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.

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.

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.

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.

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.

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 21^st and 35^th 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.

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.

Computed tomography identified factors that preclude living kidney donation

INTRODUCTION

The purpose of this study was to determine the variety and prevalence of renal and non-renal abnormalities detected on multidetector computed tomography (MDCT) that precluded patients from donating a kidney.

METHODS

Institutional review board approval was obtained and the requirement for informed consent was waived. A retrospective, single-centre review of 701 patients (444 female, 257 male; age range 18-86 years; mean age 43.2±11.9 years) that underwent renal donor protocol MDCT was conducted. A systematic review of the CT report, records from multidisciplinary renal transplantation rounds, and electronic medical records was performed to determine which patients were approved or declined as live renal donors. If declined as a donor, CT-identified reasons were categorized as abnormalities of renal vasculature, renal parenchyma, collecting system, or extra-renal.

RESULTS

A total of 81 patients were excluded as renal donors on the basis of CT findings. Abnormalities of the collecting system accounted for the most frequent cause of exclusion (n=41), with asymptomatic renal calculi being detected in 39 patients. Complex vascular anatomy and vascular abnormalities resulted in the exclusion of 29 patients. Supernumerary arteries and early arterial branching resulted in the exclusion of 20 patients, while renal vein anomalies leading to exclusion were uncommon (n=2). Abnormalities of renal parenchyma resulted in the exclusion of nine patients. Three patients were diagnosed with autosomal dominant polycystic kidney disease, two patients had renal cell carcinoma, and two patients had areas of cortical scarring. A complex cystic lesion requiring surveillance imaging was encountered in one patient and a large area of renal infarction related to prior adrenalectomy was demonstrated in one patient. Extra-renal abnormalities leading to exclusion were limited to two patients with pulmonary nodules.

CONCLUSIONS

MDCT plays a critical role in the preoperative assessment of potential renal donors by identifying contraindications to donor nephrectomy and providing accurate vascular mapping. This study is anticipated to be informative for those involved in the workup of potential living renal donors by quantifying the incidence and reasons for donor exclusion identified on CT.

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.

Simulation-Based Laparoscopic Surgery Crisis Resource Management Training-Predicting Technical and Nontechnical Skills

OBJECTIVES

To develop a unique simulation-based assessment using a laparoscopic inferior vena cava (IVC) injury scenario that allows for the safe assessment of urology resident's technical and nontechnical skills, and investigate the effect of personality traits performance in a surgical crisis.

METHODS

Urology residents from our institution were recruited to participate in a simulation-based training laparoscopic nephrectomy exercise. Residents completed demographic and multidimensional personality questionnaires and were instructed to play the role of staff urologist. A vasovagal response to pneumoperitoneum and an IVC injury event were scripted into the scenario. Technical and nontechnical skills were assessed by expert laparoscopic surgeons using validated tools (task checklist, GOALS, and NOTSS).

RESULTS

Ten junior and five senior urology residents participated. Five residents were unable to complete the exercise safely. Senior residents outperformed juniors on technical (checklist score 15.1 vs 9.9, p < 0.01, GOALS score 18.0 vs 13.3, p < 0.01) and nontechnical performance (NOTSS score 13.8 vs 10.1, p = 0.03). Technical performance scores correlated with NOTSS scores (p < 0.01) and pass/fail rating correlated with technical performance (p < 0.01 for both checklist and GOALS), NOTSS score (p = 0.02), and blood loss (p < 0.01). Only the conscientiousness dimension of the big five inventory correlated with technical score (p = 0.03) and pass/fail rating (p = 0.04).

CONCLUSIONS

Resident level of training and laparoscopic experience correlated with technical performance during a simulation-based laparoscopic IVC injury crisis management scenario, as well as multiple domains of nontechnical performance. Personality traits of our surgical residents are similar and did not predict technical skill.

A survey of Canadian renal transplant surgeons: Use of ureteric stents and technique of the ureteroneocystotomy

INTRODUCTION

The role of ureteric stenting in renal transplant has been well-demonstrated. The goal of this survey was to determine the utilization of ureteric stents by Canadian transplant surgeons, and how the ureteroneocystotomy and followup is performed.

