Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse.

BACKGROUND: The benefits of removing small (≤6 mm), asymptomatic kidney stones endoscopically is unknown. Current guidelines leave such decisions to the urologist and the patient. A prospective study involving older, nonendoscopic technology and some retrospective studies favor observation. However, published data indicate that about half of small renal stones left in place at the time that larger stones were removed caused other symptomatic events within 5 years after surgery. METHODS: We conducted a multicenter, randomized, controlled trial in which, during the endoscopic removal of ureteral or contralateral kidney stones, remaining small, asymptomatic stones were removed in 38 patients (treatment group) and were not removed in 35 patients (control group). The primary outcome was relapse as measured by future emergency department visits, surgeries, or growth of secondary stones. RESULTS: After a mean follow-up of 4.2 years, the treatment group had a longer time to relapse than the control group (P<0.001 by log-rank test). The restricted mean (±SE) time to relapse was 75% longer in the treatment group than in the control group (1631.6±72.8 days vs. 934.2±121.8 days). The risk of relapse was 82% lower in the treatment group than the control group (hazard ratio, 0.18; 95% confidence interval, 0.07 to 0.44), with 16% of patients in the treatment group having a relapse as compared with 63% of those in the control group. Treatment added a median of 25.6 minutes (interquartile range, 18.5 to 35.2) to the surgery time. Five patients in the treatment group and four in the control group had emergency department visits within 2 weeks after surgery. Eight patients in the treatment group and 10 in the control group reported passing kidney stones. CONCLUSIONS: The removal of small, asymptomatic kidney stones during surgery to remove ureteral or contralateral kidney stones resulted in a lower incidence of relapse than nonremoval and in a similar number of emergency department visits related to the surgery. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Veterans Affairs Puget Sound Health Care System; ClinicalTrials.gov number, NCT02210650.).

Using structured problem solving to promote fluid consumption in the prevention of urinary stones with hydration (PUSH) trial.

BACKGROUND: Structured Problem Solving (SPS) is a patient-centered approach to promoting behavior change that relies on productive collaboration between coaches and participants and reinforces participant autonomy. We aimed to describe the design, implementation, and assessment of SPS in the multicenter Prevention of Urinary Stones with Hydration (PUSH) randomized trial. METHODS: In the PUSH trial, individuals with a history of urinary stone disease and low urine output were randomized to control versus a multicomponent intervention including SPS that was designed to promote fluid consumption and thereby prevent recurrent stones. We provide details specifically about training and fidelity assessment of the SPS coaches. We report on implementation experiences related to SPS during the initial conduct of the trial. RESULTS: With training and fidelity assessment, coaches in the PUSH trial applied SPS to help participants overcome barriers to fluid consumption. In some cases, coaches faced implementation barriers such as variable participant engagement that required tailoring their work with specific participants. The coaches also faced challenges including balancing rapport with problem solving, and role clarity for the coaches. CONCLUSIONS: We adapted SPS to the setting of kidney stone prevention and overcame challenges in implementation, such as variable patient engagement. Tools from the PUSH trial may be useful to apply to other health behavior change settings in nephrology and other areas of clinical care. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT03244189.

Risk Factors for Increased Stent-associated Symptoms Following Ureteroscopy for Urinary Stones: Results From STENTS.

