Abstract
Survey of Endourology
West Alabama Urology Associates
Tuscaloosa, Alabama
West Alabama Urology Associates
Tuscaloosa, Alabama
Kansai Medical University
Osaka, Japan
Oregon Health and Science University
Portland, Oregon
British Urological Institute
Bristol, United Kingdom
University of Miami
Miami, Florida
Singapore Urology and Fertility Centre
Singapore
AZ Klina
Brasschaat, Belgium
McGill University
Montreal, Canada
Cornell University
New York, New York
Tauranga Hospital
Tauranga, New Zealand
Wake Forest University
Winston-Salem, North Carolina
Karolinska University Hospital
Stockholm, Sweden
University of Kansas Medical Center
Kansas City, Kansas
Spire Gatwick Park Hospital
London, United Kingdom
Penn Presbyterian Medical Center
Philadelphia, Pennsylvania
Boston University School of Medicine
Boston, Massachusetts
M.D. Anderson Cancer Center
Houston, Texas
University of Southern California
Los Angeles, California
Laparoscopy
J Urol 2013;190:44–9.
Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
DOI: 10.1016/j.juro.2012.12.102
Int J Urol 2013;20:484–91.
© 2012 The Japanese Urological Association.
DOI: 10.1111/j.1442-2042.2012.03205.x
Commentary
The use of partial nephrectomy for renal tumors ≤4 cm in size (cT1a) has gained increasing utilization over the past decade, primarily due to strong clinical data showing its nephrologic advantages over radical nephrectomy and the progressive use and popularity of minimally invasive approaches to the kidney. The early leaders of laparoscopic urologic surgery helped pioneer and develop the laparoscopic techniques that we routinely use for partial nephrectomy; back then it seemed more like flying by the seat of your pants! Today, careful vascular control, super-selective vascular control, progression to zero ischemia techniques, use of indocyanine green, use of barbed absorbable suture and, finally, robotic surgical application has made this a remarkably safe and faster procedure. Larger tumors, upwards of 7 cm (cT1b), are being taken on with careful selection.
Gill and colleagues, who have been the predominant leading force behind this evolution, report on the 10-year oncologic outcomes after laparoscopic and open partial nephrectomy. This is a retrospective but honest review on a sizeable number of patients treated with either open (254) or laparoscopic (45) partial nephrectomy. Obviously, the number in the laparoscopic group is limited due to the lengthy 10-year follow-up period. The open surgical group did have larger tumors and more patients in this group were operated on for “absolute indications,” i.e., renal insufficiency or solitary kidney.
Most importantly, the oncologic outcomes on multivariable analysis were not significantly different between the surgical approaches with respect to risk of recurrence or cancer-related mortality. This study did not evaluate the perioperative morbidity, blood loss or postoperative course which has, in the past, shown some advantage for the laparoscopic approach.
Perhaps the single factor that has increased the use of partial nephrectomy is the daVinci robotic surgical platform. As a previous strong supporter of the laparoscopic approach to partial nephrectomy, I have been convinced that the reconstructive portion of this complex procedure is far easier and faster with robotic assistance. The degree of visualization, ergonomic maneuverability and accuracy is better with the robotic platform in the hands of the vast majority of urologic surgeons.
Such robotic surgical advantages become even more critical in the situation of a tumor involving a solitary kidney as outlined in the analysis by Kaouk and colleagues. Although robotic surgery is not inexpensive and there have been a considerable number of litigious attacks on the system, I truly believe that partial nephrectomy for larger and perhaps more complex tumors may be better handled with robotic support. How does it compare with the old “trusty” open surgical approach in such cases? It appears that open partial nephrectomy may be becoming a lost surgical art in many urologic practices.
Howard N. Winfield, MD
Ureteroscopy
PLoS One 2013;8:e65060.
DOI: 10.1371/journal.pone.0065060
Commentary
The quantification of stone burden remains a problem. A variety of measures are reported in the literature, including diameter, surface area, and volume. Each of these measures can be determined using different techniques and different imaging modalities. This lack of a standardized method for reporting stone burden creates difficulty in both comparing studies and application of the stone outcomes literature to our patients.
This study examines the utility of cumulative stone diameter (CSD) as a predictor of stone-free status after ureteroscopic treatment of renal calculi. This has the limitation of being essentially a one-dimensional measure, but is quick, easy and can be performed using plain abdominal film only, avoiding the increased radiation of computed tomography (CT). This is a retrospective review of 243 ureteroscopic procedures. The authors compared CSD to stone volume (calculated using the measurements of stone length, height, and width) to predict stone-free status after ureteroscopic treatment. They found equivalent prediction of stone free status when the CSD was <20 mm, and superiority of stone volume when the CSD was >20 mm. They determined this using receiver operating characteristics, which are generally used for evaluating diagnostic tests. While I question the validity of this analysis, and other statistical manipulations the authors perform and don't fully describe, their plot of stone volume versus CSD is most revealing. This plot demonstrates the poor correlation between the one-dimensional measure (CSD) with the three-dimensional measure (volume). Although the CSD is easier to measure and does not require CT imaging, it makes sense this will be less accurate and less useful clinically as the size of the stone increases.
