Commentary

The Japanese Society of Endourology and ESWL (JSEE) conducted nationwide surveys on the number of urologic laparoscopic surgeries performed each year and the outcomes of specific laparoscopic procedures, including prostatectomies,^1,2 nephroureterectomies (current article), and partial nephrectomies (data collection).

This paper is the largest series of laparoscopic nephroureterectomies (LNUx) with over 1000 cases, and covers half of the patients who underwent LNUx in Japan during these 14 years. The results showed a comparable long-term overall and recurrence-free survival, as well as a comparable complication rate. The important finding of this paper is the novel indications for risk factors pertaining to recurrence-free survival and intravesical recurrence, including males and the hand-assisted approach. The latter factor is evident in the group receiving a retroperitoneal approach but not the transperitoneal approach, which makes the following speculation feasible: tumor manipulation in a small operative field by the hand is the cause of intravesical recurrence. The large number of cases from multiple centers revealed these new factors. A larger scale international multicenter clinical study project has been established by the Clinical Research Office of the Endourological Society (CROES). The themes left unsolved in this article such as the impact of the case volume of each institute on the outcomes would be investigated by international studies by CROES.

As commented by Dr. Anup Patel in the current article's accompanying Editorial Comment, this report from Japan is a monumental article on LNUx. Recently, the results of a randomized prospective study comparing laparoscopic and open nephroureterectomies were reported by Simone et al.³ They showed better results for the estimated blood loss and time to discharge in the laparoscopic group, and similar outcomes for the bladder tumor-free and cancer-specific survival. However, when matched for pT3 tumors, the cancer-specific survival was significantly better in the open group. The number of patients with pT3 cancers (only 25) was too small to draw definitive conclusions. Further larger scale studies are necessary to establish the role of LNUx for upper urinary tract cancers.

References

1. Arai Y, Egawa S, Terachi T, Suzuki K, Gotoh M, Kawakita M, Tanaka M, Terada N, Baba S, Okumura K, Hayami S, Ono Y, Matsuda T, Naito S. Morbidity of laparoscopic radical prostatectomy: summary of early multi-institutional experience in Japan. Int J Urol 2003;10:430–434.

2. Egawa S, Arai Y, Kawakita M, Matsuda T, Tanaka M, Naito S, Okumura K, Terachi T, Hayami S, Suzuki K, Gotoh M, Ono Y, Baba S. Surgical outcome of laparoscopic radical prostatectomy: summary of early multiinstitutional experience in Japan. Int J Clin Oncol 2003;8:97–103.

3. Simone G, Papalia R, Guaglianone S, Ferriero M, Leonardo C, Forastiere E, Gallucci M. Laparoscopic versus open nephroureterectomy: perioperative and oncologic outcomes from a randomised prospective study. Eur Urol 2009;56:520–526.

Tadashi Matsuda, M.D.

Feasibility of transvaginal NOTES-assisted laparoscopic nephrectomy. Alcaraz A, Peri L, Molina A, Goicoechea I, García E, Izquierdo L, Ribal MJ. Department of Urology, Hospital Clinic IDIBAPS—University of Barcelona, Barcelona, Spain.

Eur Urol 2009;Sep 18. [Epub ahead of print]

Background: Recently, the feasibility of a transvaginal hybrid natural orifice transluminal endoscopic surgery (NOTES) nephrectomy was demonstrated in a 23-yr-old woman with a nonfunctional atrophic kidney.

Objective: To evaluate the feasibility and reproducibility of transvaginal NOTES-assisted laparoscopic nephrectomy in female patients with and without renal cancer.

Design, Setting, and Participants: Between March 2008 and June 2009, 14 female patients were submitted to transvaginal NOTES-assisted laparoscopic nephrectomy for T1–T3a N0M0 renal cancer (n = 10), lithiasis (n = 2), or renal atrophy (n = 2) at the Hospital Clinic of Barcelona, Spain.

Surgical Procedure: Under general anaesthesia, female patients underwent laparoscopic nephrectomy by transvaginal NOTES using a deflectable camera by vaginal access and two additional 5- and 10-mm trocars in the abdomen. The renal artery and vein were dissected and taken separately between clips. The dissected kidney was removed via the vagina after enlarging the vaginal trocar incision.