PURPOSE: The STudy to Enhance uNderstanding of sTent-associated Symptoms sought to identify risk factors for pain and urinary symptoms, as well as how these symptoms interfere with daily activities after ureteroscopy for stone treatment. MATERIALS AND METHODS: This prospective observational cohort study enrolled patients aged ≥12 years undergoing ureteroscopy with ureteral stent for stone treatment at 4 clinical centers. Participants reported symptoms at baseline; on postoperative days 1, 3, 5; at stent removal; and day 30 post-stent removal. Outcomes of pain intensity, pain interference, urinary symptoms, and bother were captured with multiple instruments. Multivariable analyses using mixed-effects linear regression models were identified characteristics associated with increased stent-associated symptoms. RESULTS: A total of 424 participants were enrolled. Mean age was 49 years (SD 17); 47% were female. Participants experienced a marked increase in stent-associated symptoms on postoperative day 1. While pain intensity decreased ∼50% from postoperative day 1 to postoperative day 5, interference due to pain remained persistently elevated. In multivariable analysis, older age was associated with lower pain intensity (P = .004). Having chronic pain conditions (P < .001), prior severe stent pain (P = .021), and depressive symptoms at baseline (P < .001) were each associated with higher pain intensity. Neither sex, stone location, ureteral access sheath use, nor stent characteristics were drivers of stent-associated symptoms. CONCLUSIONS: In this multicenter cohort, interference persisted even as pain intensity decreased. Patient factors (eg, age, depression) rather than surgical factors were associated with symptom intensity. These findings provide a foundation for patient-centered care and highlight potential targets for efforts to mitigate the burden of stent-associated symptoms.

Ureteral Strictures Following Ureteroscopy for Kidney Stone Disease: A Population-based Assessment.

PURPOSE: As the prevalence of urolithiasis increases and ureteroscopy is used more frequently, the risks of uncommon complications such as ureteral stricture may become more notable. Our objective is to assess the rate and associated risk factors of ureteral stricture formation in patients undergoing ureteroscopy. MATERIALS AND METHODS: Utilizing the IBM MarketScan research database, we evaluated data from 2008 to 2019 and compared ureteral stricture rates and their management following ureteroscopy to subjects who had shock wave lithotripsy. Shock wave lithotripsy was used as a comparison group to represent the rate of stricture from stone disease alone. A third group of those having both shock wave lithotripsy and ureteroscopy was included. Patients and secondary procedures were identified using Current Procedural Terminology, and International Classification of Diseases-9 and -10 codes. RESULTS: A total of 329,776 patients received ureteroscopy, shock wave lithotripsy, or shock wave lithotripsy+ureteroscopy between 2008 and 2019. Stricture developed in 2.9% of patients after ureteroscopy, 1.5% after shock wave lithotripsy, and 2.6% after shock wave lithotripsy+ureteroscopy. In the multivariable model, rates of stricture were 1.7-fold higher after ureteroscopy vs shock wave lithotripsy (OR:1.71, 95% CI 1.62-1.81). Preoperative hydronephrosis, age, prior stones/intervention, and concurrent kidney and ureteral stones were associated with increased risk of stricture. Of those with strictures incurred after ureteroscopy, 35% required drainage, 21% had endoscopic intervention, 4.8% required reconstructive surgery, and 1.7% underwent nephrectomy. CONCLUSIONS: Ureteral stricture rate after ureteroscopy of nearly 3% was higher than expected and approximately twice the rate attributable to stone disease alone. Factors associated with the stone as well as instrumentation were found to be risk factors. The morbidity of stricture disease following ureteroscopy was significant.

Fragmentation of Stones by Burst Wave Lithotripsy in the First 19 Humans.

PURPOSE: We report stone comminution in the first 19 human subjects by burst wave lithotripsy (BWL), which is the transcutaneous application of focused, cyclic ultrasound pulses. MATERIALS AND METHODS: This was a prospective multi-institutional feasibility study recruiting subjects undergoing clinical ureteroscopy (URS) for at least 1 stone ≤12 mm as measured on computerized tomography. During the planned URS, either before or after ureteroscope insertion, BWL was administered with a handheld transducer, and any stone fragmentation and tissue injury were observed. Up to 3 stones per subject were targeted, each for a maximum of 10 minutes. The primary effectiveness outcome was the volume percent comminution of the stone into fragments ≤2 mm. The primary safety outcome was the independent, blinded visual scoring of tissue injury from the URS video. RESULTS: Overall, median stone comminution was 90% (IQR 20, 100) of stone volume with 21 of 23 (91%) stones fragmented. Complete fragmentation (all fragments ≤2 mm) within 10 minutes of BWL occurred in 9 of 23 stones (39%). Of the 6 least comminuted stones, likely causative factors for decreased effectiveness included stones that were larger than the BWL beamwidth, smaller than the BWL wavelength or the introduction of air bubbles from the ureteroscope. Mild reddening of the papilla and hematuria emanating from the papilla were observed ureteroscopically. CONCLUSIONS: The first study of BWL in human subjects resulted in a median of 90% comminution of the total stone volume into fragments ≤2 mm within 10 minutes of BWL exposure with only mild tissue injury.