Michael Conlin, MD
Urology 2013;82:773–9.
Copyright © 2013 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.urology.2013.05.019
Commentary
With the frequent utilization of percutaneous coronary intervention and expanded use of antithrombotic therapy, we are increasingly performing ureteroscopy on patients taking either warfarin, clopidogrel, aspirin, or, more frequently, dual anti-platelet therapy (clopidogrel and aspirin).1,2 We are often called from our preoperative clinic with the question of how we would like to manage the antithrombotic therapy for an upcoming ureteroscopy patient. This manuscript helps answer that question.
This is a retrospective review of the authors' ureteroscopy experience, focusing on their patients requiring antithrombotic therapy (taken within 48 hours of surgery). These patients were compared to a control group of ureteroscopy patients not on antithrombotic therapy (stopped at least 5 days prior to surgery). There were no differences in bleeding complications. There was a fatal MI in the control group at day 29 in one group, and no thrombotic events in the study group.
The authors also report their success in stone treatment which I think is critical. This helps answer an initially less obvious but no less important question regarding the performance of ureteroscopy in this “anticoagulated” setting: although the risk of clinically significant bleeding is low, is there enough bleeding intraoperatively to limit our visibility and thus our success in stone treatment? The answer appears to be no, as the rate of residual stone fragments >3 mm was actually higher in the control group (8.9%) than the study group (2.9% in the aspirin group). The authors admit the follow-up imaging for residual stones was at the discretion of the physician, and perhaps not uniform between the groups.
This study demonstrates the safety and efficacy of ureteroscopy for urolithiasis in patients on antithrombotic therapy. It should be noted this data is limited to the use of holmium laser lithotripsy and may not safely translate to other forms of intraluminal lithotripsy. Also, when performing ureteroscopy for upper tract transitional cell carcinoma, when biopsy and soft tissue ablation is required, I still try to stop antithtrombotic therapy, though I have no data to support this preference.
1. Brilakis ES, Patel VG, Banerjee S. Medical management after coronary stent implantation: a review. JAMA 2013;310:189–98.
2. Roger VL, Go AS, Lloyd-Jones DM, et al; American Heart Association Statistics Committee, and Stroke Statistics Subcommittee. Heart disease and stroke statistics—2012 update: a report from the American Heart Association. Circulation 2012;125:e2–e220.
Michael Conlin, MD
Percutaneous Surgery
J Urol 2013;190:149–56.
Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
DOI: 10.1016/j.juro.2013.01.047
PLoS One 2013;8(6):e65888.
DOI: 10.1371/journal.pone.0065888
Commentary
These two recent publications address the accuracy of predicting PCNL success or stone-free rates (SFR) based on selected preoperative parameters.
Several earlier publications reported stone size, stone number, stone location and PC (pelvicalyceal) anatomy as predictors of SFR post-PCNL.1–3 The Guy's stone score system, for example, comprises 4 grades divided by stone number, stone location, simple vs. abnormal PC system and staghorn stone status.3 The Guy's scoring system is limited by the lack of a validation process and, for the most part, is not quantitative in nature which has resulted in limited adoption in current clinical practice. In general, the ideal prediction model to predict SFR post-PCNL should be simple, accurate, validated and easily reproducible. This is the aim of the authors of the above two papers.
The paper from Smith and colleagues arises from the CROES PCNL Study Group which proposes a new nomogram for predicting PCNL success with a high predictive accuracy or AUC of 0.76. Findings were that stone burden was the best predictor of PCNL SFR. Other factors were prior stone treatment, staghorn, stone location and stone number. Using a simple stone axis to determine the score attributed to each of the above radiological parameters, a sum total is worked out, resulting in calculation of percentage of SFR post-PCNL. The group predicted a predictive value higher than the Guy's stone complexity score (AUC 0.76 vs 0.69 at p < 0.001 ) and the predicted SFR were more accurate when using KUB vs. CT post-PCNL. The authors pointed out that this nomogram was highly predictable even though it did not factor in surgeon caseload or experience. The limitations of this nomogram included the absence of calibrating for stone density, heterogeneity of the surgical practice and the individual modification to treatment strategy which includes staged PCNL and/or adjunct treatments to increase SFR. The authors suggest 60% success as the threshold for performing the procedure.
The paper from Jeong and coworkers also addresses the accuracy of predicting PCNL success. The authors developed the Seoul National University Renal Stone Complexity score, or S-ReSC, for SFR after a SINGLE tract PCNL, created by a uro-radiologist. In their system, the score was calculated by counting the number of PC sites involved regardless of stone size and stone number. In essence, they have divided the PC system into 9 sites and one point is given for each location, resulting in a maximum of 9 points in total. The authors proposed that it is the number of stone locations that better predict SFR as it correlates better with complexity of the case. In their study, S-ReSC predicts SFR better than stone burden and stone number with an AUC of 0.86 which is higher than paper from Smith et al. The major limitation of this interesting paper is that it is a single center study; a multi-center study is needed to validate the results.