Measurements: All data referring to patient demographics, surgery, pathology, and perioperative outcomes were recorded.

Results and Limitations: The procedure was completed in all patients. The mean age of the women was 59.1 yr. The mean operative time was 132.9 min and the mean estimated blood loss was 111.2 ml. None of the patients required a blood transfusion and the use of analgesics was low. The mean hospital stay was 4 d. In one case, a major complication (a colon injury) occurred. The patient underwent surgery and a temporary colostomy was performed. The patient has already undergone reconstruction.

Conclusions: Transvaginal NOTES-assisted laparoscopic nephrectomy is feasible and reproducible and may be an alternative technique for treatment of women with renal cancer. Proper selection of patients is warranted for success of this new approach. However, longer follow-up in an increasing number of patients is needed to establish its role in the treatment of renal cancer.

DOI: 10.1016/j.eururo.2009.09.025

Commentary

After 20 years of clinical experience with laparoscopic nephrectomies, we are now moving to newer and less invasive surgeries, including laparoendoscopic single site surgery (LESS) and natural orifice transluminal endoscopic surgery (NOTES). NOTES nephrectomies have already been reported in a porcine model and also in humans. This paper is the first to demonstrate the feasibility of a hybrid NOTES nephrectomy for kidney cancer patients.

Surgery without abdominal wounds is the ultimate goal of minimally invasive therapy. A pure NOTES nephrectomy was reported by Kaouk et al. recently in humans.¹ However, the procedure should have technical feasibility and reproducibility by many surgeons. A pure NOTES must be a challenging procedure without the routine coaxial configuration of working and endoscopic ports. The hybrid NOTES reported in this paper used 2 abdominal ports for working instruments, which made the entire procedure quite similar to the conventional laparoscopic surgery. A video clip of this procedure accompanies the online article on the journal's website and demonstrates well the outline of the procedure and operative view from the vaginal camera, which is similar to routine transperitoneal laparoscopic nephrectomy.

The issues to be resolved before establishing the usefulness of this hybrid method include a comparison to the simple vaginal retrieval of the kidney after a routine laparoscopic nephrectomy, and also to a LESS nephrectomy with respect to the technical feasibility, postoperative pain and cosmetic satisfaction by female patients. Another point for urologists is how to secure the patient's position to make vaginal access possible. The position used by the authors, a semilumbotomy position with separated legs, is not familiar to the majority of surgical staff, and has the risk of complications, in particular when a deeper angle of lumbotomy is used near a pure lateral position to obtain a better surgical field.

The future direction of this hybrid NOTES technique should be a step from laparoscopic surgery toward a pure transvaginal NOTES by adding another transvaginal port for a retractor or a suction device.

References

1. Kaouk JH, White WM, Goel RK, Brethauer S, Crouzet S, Rackley RR, Moore C, Ingber MS, Haber GP. NOTES transvaginal nephrectomy: first human experience. Urology 2009;74:5–8.

Tadashi Matsuda, M.D.

Commentary

At least 6 meta-analyses of medical expulsive therapy have been published based on initial clinical trials. All of them have concluded that alpha-blockers and calcium channel blockers are beneficial for patients with ureteral stones. Several recent publications, however, have failed to confirm these positive findings.

Here is another negative trial of alpha-blockers for expulsive therapy of ureteral stones. This trial was not perfect, but it was conducted well, with very few dropouts. The investigators measured important clinical variables, such as pain scores and the use of pain medication, in addition to the rate of spontaneous stone passage. While there was a slight improvement in stone passage, this did not reach statistical significance. In fact, there were no measurable differences between the treatment and control groups.

Why, after a number of trials that all showed a positive effect of alpha-blockers, have this and several other recently reported trials shown no benefit? There are a number of possible explanations, including a) the original trials were not conducted in a rigorous, double-blind fashion; b) the original trials involved the use of multiple medications (polypharmacy), making it difficult to judge the effect of each medical intervention; c) the patient population studied varies based primarily on size of stone; or d) simple publication bias in the original studies.