First Series Using Ultrasonic Propulsion and Burst Wave Lithotripsy to Treat Ureteral Stones.

PURPOSE: Our goal was to test transcutaneous focused ultrasound in the form of ultrasonic propulsion and burst wave lithotripsy to reposition ureteral stones and facilitate passage in awake subjects. MATERIALS AND METHODS: Adult subjects with a diagnosed proximal or distal ureteral stone were prospectively recruited. Ultrasonic propulsion alone or with burst wave lithotripsy was administered by a handheld transducer to awake, unanesthetized subjects. Efficacy outcomes included stone motion, stone passage, and pain relief. Safety outcome was the reporting of associated anticipated or adverse events. RESULTS: Twenty-nine subjects received either ultrasonic propulsion alone (n = 16) or with burst wave lithotripsy bursts (n = 13), and stone motion was observed in 19 (66%). The stone passed in 18 (86%) of the 21 distal ureteral stone cases with at least 2 weeks follow-up in an average of 3.9±4.9 days post-procedure. Fragmentation was observed in 7 of the burst wave lithotripsy cases. All subjects tolerated the procedure with average pain scores (0-10) dropping from 2.1±2.3 to 1.6±2.0 (P = .03). Anticipated events were limited to hematuria on initial urination post-procedure and mild pain. In total, 7 subjects had associated discomfort with only 2.2% (18 of 820) propulsion bursts. CONCLUSIONS: This study supports the efficacy and safety of using ultrasonic propulsion and burst wave lithotripsy in awake subjects to reposition and break ureteral stones to relieve pain and facilitate passage.

Quality of life impact and recovery after ureteroscopy and stent insertion: insights from daily surveys in STENTS.

BACKGROUND: Our objective was to describe day-to-day evolution and variations in patient-reported stent-associated symptoms (SAS) in the STudy to Enhance uNderstanding of sTent-associated Symptoms (STENTS), a prospective multicenter observational cohort study, using multiple instruments with conceptual overlap in various domains. METHODS: In a nested cohort of the STENTS study, the initial 40 participants having unilateral ureteroscopy (URS) and stent placement underwent daily assessment of self-reported measures using the Brief Pain Inventory short form, Patient-Reported Outcome Measurement Information System measures for pain severity and pain interference, the Urinary Score of the Ureteral Stent Symptom Questionnaire, and Symptoms of Lower Urinary Tract Dysfunction Research Network Symptom Index. Pain intensity, pain interference, urinary symptoms, and bother were obtained preoperatively, daily until stent removal, and at postoperative day (POD) 30. RESULTS: The median age was 44 years (IQR 29,58), and 53% were female. The size of the dominant stone was 7.5 mm (IQR 5,11), and 50% were located in the kidney. There was consistency among instruments assessing similar concepts. Pain intensity and urinary symptoms increased from baseline to POD 1 with apparent peaks in the first 2 days, remained elevated with stent in situ, and varied widely among individuals. Interference due to pain, and bother due to urinary symptoms, likewise demonstrated high individual variability. CONCLUSIONS: This first study investigating daily SAS allows for a more in-depth look at the lived experience after URS and the impact on quality of life. Different instruments measuring pain intensity, pain interference, and urinary symptoms produced consistent assessments of patients' experiences. The overall daily stability of pain and urinary symptoms after URS was also marked by high patient-level variation, suggesting an opportunity to identify characteristics associated with severe SAS after URS.