METHODS

An online survey was sent to the 40 surgeon members of the Canadian Society of Transplantation. The primary outcome was the rate of ureteric stent use at the time of renal transplantation. The secondary outcomes were the ureteric stent dwell time, use and type of prophylactic antibiotics, and the use of routine post-transplant ultrasonography.

RESULTS

All respondents (25) used ureteric stent routinely and 92% remove the stent between four and six weeks postoperatively. Prophylactic antibiotics were used 64% of the time for ureteric stent removal. The majority of surgeons do not routinely perform a post-stent removal ultrasound. Fifty-six percent of respondents perform a refluxing anastomosis.

CONCLUSIONS

Ureteric stents are routinely used in renal transplant in Canada. Areas for improvement and topics of debate identified from this survey are the need for peri-stent removal antibiotics, the role of post-stent removal ultrasound, the duration of stent dwell time, and the need for a non-refluxing ureteroneocystotomy.

A Rare Ureteral Injury Following Posterior Approach Lumbar Discectomy

Iatrogenic ureteral injuries account for ∼75% of all ureteral injuries and occur primarily during urologic, gynecologic, general, and vascular surgery procedures. Ureteral injury during spine surgery is a rare complication with only occasional reports in the literature. In this case report, we present a case of unrecognized left ureteral injury during an open right lumbar discectomy with a delayed presentation, and discuss the steps required for diagnosis and management. This report highlights a rare complication during laminectomy and serves to better inform patients and surgeons about this potential complication and the management options.

A case of recurrent, multifocal anastomosing haemangiomas

Anastomosing haemangiomas are relatively rare lesions, with a renal predilection, and which, given their imaging and pathologic appearance, mimic aggressive malignancies such as angiosarcoma. The imaging characteristics of this case are informative when evaluating a vascular lesion of the adrenal gland.

Shockwave lithotripsy: techniques for improving outcomes

OBJECTIVES

Shock wave lithotripsy (SWL) remains the only effective truly non-invasive treatment for nephrolithiasis. While single-treatment success rates may not equal those of ureteroscopy and percutaneous nephrolithotomy, it has an important role to play in the management of stones. In this paper, we outline the latest evidence-based recommendations for maximizing SWL outcomes, while minimizing complications.

MATERIALS AND METHODS

A comprehensive review of the current literature was performed regarding maximizing SWL outcomes.

RESULTS

Several different considerations need to be made regarding patient selection with respect to body habitus, body mass index, anatomical location and underlying urologic abnormalities. Stone composition and stone density (Hounsfield Units) are important prognostic variables. Patient positioning is critical to allow for adequate stone localization with either fluoroscopy or ultrasound. Coupling should be optimized with a low viscosity gel applied to the therapy head first and patient movement should be limited. SWL energy should be increased slowly and shockwave rates of 60 or 90 Hz should be used. Medical expulsive therapy with alpha-blockers after SWL treatment has shown benefit, particularly with stones greater than 10 mm.

CONCLUSION

While single-treatment success rates may not equal those of ureteroscopy or percutaneous nephrolithotomy, with proper patient selection, optimization of SWL technique, and use of adjunctive treatment after SWL, success rates can be maximized while further reducing the already low rate of serious complications. SWL remains an excellent treatment option for calculi even in 2017.

Intraoperative Radiographic Determination of Ureteral Length as a Method of Determining Ideal Stent Length

INTRODUCTION

Accurate determination of ureteral length (UL) and appropriate stent length remains a challenge. The objective of this study was to describe an intraoperative technique to measure UL and determine appropriate stent length, and to compare this technique with other methods of determining appropriate stent length.

