Muhannad Alsyouf

High-Frequency Dusting Versus Conventional Holmium Laser Lithotripsy for Intrarenal and Ureteral Calculi

INTRODUCTION The efficiency of holmium laser lithotripsy for urolithiasis depends upon several factors, including laser pulse energy and frequency and stone composition and retropulsion. This study investigates the complex interplay between these factors and quantifies lithotripsy efficiency using different laser settings in a benchtop kidney and ureter model. MATERIALS AND METHODS In vitro caliceal and ex vivo porcine ureteral models were constructed. Calcium oxalate monohydrate stones were fragmented using a 200-μm laser fiber. In the caliceal model, stone fragmentation and vaporization rates at settings of 0.6 J/5 Hz, 0.2 J/15 Hz, and 0.2 J/50 Hz were compared. In the ureteral model, fragmentation time, retropulsion rate, fragmentation rate, and fragmented stone weight were compared at settings of 0.6 J/5 Hz and 0.2 J/15 Hz. Retropulsive forces generated at 0.6 J/5 Hz, 0.2 J/15 Hz, and 0.2 J/50 Hz settings were compared. Analysis was performed using Students t-test and one-way ANOVA. RESULTS In the caliceal model, the 0.6 J/5 Hz setting fragmented and vaporized stones at a higher rate than the 0.2 J/15 Hz setting (0.072 vs. 0.049 mg/s; p < 0.001). However, when the 0.2 J energy setting was combined with the 50 Hz frequency, the fragmentation rate (0.069 mg/s) was similar to the fragmentation rate at 0.6 J/5 Hz (0.072 mg/s; p = 0.677). In the ureteral model, the 0.6 J/5 Hz setting produced higher fragmentation rates (0.089 vs. 0.049 mg/s; p < 0.001), but resulted in significantly lower fragmented stone weight overall (16.815 vs. 25.485 mg; p = 0.009) due to higher retropulsion rates (0.732 vs. 0.213 mm/s; p < 0.001). Retropulsive forces decreased significantly when pulse energy decreased from 0.6 to 0.2 J (0.907 vs. 0.223 N; p < 0.001). Frequency did not affect retropulsive force at 15 and 50 Hz settings (0.223 vs. 0.288 N; p = 0.509). CONCLUSIONS Laser lithotripsy of calcium oxalate monohydrate stones in the ureter should be performed using the low-energy, moderate-frequency dusting setting to minimize retropulsion and maximize efficiency. In the renal calix, the low-energy high-frequency setting performed similarly to the high-energy low-frequency setting.

Diagnosis and management of ureteral fibroepithelial polyps in children: A new treatment algorithm

INTRODUCTION Fibroepithelial polyps are benign mesenchymal tumors arising from the urinary tract. With the advent of endoscopy in the pediatric population, more reports of endoscopic diagnosis and treatment have appeared. OBJECTIVE The present study reports experience with the diagnosis and treatment of fibroepithelial polyps of the upper urinary tract in the pediatric population. Incorporating past experience from literature, we propose an algorithm to guide the clinical diagnosis and treatment plan. STUDY DESIGN Four pediatric patients undergoing pyeloplasty for ureteropelvic junction (UPJ) obstruction were diagnosed with ureteral polyps. Their demographics, radiologic, surgical and pathologic information were reviewed. In addition, a comprehensive literature search using the MEDLINE database yielded 37 reports containing 126 cases of ureteral polyps, including 5 series with 57 cases and 9 cases of synchronous bilateral ureteral polyps. RESULTS Of 123 pediatric patients undergoing pyeloplasty from 2008 to 2013, four (3.3%) were found to have fibroepithelial polyps of the upper urinary tract. All patients were male and the mean age of presentation was 12 years. Ureteral polyps predominantly occurred unilaterally in the left ureter (75%) and one case of bilateral ureteral polyps was encountered. Along with three other recent case series [1-3], the combined incidence of ureteral polyps in patients undergoing evaluation for ureteral obstruction was 5.2%. Intraoperative retrograde pyelogram was used to identify filling defects in 4 of 5 affected ureters (see Figure). Ureterorenoscopy was performed in all three patients with filling defects for polyp mapping along the ureter and evaluation of the macroscopic polyp appearance. Based on ureteroscopic findings, Holmium laser polypectomy was performed in two patients with single, pedunculated polyps. Anderson-Hynes dismembered pyeloplasty was performed in three patients with broad based, multilobulated polyps too large for endoscopic treatment and in one patient for undiagnosed polyp prior to pyeloplasty. DISCUSSION The present study finds that the 5.2% combined incidence of ureteral polyps in contemporary reports may be higher than previously described [4]. Retrograde pyelogram was an effective tool in diagnosing ureteral polyp and ureteroscopy can be employed if ureteral polyps are suspected for both diagnostic and therapeutic purposes. Although clinical experience is limited, endoscopic laser treatment seems to be effective for the single, pedunculated ureteral polyps, while dismembered pyeloplasty is required for the broad based, multilobulated polyps. The study was limited by the rarity of ureteral polyps. Future multi-institutional collaborative studies are required to validate the diagnostic and treatment algorithm proposed. CONCLUSION Ureteral polyps cause approximately 5% of UPJ obstruction in the pediatric population. Diagnosis can be made in certain cases by intraoperative retrograde pyelogram. If a filling defect is encountered, ureteroscopy is indicated for polyp mapping. The treatment modality is dictated by the endoscopic appearance of the ureteral polyp.

