John Denstedt

The University of Western Ontario | UWO · Department of Surgery

Mastering a surgical skill requires experience and repetition, yet opportunities for surgical trainees to gain real experience is variable and limited by case load. Surgical simulators have emerged in an attempt to overcome these limitations. However, the few currently available skills simulators for flexible endoscopy are costly, have limited acce...

Background Retrograde intrarenal surgery (RIRS) has become the preferred treatment modality for nephrolithiasis. However, because of ongoing uncertainties regarding the optimal perioperative management, operative technique, and postoperative follow-up, as well as a lack of standardization for outcome reporting, consensus is needed to achieve more u...

Ureteral stents are commonly used to prevent urinary obstruction but can become colonized by bacteria and encrusted, leading to clinical complications. Despite recent discovery and characterization of the healthy urinary microbiota, stent-associated bacteria and their impact on encrustation are largely underexplored. We profile the microbiota of pa...

Purpose: Splenic injury is a rare complication after left sided percutaneous nephrolithotomy (PCNL). Although initial observation is often espoused, the natural history of non-operative, conservative management is not well established and the implications of splenic injury are not fully defined in this context. We sought to describe outcomes of co...

Purpose Stone burden has been reported as an independent predictor of stone free rate after percutaneous nephrolithotomy (PCNL), however no consensus exists on a standardized method for measuring stone burden. Recently, stone volume has been advocated as the most accurate means of measuring stone burden. We aimed to compare different measuring meth...

Urinary stone disease in pregnancy is an important clinical scenario which presents unique challenges to the urologist. In order to ensure safe and comprehensive care of both the mother and the fetus, a multidisciplinary approach is highly recommended. A high degree of suspicion is required for the prompt and accurate diagnosis of renal colic durin...

Urolithiasis during pregnancy is an anxiety‐provoking problem to both patients and physicians. It can be associated with severe maternal and/or fetal morbidity and mortality. The main challenge is the accurate diagnosis of the disease, since elaborate radiological investigations are limited due to the biohazards of radiation on the fetus. With adva...

Introduction: After 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 liter...

Purpose: To compare the efficiency (stone fragmentation and removal time) and complications of three models of intracorporeal lithotripters in percutaneous nephrolithotomy (PCNL). Materials and methods: Prospective, randomized controlled trial at nine centers in the North America from 2009 to 2016. Patients were randomized to one of three lithot...

Context: The recent evolution of management options for urolithiasis has presented a unique dilemma for the modern urologist. A comprehensive understanding of epidemiological trends along with current provider preferences in treating urinary stones would be beneficial. Objective: To review trends in the prevalence, treatments, and costs of uroli...

OBJECTIVE To determine whether passive ureteral dilation (PUD) would occur after an indwelling ureteral stent was left in place in healthy dogs for 2 or 6 weeks, ureteroscopy would be possible at the time of stent removal, and PUD would be reversible after stent removal. ANIMALS 5 healthy adult female Beagles. PROCEDURES A ureteral stent was cystos...

Although ureteral stents are extensively used in urological surgery throughout the world, they are fraught with complications such as infection, encrustation, haematuria and pain. To increase biocompatibility, a multitude of different strategies in coated and drug-eluting stents have been researched. As an ideal stent has not been invented yet, the...

Ureteral stents are a fundamental technology in daily urology practice. Similar to other instruments and equipment, ureteral stents have been through a long history of development and improvement. Variable new technologies have been implemented in the stent industry to improve its physical properties and decrease the impact on patient health relate...

This report documents two instances of retained flexible ureteroscopes at the time of ureteroscopy and laser lithotripsy in a healthy 37-year-old male and a 53-year-old male with a pelvic kidney. We describe maneuvers to remove the ureteroscope endoscopically in the first case, while the second case required conversion to open surgery for ureterosc...