These two recent publications help us to better predict SFR post-PCNL and attempts to both quantify and manage both patient and surgeon expectations for the procedure.
1. Shahrour K, Tomaszewski J, Ortiz T, et al. Predictors of immediate postoperative outcome of single-tract percutaneous nephrolithotomy. Urology 2012;80:19–25.
2. Olbert PJ, Hegela A, Schrader AJ, et al. Pre- and perioperative predictors of short-term clinical outcomes in patients undergoing percutaneous nephrolitholapaxy. Urology 2007;35:225–30.
3. Thomas K, Smith NC, Hegarty N, et al. The Guy's stone score-grading the complexity of percutaneous nephrolithotomy procedures. Urology 2011;78:277–81.
Michael Y.C. Wong, MBBS
Extracorporeal Shock Wave
Urolithiasis 2013;41:231–4.
Use of extracorporeal lithotripsy is declining in North America and many European countries despite international guidelines advocating it as a first-line therapy. Traditionally, lithotripsy is thought to have poor efficacy at treating lower pole renal stones. We evaluated the success rates of lithotripsy for lower pole renal stones in our unit. 50 patients with lower pole kidney stones ≤15 mm treated between 3/5/11 and 19/4/12 were included in the study. Patients received lithotripsy on a fixed-site Storz Modulith SLX F2 lithotripter according to a standard protocol. Clinical success was defined as stone-free status or asymptomatic clinically insignificant residual fragments (CIRFs) ≤3 mm at radiological follow-up. The mean stone size was 7.8 mm. The majority of stones (66%) were between 5 and 10 mm. 28% of stones were between 10 and 15 mm. For solitary lower pole stones complete stone clearance was achieved in 63%. Total stone clearance including those with CIRFs was achieved in 81% of patients. As expected, for those with multiple lower pole stones the success rates were lower: complete clearance was observed in 39% and combined clearance including those with CIRFs was 56%. Overall, complete stone clearance was observed in 54% of patients and clearance with CIRFs was achieved in 72% of patients. Success rate could not be attributed to age, stone size or gender. Our outcome data for the treatment of lower pole renal stones (≤15 mm) compare favourably with the literature. With this level of stone clearance, a non-invasive, outpatient-based treatment like lithotripsy should remain the first-line treatment option for lower pole stones. Ureteroscopy must prove that it is significantly better either in terms of clinical outcome or patient satisfaction to justify replacing lithotripsy.
DOI: 10.1007/s00240-013-0549-8.
Commentary
This study starts with a most important statement, that “the use of ESWL is declining in North America and many European countries despite international guidelines advocating it as a first-line therapy.” What is wrong then?
The practice of ESWL proves the victim of its own non-invasiveness and absence of major complications. Due to an under-estimation of the complexity of shock wave administration, proper training in the performance of ESWL has been neglected for a very long time, resulting in a lack of skill and experience. Only recently has the importance of proper training leading to the necessary skill and experience to obtain good results with ESWL been recognized. In the meantime, patients often are subjected to more invasive treatment methods with a higher complication rate.
The problem with ESWL for lower pole stones is not fragmentation per se, but the poorer clearance of fragments which has been attributed to a number of factors, the gravity-dependent position of the lower pole probably being the most important.
Alternative modalities for the treatment of lower pole stones are PCNL and RIRS. For stones <10 mm there proves to be no difference in outcome between ESWL and PCNL. For stones ½10 mm PCNL is favored. For stones <20 mm ESWL is more cost-effective; for stones larger than 20 mm PCNL is more cost-effective. Though independent of body habitus, limiting factors for RIRS are stone burden and the anatomy of the lower pole calyx. Both PCNL and RIRS are more invasive and associated with higher morbidity.
In children there is a statistically significant better outcome with ESWL for lower pole stones than in adults for all parameters, irrespective of stone size.1 The smaller SSD (skin-to-stone distance) is considered an important factor in this. With increasing SSD, proper targeting and focusing of the stones becomes a problem. Although this would need clinical validation, it can be expected that lithotripters with high resolution imaging systems and an increased penetration depth of up to 170 mm, operated by experienced surgeons with proper attention to completely bubble-free coupling, would yield improved results in general and in lower pole stones in particular.
The importance of proper administration of shok waves (dedication of an experienced team, accurate targeting, appropriate analgesia, etc.) is therefore rightly emphasized by Cui and colloeagues. They correctly conclude that outpatient-based ESWL should remain the first-line treatment of choice for lower pole stones because of its non-invasiveness, excellent clearance rates and patient satisfaction. The excellent clearance rate (including CIRFs ≤3 mm) of 72% for stones up to 10 mm and the very nice 71% for stones 10–15 mm are testimony to their adequate approach. Unless endoscopic techniques can prove to be significantly better in terms of clinical outcome and patient satisfaction they should be reserved for larger stones (≥20 mm), failed ESWL cases or contraindications for ESWL.