Prevention of Urinary Stones With Hydration (PUSH): Design and Rationale of a Clinical Trial.

RATIONALE & OBJECTIVE: Although maintaining high fluid intake is an effective low-risk intervention for the secondary prevention of urinary stone disease, many patients with stones do not increase their fluid intake. STUDY DESIGN: We describe the rationale and design of the Prevention of Urinary Stones With Hydration (PUSH) Study, a randomized trial of a multicomponent behavioral intervention program to increase and maintain high fluid intake. Participants are randomly assigned (1:1 ratio) to the intervention or control arm. The target sample size is 1,642 participants. SETTING & PARTICIPANTS: Adults and adolescents 12 years and older with a symptomatic stone history and low urine volume are eligible. Exclusion criteria include infectious or monogenic causes of urinary stone disease and comorbid conditions precluding increased fluid intake. INTERVENTIONS: All participants receive usual care and a smart water bottle with smartphone application. Participants in the intervention arm receive a fluid intake prescription and an adaptive program of behavioral interventions, including financial incentives, structured problem solving, and other automated adherence interventions. Control arm participants receive guideline-based fluid instructions. OUTCOMES: The primary end point is recurrence of a symptomatic stone during 24 months of follow-up. Secondary end points include changes in radiographic stone burden, 24-hour urine output, and urinary symptoms. LIMITATIONS: Periodic 24-hour urine volumes may not fully reflect daily behavior. CONCLUSIONS: With its highly novel features, the PUSH Study will address an important health care problem. FUNDING: National Institute of Diabetes and Digestive and Kidney Diseases. TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT03244189.

Estimating the health-related quality of life of kidney stone patients: initial results from the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA).

OBJECTIVE: To build the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA) to predict urolithiasis patients' health-related quality of life (HRQoL) based on demographic, symptomatic and clinical data collected for the validation of the Wisconsin Stone Quality-of-Life (WISQOL) questionnaire, an HRQoL measurement tool designed specifically for patients with kidney stones. MATERIAL AND METHODS: We used data from 3206 stone patients from 16 centres. We used gradient-boosting and deep-learning models to predict HRQoL scores. We also stratified HRQoL scores by quintile. The dataset was split using a standard 70%/10%/20% training/validation/testing ratio. Regression performance was evaluated using Pearson's correlation. Classification was evaluated with an area under the receiver-operating characteristic curve (AUROC). RESULTS: Gradient boosting obtained a test correlation of 0.62. Deep learning obtained a correlation of 0.59. Multivariate regression achieved a correlation of 0.44. Quintile stratification of all patients in the WISQOL dataset obtained an average test AUROC of 0.70 for the five classes. The model performed best in identifying the lowest (0.79) and highest quintiles (0.83) of HRQoL. Feature importance analysis showed that the model weighs in clinically relevant factors to estimate HRQoL, such as symptomatic status, body mass index and age. CONCLUSIONS: Harnessing the power of the WISQOL questionnaire, our initial results indicate that the WISQOL-MLA can adequately predict a stone patient's HRQoL from readily available clinical information. The algorithm adequately relies on relevant clinical factors to make its HRQoL predictions. Future improvements to the model are needed for direct clinical applications.

National Imaging Trends after Ureteroscopic or Shock Wave Lithotripsy for Nephrolithiasis.

