Philip May

Stone-mode ultrasound for determining renal stone size

PURPOSE The purpose of this study was to measure the accuracy of stone-specific algorithms (S-mode) and the posterior acoustic shadow for determining kidney stone size with ultrasound (US) in vivo. MATERIALS AND METHODS Thirty-four subjects with 115 renal stones were prospectively recruited and scanned with S-mode on a research US system. S-mode is gray-scale US adjusted to enhanced stone contrast and resolution by minimizing compression and averaging, and increasing line density and frequency. Stone and shadow width were compared with a recent CT scan and, in 5 subjects with 18 stones, S-mode was compared with a clinical US system. RESULTS Overall, 84% of stones identified on CT were detected on S-mode and 66% of these shadowed. Seventy-three percent of the stone measurements and 85% of the shadow measurements were within 2 mm of the size on CT. A posterior acoustic shadow was present in 89% of stones over 5 mm versus 53% of stones under 5 mm. S-mode visualized 78% of stones, versus 61% for the clinical system. S-mode stone and shadow measurements differed from CT by 1.6 ± 1.0 mm and 0.8 ± 0.6 mm, respectively, compared with 2.0 ± 1.5 mm and 1.6 ± 1.0 mm for the clinical system. CONCLUSIONS S-mode offers improved visualization and sizing of renal stones. With S-mode, sizing of the stone itself and the posterior acoustic shadow were similarly accurate. Stones that do not shadow are most likely <5 mm and small enough to pass spontaneously.

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.

Prostate cancer that is within 0.1 mm of the surgical margin of a radical prostatectomy predicts greater likelihood of recurrence

Abstract: Surgical margin status at prostatectomy is an important predictor of biochemical recurrence (BCR). The current convention is to categorize a margin as negative if tumor cells are not at the inked margin, even if they are within a few cells of the margin. We hypothesized that cancer within 0.1 mm of the margin conferred an increased risk for BCR. We determined the risk for BCR on the bass of surgical margin status in a cohort of 1588 patients who underwent radical prostatectomy for prostate cancer (PCa) between 1998 and 2011. Surgical margins were categorized as positive, close (<0.1 mm from tumor cells), or negative. Multivariate hazard ratios (HRs) for BCR were determined by margin status. We identified 1588 patients, of whom 193 had PCa recurrence. The margin status was negative in 1058 (67%), close in 232 (15%), and positive in 298 (19%). Cancer that was close to the margin was a significant and independent predictor of BCR (HR 1.53; 95% confidence interval, 1.00-2.32) and was not statistically different than a positive surgical margin (HR 2.10; 95% confidence interval, 1.48-2.99). Cancer that is within 0.1 mm of the surgical margin of a prostatectomy is associated with an increased risk for PCa recurrence. Patients with that margin status may be reasonable candidates for adjuvant local therapy.

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.

The Morbidity of Ureteral Strictures in Patients with Prior Ureteroscopic Stone Surgery: Multi-Institutional Outcomes

PURPOSE Nephrolithiasis is an increasingly common ailment in the United States. Ureteroscopic management has supplanted shockwave lithotripsy as the most common treatment of upper tract stone disease. Ureteral stricture is a rare but serious complication of stone disease and its management. The impact of new technologies and more widespread ureteroscopic management on stricture rates is unknown. We describe our experience in managing strictures incurred following ureteroscopy for upper tract stone disease. MATERIALS AND METHODS Records for patients managed at four tertiary care centers between December 2006 and October 2015 with the diagnosis of ureteral stricture following ureteroscopy for upper tract stone disease were retrospectively reviewed. Study outcomes included number and type (endoscopic, reconstructive, or nephrectomy) of procedures required to manage stricture. RESULTS Thirty-eight patients with 40 ureteral strictures following URS for upper tract stone disease were identified. Thirty-five percent of patients had hydronephrosis or known stone impaction at the time of initial URS, and 20% of cases had known ureteral perforation at the time of initial URS. After stricture diagnosis, the mean number of procedures requiring sedation or general anesthesia performed for stricture management was 3.3 ± 1.8 (range 1-10). Eleven strictures (27.5%) were successfully managed with endoscopic techniques alone, 37.5% underwent reconstruction, 10% had a chronic stent/nephrostomy, and 10 (25%) required nephrectomy. CONCLUSIONS The surgical morbidity of ureteral strictures incurred following ureteroscopy for stone disease can be severe, with a low success rate of endoscopic management and a high procedural burden that may lead to nephrectomy. Further studies that assess specific technical risk factors for ureteral stricture following URS are needed.

MP75-19 NATIONAL TRENDS IN IMAGING FOLLOWING URETEROSCOPY & SHOCKWAVE LITHOTRIPSY

INTRODUCTION AND OBJECTIVES: Imaging after ureteroscopy (URS) and shockwave lithotripsy (SWL) is suggested by the American Urologic Association to ensure stone fragment clearance, resolution of hydronephrosis, and rule out ureteral stricture formation. To our knowledge, no prior studies have examined large-scale national imaging patterns after procedural intervention for nephrolithiasis. We sought to characterize imaging utilization patterns after URS and SWL. METHODS: Using Marketscan, a private employer-based insurance database, we identified patients 17-64 years old undergoing URS or SWL between 2007-2014. A minimum of 12 months of enrollment was required and patients were excluded if they received more than 1 lithotripsy procedure of any type within 90 days. Imaging modalities identified by CPT and ICD-9 codes included computed tomography (CT), renal ultrasound (US), abdominal X-ray (KUB), and intravenous pyelogram (IVP), and were tracked postoperatively. Utilization patterns by demographic factors were assessed using chisquared test. RESULTS: A total of 100,710 patients met inclusion criteria following URS, with 39% having no post-operative imaging within 12 months. Only 45% underwent imaging within 3 months of URS, most commonly KUB (28%). At 3, 6, and 12 months, only 26%, 33%, and 42%, respectively, of URS patients had any anatomic imaging (US, CT, or IVP). A total of 109,237 patients met inclusion criteria following SWL, with 16% having no postoperative imaging within 12 months. 78% underwent imaging within 3 months; most commonly KUB (69%). By 3, 6, and 12 months, 19%, 26%, and 36%, respectively, of SWL patients had any anatomic imaging. KUB was the most common imaging modality after either intervention type (38% of URS, 74% of SWL) within 12 months, followed by CT (25% of URS, 24% of SWL), then US (23% of URS, 17% of SWL). Over the 7 year study interval US increased by 10% after URS and 6% after SWL, while CT use decreased by 4%. Older age and female sex were independently associated with higher rates of imaging (p<0.001). US use was 13% higher in the Northeast, and more likely to be utilized in patients in metropolitan statistical areas or enrolled in health maintenance organizations. CONCLUSIONS: Despite recommendations for routine imaging after stone procedures, a large proportion of insured patients received none, especially following URS. The majority of URS and SWL patients did not receive any postoperative anatomic imaging, which may raise the risk of undiagnosed ureteral strictures, silent obstruction, and renal function loss. Although RUS use is slowly increasing, it remains underutilized compared to CT.