1. Mandal S, Sankhwar SN, Singh MK, et al. Comparison of extracorporeal shock wave lithotripsy for inferior caliceal calculus between children and adults: a retrospective analysis – why do results vary? Urology 2012;80:1209–13.
Geert G. Tailly, MD
Urolithiasis 2013;41:437–41.
Few studies show that “emergency extracorporeal shockwave lithotripsy (eESWL)” reduces the incidence of ureteroscopy in patients with ureteric calculi. We assess success of eESWL and look to study and identify factors which predict successful outcome. We retrospectively studied patients presenting with their first episode of ureteric colic undergoing eESWL (within 72 h of presentation) over a 5-year period. Patient's age, gender, stone size and location, time between presentation and ESWL, number of shock waves and ESWL sessions, and Hounsfield units (HU) were recorded. 97 patients (mean age 40 years; 76 males, 21 females) were included. 71 patients were stone free after eESWL (73.2%) (group 1) and 26 patients failed treatment and proceeded to ureteroscopy (group 2). The two groups were well matched for age and gender. Mean stone size in group 1 and 2 was 6.4 mm and 7.7 mm, respectively, (p = 0.00141). Stone location was 34, 21, and 16 in upper, middle and lower ureter in group 1 compared to 11, 5, and 10 in group 2, respectively. Mean HU in group 1 was 480 and 612 in group 2 (p value 0.0036). In group 2, significantly, more patients received treatment after 24 h compared with group 1 (38 vs 22.5 %). The number of shock waves, maximal intensity, and ESWL sessions were not significantly different in the two groups. No complications were noted. eESWL is safe and effective in patients with ureteric colic. Stone size and Hounsfield units are important factors in predicting success. Early treatment (≤24 h) minimizes stone impaction and increases the success rate of ESWL.
DOI: 10.1007/s00240-013-0580-9
Commentary
Although there is a continuous quest to find minimally invasive therapies in all areas of urology, the discussion on the best treatment choice for ureteral stones – ESWL or URS – continues. However, the answer seems simple: the least invasive modality that solves the problem is preferred. The least invasive treatment modality in ureteral stones is spontaneous passage. Spontaneous passage rate is dependent on stone size and stone location. Stones <5 mm have a 46–85% chance of spontaneous passage, compared to 36–59% for stones 5–10 mm. Stones in the distal ureter have a 70% chance as compared to 45% in the middle and 25% in the proximal ureter. Spontaneous passage rates can be increased by 29–65% with the administration of α-blockers (MET).
When “active” treatment is needed the joint AUA/EAU guidelines positively favor URS only for distal ureteral stones ½10 mm. For all other locations and sizes ESWL and URS are considered more or less equivalent in terms of SFR. Of course, factors other than SFR do play a role in the equation. Although complication rates following URS are low, acute complications following in situ and de novo ESWL are extremely rare.
The disadvantage of a higher retreatment rate in ESWL is counterbalanced by the much higher need for anesthesia in URS.1 Apart from this, availability of equipment, surgeon expertise and patient preference are also important factors. Despite the fact that URS tends to render patients stone-free faster, most patients still prefer ESWL.2
In terms of equipment and expertise ESWL definitely is at a disadvantage. First of all, not all lithotripters are created equal. More importantly, training in ESWL more often than not is substandard leading to a lack of expertise in this treatment modality. In URS there usually is extensive training and tutoring. Tutoring in the basic physics of shockwaves and better training in the efficient administration of SW should improve day-to-day practice of ESWL.
The performance of emergency ESWL (eESWL) should further tip the balance in favor of ESWL. Apart from offering improved fragmentation, a shorter time to achieve complete stone clearance, an increase in SFR, a reduced need for repeat ESWL sessions and treatment of the renal colic itself,3 according to this study eESWL also reduces the need for more invasive therapies, i.e. URS. The authors rightly conclude that eESWL is their first treatment of choice for ureteral stones <10 mm irrespective of location because of its good results, non-invasiveness and performance on an outpatient basis.
The strategy seems obvious: spontaneous passage (+/− MET) → (e)ESWL → URS.
1. Tiselius HG. Removal of ureteral stones with extracorporeal shock wave lithotripsy and ureteroscopic procedures. What can we learn from the literature in terms of results and treatment efforts? Urol Res 2005;33:185–190.
2. Karlsen SJ, Renkel J, Tahir AR, et al. Extracorporeal shockwave lithotripsy versus ureteroscopy for 5- to 10-mm stones in the proximal ureter: prospective effectiveness patient-preference trial. J Endourol 2007;21:28–33.
3. Picozzi S, Ricci C, Gaeta M, et al. Urgent shock wave lithotripsy as first-line treatment for ureteral stones: a meta-analysis of 570 patients. Urol Res 2012;40:725–31.
Geert G. Tailly, MD
Transurethral Procedures
These two articles provide an insight to the availability, diversity and nuances of the large variety of procedures available to accomplish, or attempt to accomplish, the same surgical goals and outcomes—to debulk the prostatic urethra of tissue obstruction to allow increased flow with minimal morbidity. The first focuses on economics and the second on modifications of a surgical technique that is growing in popularity with large glands.