Elevated Renal Pelvic Pressures during Percutaneous Nephrolithotomy Risk Higher Postoperative Pain and Longer Hospital Stay

Purpose Renal pelvic pressure may vary during percutaneous nephrolithotomy. We sought to determine the relationship of postoperative pain to endoscope caliber, renal pelvic pressure and hospital stay. Materials and Methods We reviewed the records of 20 percutaneous nephrolithotomies done under ureteroscopic guidance with renal pelvic pressure monitoring. The ureteroscope working channel was connected to a pressure transducer and used to determine renal pelvic pressure at baseline, when irrigating with a 26Fr rigid nephroscope and a 16Fr flexible nephroscope, and during suction. Patient demographics, operative characteristics, Likert pain scores and length of hospital stay were compared as stratified by average renal pelvic pressure. The Mann‐Whitney U and Fisher exact tests were used with p <0.05 considered significant. Results A total of 220 measurements were recorded in 20 patients undergoing single access percutaneous nephrolithotomy. Mean patient age was 55.2 years (range 20 to 77) and mean body mass index was 32.4 kg/m2 (range 18 to 53.3). Rigid nephroscopy resulted in significantly higher average renal pelvic pressure than flexible nephroscopy (30.3 vs 12.9 mm Hg, p = 0.007). Average renal pelvic pressure was 30 mm Hg or greater in 7 patients (35%) undergoing rigid nephroscopy and in none (0%) undergoing flexible nephroscopy (p <0.01). Patients exposed to an average renal pelvic pressure of 30 mm Hg or greater during rigid nephroscopy had significantly higher average pain scores (p = 0.004) and longer hospital stays (p = 0.04) than patients with renal pelvic pressure less than 30 mm Hg. Average renal pelvic pressure 30 mm Hg or greater during rigid nephroscopy was also associated with a longer skin to calyx distance (105.5 vs 79.7 mm, p = 0.03). Conclusions Knowledge of the factors that influence renal pelvic pressure and methods to control pressure extremes may improve patient outcomes during percutaneous nephrolithotomy.

Transurethral needle biopsy: A novel technique for pathologic diagnosis of bladder tumors in children

Although rare, both benign and malignant bladder tumors are occasionally encountered in the pediatric population. In the present article, the technique of transurethral needle biopsy, which utilizes an 18-gauge core biopsy instrument inserted through a 9.5 French offset pediatric cystoscope to obtain diagnostic biopsies, is described. This technique has been used successfully in two patients, both of whom had an inflammatory myofibroblastic tumor on biopsy and on final pathology from partial cystectomy. This provides an alternative technique, which may be used when a pediatric resectoscope is not available or in patients with a small caliber urethra.