OBJECTIVE To compare perioperative characteristics of dogs with cystic calculi treated via open versus laparoscopic-assisted cystotomy (LAC). DESIGN Retrospective case series. ANIMALS 89 client-owned dogs that underwent open cystotomy (n = 39) or LAC (50). PROCEDURES Medical records of dogs that underwent cystotomy between 2011 and 2015 were review...

Introduction: Partial or complete obstruction of the urinary tract is a common and challenging urological condition that may occur in patients of any age. Serum creatinine is the most commonly used method to evaluate global renal function, although it has low sensitivity for early changes in the glomerular filtration rate or unilateral renal patho...

Technical innovations in all aspects of percutaneous nephrolithotomy have changed the field considerably. The current review is aimed at reporting on the most recent advancements in the field of percutaneous nephrolithotomy. Improvements in CT imaging and the possibility of 3D rendering have dethroned the intravenous pyelogram as gold standard for...

Objective: To investigate the impact of distraction on the performance of a simulator-based laparoscopic task in veterinary students. Study design: Prospective, randomized trial. Sample population: Years 1-4 veterinary students (n=41). Methods: Participants repeated a simulated laparoscopic peg transfer task to eliminate any learning effects...

Introduction Several anatomical and clinical factors have been implicated in the failure rates of Shock Wave Lithotripsy (SWL), including the attenuating effects of bony structures. We designed an in vitro model which incorporates the lumbar spine including vertebral bodies and transverse processes along the pathway of shockwaves, to mimic the clin...

Background and purpose: Several scoring systems have recently emerged to predict stone free rate (SFR) and complications after percutaneous nephrolithotomy (PCNL). We aimed to compare the most commonly used scoring systems (Guy's stone score, S.T.O.N.E. nephrolithometry and CROES nomogram), assess their predictive accuracy for SFR and other post-o...

Introduction and objectives: The mineral composition of a urinary stone may influence its surgical and medical treatment. Previous attempts at identifying stone composition based on mean Hounsfield Units (HUm) have had varied success. We aimed to evaluate the additional use of standard deviation of HU (HUsd) to more accurately predict stone compos...

Objective: To assess the potential effect of simple renal cysts (SRC) on stone fragmentation during shock wave lithotripsy (SWL) in an in vitro model. Materials and methods: The in vitro model was constructed using 10% Ordnance Gelatin (OG). Models were created to mimic 4 clinical scenarios: model A- with an air-filled cavity (suboptimal for sto...

Thrombin plays a key role in thrombosis and hemostasis. The abnormal level of thrombin in body fluids may lead to different diseases, such as rheumatoid arthritis, glomerulonephritis, etc. Detection of thrombin level in blood and/or urine is one of important methods for medical diagnosis. Here, a bioluminescent sensor is developed for non-invasivel...

Ureteral stents are commonly used following urological procedures to maintain ureteral patency. However, alongside the benefits of the device, indwelling stents frequently cause significant patient discomfort (pain, urgency, frequency) and can become encrusted and infected. The importance of these sequelae is that they are not only bothersome to th...

The last 3 decades have witnessed great improvements in the technology and clinical applications of many minimally invasive procedures in the urological field. Flexible ureteroscopy (fURS) has advanced considerably to become a widely utilized diagnostic and therapeutic tool for multiple upper urinary tract pathologies. The most common indication fo...

Percutaneous nephrolithotomy (PCNL) has surpassed open stone surgery as the operation of choice for large and complex stone burdens (figure). Although the procedure was developed in adults, its principles have been extrapolated to children. There is a paucity of literature comparing outcomes of PCNL in adults and children for similar stone burdens....

To describe and evaluate the complications related to percutaneous nephrolithotomy (PCNL) and to identify risk factors of morbidity according to the modified Clavien scoring system. We also wished to specify which perioperative factors are associated with minor and major complications. A retrospective analysis was performed using data from patients...

