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.

Digital Tomosynthesis: A Viable Alternative to Noncontrast Computed Tomography for the Follow-Up of Nephrolithiasis?

OBJECTIVE

Digital tomosynthesis (DT) is a new X-ray-based imaging technique that allows image enhancement with minimal increase in radiation exposure. The purpose of this study was to compare DT with noncontrast computed tomography (NCCT) and to evaluate its potential role for the follow-up of patients with nephrolithiasis in a nonemergent setting.

METHODS

A retrospective review of patients with nephrolithiasis at our institution that underwent NCCT and DT from July 2012 to September 2013 was performed. Renal units (RUs) that did not undergo treatment or stone passage were randomly assigned to two blinded readers, who recorded stone count, size area (mm(2)), maximum stone length (mm), and location, for both DT and NCCT. Mean differences per RU were compared. Potential variables affecting stone detection rate, including stone size and body mass index (BMI), were evaluated. Interobserver agreement was determined using the intraclass correlation coefficient to measure the consistency of measurements made by the readers.

RESULTS

DT and NCCT demonstrated similar stone detection rates in terms of stone counts and stone area mm(2). Of the 79 RUs assessed, 41 RUs showed exact stone counts on DT and NCCT. The mean difference in stone area was 16.5 mm(2) (-4.6 to 38.5), p = 0.121. The mean size of the largest stone on NCCT and DT was 9.27 and 8.87 mm, respectively. Stone size and BMI did not cause a significant difference in stone detection rates. Interobserver agreement showed a strong correlation between readers and adequate reproducibility.

CONCLUSION

We found DT to be a comparable imaging modality to NCCT for the detection of intrarenal stones, without a significant effect from stone size and BMI and adequate reproducibility between multiple readers. DT appears to be an ideal alternative for following patients with nephrolithiasis due to its acceptable stone detection rates, low radiation exposure, and decreased cost compared to NCCT.

ACR Appropriateness Criteria indeterminate renal mass

Renal masses are increasingly detected in asymptomatic individuals as incidental findings. An indeterminate renal mass is one that cannot be diagnosed confidently as benign or malignant at the time it is discovered. CT, ultrasonography, and MRI of renal masses with fast-scan techniques and intravenous (IV) contrast are the mainstays of evaluation. Dual-energy CT, contrast-enhanced ultrasonography, PET/CT, and percutaneous biopsy are all technologies that are gaining traction in the characterization of the indeterminate renal mass. In cases in which IV contrast cannot be used, whether because of IV contrast allergy or renal insufficiency, renal mass classification with CT is markedly limited. In the absence of IV contrast, ultrasonography, MRI, and biopsy have some advantages. Owing to the low malignant and metastatic potential of small renal cell carcinomas (≤4 cm in diameter), active surveillance is additionally emerging as a diagnostic strategy for patients who have high surgical risk or limited life expectancy. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and application by the panel of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Minimizing radiation exposure during percutaneous nephrolithotomy

Given the recent trends in growing per capita radiation dose from medical sources, there have been increasing concerns over patient radiation exposure. Patients with kidney stones undergoing percutaneous nephrolithotomy (PNL) are at particular risk for high radiation exposure. There exist several risk factors for increased radiation exposure during PNL which include high Body Mass Index, multiple access tracts, and increased stone burden. We herein review recent trends in radiation exposure, radiation exposure during PNL to both patients and urologists, and various approaches to reduce radiation exposure. We discuss incorporating the principles of As Low As reasonably Achievable (ALARA) into clinical practice and review imaging techniques such as ultrasound and air contrast to guide PNL access. Alternative surgical techniques and approaches to reducing radiation exposure, including retrograde intra-renal surgery, retrograde nephrostomy, endoscopic-guided PNL, and minimally invasive PNL, are also highlighted. It is important for urologists to be aware of these concepts and techniques when treating stone patients with PNL. The discussions outlined will assist urologists in providing patient counseling and high quality of care.