Renal Vascular Clamp Placement: A Potential Cause of Incomplete Hilar Control during Partial Nephrectomy

PURPOSE Previous benchtop studies have shown that robotic bulldog clamps provide incomplete vascular control of a Penrose drain. We determined the efficacy of robotic and laparoscopic bulldog clamps to ensure hemostasis on the human renal artery. The effect of clamp position on vascular control was also examined. MATERIALS AND METHODS Fresh human cadaveric renal arteries were used to determine the leak point pressure of 7 bulldog clamps from a total of 3 manufacturers. Five trials were performed per clamp at 4 locations, including the fulcrum, proximal, middle and distal positions. Comparison was done using the Kruskal-Wallis test with p <0.05 considered significant. RESULTS None of the bulldog clamps leaked at a pressure less than 215 mm Hg when applied at the proximal, middle or distal position. In general leak point pressure decreased as the artery was positioned more distal along the clamp. The exception was when the vessel was placed at the fulcrum position. At that position 80% to 100% of trials with the Klein laparoscopic, 100% with the Klein robotic (Klein Robotic, San Antonio, Texas) and 60% to 80% with the Scanlan robotic (Scanlan International, Saint Paul, Minnesota) clamp leaked at pressure below 215 mm Hg. CONCLUSIONS Each vascular clamp adequately occluded flow at physiological pressure when placed at the proximal, middle or distal position. Furthermore, these results demonstrate that there is leakage at physiological pressure when the artery is placed at the fulcrum of certain clamp types. These results suggest that applying a bulldog clamp at the fulcrum could potentially lead to inadequate vessel occlusion and intraoperative bleeding.

PD21-04 COMPARISON OF ULTRASOUND-GUIDED, CONVENTIONAL FLUOROSCOPIC, AND A NOVEL LASER DIRECT ALIGNMENT RADIATION REDUCTION TECHNIQUE FOR PERCUTANEOUS NEPHROLITHOTOMY

There was no association between patient0s CCI, age, race, insurance, hospital location (urban vs non-urban, and hospital type (teaching vs non-teaching) with regard to physician specialty obtaining RA. On multivariable analysis, RA by urologist was associated with lower rates of any complication (Clavien 1-5), shorter hospitalization (<2 days) and lower direct admission costs (<

PD19-05 THE OPTIMAL GUIDEWIRE TYPE AND EFFECT OF PRIOR USE ON THE EASE OF URETERAL STENT INSERTION

12,515) Figure 1. CONCLUSIONS: PCNL is performed with urologists obtaining percutaneous access the minority of the time in the United States. Highvolume urologists are more likely to obtain their own access. Access by urologist is associated with lower overall complications, shorter hospitalizations, and lower direct hospital costs.

MP81-08 HOW WELL CAN UROLOGY TRAINEES DETECT SUBURETHRAL MESH USING TRANSLABIAL ULTRASOUND IN COMPARISON TO A RADIOLOGIST?

INTRODUCTION AND OBJECTIVES: Ureteral stent insertion is a frequent procedure in endourology, with no clear consensus on the best wire type to facilitate stent insertion. Use of wires may result in deterioration of their protective coating, requiring greater force for stent insertion. The purpose of this study was to identify the effect of wire type, and prior use, upon average insertion force needed for a 6Fr ureteral stent. METHODS: Stent insertion was tested using an ex vivo porcine urinary tract model with continuous water infusion (1cc/min) to simulate urine production. For each trial, a new, soft, 6Fr Cook JJ ureteral stent was advanced over new and used 0.03800 diameter guide wires including the Glidewire (Terumo), Standard Teflon-coated wire (Cook), Superstiff wire (Cook), Sensor wire (Boston Scientific), Zip-wire (Boston Scientific), and Zebra wire (Boston Scientific). A Mark-10 digital force gauge was attached to the stent, and at a constant advancing rate of 2 rotations per second, the forces to advance the stent over the wire were calculated. 10 trials of stent insertion were randomly performed on 12 new and 12 used guide wires (total of 240 placements). RESULTS: The new Glidewire had the lowest average force required for stent advancement (0.18N). The forces for insertion of all other new wires were significantly higher; Standard (1.25N; p<0.01), Superstiff (2.03N; p<0.01), Sensor (1.87; p<0.01), Zip (0.22N; p<0.01), and Zebra (0.61; p<0.01). When comparing the average insertion force between new and used wires, the used wires required greater mean force in the Standard (2.42N vs. 1.25N; p <0.01), Superstiff (2.68N vs. 2.03N; p <0.01), and Zipwire (0.36N vs. 0.22N; p <.01), but there was no statistical difference between used and new fibers in the Glidewire (0.28N vs. 0.18N; p1⁄40.14), Sensor ( 1.66N vs. 1.87N; p1⁄40.18) and Zebra wire (0.59N vs.0.61N; p1⁄40.67). CONCLUSIONS: The Glidewire resulted in the lowest force for ureteral stent insertion. It may be used several times with no significant effect on ureteral stent insertion force due its resilient lubricious hydrophilic coating. Employing a used Standard, Superstiff and Zip-wire may result in additional stent insertion force. Knowledge of the forces required for stent insertion over various guide wires may allow surgeons to improve the ease and safety of stent placement.