The trial was not particularly large, so it is distinctly possible that a positive finding may have been missed due to a type 1 statistical error. Nevertheless, this trial is larger than the average study that showed a positive effect. The average size of the stone in this trial was only 3.6 mm, compared to as high as 7 mm in some other studies. It is possible that the efficacy of medical expulsive therapy varies according to size of stone. Only a very large, multicenter study can address these issues.

Francis X. Keeley, Jr., M.D.

Endoluminal isoproterenol reduces renal pelvic pressure during semirigid ureterorenoscopy: a porcine model. Jakobsen JS, Jung HU, Gramsbergen JB, Osther PJ, Walter S. Institute of Medical Biology, University Hospital of Southern Denmark, Odense, Denmark.

BJU Int 2010;105:121–124.

Objective: To investigate the effects on the pressure-flow relation of renal pelvic pressure during semirigid ureterorenoscopy and endoluminal perfusion of isoproterenol (ISO) 0.1 microg/mL, with emphasis on local effects and cardiovascular side-effects, as topically administered ISO effectively and dose-dependently causes relaxation of the upper urinary tract in pigs with no concomitant cardiovascular side-effects.

Materials and Methods: In anaesthetized female pigs (60 kg), 16 macroscopically normal upper urinary tract systems were subjected to ureterorenoscopy. Via a subcostal incision a 6-F catheter was placed in the renal pelvis for pressure measurements, and a semirigid ureteroscope (7.8 F) was inserted retrogradely in the renal pelvis, through which the pelvis was perfused. The blood pressure and heart rate were recorded. The increase in renal pelvic pressure was examined with increasing flow rates (0, 4, 8, 12, 16, 25 and 33 mL/min) with saline alone or saline + ISO 0.1 microg/mL. Perfusion was initiated on the left side, with randomization for adding ISO or not. Thereafter perfusion was done on the right side as a control in each pig. The surgeons were unaware of whether ISO was added or not.

Results: The mean (sd) baseline pelvic pressures in the saline and ISO group were 28 (7.1) and 25 (9.8) mmHg, respectively, with no significant difference (P = 0.079). Endoluminal perfusion with ISO significantly inhibited the pelvic pressure increase to perfusion at all perfusion rates. The pressure-flow relation was linear; the maximum relaxation (27%) was obtained at 4 mL/min, from 52 to 38 mmHg during saline alone and ISO 0.1 microg/mL perfusion, respectively. The mean blood pressure did not change significantly (P = 0.330). The mean (sd) heart rate in the saline and ISO group were 109 (4.5) and 97 (2.1) beats/min, respectively (P < 0.001), i.e. a markedly greater rate in the saline than in the ISO group.

Conclusion: The pressure-flow relation during semirigid ureterorenoscopy was linear. ISO 0.1 microg/mL in saline significantly reduced the pressure-flow relation during semirigid ureterorenoscopy in this porcine model. ISO might be a potential additive to the irrigation fluid during upper urinary tract endoscopic procedures, minimizing pressure increases due to irrigation and manipulation.

DOI: 10.1111/j.1464-410X.2009.08678.x

Commentary

All urologists are aware of the potential for extravasation of irrigation fluid during ureteroscopy based on the all too common observation of extravasation during retrograde pyelography. Although intraoperative extravasation is associated with few measurable postoperative complications, high intrapelvic pressure can lead to bleeding, sepsis and, in the case of upper tract TCC, dissemination of tumor cells. Efforts to reduce pressures during ureteroscopy thus far have largely focused on equipment, such as miniaturization of endoscopes and the adoption of ureteral access sheaths. In light of recent advances in thinking on expulsive stone therapy, why not use pharmacology in addition to engineering to solve this problem?

This manuscript is part of an ongoing project by this Danish group investigating intraoperative ureteral relaxation using irrigation fluid with a pharmaceutical agent. They have taken the clinical problem of high intrarenal pressures and tackled it in a logical, methodical fashion. They have performed a series of studies in vitro, in animals, and in the clinical setting to determine whether isoproterenol in irrigation fluid is safe and effective in reducing intrarenal pressures.