Use of ureteral access sheaths in ureteroscopy

The ureteral access sheath (UAS) facilitates the use of flexible ureteroscopy, enabling improved minimally invasive management of complex upper urinary tract diseases. The UAS, which comes in a variety of diameters and lengths, is passed in a retrograde fashion, aided by a hydrophilic coating and other features designed to confer smooth passage into the ureter with sufficient resistance to kinking and buckling. Use of a UAS has the advantage of enabling repeated passage of the ureteroscope while minimizing damage to the ureter, thus improving the flow of irrigation fluid and visualization within the urethra with reductions in operative times, which improves both the effectiveness of the surgery and reduces the costs. Placement of the UAS carries an increased risk of ureteral wall ischaemia and injury to the mucosal or muscular layers of the ureter, and a theoretically increased risk of ureteral strictures. A ureteral stent is typically placed after ureteroscopy with a UAS. Endourologists have found several additional practical uses of a UAS, such as the percutaneous treatment of patients with ureteral stones, and solutions to other endourological challenges.

Kidney stones: flexible ureteroscopy

INTRODUCTION

The age of peak incidence for stone disease is 20 to 40 years, although stones are seen in all age groups. There is a male to female ratio of 3:2.

METHODS AND OUTCOMES

We conducted a systematic overview, aiming to answer the following clinical question: What are the effects of flexible ureteroscopy for the removal of renal stones? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2014 (Clinical Evidence overviews are updated periodically; please check our website for the most up-to-date version of this overview).

RESULTS

At this update, searching of electronic databases retrieved 197 studies. After deduplication and removal of conference abstracts, 118 records were screened for inclusion in the overview. Appraisal of titles and abstracts led to the exclusion of 99 studies and the further review of 18 full publications. Of the 18 full articles evaluated, one systematic review and four RCTs were added at this update. We performed a GRADE evaluation for eight PICO combinations.

CONCLUSIONS

In this systematic overview, we categorised the efficacy for four interventions, based on information relating to the effectiveness and safety of: flexible ureteroscopy (combined with snare or basket or laser lithotripsy) versus expectant management, flexible ureteroscopy (combined with snare or basket or laser lithotripsy) versus extracorporeal shockwave lithotripsy, flexible ureteroscopy (combined with snare or basket or laser lithotripsy) versus percutaneous nephrolithotomy.

Balloon Dilation of the Ureter: A Contemporary Review of Outcomes and Complications

PURPOSE

During ureteroscopy ureteral balloon dilation may be necessary to allow for passage of endoscopic instruments or access sheaths. We assessed the efficacy and complications associated with ureteral balloon dilation.

MATERIALS AND METHODS

We retrospectively reviewed the records at 2 institutions from 2000 to 2012 to identify patients who underwent ureteral balloon dilation during ureteroscopic treatment of upper tract stones. An 18Fr balloon dilator was used in all cases. Patients with documented ureteral stricture, radiation therapy or urothelial cancer were excluded from analysis. Primary outcomes were the stone-free rate, operative complications, balloon dilation failure and the postoperative ureteral stricture rate. Complications were divided into intraoperative and postoperative groups according to the Satava and Clavien-Dindo classifications, respectively.

RESULTS

A total of 151 patients fulfilled study criteria. Median followup was 12 months. The stone-free rate was 72% and median time to first postoperative imaging was 2.8 months. Balloon dilation failed in only 8 patients (5%). Eight intraoperative ureteral perforations (5%) were identified, which were managed by a ureteral stent in 7 patients and a percutaneous tube in 1. Endoscopic re-treatment was required in 4 patients with Satava 2b postoperative complications. The postoperative complication rate was 8% (11 cases). A single ureteral stricture was attributable to balloon dilation.

CONCLUSIONS

In this contemporary review balloon dilation of the ureter before endoscopic treatment of stone disease was associated with a high success rate and few complications. Ureteral balloon dilation may decrease the need for a secondary procedure in patients undergoing ureteroscopy to manage proximal ureteral and intrarenal stones.