PURPOSE: The study of diagnostic imaging after procedural intervention for nephrolithiasis is limited. We sought to characterize actual national imaging patterns and longitudinal trends after ureteroscopic or shock wave lithotripsy. MATERIALS AND METHODS: We analyzed the MarketScan® database and identified a nationally representative sample of insured, employed patients, 17 to 64 years old who underwent ureteroscopic or shock wave lithotripsy for nephrolithiasis between 2007 and 2014. Patients were excluded from study if they lacked at least 1 year of postoperative database enrollment or underwent a repeat nephrolithiasis procedure of any type within 90 days after the initial procedure. We identified and tracked postoperative imaging modalities by medical billing codes. RESULTS: We identified 101,554 patients treated with ureteroscopy, of whom 55% and 39% underwent no postoperative imaging within 3 and 12 months, respectively. Of the 101,590 patients treated with shock wave lithotripsy 23% and 16% underwent no postoperative imaging within 3 and 12 months, respectively. Abdominal x-ray was the most common imaging modality after either procedure type. Ultrasound use increased with time while computerized tomography decreased. In about 25% of ureteroscopy and shock wave lithotripsy cases at least 1 postoperative computerized tomography was done within a year. Female gender and older age were associated with higher imaging rates. Ultrasound was more commonly performed in the northeast region and in more densely populated areas. CONCLUSIONS: A notable portion of patients treated with ureteroscopy and a smaller percent treated with shock wave lithotripsy do not undergo any followup imaging within 1 year. In the majority who undergo imaging abdominal x-ray is done, precluding the ability to screen for hydronephrosis or silent obstruction in almost 75% of patients treated with ureteroscopy.

National Imaging Trends after Percutaneous Nephrolithotomy.

PURPOSE: Followup imaging after percutaneous nephrolithotomy serves to detect postoperative complications, residual fragments and silent hydronephrosis. However, the timing and optimal imaging modality remain poorly defined. We describe imaging use patterns after percutaneous nephrolithotomy. MATERIALS AND METHODS: In the MarketScan® database we identified patients 17 to 64 years old who underwent percutaneous nephrolithotomy between 2007 and 2014. Imaging modalities were identified by CPT, and ICD-9 and 10 codes, and tracked for 1 year after percutaneous nephrolithotomy. The modalities included computerized tomography, renal ultrasound, abdominal x-ray and intravenous pyelogram. Cumulative longitudinal use patterns were characterized and the association with demographic factors was assessed by the chi-square test. RESULTS: Of the 6,495 patients included in analysis 29% and 15% had undergone no postoperative imaging by 3 and 12 months, respectively. While abdominal x-ray was the most common modality at 3, 6 and 12 months, performed in 46%, 53% and 62% patients, respectively, nearly 50% underwent computerized tomography by 1 year. Of these patients 34% underwent computerized tomography within 3 months, which was done within the first 3 days in 69%. During the study period renal ultrasound use increased by 13% while computerized tomography and abdominal x-ray use remained relatively stable. Female gender, residence in the Northeast, no health maintenance organization status and treatment in a metropolitan statistical area were independently associated with higher rates of renal ultrasound on multivariate analyses (p <0.05). CONCLUSIONS: Among insured adults national imaging patterns vary following percutaneous nephrolithotomy. Many patients do not receive any followup imaging while approximately half undergo computerized tomography within a year. Imaging patterns may be evolving with the increased use of ultrasound.

Retrospective comparison of measured stone size and posterior acoustic shadow width in clinical ultrasound images.

PURPOSE: Posterior acoustic shadow width has been proposed as a more accurate measure of kidney stone size compared to direct measurement of stone width on ultrasound (US). Published data in humans to date have been based on a research using US system. Herein, we compared these two measurements in clinical US images. METHODS: Thirty patient image sets where computed tomography (CT) and US images were captured less than 1 day apart were retrospectively reviewed. Five blinded reviewers independently assessed the largest stone in each image set for shadow presence and size. Shadow size was compared to US and CT stone sizes. RESULTS: Eighty percent of included stones demonstrated an acoustic shadow; 83% of stones without a shadow were ≤ 5 mm on CT. Average stone size was 6.5 ± 4.0 mm on CT, 10.3 ± 4.1 mm on US, and 7.5 ± 4.2 mm by shadow width. On average, US overestimated stone size by 3.8 ± 2.4 mm based on stone width (p < 0.001) and 1.0 ± 1.4 mm based on shadow width (p < 0.0098). Shadow measurements decreased misclassification of stones by 25% among three clinically relevant size categories (≤ 5, 5.1-10, > 10 mm), and by 50% for stones ≤ 5 mm. CONCLUSIONS: US overestimates stone size compared to CT. Retrospective measurement of the acoustic shadow from the same clinical US images is a more accurate reflection of true stone size than direct stone measurement. Most stones without a posterior shadow are ≤ 5 mm.