Alexis Te, MD
Urology 2013;81:1177–82.
Copyright © 2013 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.urology.2013.01.051
Commentary
Lasers are marketable medical devices that gain quick adoption in direct-to-consumer markets. However, the over 20-year history with BPH therapies presents caveats in adoption that sound the consumer mantra “let the buyer beware!” Often, new technology is the promise of a better result with less complication. However, like any new consumer product, early adopters pay a premium to use it. This particular paper is a general socioeconomic overview of laser technology adoption. It is clear that socioeconomic environments with greater financial advantage can more easily adopt this higher cost technology. However, if one focused on a less marketable technology such as TURP, the impact of financial advantage is minimal. This is interesting since TURP has come a long way, especially in terms of decreased morbidity. The introduction of better anesthetic control, bipolar technology and advances in electrosurgical techniques such as electrovaporization have effectively decreased TUR syndrome and improved hemostasis. And while there is no difference found by the authors, if one were to examine the various equipment utilized to perform a TURP, it may be more than probable that advanced TURP technology is being adopted in more advantaged socioeconomic environments. As always, efficacy is still dictated by the skill of the surgeon and good patient selection. However, this technology is not as marketable as lasers. The laser market, however, is more interesting because of the vast variety of techniques and technology represented within it. Not all lasers employ the same technique and each type requires a specific understanding of mechanism of action to affect the best result. Additionally, costs vary among lasers due to not only the cost of the equipment itself but of maintaining disposable equipment stock such as fibers, though some lasers do have multiuse capability. The complexity of adoptions is further complicated by other financial parameters such as length of hospital stay and financial impact of complications. In an advantaged socioeconomic environment, the marketability, potential for better margins due to shorter hospital stay and lower complication rates may be better understood where efficiency is sought and employed.
Finally, not all lasers represent an advancement over TURP. Older laser technologies are still employed that do not confer a great advantage to current TURP. While there are laser technologies with clearly improved safety profiles, efficacy still remains in the domain of skill and judgment of the surgeon. This is because with all transurethral technology, the primary skill is still dependent on effecting a surgical result via a long endoscopic tube with a manually controlled surgical instrument via a limited visual endoscopic view.
Alexis Te, MD
BJU Int 2013;111:793–803.
© 2013 BJU International.
DOI: 10.1111/j.1464-410X.2012.11730.x
Commentary
This series represents a growing trend in mastering the transurethral enucleation technique first popularized by holmium laser technology users. With this technique, enucleation is accomplished via a transurethral approach to remove analogous portions of the prostate that are removed via open prostatectomy. In concept, the procedure is actually a manual enucleation utilizing the tip of the scope as one uses fingers during an open prostatectomy to enucleate the central portion of prostate. Cutting and hemostasis are accomplished by the holmium laser. With holmium enucleation, a morcellator is needed to make the tissue smaller and removable via resectoscope. It is well known that it is a challenging procedure, but when proficient, it is an efficacious procedure comparable in long-term outcomes to open prostatectomy, and yet much safer with less morbidity. Recently, this transurethral technique has also been applied utilizing other types of lasers such as the 532 nm high power laser system also known as greenlight.
While challenging in large glands, it is possible to perform without a morcellator since 50% of the tissue is often vaporized in the process, and is then easily removed via a resectoscope sheath. With the bipolar system as described in this study, enucleation is accomplished in similar fashion with the electrosurgical tip utilized to cut, vaporize and coagulate tissue. While the authors employed a morcellator to remove the tissue, another advantage with bipolar is the ability to cut the enucleated tissue into small pieces with the bipolar loop if a morcellator is not available. This is not possible with monopolar technology. The caveat to all these procedures is that transurethral skill and experience is necessary to achieve a safe and durable result. The anatomy can be challenging with intravesical lobes and long prostatic urethras presenting as obstacles even for the most proficient surgeon. Of note, all these procedures confer similar advantages. They utilize normal saline as an irrigant, and thereby remove the risk associated with dilutional hyponatremia. Additionally, since fluid absorption with higher intravesical pressure is less of a concern with normal saline, hemostasis can be better controlled and managed much like insufflation pressure provides hemostasis during laparoscopic procedures. The results of this paper compared to open prostatectomy are consistent with that of holmium laser enucleation techniques, and is not surprising.
Alexis Te, MD
Medical Aspects of Endourology
J Urol 2013;190:1255–9
DOI: 10.1016/j.juro.2013.03.074
Comments
Previous studies from these three large epidemiologic cohorts have demonstrated that low dietary calcium intake is a risk factor for the development of an incident kidney stone. This study addresses whether the type of dietary calcium—dairy or non-dairy—impacts this risk. Male health professionals greater than 60 years of age were not included as these investigators previously demonstrated that dietary calcium did not have this inverse relationship with stone risk. The findings that the intake of both sources of dietary calcium has an inverse relationship with incident development of kidney stones is of practical value as those with lactose intolerance can use non-dairy calcium sources to limit stone risk. These relationships are attributed to interactions between calcium and oxalate in the enteric stream that regulate the process of gastrointestinal oxalate absorption.