The methods of this study deserve scrutiny, since there are many areas of potential bias in a surgical study. The investigators were blinded to the content of the irrigation fluid. Each pig underwent ureteroscopy on the contralateral kidney as a further control. The irrigation rates were varied in the saline and isoproterenol groups so that multiple measurements of intrapelvic pressure could be made. The resultant curves clearly showed lower pressures at every flow rate in the isoproterenol group. The curves also show that higher flows, unsurprisingly, are associated with higher pressures. Blood pressure did not vary between the groups, but the heart rate was higher in the saline group, possibly due to the effect of the higher pressures. Insignificant levels of isoproterenol were found in serum samples.

Where will this work ultimately lead? One might imagine using a systemic drug such as an alpha blocker or calcium channel blocker on induction of anesthesia, but these agents are associated with lower systemic vascular resistance. It would be far better to use a topical agent with little or no systemic absorption which would only affect the ipsilateral ureter and renal pelvis. It would also be interesting to see if patients have less postoperative pain. Perhaps an alpha blocker also might be routinely used in the postoperative period to help patients cope better with a stent.

Until recently, very little was known about the upper urinary tract in terms of its response to pharmacological agents. Work like this will hopefully allow us to carry out ureterorenoscopy more safely and with less morbidity.

Francis X. Keeley, Jr., M.D.

Commentary

The main finding in this study is that stone burden is the sole determinant of cost and clinical outcomes in PCNL. All other factors which might be suspected of contributing—increased body mass index, comorbidities, multiple tracts, blood transfusions, complications—are all subordinate to stone size and configuration on multivariate analysis. This finding is not surprising given that most of these other factors are directly related to stone burden. Furthermore, the single driving factor for the relationship of stone burden to cost in this particular series was whether a second-look nephroscopy procedure was necessary. If a second look was not performed, there was no single variable significantly driving the cost of PCNL. The effect of second-look was a result of the additional operating room time and the additional length of stay required. The authors speculate, and I would agree with them, that tubeless PCNL (i.e., no second-look even possible) would greatly decrease the costs of this operation. Another approach that might reduce costs by potentially lessening the need for a second procedure is adding retrograde flexible ureteroscopy via a ureteral access sheath during initial PCNL, when it is necessary to visualize calyces that might not be accessible with the rigid or flexible nephroscopes percutaneously, and one does not wish to perform an additional (or multiple) renal puncture(s). The findings of this study lead to the realization that the costs of PCNL are not only related to stone burden, but also to how aggressive the surgeon wants to be about ensuring that all of the stone burden is removed.

Robert Marcovich, M.D.

Risks, advantages, and complications of intercostal vs. subcostal approach for percutaneous nephrolithotripsy. Lang E, Thomas R, Davis R, Colon I, Allaf M, Hanano A, Kagen A, Sethi E, Emery K, Rudman E, Myers L. Department of Radiology, SUNY Downstate Medical School, Brooklyn, NY.

Urology 2009;74:751–755.

Objectives: To establish the efficacy of nephrolithotripsy via intercostal access route vs. subcostal access route with respect to attained stone-free status, operating time, and complications.

Methods: Percutaneous nephrolithotripsies via the upper pole were performed in 142 patients (93 male, 49 female, age 24–78 years) from 1998 to 2005 at our 4 academic medical centers. Selection criteria for nephrolithotripsy via upper pole access were staghorn calculi ≥5.5 cm3, upper pole calyx calculi ≥2.5 cm, and abnormal or high lying kidney, often in combination with obesity. Of 68 staghorn calculi, 49 were accessed via intercostal and 19 via subcostal route. Of 57 upper calyx calculi 38 were accessed via intercostal and 19 via subcostal route; all calculi in the upper ureter considered easily accessible via the intercostal route.

Results: Of 103 patients with intercostal access, 91 attained a stone-free status. There were 4 major and 6 minor complications. Depending on stone location, mean operating times varied from 42 to 152 minutes. Of 39 patients in whom a subcostal access route was chosen, 29 were made stone-free. There were 3 major and 8 minor complications. The mean operating time varied from 108 to 145 minutes.

Conclusions: The significantly higher rate of achieving stone-free status, lower rate of complications, and markedly reduced operating time when using intercostal access make this the route of choice for upper pole nephrolithotripsy.