METHODS

Patients undergoing ureteroscopy requiring postoperative stenting and who had a preoperative CT were prospectively identified. Gender, age, height, body mass index, L1 to L5 lumbar height on CT, and surgeon's estimate of UL were recorded. UL was measured using four methods: direct measurement with a ureteral catheter, ureteropelvic junction (UPJ) to ureterovesical junction distance on axial and coronal CT, and using a novel intraoperative radiographic technique. Radiographic measurement was performed using a radiographic nipple marker affixed to the skin over the ureteral orifice (UO) and an angiographic catheter with radiopaque markings at 1 cm intervals. UL was the distance from the UPJ to the marker at the UO measured using the catheter markers. Correlation between direct measurement and the recorded variables and methods of ureteral measurement were calculated. Stent length was chosen based on radiographic measurement. Stents were deemed of appropriate length if they showed a proximal coil in the renal pelvis and a distal coil in the bladder without crossing midline.

RESULTS

Twenty-five ureters from 23 patients were included. Radiographically measured UL was strongly correlated with direct measurement. (r = 0.873, p < 0.01). Coronal and axial CT ULs were significantly associated with direct measurement (p < 0.05). Height, lumbar height, and surgeon's estimate of UL were not. Stents were deemed of appropriate length in 23/25 cases (92%).

CONCLUSIONS

This new method for radiographic UL measurement is strongly correlated with directly measured UL. A length of stent chosen based on radiographic UL resulted in an appropriate stent length.

Best Stent Length Predicted by Simple CT Measurement Rather than Patient Height

INTRODUCTION AND OBJECTIVES

Ureteral stent length is important, as stents that are too long might worsen symptoms and too short are at higher risk of migration. The purpose of this study was to determine if patient or radiologic parameters correlate with directly measured ureteral length and if directly measured ureteral length predicts proper stent positioning.

METHODS

During stent placement, ureteral length (ureteropelvic junction to ureterovesical junction distance) was directly measured by endoscopically viewing a ureteral catheter (with 1-cm marking) emanating from the ureteral orifice. A 22, 24, or 26 cm stent was chosen to be closest to the measured ureteral length. For ureters >26 cm, a 26 cm stent was chosen. Ends of an "ideally positioned" stent were fully curled in the renal pelvis and bladder, without crossing the bladder midline. Rates of ideal stent position were compared between patients with matching stent and ureteral lengths and those with stent lengths differing by ≥1 cm (mismatched). The measured ureteral length was correlated with patient height, L1-L5 height, and length measured on CT.

RESULTS

Fifty-nine ureters from 57 patients were included. Height was reasonably correlated with L1-L5 height (Spearman correlation coefficient [rho] = 0.79), although both were poorly correlated with directly measured ureteral length (rho = 0.18 for height and 0.32 for lumbar height). Ureteral lengths measured on CT correlated well with direct measurement (rho = 0.63 for axial cuts and rho = 0.64 for coronal cuts). Matched stent length was associated with higher rates of ideal stent position than mismatched (100% vs 70.9%, p = 0.006).

CONCLUSIONS

CT measurements, rather than height, correlate well with measured length and could be used to choose the appropriate stent length. Stents matching directly measured ureteral lengths are associated with high rates of ideal stent position.

Shockwave Lithotripsy Practice Pattern Variations Among and Between American and Canadian Urologists: In Support of Guidelines

PURPOSE

Shockwave lithotripsy (SWL) is a widely utilized form of treatment for urolithiasis. There are new evidence-based recommendations regarding pre-SWL patient work-up and the performance of SWL. The purpose of this study is to determine practice patterns for SWL and to determine if regional variation exists between Canada and the United States.

MATERIALS AND METHODS

A 19-question survey was prepared. Canadian urologists were surveyed through e-mail correspondence. In the United States, members of the Endourologic Society and members of two large stone management groups were surveyed. Canadian and American results were compared using the chi-square and Fisher's exact tests.