INTRODUCTION & OBJECTIVES: Percutaneous nephrolithotomy (PCNL) is the most commonly used surgical modality for large kidney stones. Prediction of surgical outcomes and risk estimation is of paramount importance in these patients. Several stone scoring systems have recently emerged attempting to predict stone free status and complications after PCNL...

INTRODUCTION AND OBJECTIVES: Several stone scoring systems have recently emerged attempting to predict stone free status and complications after percutaneous nephrolithotomy (PCNL). We aimed to compare the three most commonly used scoring systems to identify the most accurate in predicting post-operative outcomes. METHODS: Patients from 3 academic...

Surface and interface modifications of synthetic silicone hydrogels used for wearable and implantable medical devices, e.g. catheter, contact lenses, are critical to overcome their poor mechanical properties and biofouling. In this paper, silica nanoparticles (SiO2 NPs) were incorporated within silicone hydrogels through photo-polymerization. As co...

Despite lack of a well-delineated definition, chronic ureteral obstruction (CUO) imposes significant quality of life loss, increased pathologic morbidity and risk of mortality as well as substantial economic burden. Ureteral stenting serves as an important therapeutic option to alleviate the obstruction. We thus assessed the recently-published lite...

Background and purpose: Patients with urinary tract abnormalities are at an increased risk of stone formation. Percutaneous nephrolithotomy (PCNL) plays an important role in the treatment of this patient population; however, outcomes are less well defined compared with patients with normal urinary tract anatomy. Our objective was to evaluate the i...

Introduction and Objectives: The occurrence of nephrolithiasis and the use of percutaneous nephrolithotomy (PCNL) are increasing in North America. Rendering patients stone free is of paramount importance during PCNL. Therefore our objective is to identify independent predictors of residual stones 3 months post-PCNL. Methods: Between July 1990 and...

Introduction and Objectives: Obesity is a significant health concern in North America and has been associated with the increasing prevalence of nephrolithiasis. Understanding the clinical implications of BMI for patients who undergo percutaneous nephrolithotomy (PCNL) is important to improving patient care. Our objective was to evaluate the role of...

Background: Efficacy and safety of percutaneous nephrolithotomy (PCNL) have been demonstrated in obese individuals. Yet, there is a paucity of data on the outcomes of PCNL in morbidly obese patients (body mass index [BMI] >40). Methods: Perioperative and stone-related outcomes following PCNL in morbidly obese patients was assessed using a prospe...

Background and purpose: There exist no global standards for defining patient outcomes in renal stone surgery. The objective of this study was to evaluate the quality of reporting of outcomes in studies investigating percutaneous nephrolithotomy (PCNL) and to propose standardized consensus definitions for common outcomes. Methods: We performed a...

Accurate reporting of complications is an essential component to critical appraisal and innovation in surgery and specifically with percutaneous nephrolithotomy (PCNL). We review the evolution of complication reporting for PCNL and suggest future directions for innovation. A selective review was carried out using Pubmed. Key search terms and their...

Since its initial description by Fernstrom and Johansson in 1976, percutaneous nephrolithotomy (PCNL) has evolved with improvements in technique and equipment to become the gold standard form of management for large stones in the upper urinary tract. It has now largely replaced open surgery in this context. Although alternatives such as supine pati...

The indications for percutaneous nephrolithotripsy have greatly expanded. Percutaneous nephrolithotripsy in general is indicated if a kidney stone is unlikely to pass spontaneously and cannot be treated by less invasive techniques like shock wave lithotripsy or ureteroscopy. Refinements in percutaneous nephrolithotripsy techniques along with proper...

Purpose: To assess the current indications for ureteroscopy (URS) treatment, outcome in terms of stone-free rate, and intra- and postoperative complications using the modified Clavien grading system. Patients and methods: The Clinical Research Office of the Endourological Society collected prospective data as part of the URS Global Study for con...

The Post-Ureteroscopic Lesion Scale (PULS) offers a simple grading system for the description of ureteral lesions after ureteroscopy. In this article, we present the results of a video-based multicenter evaluation of the inter-rater reliability of clinically important PULS grades 0-3. Video sequences at the end of ureteroscopy (final passage) were...