DOI: 10.1016/j.urology.2009.04.087

Commentary

This multi-institutional review of 142 percutaneous nephrolithotomies compares intercostal versus subcostal access to the upper pole calyx. Intercostal access to the upper pole yielded an 88% stone-free rate versus 74% when the upper pole was accessed via a subcostal puncture. The relatively low success rate is explained by use of postoperative day 1 CT scan to determine stone-free status. Interestingly, the authors noted a significantly lower rate of major and minor complications in the intercostal access group, a conclusion contrary to most published reports. This provides an excellent opportunity to briefly review the advantages of upper pole access and to speculate why intercostal upper pole access might be safer than subcostal upper pole access.

An upper pole approach for percutaneous renal surgery is advantageous from an anatomical standpoint because the kidney's cephalocaudal orientation is oblique to the coronal axis of the body. In other words, the upper pole of the kidney is more posterior than the lower pole. Thus, upper pole access allows an entry orientation that is more in line with the axis of the kidney, while lower pole access requires an entry orientation that is nearly perpendicular to the renal axis. The latter explains the propensity for the lower pole of the kidney to swing medially during tract dilation maneuvers, especially in thin patients, as well as for the need to torque the scope caudally to a greater degree, which is often limited by the hips and buttocks. An intercostal upper pole puncture probably augments the likelihood that the tract is in line with the renal axis, whereas a subcostal approach to the upper pole is likely almost as perpendicular as a lower pole or interpolar puncture. The intercostal approach is also more likely to orient the tract directly end-on to the tip of the posterior upper pole calyx, facilitating nephroscopy and lithotripsy compared to situations in which the tract is positioned obliquely. The former results in being able to pass the scope through the sheath and visualize the renal pelvis from the upper pole calyx with little or no maneuvering of the sheath and scope.

Lang and colleagues also noted that using “Y-tracts” for access into adjacent upper pole calyces resulted in worse outcomes versus when Y-tracts were not used. This finding is also likely related to the oblique axis of the tract in comparison to the initial end-on puncture. Overall, this paper highlights the importance of understanding the anatomic principles underlying what is clearly the most important aspect of percutaneous renal surgery—minimally traumatic, maximally useful access.

Robert Marcovich, M.D.

Commentary

These two reports provide contrasting results assessing shock wave lithotripsy of ureteral calculi. Honey et al, in a multi-center randomized controlled trial utilizing the Philips LithoTron^TM spark gap lithotripter, assessed the results of SWL at slow (60 sw/min) versus fast (120 sw/min) rate treating solitary radiopaque proximal ureteral calculi (>5mm). A number of important take-home messages are quickly evident to the reader. Most importantly, the authors build on their track record of demonstrating improved stone-free rates, with a reduction in additional treatments, when utilizing a slow rate of SWL delivery. However, this benefit occurred at the cost of a significantly longer treatment time (44.3 vs. 24.5 minutes) despite a small reduction in the total shocks delivered in the slow rate group. For high volume lithotripsy centers working within a fixed box of hospital resource, a change in policy toward treating all patients at a slow rate will result in an immediate need to reduce the number of patients treated daily. This effect is acknowledged within the Materials and Methods section, as the researchers had to limit enrollment to a single slow-rate case per daily lithotripsy slate to reduce the impact of the study on clinical practice. For low volume centers, this admission by the authors is less relevant, but internationally, where the high capital cost of lithotripters result in centralization of the resource, this is an important consideration. An ethical debate may occur at high volume centers between the duty to improve care for the individual by increasing the chances of a stone-free state (luckily a low number needed to treat of only 6) at a cost of delaying access to care for the overall stone population awaiting SWL. In time, the reduction in repeat treatments through a higher initial success rate, combined with earlier movement to ureteroscopy or percutaneous nephrolithotomy for clear SWL failures, will negate this debate.

Despite optimizing the potential for success with frequent fluoroscopy (every 200 shocks) during SWL of easily visible stones, as well as a new electrode for each case, the authors report sobering results of SWL for proximal ureteral calculi in our North American population (BMI overall of 27.4 ± 6.5); 64.9% vs. 48.8% stone-free after a single treatment at 3 months for slow and fast rate, respectively. Finally, the authors, working within a setting of centralized lithotripsy access, invested substantially in careful patient selection that explains a long accrual period, and they must be commended for impressive patient follow-up.