RESULTS

Ninety-four Canadian urologists and 187 U.S. urologists completed the survey. Practice patterns differed between countries. Intravenous sedation was more commonly used in Canada (Canada 94.7% vs United States 17.9%, p < 0.001); routine antibiotics were more commonly given in United States (Canada 2.1% vs United States 78.1%, p < 0.001); a shock rate of 2 Hz was more common in Canada (Canada 76.6% vs United States 16.2%, p < 0.00001); rate of discontinuing ASA for renal and ureteral stone treatment was higher in the United States (renal Canada 88.3% vs United States 95.7%, p < 0.02; ureteral Canada 62.4% vs 90.3%, p < 0.0001); and ureteral stents were more commonly used if treating a large stone or patients with solitary kidneys in the United States (large stones Canada 58.2% vs United States 88.8%, p = 0.0001; solitary kidney Canada 50.6% vs 66.3%, p = 0.02).

CONCLUSIONS

This study highlights the absence of standardization of SWL. Significant regional differences exist in practice patterns and performance of SWL between Canadian and American urologists.

Surgical Management of Stones: American Urological Association/Endourological Society Guideline, PART II

PURPOSE

This Guideline is intended to provide a clinical framework for the surgical management of patients with kidney and/or ureteral stones. The summary presented herein represents Part II of the two-part series dedicated to Surgical Management of Stones: American Urological Association/Endourological Society Guideline. Please refer to Part I for introductory information and a discussion of pre-operative imaging and special cases.

MATERIALS AND METHODS

A systematic review of the literature (search dates 1/1/1985 to 5/31/2015) was conducted to identify peer-reviewed studies relevant to the surgical management of stones. The review yielded an evidence base of 1,911 articles after application of inclusion/exclusion criteria. These publications were used to create the Guideline statements. Evidence-based statements of Strong, Moderate, or Conditional Recommendation were developed based on benefits and risks/burdens to patients. Additional directives are provided as Clinical Principles and Expert Opinions when insufficient evidence existed.

RESULTS

The Panel identified 12 adult Index Patients to represent the most common cases seen in clinical practice. Three additional Index Patients were also created to describe the more commonly encountered special cases, including pediatric and pregnant patients. With these patients in mind, Guideline statements were developed to aid the clinician in identifying optimal management.

CONCLUSIONS

Proper treatment selection, which is directed by patient- and stone-specific factors, remains the greatest predictor of successful treatment outcomes. This Guideline is intended for use in conjunction with the individual patient's treatment goals. In all cases, patient preferences and personal goals should be considered when choosing a management strategy.

Baseline Laparoscopic Skill May Predict Baseline Robotic Skill and Early Robotic Surgery Learning Curve

INTRODUCTION

Robotic surgery is associated with a learning curve unique to each trainee. Knowledge about a trainee's baseline skill and learning curve would facilitate the development of a more individualized training curriculum. The aim of our study was to determine whether baseline laparoscopic skill is predictive of one's baseline robotic skill and short-term learning curve.

METHODS

Trainees from four different surgical specialties were included in the study. Each trainee participated in a 4-week, simulation-based robotic surgery basic skills training course. Precourse, baseline laparoscopic and robotic skills were assessed using validated test tasks; a basic peg transfer (PT) and an advanced intracorporeal suturing and knot tying (ISKT) task. Trainee robotic skill was assessed again 1 week postcourse. Each task performance was video recorded and scored by two blinded expert surgeons.

RESULTS

A total of 32 trainees were included; 14 urology, 7 gynecology, 8 thoracic Sx, 3 general Sx. Most (91%) were senior residents or clinical fellows and 50% had no prior robotic experience. There were no differences in baseline laparoscopic and robotic skill related to reported prior robotic experience. Between specialties, no differences were seen on baseline laparoscopic skill and only small differences were seen on baseline robotic skill. Both baseline Lap PT (p = 0.01) and Lap ISKT (p = 0.01) performances correlated with baseline robotic ISKT performance, but not robotic PT scores. Only baseline Lap ISKT performance correlated with postcourse robotic PT (p = 0.01) and ISKT (p < 0.01) performance. Baseline robotic ISKT scores, but not PT scores, correlated with postcourse robotic performance (p = 0.02 for PT, p < 0.01 for ISKT).