Dean G. Assimos, MD
J Clin Endocrinol Metab 2013;98:2589–94.
DOI: 10.1210/jc.2013-1301
Comments
Hypercalciuria is recognized as a major risk factor for the development of calcium oxalate, calcium phosphate and mixed calcium oxalate stones. It has previously been demonstrated that individuals with idiopathic hypercalciuria (IH) have an exaggerated calciuric response to carbohydrate loading. A more profound postprandial increase in calcium excretion is also seen in this cohort and is attributed to reduced renal calcium reabsorption. This study suggests that this differential response between those with IH and controls is most likely not modulated by insulin responsiveness.
Dean G. Assimos, MD
Investigative Endourology
J Urol 2013;190:1090–5.
Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
doi: 10.1016/j.juro.2013.03.120.
Commentary
Residual stone fragments that remain after shock wave lithotripsy or ureteroscopy often become “clinically significant” even if they are considered “clinically insignificant” after initial therapy.1 The difficulty in clearing small stone fragments in a lower pole stone location can be especially challenging.2 What if we could non-invasively relocate small stones or residual fragments to encourage spontaneous passage and avoid future stone-related events?
Harper et al continue to work toward improving a prototype ultrasound device which is capable of using focused ultrasound to propel kidney stones into different locations within the collecting system. This study evaluates a newer prototype ultrasound propulsion machine for the efficacy of stone movement and the safety of the device in a live porcine model. The current device delivers 1-second “push bursts” that can be roughly compared to shock wave delivery, but at half the pressure and only a quarter of energy that current shock wave lithotripters deliver.
The authors demonstrated the ability to cause movement in all stones implanted into a porcine model (ranging from 2–8 mm), and reported 65% success in relocating the stones from a calyx to a more favorable location. On histological evaluation, no evidence of injury to the parenchyma could be demonstrated. Therefore, it appears to be a safe technology.
Weaknesses of the study include a porcine model with implanted stones and completely anesthetized subjects. In this ideal setting, the average manipulation time was 15 minutes. It is unclear how the less favorable collecting system anatomy of humans, along with greater source-to-target distance, will affect the focused ultrasound's ability to move a stone or the time required to perform the task. The authors also comment that they have no data on whether the treatment causes pain.
Overall, though, I look forward to this technology with great promise. I believe it could be very beneficial in an outpatient clinical setting to move small stones or residual fragments. The technology may also be useful as an adjunctive technique during shock wave lithotripsy or ureteroscopy to relocate difficult to target or treat stones. The authors are currently awaiting approval from the FDA to pursue human feasibility trials.
1. Streem SB, Yost A, Mascha E. Clinical implications of clinically insignificant stone fragments after extracorporeal shock wave lithotripsy. J Urol 1996;155:1186–90.
2. Pearle MS, Lingeman JE, Leveillee R, et al. Prospective randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less. J Urol 2008;179:S69–73.
David A. Duchene, MD
J Urol 2013;190:1096–101.
Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
DOI: 10.1016/j.juro.2013.02.074
Commentary
Newer generation shock wave lithotripters have had multiple design changes over the years. These design changes have improved the ease of shockwave delivery and the consistency of the shock waves, provided the ability of machine transportation between locations, and allowed more comfortable treatment to a patient under sedation. As a drawback, the newer generation machines have been shown to have lower stone fragmentation efficacy.1 One reason behind the decreased efficacy is thought to be the narrow focal width of the newer machines. Many urologists have noticed this decrease in stone fragmentation in clinical practice and long for the efficacy of the original Dornier HM3 device.
The authors of this article decided to modify the acoustic lens of a Modularis electromagnetic (EM) shock wave lithotripter to better simulate the pressure waveform and focal zone of the HM3 machine. The authors contend that current EM lithotripters have an inferior pulse profile compared to electrohydraulic machines due to a second compressive wave caused by the oscillation in the EM coil (which suppresses cavitation activity). Cavitation energy is an important part in stone fragmentation and suppression should be minimized. The current EM lithotripters also have only a 4–7 mm beam width compared to the HM3 beam width of 10–12 mm. Therefore, the modified acoustic lens was designed to minimize the second compressive wave and to increase the beam width of the machine to approximately 10 mm. These modifications allow the EM device to better reflect the HM3 characteristics.
This study was performed in two parts. The first part was to determine the efficacy of the standard lens versus the modified lens in a porcine phantom stone model. The second portion was to assess for tissue injury in the porcine model between the original and modified lenses.
The results showed no difference in stone fragmentation efficacy between the two lenses after 500 shocks, but the modified lens had statistically significant improvement in stone fragmentation after 2000 shocks. Tissue damage caused by the two lenses was minimal and without any differences between the two lenses.
It appears that our technological advances are taking us back to some of the key features which allowed the HM3 lithotripter to be so successful. The modified lens still needs to be trialed in humans, however, before we know if the modification will prove to be clinically relevant. If this proves to be a true design improvement, we may need to alter our lithotripter machines. As the authors point out, these new lenses could potentially be retrofitted to current lithotripters to improve stone fragmentation.