In contrast, the cohort study of Seitz et al presents SWL results utilizing the Lithoskop^® electromagnetic machine to treat radiopaque renal and ureteral calculi from two centers in Europe (BMI not reported). SWL of ureteral stones (stones in the proximal, mid and distal ureter with relatively small median stone diameters of 6.0 and 6.5 mm in nonstented and stented groups, respectively) was performed using maximum settings (energy level of 8 and shock wave number of 4000) with an intermediate rate of SW delivery (90/min.). Follow-up post-SWL consisted of a plain film x-ray and renal ultrasound compared to a high percentage of non-contrast CT follow-up in the Honey et al study. Seitz and colleagues report an impressive overall success rate (91.4 and 93.5 % in nonstented and stented groups respectively). However, this eventual high success rate is achieved through multiple SWL sessions (1.4 ± 0.7 in the nonstented group vs. 1.7 ± 0.7 in the stented group) and unfortunately, the authors do not simplify data presentation for the reader. Instead of reporting success rates after a single SWL session at a set time point, the authors indicate that for ureteral stones, “one session was required in 72.4% vs. 52.2% of nonstented vs. stented cases, after which 94.6% and 95.8% were stone free, respectively.” Given the authors' definition of any residual ureteral stone fragment ≤4 mm as a failure, the natural assumption is that the success of a single treatment is not substantially different between the two lithotripters in each of these highlighted studies. In addition, the authors report a positive correlation between the number of SW sessions and a more proximal ureteral stone location, further reducing the stone-free rate for a single treatment of a proximal ureteral stone in this series. Finally, the authors are able to achieve this high success rate with a low need for ancillary procedures and stent status had minimal influence on SWL success but did result in a reduction in complications necessitating hospitalization and ancillary measures.

Ryan F. Paterson, M.D.

Commentary

It has been more than a decade since the introduction of plasmakinetic quasi-bipolar (PK-TURP) and bipolar transurethral resection of the prostate, and yet there is a worrying paucity of high quality published data that convinces us of the true merits of this technology over its more affordable monopolar TURP counterpart, which has dominated for almost a century.

This meta-analysis highlights the overall poor quality of existing trial design and the alarming lack of IRB ethical approval or informed patient consent procedures according to ICH-GCP standards, before embarking on technology-based randomized controlled trials, and the lack of either adequate quality parameters in trial design, multicenter inclusion, or appropriate powering to draw meaningful conclusions. Furthermore, neither the technology nor the technique have been optimized or standardized in any way even after all this time, and most trials to date still seem to have incorporated a learning curve experience with the new technology, which of course does not apply to the reference standard.

The European trials base in this analysis consisted of less than 500 men, the American trials base was non-existent (suggesting that it is no longer possible to perform such studies in the contemporary healthcare environment in that country) and most of the other data comes from Turkey and Asia, where high quality work has been done in selected centers, but the strict adherence to regulatory issues may be subject to large regional variations, and where many new technologies seem to find new early adopters due to lower study operational costs and less bureaucratic institutional infrastructure.

A meta-analysis of RCTs is ultimately only as good as its source material, and despite an extensive literature search the authors were able to include only 16 RCTs with 1406 patients in their thorough analysis, though less than a third of these had more than 50 men in each arm. Just to put it into perspective, this is still considerably more than in most contemporary laser studies. The fact that the authors found no clinically significant differences in standard objective efficacy outcomes parameters is hardly surprising due to the short follow-up, as is the case with most of the studies with new technologies. The finding that treating 50 and 20 patients, respectively, with the more expensive bipolar-TURP resulted in one less transurethral resection (TUR) syndrome and one less clot retention, is relatively meaningless information in my view, given that saline irrigant is mandatory for the bipolar and quasi-bipolar technologies, and very few studies included a population with large vascular glands to have sufficient events of this type to show a true difference even if one were to exist, in order to justify the extra costs involved in using this technology. Moreover, there is scant mention of the true impact of saline absorption in susceptible men with cardiovascular co-morbidity.