National Trends in Secondary Procedures Following Pediatric Pyeloplasty.

PURPOSE: Although reported success rates after pediatric pyeloplasty to correct ureteropelvic junction are high, failure may require intervention. We sought to characterize the incidence and timing of secondary procedures after pediatric pyeloplasty using a national employer based insurance database. MATERIALS AND METHODS: Using the MarketScan® database we identified patients 0 to 18 years old who underwent pyeloplasty from 2007 to 2013 with greater than 3 months of postoperative enrollment. Secondary procedures following the index pyeloplasty were identified by CPT codes and classified as stent/drain, endoscopic, pyeloplasty, nephrectomy or transplant. The risk of undergoing a secondary procedure was ascertained using Cox proportional hazards models adjusting for demographic and clinical characteristics. RESULTS: We identified 1,976 patients with a mean ± SD followup of 23.9 ± 19.8 months. Overall 226 children (11.4%) had undergone at least 1 post-pyeloplasty procedure. The first procedure was done within 1 year in 87.2% of patients with a mean postoperative interval of 5.9 ± 11.1 months. Stents/drains, endoscopic procedures and pyeloplasties were noted in 116 (5.9%), 34 (1.7%) and 71 patients (3.1%), respectively. Length of stay was associated with undergoing a secondary procedure. Compared with 2 days or less the HR of 3 to 5 and 6 days or greater was 1.65 and 3.94 (p = 0.001 and <0.001, respectively). CONCLUSIONS: Following pediatric pyeloplasty 1 of 9 patients undergoes at least 1 secondary procedure with the majority performed within the first year. One of 11 patients undergoes intervention more extensive than placement of a single stent or drain, requiring management strategies that generally signify recurrent or persistent obstruction. Estimates of pyeloplasty success in this national data set are lower than in other published series.

First in Human Clinical Trial of Ultrasonic Propulsion of Kidney Stones.

PURPOSE: Ultrasonic propulsion is a new technology using focused ultrasound energy applied transcutaneously to reposition kidney stones. We report what are to our knowledge the findings from the first human investigational trial of ultrasonic propulsion toward the applications of expelling small stones and dislodging large obstructing stones. MATERIALS AND METHODS: Subjects underwent ultrasonic propulsion while awake without sedation in clinic, or during ureteroscopy while anesthetized. Ultrasound and a pain questionnaire were completed before, during and after propulsion. The primary outcome was to reposition stones in the collecting system. Secondary outcomes included safety, controllable movement of stones and movement of stones less than 5 mm and 5 mm or greater. Adverse events were assessed weekly for 3 weeks. RESULTS: Kidney stones were repositioned in 14 of 15 subjects. Of the 43 targets 28 (65%) showed some level of movement while 13 (30%) were displaced greater than 3 mm to a new location. Discomfort during the procedure was rare, mild, brief and self-limited. Stones were moved in a controlled direction with more than 30 fragments passed by 4 of the 6 subjects who had previously undergone a lithotripsy procedure. The largest stone moved was 10 mm. One patient experienced pain relief during treatment of a large stone at the ureteropelvic junction. In 4 subjects a seemingly large stone was determined to be a cluster of small passable stones after they were moved. CONCLUSIONS: Ultrasonic propulsion was able to successfully reposition stones and facilitate the passage of fragments in humans. No adverse events were associated with the investigational procedure.

Use of the Acoustic Shadow Width to Determine Kidney Stone Size with Ultrasound.