CONCLUSIONS

In this study, a trainee's baseline laparoscopic skill correlated with certain baseline robotic skills. Better baseline performance on an advanced, but not basic, laparoscopic and robotic skill task may correlate with a shorter learning curve for basic robotic skills. Further exploration of this finding may yield better training curricula.

Changing Patient Position Can Eliminate Arrhythmias Developing During Extracorporeal Shockwave Lithotripsy

INTRODUCTION

Extracorporeal shockwave lithotripsy (SWL) has a low complication rate. While serious complications are rare, cardiac arrhythmias, such as ventricular tachycardia, may occur. The etiology of these arrhythmias is poorly understood, but it appears to be due to stimulation of the heart by the shock waves.

OBJECTIVE

This study examines the effect of rotating the patient 15° to 20° when an arrhythmia occurs.

METHODS

Eight hundred nineteen patients were prospectively evaluated for arrhythmias during SWL. The initial patient position was dependent on the location of the stone and the body mass index (BMI) of the patient. If a sustained arrhythmia developed, treatment was withheld for 2 minutes and then recommenced. If the patient developed an arrhythmia again, the patient was rotated 15°-20° away from the original position and treatment recommenced.

RESULTS

Twenty patients developed significant arrhythmias during SWL. Arrhythmias occurred more frequently in patients with a lower BMI (p < 0.01), of younger age (p = 0.01), and with right-sided stones (p = 0.035). After the first rotation, 11 patients had no further arrhythmias, and 4 patients had a reduction of their arrhythmia to unsustained minor arrhythmias that did not require cessation of the treatment. The remaining five patients required a second repositioning. Three of these patients required gated SWL to abolish the arrhythmia.

CONCLUSION

Changing the position of the patient by rotating the patient by 15 to 20° can eliminate arrhythmias that develop during SWL.

CUA Guideline: Management of ureteral calculi

The focus of this guideline is the management of ureteral stones. Specifically, the topics covered include: conservative management, medical expulsive therapy, active intervention with either shockwave lithotripsy (SWL) or ureteroscopy (URS), factors affecting SWL treatment success, optimizing success, and special considerations (e.g., pregnancy, urinary diversion). By performing extensive literature reviews for each topic evaluated, we have generated an evidence-based consensus on the management of ureteral stones. The objective of this guideline is to help standardize the treatment of ureteral stones to optimize treatment outcomes.

Simulation-based flexible ureteroscopy training using a novel ureteroscopy part-task trainer

INTRODUCTION

Simulation-based training (SBT) is being increasingly used for novice trainees as a means of overcoming the early learning curve associated with new surgical skills. We designed a SBT flexible ureteroscopy (fURS) course using a novel inanimate training model (Cook Medical, Bloomington, IN; URS model). We evaluated the course and validated this Cook URS model.

METHODS

A 2-week SBT fURS course was designed for junior level urology trainees at 2 Canadian universities. The curriculum included didactic lectures, hands-on training, independent training sessions with expert feedback, and use of the Cook URS part-task model. Baseline and post-course assessments of trainee fURS skills were conducted using a standardized test task (fURS with basket manipulation of a calyceal stone). Performances were video-recorded and reviewed by 2 blinded experts using a validated assessment device.

RESULTS

Fifteen residents (postgraduate years [PGY] 0-3) participated in the course. Of the participants, 80% rated the Cook URS model as realistic (mean = 4.2/5) and 5 endourology experts rated it as useful as a training device (mean = 4.9/5), providing both face and content validity. The mean overall performance scores, task completion times, and passing ratings correlated with trainee clinical fURS experience - demonstrating construct validity for the Cook URS model. The mean post-course task completion times (15.76 vs. 9.37 minutes, p = 0.001) and overall performance scores (19.20 vs. 25.25, p = 0.007) were significantly better than at baseline. Post-course performance was better in all domains assessed by the validated assessment device.

CONCLUSIONS

This study demonstrates that a SBT curriculum for fURS can lead to improved short-term technical skills among junior level urology residents. The Cook URS model demonstrated good face, content and construct validity.