On the plus side, Mamoulakis et al reported lower rates of clot retention, shorter irrigation and catheterization duration for bipolar and PK TURP, inferring better surface hemostasis, which is inherently possible with all bipolar surgical devices, given the physics principles involved and most importantly, provided the electrode excursion speed is optimized to allow the energy in the plasma vapor pocket around the active electrode to interact with small and medium sized tissue blood vessels. There was also no extra risk of stricture formation, which may be relevant to longer resection times or use of larger resectoscopes in larger glands. The one lingering down side of monopolar prostate electrosurgery may be the irritative symptoms post-resection, but the authors were unable to shed any light on this vexing issue and whether bipolar was better here, as the source studies did not focus on this at all. Most worrisome was the lack of any outcomes data beyond 1 year, which is a pre-requisite for any new technology platform if it is to establish a secure beachhead in the war versus monopolar TURP. The champion is still seeking truly worthy challengers given the data presented here, especially once the economics are factored in!

Anup Patel, M.D.

Commentary

It is of interest to note the discrepant attitudes that patients and urologists have to medical recurrence prevention and active stone removal. The patients' positive attitude in terms of risk factor analysis and medical advice is in line with results from questionnaires that previously were sent to American and Swedish patients.^1,2 As pointed out in the article, there are well documented effects of pharmacological treatment programs and the negative response from urologists is difficult to understand. Most certainly a lack of interest in biochemistry and knowledge of crystallization risk factors explains at least partly why they prefer a surgical solution. Although the methods for stone removal today are non-invasive or minimally invasive, they still are associated with obvious complications, discomfort and costs. All these factors are undoubtedly significantly lower than they used to be when we did open surgery, but they are not non-existent.

Even if we accept one or several repeated stone episodes, a suddenly occurring ureteral obstruction with renal colic can be extremely difficult to manage by the patient and in many cases dangerous. It goes without saying that an ideal medical agent for prevention of stone recurrences does not exist. A patient's compliance moreover might be poor, but if not even the treating physician/urologist believes in recurrence prevention, how can we expect our patients to comply with the treatment? With a nihilistic attitude there will be no driving force and no research interest for development of new and better medical treatment regimens.

Also, if only dietary advice is to be given, such a step needs to be based on an appropriate analysis of risk factors in urine. In case of insufficient clinical response, repeated analysis should be used to correct the medical advice/treatment.

I assume that the urologists who think patients prefer one or two additional stone episodes with or without active stone removal before medical treatment all have remained stone-free so far. For the future of urology, for our patients' well-being and for the health economy, it seems worthwhile to spend a little more interest in metabolic risk factors and recurrence prevention.

References

1. Grampsas SA, Moore M, Chandhoke PS. 10-year experience with extracorporeal shockwave lithotripsy in the state of Colorado. J Endourol 2000;14:711–4.

2. Tiselius HG. Patients' attitudes on how to deal with the risk of future stone recurrences. Urol Res 2006;34:255–260.

Hans-Göran Tiselius, M.D., Ph.D.

Association of body mass index and urine pH in patients with urolithiasis. Li WM, Chou YH, Li CC, Liu CC, Huang SP, Wu WJ, Chen CW, Su CY, Lee MH, Wei YC, Huang CH. Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.

Urol Res 2009;37:193–196.

Increase in body size increases the risk of renal stone formation. The mechanism explaining this relationship remains unclear. Urine pH is one of the important factors for urinary stone formation. The purpose of this study was to determine whether there is an association between urine pH and body mass index (BMI) in patients with urolithiasis. Medical charts review that included 342 urinary stone formers (248 men and 94 women). Data obtained included patient sex, age, BMI, urine pH at diagnosis, and stone composition. The patients were classified as normal weight (18.5 ≤ BMI < 24), overweight (24 ≤ BMI < 27), or obese (BMI ≥ 27). The mean urine pH of the normal body weight, overweight, and obese groups was 6.25, 6.14, and 6.00, respectively (P < 0.05). Urine pH is inversely related to BMI among patients with urolithiasis. Among patients with urolithiasis, higher BMI will have lower urine pH. This may explain why obesity is associated with an increased risk of nephrolithiasis. Weight loss should be explored as a potential treatment to prevent kidney stone formation. The prevention of urinary stone disease gives clinicians an additional reason to encourage weight reduction through diet.