V9-05 A SIMPLIFIED TECHNIQUE FOR PERFORMANCE OF FLUOROLESS URETEROSCOPY

INTRODUCTION AND OBJECTIVES: Suburethral mesh implantation for stress urinary incontinence can result in erosion, extrusion, infection, pain, and irritative voiding symptoms. Surgical mesh removal can be challenging when operative records are not available, portions of mesh have been removed, mesh position has changed, or it’s not palpated on physical exam. Translabial ultrasonography is a diagnostic tool that can detect synthetic mesh. The purpose of this study was to compare a group of Urology trainees’ and a radiologist’s ability to identify pelvic landmarks, localize and assess completeness of suburethral mesh. METHODS: Eight urology trainees received a 15-minute lecture on anatomical landmarks and techniques of translabial ultrasound as well as instruction on detection of suburethral mesh. The trainees then reviewed 18 different US studies. Trainees were asked a total of 126 questions including identification of anatomical planes, pelvic structures in different planes, mesh presence, disruption of mesh, and its location along the urethra. The overall correct response rate of all questions was compared to a Board-certified radiologist specialized in translabial ultrasound, which served as our control. The radiologist and trainees were blinded to patient history, clinical, and operative findings. RESULTS: Overall, trainees answered correct on average 83.9% (105/126) of all questions compared to the radiologist 94.4% (119/126; p1⁄40.023). Per category the average trainee was able to correctly identify the anatomical plane in 94.4% (17/18) of questions, detect presence or absence of mesh in 95.8% (17/18), determine mesh disruption in 83.3% (15/18), correctly identify pelvic anatomical structures in 83.3% (15/18), and determine location of mesh in correspondence to the urethra in 72.2 % (13/18). CONCLUSIONS: Urology trainees can learn in a reasonable time how to identify anatomical landmarks on translabial ultrasound and consistently detect the presence of suburethral mesh. Translabial ultrasound can be utilized by urologists to aid in preoperative planning for mesh removal or clinical diagnostics for symptomatic mesh.

MP20-05 VARIATIONS IN INTRAPELVIC RENAL PRESSURES DURING PERCUTANEOUS NEPHROLITHOTOMY – A PORCINE STUDY

INTRODUCTION AND OBJECTIVES: Percutaneous nephrolithotomy (PCNL) remains a challenging procedure associated with significant potential for patient morbidity. In an attempt to decrease the morbidity of PCNL, we have developed a novel technique employing direct visualization with ureteroscopy to decrease ambiguity associated with fluoroscopy guidance, while eliminating ionizing radiation exposure. In this video, we demonstrate PCNL techniques that obviate the need for fluoroscopy. METHODS: This video demonstrates fluoroless PCNL in a 56 year-old female with large left renal stone burden (>4 cm). The patient was positioned prone and split-leg. Utilizing visual and tactile cues, a super-stiff and standard guidewire were placed from below using a flexible cystoscope. Using flexible ureteroscopy, the ideal calyx for access was selected. Under ultrasound guidance, an access needle was placed into the selected calyx, which was directly visualized on ureteroscopy. With the aid of a stone basket, an access wire was pulled into the ureter to allow for subsequent exchange to a super-stiff guidewire. Under direct visualization with the ureteroscope, the balloon and access sheath were positioned. The ureteroscope was left with the tip occluding the ureteropelvic junction to prevent distal migration of fragments. Stone comminution was accomplished with an ultrasonic lithotripter. Stone-free status was assured intraoperatively using a combination of flexible nephroscopy and ureteroscopy. A nephrostomy tube and multipurpose angled ureteral catheter were placed under direct vision ureteroscopically to conclude the procedure. RESULTS: Operative time was 4 hours 36 minutes. Estimated blood loss was <50 mL. On post-operative day one, a 15 mAs low-dose CT (<1 mSv) demonstrated stone-free status. CONCLUSIONS: This technique combines the methods of many pioneering endourologic surgeons in a unique way to perform PCNL under direct visualization. We believe this technique offers significant promise both by eliminating uncertainties encountered when operating under fluoroscopic guidance and reducing the risk of radiation exposure to patients and operating room staff.