1. Gerber R, Studer UE, Danuser H. Is newer always better? A comparative study of 3 lithotriptor generations. J Urol 2005;173:2013–16.
David A. Duchene, MD
Robotics
BJU Int 2013;112:E295–300.
© 2013 BJU International.
DOI: 10.1111/bju.12163
Commentary
In many centers, laparoscopic nephroureterectomy has become the preferred approach to upper tract transitional cell carcinomas when nephroureterectomy is required. In addition to the pure laparoscopic technique, other minimally invasive approaches to nephroureterectomy include hand-assisted laparoscopic and robotic approaches. However, there is no consensus as to the best approach to removing the distal ureter, and indeed various techniques, including endoscopic, transvesical, and traditional open approaches have all been reported. Generally, from an oncologic standpoint, the surgeon should remove the entire distal ureter with a small cuff of bladder to prevent a retroperitoneal recurrence. Retroperitoneal recurrences of high grade urothelial tumors can be problematic and on occasion partial or even radical cystectomy could be required.
In this multi-institutional study, surgeons from three different academic centers performed 43 robotic-assisted nephroureterectomy (RANU) procedures for upper tract urothelial carcinomas. In all cases, the entire nephroureterectomy procedure, including removal of the distal ureter, was performed entirely using the robotic technique. It was the preference of some surgeons to perform the operation using a single robot-docking technique in the modified flank position. In other cases, a two robot-docking technique was used, where the nephrectomy was performed first and the robot was then re-docked to gain better access to the distal ureter and bladder. In all cases, via an extravesical approach, the distal ureter was removed with a small cuff of the bladder.
In this study the complication rate was low, though there were two cases of rhabdomyolysis which both involved morbidly obese patients and in one case was associated with prolonged operative time (330 minutes). Also, one patient had a splenic bleed requiring emergency takeback splenectomy. There also were nine recurrences, including six in the bladder, one in the other collecting system, and two in the retroperitoneum with follow-up of nine months.
The primary advantage of RANU seems to be the management of the distal ureter and the bladder cuff. For those surgeons who are skilled at performing laparoscopic nephrectomy, there is probably little advantage of the robotic technique for the nephrectomy portion of this case. It is clear that removing the entire ureter, including a cuff of the bladder, is absolutely critical when performing nephroureterectomy. As such, many surgeons who perform laparoscopic nephroureterectomy still prefer to remove the distal ureter via a small Gibson incision to ensure that the distal ureter is removed with a small bladder cuff. Both intravesical and extravesical techniques have been used.
The robotic approach to removing the distal ureter may be a feasible alternative to other open or laparoscopic techniques, as the technique seems similar to the open approach. However, long-term oncologic outcomes are necessary to confirm that the efficacy is equivalent to the open approach.
David S. Wang, MD
BJU Int 2013;112:E290–4.
© 2013 BJU International.
DOI: 10.1111/bju.12167
Commentary
In the United States, robotic-assisted radical prostatectomy has replaced the traditional open radical retropubic prostatectomy in most academic and nonacademic centers. However, this does not seem to be the case for radical cystectomy. While many centers of excellence are performing robotic-assisted radical cystectomy (RARC), standard open radical cystectomy (ORC) is still commonly and routinely performed. There are many reasons for reluctance to perform RARC, including the perceived inability to perform a thorough lymph node dissection, the notion that an open incision is required to perform the urinary diversion, lack of surgeon experience with robotic approach, potentially locally aggressive disease, and unclear benefit of the robotic approach.
In this single-institution retrospective study, 100 consecutive cases of RARC were compared to a historical series of patients who had undergone standard ORC. Complications and perioperative outcomes were examined. There were no differences noted in preoperative characteristics. Intraoperative characteristics were examined; operative times were shorter in the ORC group, but blood loss and transfusion rates were lower in the RARC group. Overall 90-day complication rates were lower in the RARC group (35% vs 57%), and major complication rates were also lower (10% vs 22%). Perioperative pathologic results were similar in both groups regarding positive lymph nodes (30% RARC vs 24% ORC) and average lymph node yield (17.7 RARC vs 15.7 ORC).
In this study, the complication rate following RARC was lower than that of ORC. Traditional ORC has been associated with a high complication rate, as high as 50–70% even in experienced centers. In this study, an overall complication rate of 57% in the ORC is consistent with the literature. The overall and major complication rate (35% and 10%) of RARC, while high, is still lower than the complication rate of ORC at most centers. It seems that the decreased blood loss, less need for intravenous hydration, and decreased fluid shifts are distinct advantages of RARC.
Unlike most cases of prostate cancer, the patient with high grade bladder cancer has a potentially lethal cancer. When radical cystectomy is indicated, adherence to strict oncologic principles is required, and this includes radical cystectomy with extensive lymph node dissection. In experienced hands, RARC is an effective alternative to ORC with a lower complication rate and equivalent pathologic results. However, long-term oncologic outcomes and also functional results will likely be required before this technique becomes as prevalent as robotic radical prostatectomy.