PURPOSE: Ultrasound is known to overestimate kidney stone size. We explored measuring the acoustic shadow behind kidney stones combined with different ultrasound imaging modalities to improve stone sizing accuracy. MATERIALS AND METHODS: A total of 45 calcium oxalate monohydrate stones were imaged in vitro at 3 different depths with the 3 different ultrasound imaging modalities of conventional ray line, spatial compound and harmonic imaging. The width of the stone and the width of the acoustic shadow were measured by 4 operators blinded to the true size of the stone. RESULTS: Average error between the measured and true stone width was 1.4 ± 0.8 mm, 1.7 ± 0.9 mm, 0.9 ± 0.8 mm for ray line, spatial compound and harmonic imaging, respectively. Average error between the shadow width and true stone width was 0.2 ± 0.7 mm, 0.4 ± 0.7 mm and 0.0 ± 0.8 mm for ray line, spatial compound and harmonic imaging, respectively. Sizing error based on the stone width worsened with greater depth (p <0.001) while the sizing error based on the shadow width was independent of depth. CONCLUSIONS: Shadow width was a more accurate measure of true stone size than a direct measurement of the stone in the ultrasound image (p <0.0001). The ultrasound imaging modality also impacted the measurement accuracy. All methods performed similarly for shadow size while harmonic imaging was the most accurate stone size modality. Overall 78% of the shadow sizes were accurate to within 1 mm, which is similar to the resolution obtained with clinical computerized tomography.

Ultrasonic propulsion of kidney stones.

PURPOSE OF REVIEW: Ultrasonic propulsion is a novel technique that uses short bursts of focused ultrasonic pulses to reposition stones transcutaneously within the renal collecting system and ureter. The purpose of this review is to discuss the initial testing of effectiveness and safety, directions for refinement of technique and technology, and opinions on clinical application. RECENT FINDINGS: Preclinical studies with a range of probes, interfaces, and outputs have demonstrated feasibility and consistent safety of ultrasonic propulsion with room for increased outputs and refinement toward specific applications. Ultrasonic propulsion was used painlessly and without adverse events to reposition stones in 14 of 15 human study participants without restrictions on patient size, stone size, or stone location. The initial feasibility study showed applicability in a range of clinically relevant situations, including facilitating passage of residual fragments following ureteroscopy or shock wave lithotripsy, moving a large stone at the ureteropelvic junction with relief of pain, and differentiating large stones from a collection of small fragments. SUMMARY: Ultrasonic propulsion shows promise as an office-based system for transcutaneously repositioning kidney stones. Potential applications include facilitating expulsion of residual fragments following ureteroscopy or shock wave lithotripsy, repositioning stones prior to treatment, and repositioning obstructing ureteropelvic junction stones into the kidney to alleviate acute renal colic.

National Trends in Followup Imaging after Pyeloplasty in Children in the United States.

PURPOSE: Radiographic followup after pyeloplasty for the correction of ureteropelvic junction obstruction is not well defined in children. We characterize trends in frequency and modality of postoperative imaging after open and minimally invasive pediatric pyeloplasty. MATERIALS AND METHODS: Using the MarketScan® database, we identified patients 0 to 18 years old undergoing pyeloplasty between 2007 and 2013. Followup imaging was classified as functional (diuretic renography, excretory urography) or nonfunctional (ultrasound, computerized tomography, magnetic resonance imaging). We excluded patients with less than 24 months of postoperative enrollment in MarketScan. Multivariate logistic regression was performed to determine associations between demographic variables and imaging use patterns. RESULTS: We identified 926 patients with a mean ± SD followup of 3.6 ± 1.3 years, of whom 30% underwent minimally invasive pyeloplasty. Overall 5.9% of patients had no postoperative imaging available. Within the first 6 months postoperatively 853 patients (91%) underwent at least 1 imaging study and 192 (24%) underwent renography. Within the first 12 months postoperatively 91% of patients underwent at least 1 imaging study, most commonly ultrasound. After 12 months almost a third of the patients were not followed with imaging. Of the 71% undergoing imaging most underwent ultrasound. Younger age and female gender were independently associated with frequent imaging (at least yearly) on multivariate logistic regression. CONCLUSIONS: Following pediatric pyeloplasty there is variation in modality and frequency of imaging followup. The majority of patients are followed with renal ultrasound, with less frequent use of functional imaging. Almost a third of patients do not undergo followup imaging after 1 year.