Development of a novel classification system for anatomical variants of the puboprostatic ligaments with expert validation

INTRODUCTION

We propose a novel classification system with a validation study to help clinicians identify and typify commonly seen variants of the puboprostatic ligaments (PPL).

METHODS

A preliminary dissection of 6 male cadavers and a prospective dataset of over 300 robotic-assisted laparoscopic radical prostatectomies (RARP) recorded on video were used to identify 4 distinct ligament types. Then the prospectively collected database of surgical videos was used to isolate images of the PPL from RARP. Over 300 surgical videos were reviewed and classified with 1 to 5 pictures saved for reference of the type of PPL. To validate the new classification system, we selected 5 independent, blinded expert robotic surgeons to classify 100 ligaments based on morphology into a 4-type system: parallel, V-shaped, inverted V-shape, and fused. One week later, a subset of 25 photographs was sent to the same experts and classified. Statistical analyses were performed to determine both the intra-rater and inter-rater reliability of the proposed system.

RESULTS

Inverted V-shaped ligaments were noted most frequently (29.97%), parallel and V-shaped ligaments were found at 19.19% and 11.11%, respectively and fused ligaments were noted less frequently (6.06%). There was good intra-rater agreement (κ = 0.66) and inter-rater agreement (κ = 0.67) for the classification system.

CONCLUSIONS

This classification system provided standardized descriptions of ligament variations that could be adopted universally to help clinicians categorize the variants. The system, validated by several blinded expert surgeons, demonstrated that surgeons were able to learn and correctly classify the variants. The system may be useful in helping to predict peri- and postoperative outcomes; however, this will require further study.

The Role of Prophylactic versus Selective Ureteric Stenting in Kidney Transplant Patients: A Retrospective Review

Objective

To evaluate the role of prophylactic versus selective ureteric stenting in the development of postoperative ureterovesical complications in kidney transplant recipients.

Methods

Records of 614 transplant patients seen from January 2006 to May 2011 were retrospectively reviewed. The primary outcome was the rate of ureterovesical complications, defined as the development of ureteric obstruction or a ureterovesical anastomotic leak. The secondary outcomes were the rate of urinary tract infections and forgotten stents. Using a χ2 test, we compared the primary and secondary outcomes across the selective and prophylactic cohorts. Logistic regression was used to compare the 2 cohorts while adjusting for potential confounders.

Results

The selective and prophylactic cohorts consisted of 258 and 330 patients, respectively. Unadjusted analysis showed that the prophylactic group had a significantly lower rate of ureterovesical complications than did the selective group (2.12% vs 6.20%; odds ratio, 0.33; P = .01). After adjustment for differences in sex and donor type, the prophylactic group still had a lower risk for ureterovesical complications (odds ratio, 0.30; P = .009). Rates of urinary tract infections and forgotten stents did not differ significantly between the 2 groups.

Conclusions

Prophylactic stenting is associated with a significantly lower rate of ureterovesical complications than is selective stenting.

Surgeon-specific factors affecting treatment decisions among Canadian urologists in the management of pT1a renal tumours

INTRODUCTION

The ubiquitous use of diagnostic imaging has resulted in an increased incidental detection of small renal masses (SRM). Patient- and tumour-related factors affect treatment decisions greatly; however, with multiple treatment options available, surgeon-specific characteristics and biases may also influence treatment recommendations. We determine the impact of surgeon-specific factors on treatment decisions in the management of SRM in Canada.

METHODS

An online survey study was conducted among Canadian urologists currently registered with the Canadian Urological Association. The questionnaire collected demographic information and recommended treatments for 6 SRM index cases involving theoretical patients of various ages (51-80 years) and comorbidities.