PURPOSE: The Post-Ureteroscopic Lesion Scale (PULS) offers a simple grading system for the description of ureteral lesions after ureteroscopy. In this article, we present the results of a video-based multicenter evaluation of the inter-rater reliability of clinically important PULS grades 0-3. METHODS: Video sequences at the end of ureteroscopy (fi...

A thorough appreciation of the common congenital and acquired anatomical anomalies of the genitourinary tract is necessary prior to any contemplated surgical intervention. Anomalous anatomy predisposes to a range of benign and malignant conditions which may require endourological management. As with any form of surgical management, definitive treat...

Purpose: The aim of this study was to compare the efficacy of comprehensive bowel preparation to that of limited bowel preparation in prevention of postoperative complications in elective urinary diversion surgery by using ileum. Methods: Literature search of PubMed, EMBASE and the Cochrane Library was done to identify randomized controlled tria...

Despite recent advances in the surgical techniques and equipment available for the management of urinary lithiasis, the prevalence of this condition continues to increase in the North American population. Associated costs are estimated to exceed 5.3 billion US dollars each year. Epidemiological studies have implicated a range of contributory dietar...

Purpose: To determine the incidence of and evaluate the potential risk of a symptomatic perinephric hematoma (PNH) after shockwave lithotripsy (SWL) with the Storz Modulith SLX-F2 device. Patients and methods: Patient and treatment-related data from 6172 SWL treatments for proximal ureteral and kidney stones were collected prospectively from Apr...

In addition to more commonly forming stones, obese patients present a number of challenges when undergoing percutaneous nephrolithotomy. We evaluated percutaneous nephrolithotomy outcomes in 3,709 patients stratified by body mass index. A prospective database administered by CROES (Clinical Research Office of the Endourological Society) captured da...

For centuries, China was the world’s dominant civilization, including being the cradle of scientific, engineering and architectural discovery and innovation. Early discoveries in the field of medicine were often dominated by the Chinese, including sterilization by steaming (AD980), documentation of urinary steroids (AD1025), thyroid treatment (4th...

Renal stone disease is common among patients with spinal cord injury (SCI). They frequently have recurrent stones, staghorn calculi, and bilateral stone disease. The potential risk factors for stones in the SCI population are lesion level, bladder management strategy, specific metabolic changes, and frequent urinary tract infections. There has been...

Study Type – Therapy (RCT) Level of Evidence 1b What's known on the subject? and What does the study add? Infection, encrustation and ureteral-stent-related symptoms (USRS) including pain, urgency and frequency are all major problems associated with stent use. No current ureteral stent or exogenously applied therapy adequately deals with these prob...

Urolithiasis during pregnancy presents a clinical situation with unique diagnostic and treatment dilemmas and challenges. Decision-making requires consideration of both fetal and maternal safety and well-being. The exact incidence of urolithiasis during pregnancy is uncertain, but it is estimated to be between 1 in 244 and 2000 pregnancies. The man...

Staphylococcus saprophyticus is a frequent cause of both uncomplicated and complicated urinary tract infections (UTI) in young females and has recently been established as the most prominent gram-positive uropathogen. Although the effects of subinhibitory concentrations of antimicrobials on numerous other pathogenic bacteria have been studied, litt...

Caliceal diverticula are rare renal anomalies present in approximately 0.6% of the population. They are associated with calculi in 50% of cases. Therapeutic options include several minimally invasive techniques. We report a retrospective review of outcomes and complications from our series of patients who were treated with a percutaneous approach....

To compare the operative techniques and perioperative outcomes of patients with urinary intestinal diversions undergoing percutaneous nephrolithotripsy (PCNL), to a control cohort of patients without diversions. The medical records of all patients who were treated with PCNL from 1990 to 2009 were retrospectively reviewed. Each urinary diversion pat...