Fragmentation of urinary calculi in vitro by burst wave lithotripsy.

PURPOSE: We developed a new method of lithotripsy that uses short, broadly focused bursts of ultrasound rather than shock waves to fragment stones. We investigated the characteristics of stone comminution by burst wave lithotripsy in vitro. MATERIALS AND METHODS: Artificial and natural stones (mean ± SD size 8.2 ± 3.0 mm, range 5 to 15) were treated with ultrasound bursts using a focused transducer in a water bath. Stones were exposed to bursts with focal pressure amplitude of 6.5 MPa or less at a 200 Hz burst repetition rate until completely fragmented. Ultrasound frequencies of 170, 285 and 800 kHz were applied using 3 transducers, respectively. Time to fragmentation for each stone type was recorded and fragment size distribution was measured by sieving. RESULTS: Stones exposed to ultrasound bursts were fragmented at focal pressure amplitudes of 2.8 MPa or greater at 170 kHz. Fractures appeared along the stone surface, resulting in fragments that separated at the surface nearest to the transducer until the stone was disintegrated. All natural and artificial stones were fragmented at the highest focal pressure of 6.5 MPa with a mean treatment duration of 36 seconds for uric acid stones to 14.7 minutes for cystine stones. At a frequency of 170 kHz the largest artificial stone fragments were less than 4 mm. Exposure at 285 and 800 kHz produced only fragments less than 2 mm and less than 1 mm, respectively. CONCLUSIONS: Stone comminution with burst wave lithotripsy is feasible as a potential noninvasive treatment method for nephrolithiasis. Adjusting the fundamental ultrasound frequency allows for stone fragment size to be controlled.

Overuse of antimicrobial prophylaxis in community practice urology.

PURPOSE: We examined index urological surgeries to assess utilization patterns of antimicrobial prophylaxis in a large, community based population. MATERIALS AND METHODS: From the Premier Perspectives Database we identified patients who underwent inpatient urological surgeries that are considered index procedures by the ABU (American Board of Urology), including radical prostatectomy, partial or radical nephrectomy, radical cystectomy, ureteroscopy, shock wave lithotripsy, transurethral resection of the prostate, percutaneous nephrostolithotomy, transvaginal surgery, inflatable penile prosthesis, brachytherapy, transurethral resection of bladder tumor and cystoscopy. Procedures were identified based on ICD-9 procedure codes for 2007 to 2012. Antimicrobial administration, class and duration were abstracted from patient billing data. The class and duration of antimicrobials concordant with the 2008 AUA Best Practice Policy Statement was used to determine compliance. RESULTS: The overall compliance rate was 53%, ranging from 0.6% for radical cystectomy to 97% for shock wave lithotripsy. Antimicrobial use consistent with AUA Best Practices included the appropriate class in 67% of cases (range 34% to 80%) and the recommended duration in 78% (range 1.2% to 98%). Average prophylaxis duration for procedures for which it is recommended ranged from 1.1 days after brachytherapy to 10.3 days after radical cystectomy. The compliance rate increased from 46% overall in 2007 to 59% overall in 2012. CONCLUSIONS: We documented considerable variation in antimicrobial prophylaxis for urological surgery. Compliance with AUA Best Practices increased with time but overall rates remain less than 60%. Efforts are needed to better understand the reasons for variation from recommended antimicrobial prophylaxis for common inpatient urological procedures to help decrease resultant complications and improve outcomes.