare databases. The primary outcome was the development of DM >90 days after treatment. The Kaplan-Meier method was used for unadjusted survival analysis and multivariable analysis with Cox proportional hazards regression was used to assess the risk of DM between the ESWL and URS groups whilst controlling for age, gender, region of residence, income quintile, year of treatment, and comorbidity index. A sensitivity analysis with a subset of ESWL patients treated for left renal or proximal ureteric stones was completed. RESULTS: We identified 106 963 patients who underwent ESWL or URS over the study period with a median follow-up of 6.6 years (ESWL 8.5 years, URS 5.6 years). Unadjusted survival analysis showed an increased risk of developing DM in the ESWL group compared to the URS group (P < 0.001); however, multivariable analysis showed no increased risk of DM in the ESWL cohort (hazard ratio [HR] 0.97, 95% confidence interval [CI] 0.91-1.02; P = 0.25). Similarly, sensitivity analysis showed no increased risk of DM in the left renal/proximal ureteric stone ESWL cohort compared to the URS cohort (HR 1.04, 95% CI 0.96-1.13; P = 0.35). CONCLUSIONS: Our population-based cohort study demonstrated no increased risk of DM in patients undergoing ESWL compared to URS.

Indications and contraindications for shock wave lithotripsy and how to improve outcomes.

For over 35 years shock wave lithotripsy has proven to be an effective, safe and truly minimally invasive option for the treatment of nephrolithiasis. Various technical factors as well as patient selection can impact the success of the procedure. We used published work focusing on outcomes of shock wave lithotripsy, risk of complications, and strategies for improving stone fragmentation to create this review. Multiple patient and technical factors have been found to impact success of treatment. Skin to stone distance, stone density and composition, size and location of the stone within the urinary system all influence stone free rates. A slower rate with a gradual increasing voltage, precise targeting, proper coupling will improve stone fragmentation and decrease risk of complications. The selection of appropriate patients through a shared decision making process and attention to the technical factors that improve stone free rates is key to providing an effective treatment and patient satisfaction.

Dual usage of a stone basket: Stone capture and retropulsion prevention.

INTRODUCTION: Stone migration during ureteroscopy (URS) for proximal ureteric calculi is a constant challenge. Several retropulsion prevention devices have been developed to optimize URS outcomes. Our technique involves capturing the stone within a four-wire Nitinol stone basket and then performing laser lithotripsy to dust the stone while it is engaged in the basket. The dusted fragments wash out with the irrigation fluid and once small enough, the remaining stone is removed intact. METHODS: A retrospective chart review was performed of all proximal semi-rigid URS procedures for a solitary calculus (2000-2016). We compared our new technique introduced in 2010 to URS control procedures that did not use retropulsion prevention techniques or devices. RESULTS: One hundred and forty patients underwent URS for proximal ureteric calculi. Mean stone diameter was 9.3±3.4 mm, with similar impaction rate between both groups (44.1% vs. 43.1% control; p=n/s). The mean surgical procedure time was 53.3±17.9 minutes for the new technique and 65.2±29.2 minutes for the control group (p=0.005). Compared to the new technique, the control group had a higher rate of retropulsion (33.3% vs. 14.7%; p=0.01) and required flexible URS more often to exclude or remove residual fragments (24.1% vs. 59.1%; p=0.001). Using the new technique, stone-free rates were higher (79.1% vs. 69.4%; p=n/s) and there was a lower likelihood of leaving residual fragments both <3 mm and ≥3 mm (p=0.001). CONCLUSIONS: Our novel technique results in shorter operative times, lower retropulsion rates, and decreases postoperative residual stone fragments.