• To compare the Cyberwand (Gyrus/ACMI, Southborough, MA, USA), a dual-probe ultrasonic lithotrite, with a single-probe ultrasonic lithotrite. • The Cyberwand incorporates coaxial high- and low-frequency ultrasonic probes that work synergistically. • An institutional review board-approved, multicentre, randomized controlled trial to compare the Cyb...

Stents are typically placed to prevent or relieve ureteral obstruction caused by intrinsic or extrinsic etiologies. Stent design and biomaterials have improved in recent years from the first described double-J stent in 1978. The indications for placement of a ureteral stent include obstructing ureteral calculi, ureteral strictures, congenital anoma...

We evaluated the short-term safety and efficacy of a ketorolac loaded ureteral stent compared to a standard stent (control). In this prospective, multicenter, double-blind study patients were randomized 1:1 to ketorolac loaded or control stents after ureteroscopy. The primary end point was an intervention for pain defined as unscheduled physician c...

To evaluate the modalities of electrocautery, holmium:yttrium-aluminum-garnet (YAG) laser, hydrodissection, and combined holmium:YAG laser with hydrodissection applied to laparoscopic partial nephrectomy (LPN) in a porcine model. A total of 16 Yorkshire pigs were divided into 4 equal groups (electrocautery, hydrodissection, holmium:YAG laser, and c...

Ureteral stents often cause significant patient morbidity that can be difficult to treat. Drug-eluting stent technology allows the local delivery of a drug. Our previous work demonstrated that ketorolac instilled intravesically at the time of ureteral stent insertion significantly decreased flank pain compared with controls. We sought to determine...

The placement of a ureteral stent is one of the most commonly performed urologic procedures. Indwelling ureteral stents are often accompanied by significant patient morbidity, including lower urinary tract symptoms, flank pain, and urinary tract infections. This article reviews the current state of ureteral stent technology developed to address the...

To develop a novel in vitro model for the study of bladder and kidney epithelial cell injury akin to stent movement, as ureteric stents are associated with urinary tract complications that can significantly add to patient morbidity. These sequelae may be linked to inflammation triggered by stent-mediated mechanical injury to the urinary tract. T24...

Complicated choledocholithiasis cannot always be managed by standard surgical, radiologic or endoscopic methods. One additional approach is to use percutaneous techniques developed by endourologists to treat renal calculi. In this report, we present our experience over the past 10 years with this novel approach. We conducted a retrospective review...

Percutaneous nephrolithotomy (PCNL) for staghorn calculi is one of the more challenging endourologic procedures. Although excellent stone-free rates are universally reported in the literature, complication rates vary widely, especially related to the need for blood transfusion. The purpose of this study was to evaluate the outcomes of PCNL for pati...

Abstract Since the first description of percutaneous nephrolithotripsy (PNL) over 30 years ago, the indications for this procedure in the management of upper tract urinary stones has greatly expanded. Despite recent advances in shock wave lithotripsy and ureteroscopic technologies, PNL maintains a dominant role in the management of complex and larg...

Long-term use of ureteral stents is prevented by biofilm-related infection and encrustation mandating stent changes every few months. Triclosan is a broad-spectrum antimicrobial in numerous consumer and medical products and has been incorporated into a ureteral stent. We sought to determine the clinical effects of the triclosan-eluting stent in pat...

Biofilms continue to be a major limiting factor in the long-term use of ureteral stents, promoting the development of chronic infections and antibiotic resistance and encrustation. Apart from stent removal in conjunction with antibiotic therapy, there is currently no treatment proven successful for completely eradicating a biofilm-related infection...

Infrared spectroscopy (IRS) is a standard method of stone analysis that yields relative proportions of stone materials within a sample. IRS is destructive, as it analyzes only powdered samples, with only a fraction of the stone being analyzed. This leads to sampling bias with components over- or underestimated or even missed entirely. IRS fails to...