Combined Endoscopic and Percutaneous Retrieval of a Retained 4-Wire Ureteral Stone Basket

Complex endourologic procedures may require the use of a combined ureteroscopic and percutaneous approach. Endoscopic removal of a retained 4-wire ureteral stone basket is particularly complex, as broken tines can potentially injure the ureter if the basket is removed in a retrograde manner. The patient in this case presented with a ureteral stone basket embedded within the urothelium of the upper pole of the kidney. Holmium laser incision of the overlying urothelium allowed retrieval of the basket, although the tines were broken. Endoscopically guided percutaneous access to the kidney was obtained to allow for direct passage of the retained basket out of a nephrostomy sheath, thereby protecting the kidney.

ACR Appropriateness Criteria(®) on renal failure

Imaging plays a role in the management of patients with acute kidney injury or chronic kidney disease. However, clinical circumstances strongly impact the appropriateness of imaging use. In patients with newly detected renal dysfunction, ultrasonography can assess for reversible causes, assess renal size and echogenicity, and thus, establish the chronicity of disease. Urinary obstruction can be detected, but imaging is most useful in high-risk groups or in patients in whom there is a strong clinical suspicion for obstruction. Computed tomography, computed tomography or magnetic resonance arteriography, and percutaneous ultrasound-guided renal biopsy are valuable in other clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Does the nephrostomy tract length impact the outcomes of percutaneous nephrolithotomy (PNL)?

PURPOSE

Different factors can determine the outcomes of percutaneous nephrolithotomy (PNL). We analyzed the effect of tract length (TL) on outcomes after PNL.

METHODS

We performed a retrospective review of patients undergoing PNL between 2006 and 2011. Patients with preoperative computed tomography (CT), one percutaneous access tract and follow-up imaging within 3 months were included. TL was defined as distance between the skin to the calyx of puncture as measured on preoperative CT. Measurements were independently performed by two urologists and the average was used for analysis. Stone-free rate (SFR) was defined as zero fragments on follow-up imaging. Factors independently associated with the likelihood of being stone-free after PNL were determined using multivariable analysis adjusted for TL, location of access, the presence of incomplete or complete staghorn calculi and type of follow-up imaging. Complications (Clavien score) were independently assessed.

RESULTS

A total of 222 patients were included. Median stone burden and body mass index (BMI) was 239.4 mm(2) and 30.5 [interquartile range (IQR): 25.7-36.2]. The median TL was 85.0 mm (IQR: 70.3-100.0) and highly correlated with BMI (ρ = 0.66, p < 0.001). A total of 101 patients (45.5 %) were stone-free. TL was not associated with SFR (p = 0.53). Clavien 1 and 2 complications occurred in 38 (17 %) while Clavien 3 and 4 complications occurred in 17 (8 %) patients. Multivariable analysis revealed no association between complications and TL even when adjusted for gender.

CONCLUSIONS

Percutaneous TL is not associated with outcomes of PNL. PNL is a safe and effective treatment for stones in patients with differing body habitus.

Shock wave lithotripsy: the new phoenix?

INTRODUCTION

Following its introduction in 1980, shock wave lithotripsy (SWL) rapidly emerged as the first-line treatment for the majority of patients with urolithiasis. Millions of SWL therapies have since been performed worldwide, and nowadays, SWL still remains to be the least invasive therapy modality for urinary stones. During the last three decades, SWL technology has advanced in terms of shock wave generation, focusing, patient coupling and stone localization. The implementation of multifunctional lithotripters has made SWL available to urology departments worldwide. Indications for SWL have evolved as well. Although endoscopic treatment techniques have improved significantly and seem to take the lead in stone therapy in the western countries due to high stone-free rates, SWL continues to be considered as the first-line therapy for the treatment of most intra-renal stones and many ureteral stones.