RESULTS

A total of 110 urologists responded (17% response rate) to the survey. Of these, 18% were over 65 years old and 45% were from academic centres. With increasing patient age and comorbidity, active surveillance and thermal ablative therapies were more the recommended treatment. Laparoscopic/robotic surgery was more commonly recommended by academic urologists and those under 65. Recommending surgery (radical nephrectomy or partial nephrectomy) for both elderly (about 80 years old) index patients correlated with surgeon age (surgeons over 65, p < 0.001), surgeons with no oncologic fellowship training (p = 0.021), surgeons with a non-academic practice (p = 0.003), surgeons with a personal history of cancer (p = 0.038) and surgeons with a family history of cancer death in the last 10 years (p = 0.022).

CONCLUSIONS

There are various factors that influence the management options offered to patients with SRMs. Our results suggest that surgeon age, personal history of cancer, practice-type and other surgeon-specific variables may affect treatments offered among urologists across Canada.

The surgical management of kidney stone disease: a population based time series analysis

PURPOSE

We evaluate population based trends in the use of extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy during the last 20 years, as well as assess the re-treatment rate and morbidity from treatment over time.

MATERIALS AND METHODS

Using administrative databases in the province of Ontario, Canada, a population based cross-sectional time series analysis was performed between July 1, 1991 and December 31, 2010. All extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy procedures were identified, along with all hospital readmissions and emergency department visits within 7 days of treatment. The primary outcome was treatment use, and secondary outcomes were the need for ancillary treatment and hospital readmission or emergency department visit after treatment. Exponential smoothing and autoregressive integrated moving average (ARIMA) models were used to assess trends over time.

RESULTS

We identified 194,781 kidney stone treatments performed during the study period. Time series modeling revealed a significant increase in the use of ureteroscopy over time (25% to 59% of all procedures, p <0.0001) and a reciprocal decrease in the use of extracorporeal shock wave lithotripsy (69% to 34% of all procedures, p <0.0001). A corresponding significant decrease in the need for ancillary treatment over time (23% to 15%, p <0.0001) and increase in the need for hospital readmission (7% to 11%, p <0.0001) or emergency department visit (7% to 11%, p=0.0024) after treatment were also demonstrated.

CONCLUSIONS

Our population based study demonstrates a shift in the treatment paradigm with increased use of ureteroscopy over time and a reciprocal decrease in the use of extracorporeal shock wave lithotripsy. We also observed a corresponding decrease in ancillary treatment and increase in posttreatment morbidity over time.

Robotic surgery basic skills training: Evaluation of a pilot multidisciplinary simulation-based curriculum

PURPOSE

Simulation-based training improves clinical skills, while minimizing the impact of the educational process on patient care. We present results of a pilot multidisciplinary, simulation-based robotic surgery basic skills training curriculum (BSTC) for robotic novices.

METHODS

A 4-week, simulation-based, robotic surgery BSTC was offered to the Departments of Surgery and Obstetrics & Gynecology (ObGyn) at the University of Toronto. The course consisted of various instructional strategies: didactic lecture, self-directed online-training modules, introductory hands-on training with the da Vinci robot (dVR) (Intuitive Surgical Inc., Sunnyvale, CA), and dedicated training on the da Vinci Skills Simulator (Intuitive Surgical Inc., Sunnyvale, CA) (dVSS). A third of trainees participated in competency-based dVSS training, all others engaged in traditional time-based training. Pre- and post-course skill testing was conducted on the dVR using 2 standardized skill tasks: ring transfer (RT) and needle passing (NP). Retention of skills was assessed at 5 months post-BSTC.

RESULTS

A total of 37 participants completed training. The mean task completion time and number of errors improved significantly post-course on both RT (180.6 vs. 107.4 sec, p < 0.01 and 3.5 vs. 1.3 sec, p < 0.01, respectively) and NP (197.1 vs. 154.1 sec, p < 0.01 and 4.5 vs. 1.8 sec, p = 0.04, respectively) tasks. No significant difference in performance was seen between specialties. Competency-based training was associated with significantly better post-course performance. The dVSS demonstrated excellent face validity.

CONCLUSIONS

The implementation of a pilot multidisciplinary, simulation-based robotic surgery BSTC revealed significantly improved basic robotic skills among novice trainees, regardless of specialty or level of training. Competency-based training was associated with significantly better acquisition of basic robotic skills.