David S. Wang, MD
Thermal/Ablative Technology
Urol Oncol 2013;31:686–92.
Copyright © 2013 Elsevier Inc. All rights reserved.
DOI: 10.1016/j.urolonc.2011.05.008
Commentary
Yang et al evaluate their institutional experience with probe ablation as salvage therapy for renal tumors in VHL disease. They report on 14 patients (of whom 12 had solitary kidneys) who underwent a total of 33 tumor ablations (1–5 procedures/patient, median 2) by percutaneous cryoablation (n = 13), percutaneous RFA (n = 14), or laparoscopic cryoablation (n = 3). Mean tumor size was 2.6 ± 1 cm. There were no intraoperative or postoperative complications recorded in this retrospective review. With an average follow-up of over 3 years (37.6 months), 4 (26%) had suspicious findings on imaging, with retreatment performed in three. Actuarial overall and cancer-specific survival was 92% and 100%, respectively.
This paper highlights the important balance that one needs to achieve when devising a treatment strategy for patients with VHL. There are three interrelated factors to consider: 1) the need to balance oncologic intervention, which is inherently to some degree renal-wasting, with 2) renal preservation, and 3) keeping an eye on the long-term horizon facing these patients, who not only have a 50% likelihood of RCC recurrence within 5 years, but as well other multi-organ tumors (eye, CNS, adrenals, pancreas) subjecting them to lifelong, surgical interventions. So while partial nephrectomy is an excellent operation (and is usually necessary in these patients, who may have multiple, large, or cystic tumors) it is associated with significant scarring and desmoplasia on reoperation. Thus at many centers, the first choice is ablative therapy if the opportunity presents for effective percutaneous treatment.
Take-home points from this publication are that VHL patients represent a unique population requiring a thoughtful long-term view for renal preservation and probability of reoperation without risking metastatic progression. This study by Yang et al supports the concept of ablative therapy as a good option for salvage therapy.
Surena F. Matin, MD
AJR Am J Roentgenol 2013;200:1365–9.
DOI: 10.2214/AJR.12.9336
Commentary
Allen et al report on percutaneous RFA of cystic renal (Bosniak 3 and 4) neoplasms at their institution. Thirty-eight patients underwent RFA of 40 cystic lesions. Biopsy (consisting of both FNA and cores) of the nodular elements or septations was done in 90% of patients immediately before ablation, and no cyst aspiration was performed. Mean follow-up was 2.8 years, but only for 21 patients who had at least 1 year of follow-up. Biopsy showed 61% of lesions to be malignant, and 39% were inconclusive. Technical success was 100%. The authors reported no local recurrences or new metastatic disease in this retrospective study, while 1 patient developed a new tumor, presumably in a different location than the original treatment but this was not specified. There were 5.3% minor complications, and one (2.6%) major complication consisting of flash pulmonary edema. The authors conclude that percutaneous RFA is an effective and safe treatment of Bosniak 3 and 4 renal neoplasms.
So does this report convince the reader that this approach is in fact “effective” and “safe”? Cystic tumors have traditionally been considered a contraindication for probe ablative therapy, given the need to puncture the tumor and the resulting potential for tumor spillage. For those of us who study and routinely treat kidney cancer throughout the stages of disease, certain gaps are evident. First, cystic RCC tumors tend to be relatively indolent and low grade; concerns regarding possible local recurrence due to spillage are probably not allayed by 1-, 2-, or even 3-year follow-up periods. Thus one question is whether 2.8 years' mean follow-up on a subset of patients is long enough to convince the urologic reader that this is oncologically adequate. Second, the average tumor size was 2.4 cm. Keeping in mind the indolent nature of cystic RCC, as well as the fact that 69% of patients had significant cardiopulmonary comorbidities and 42% threatened renal function, how would these patients have fared with surveillance alone, the ultimate renal preserving, low-risk option? Data shows that even with a solid renal tumor (which is more likely to be RCC than an indeterminate cystic mass) <3 cm, elderly patients are much more likely to die of non-cancer causes.1 In fact, using a recently published nomogram, a 75-year-old patient with a 3 cm renal mass and a Charlson score of 3 has a 13% risk of noncancer death in 5 years, but less than 3% risk of a renal cancer death.1 So one could reasonably ask, what was the relative benefit of intervention to these patients? Third, the authors have fallen in the trap of reporting data for all patients regardless of histologic findings. A lesson that has been learned in the past few years is that reports need to specify oncologic outcomes for those with biopsy-proven RCC given the high incidence of benign lesions, especially in this population.
Thus, particularly for this reader, the take-home message from this report is that, yes, RFA can be done on these patients and, as one would expect, with low short-term morbidity. Whether it actually helped these patients and whether it was oncologically valid remains to be seen, with longer follow-up and with further studies that compare outcomes to surveillance.
1. Kutikov A, Egleston BL, Cantera D, et al. Competing risks of death in patients with localized renal cell carcinoma: a comorbidity based model. J Urol 2012;188:2077–83.
Surena F. Matin, MD