METHODS

This paper reviews the fundamentals of SWL physics to facilitate a better understanding about how a lithotripter works and should be best utilized.

RESULTS

Advances in lithotripsy technology such as shock wave generation and focusing, advances in stone localization (imaging), different energy source concepts and coupling modalities are presented. Furthermore adjuncts to improve the efficacy of SWL including different treatment strategies are reviewed.

CONCLUSION

If urologists make use of a more comprehensive understanding of the pathophysiology and physics of shock waves, much better results could be achieved in the future. This may lead to a renaissance and encourage SWL as first-line therapy for urolithiasis in times of rapid progress in endoscopic treatment modalities.

Disposable devices for RIRS: where do we stand in 2013? What do we need in the future?

PURPOSE

Disposable devices for retrograde intrarenal surgery (RIRS) form a significant part of the urologist's armamentarium for the endoscopic management of urologic diseases. Herein, we provide an overview of the literature regarding the advances and controversies of these devices.

METHODS

A PubMed search was used to identify the literature discussing the subject of disposable devices for RIRS. Articles published between 2012 and 2013 were considered.

RESULTS

Ureteral access implements including access sheaths, wires, and dilators are an area of both improvement and controversy regarding their proper use. The safety, effectiveness, and limitations of lithotrites continue to be refined. Stone retrieval devices are undergoing persistent miniaturization, and their use may prove to be cost effective. The debate over perioperative stenting remains, while symptom management is explored. A cost-effective option for disposable flexible ureteroscopy shows promise.

CONCLUSIONS

While rapid advances in technology and knowledge continue, continual improvements are necessary. Disposable equipment needs persistent refinement and possible miniaturization. More efficient fragment retrieval devices are needed. Durability of laser fibers and safety within ureteroscopes needs to be improved. Reducing stent morbidity remains an ongoing challenge. Lastly, costs need to be reduced by the further development of disposable flexible ureteroscopes and in the recyclability of disposable devices to improve availability worldwide.

A prospective, multi-institutional study of flexible ureteroscopy for proximal ureteral stones smaller than 2 cm

PURPOSE

Flexible ureteroscopy is rapidly becoming a first line therapy for many patients with renal and ureteral stones. However, current understanding of treatment outcomes in patients with isolated proximal ureteral stones is limited. Therefore, we performed a prospective, multi-institutional study of ureteroscopic management of proximal ureteral stones smaller than 2 cm to better define clinical outcomes associated with this approach.

MATERIALS AND METHODS

Adult patients with proximal ureteral calculi smaller than 2 cm were prospectively identified. Patients with concomitant ipsilateral renal calculi or prior ureteral stenting were excluded from study. Flexible ureteroscopy, holmium laser lithotripsy and ureteral stent placement was performed. Ureteral access sheath use, laser settings and other details of perioperative and postoperative management were based on individual surgeon preference. Stone clearance was determined by the results of renal ultrasound and plain x-ray of the kidneys, ureters and bladder 4 to 6 weeks postoperatively.

RESULTS

Of 71 patients 44 (62%) were male and 27 (38%) were female. Mean age was 48.2 years. ASA(®) score was 1 in 12 cases (16%), 2 in 41 (58%), 3 in 16 (23%) and 4 in 2 (3%). Mean body mass index was 31.8 kg/m(2), mean stone size was 7.4 mm (range 5 to 15) and mean operative time was 60.3 minutes (range 15 to 148). Intraoperative complications occurred in 2 patients (2.8%), including mild ureteral trauma. Postoperative complications developed in 6 patients (8.7%), including urinary tract infection in 3, urinary retention in 2 and flash pulmonary edema in 1. The stone-free rate was 95% and for stones smaller than 1 cm it was 100%.

CONCLUSIONS

Flexible ureteroscopy is associated with excellent clinical outcomes and acceptable morbidity when applied to patients with proximal ureteral stones smaller than 2 cm.