Prone versus supine lasix renal scan to assess surgical success after laparoscopic and robot-assisted pyeloplasty

PURPOSE

Success after laparoscopic pyeloplasty (LP) for ureteropelvic junction obstruction is determined based on renal scan (RS) results and patient symptoms ± ultrasonography. The upright or prone position during RS may facilitate drainage. This study reports on outcomes after LP and robot-assisted pyeloplasty (RALP) and determines if patient position (supine vs prone) alters the results of the postoperative RS and surgical "success."

PATIENTS AND METHODS

A retrospective review of LP and RALP performed by one surgeon between 2005 and 2012 was performed. Follow-up consisted of RS ± ultrasonography. The paired t test was used to assess for a significant difference between mean T1/2 for supine vs prone scans in each patient. Linear regression was used to determine if preoperative split renal function on the affected side or degree of preoperative hydronephrosis predicted difference in supine vs prone T1/2.

RESULTS

There were 11 LP and 81 RALP performed; 84 had follow-up data. There were four (4.3%) failures. Thirty-eight patients had sufficient supine and prone RS for analysis. The difference in T1/2 between supine and prone RS was significant (mean difference 10.18 ± 27.28 min, P = 0.03). Strict success increased to 65.8% from 44.7% and combined strict plus technical success increased to 78.9% from 63.1% on prone vs supine RS. Split function and degree of hydronephrosis were not predictors of difference in RS results.

CONCLUSIONS

LP and RALP have good technical results. Prone position for RS may facilitate drainage and may be a more accurate representation of postoperative outcome after pyeloplasty, particularly in equivocal cases.

A randomized, double-blinded, placebo-controlled trial of intercostal nerve block after percutaneous nephrolithotomy

BACKGROUND AND PURPOSE

The optimal method of pain control after percutaneous nephrolithotomy (PCNL) remains controversial. We sought to determine whether intercostal nerve block with bupivicaine provided superior pain control, when compared with placebo, with a lower need for narcotics and improved health-related quality of life (HRQL) in the immediate postoperative period.

PATIENTS AND METHODS

Sixty-three patients were randomized to receive intercostal blockade with either 20 mL of 0.5% bupivacaine with epinephrine or 20 mL physiologic saline. All patients received intravenous narcotic patient-controlled analgesia (PCA) postoperatively. Data were collected on stone parameters, demographics, analgesic usage, length of stay, and HRQL as assessed by the Postoperative Recovery Scale.

RESULTS

The mean age was 47.7±1.2 years; mean body mass index was 28.0±5.0 kg/m(2); mean stone diameter was 29.2±15.8 mm. Within the first 3 to 6 hours after surgery, there was a significant reduction in narcotic use for the group receiving intercostal nerve blockade with bupivacaine compared with placebo. At 3 hours, narcotic use was 2.4±3.1 mg vs 4.3±3.8 mg morphine equivalents (P=0.034), and within 6 hours of surgery, narcotic use was 5.9±6.1 mg vs 8.8±7.4 mg (P=0.096). Durable improvement in HRQL was also observed in patients receiving intercostal nerve blockade with bupivacaine compared with placebo (P=0.034). No complications were attributable to the intercostal nerve blocks in either group.

CONCLUSIONS

Intercostal blockade with bupivacaine significantly improves both pain control and HRQL in the early postoperative period. The effectiveness of bupivacaine disappears within 6 hours of surgery, after which narcotic use becomes indistinguishable. Intercostal nerve blockade is an easy, safe, and inexpensive method that can be used to optimize pain control after PCNL.

Flank bulge following supracostal percutaneous nephrolithotomy: A report of 2 cases

Damage to intercostal nerves during surgical procedures has been associated with a postoperative flank bulge, due to denervation of the anterolateral abdominal wall musculature. This complication has not been reported following percutaneous nephrolithotomy (PCNL). We are aware of 3 cases, but have details on 2 cases of postoperative flank bulge following supracostal PCNL which are reported here. We also suggest how this complication could potentially be minimized.