DOI: 10.1007/s00240-009-0194-4

Commentary

The important role of the metabolic syndrome for urinary tract stone formation during recent years has been placed in focus. Reduction of a high body weight seems to be a fundamental tool in prevention of recurrent stone formation. The increased risk of calcium as well as uric acid stones in patients with a high BMI is well recognized, but the determinants are incompletely understood. Although a low urine pH strongly increases the risk of uric acid precipitation, the effects of pH on calcium oxalate (CaOx) stone formation has remained less obvious.

That urine pH, in the calcium stone forming patients in the current study, decreased with increasing BMI is highly interesting and in line with previously published results.¹ Moreover, the authors were able to show that patients with calcium phosphate (CaP) stones had the highest mean pH and that those with pure CaOx stones had the lowest pH. For those patients in whom mixed CaOx/CaP stones were recorded, the mean pH was between the previous two levels.

This observation gives further support to the hypothesis that a low urine pH, probably by dissolution of CaP crystals or Randall's plaques, initiates CaOx precipitation.^2–5 With sufficiently low pH levels, no CaP will remain, whereas at high pH levels, CaP will be the dominating crystal phase. At extremely low pH levels the precipitate will be uric acid.

Another factor that is touched upon by the authors is the relationship between high concentrations of urate and CaOx crystal formation. Whatever the mechanism for such a relation might be, it seems likely that the risk is most pronounced in overweight patients. This is a possible explanation for divergent results in different populations.^6–7

The bottom line of the findings in this report is that accurate measurements of urine pH should be a natural part of every risk evaluation in patients with recurrent stone formation. There is certainly a need for standardizing such measurements and some kind of pH profile seems most informative in this regard.

References

1. Maalouf NM, Cameron MA, Moe OW, et al. Low urine pH: a novel feature of the metabolic syndrome. Clin J Am Soc Nephrol 2007;2:883–888.

2. Kok DJ. Free and fixed particle mechanism, a review. Scan Microsc 1996;10:471–486.

3. Tiselius HG, Lindbäck B, Fornander AM, Nilsson MA. Studies on the role of calcium phosphate in the process of calcium oxalate crystal formation. Urol Res 2009;37:181–192.

4. Öhman S, Larsson L. Evidence for Randall's plaques to be the origin of primary renal stones. Med Hypotheses 1992;39:360–363.

5. Evan AP, Coe FL, Lingeman JE, Shao Y, Sommer AJ, Bledsoe SB, Andersson JC, Worcester EM. Mechanism of formation of human calcium oxalate renal stones on Randall's plaque. Anat Rec (Hoboken) 2007;290:1315–1323.

6. Grover PK, Ryall RL. Allopurinol for stones; right drug–wrong reasons. Am J Med 2007;120:380.

7. Tracy CR, Pearle MS. Update on the medical management of stone disease. Curr Opinion Urol 2009;19:200–204.

Hans-Göran Tiselius, M.D., Ph.D.

Commentary

Flexible ureteroscopy is a standard procedure in modern stone therapy. However, the procedure is technically demanding and related to relevant maintenance cost due to instrument fragility. Most often, damage occurs to the working channel or distal tip during surgery, or to the optic unit during sterlization.

The authors compare a disposable flexible ureterorenoscope with 6 commercially available scopes and evaluate scope performance, as measured by deflection, loss of flow and field of view with different tools inserted into the working channel. Despite conclusive baseline characteristics, the disposable ureterorenoscope has the highest loss of deflection and irrigation volume compared to standard scopes. On the other hand, optical performance was comparable, and maintenance and repair costs were not higher. The authors conclude that the disposable flexible ureterorenoscope offers acceptable performance as compared to standard devices, but further evaluation will be necessary to define usefulness.

The principle of having a disposable, high performance flexible ureterorenoscope that overcomes the possible limitations of conventional scopes is intriguing. One could expect the optimal scope performance in every new patient. One limitation of the presented study is clearly the choice of selected scopes that were compared to the disposable model. Other than the Dur-8 Elite and the FlexX, all tested scopes are basically old models, which have been substituted by newer generations of flexible ureterorenoscopes. In particular, the newer ureterorenocopes (K. Storz, FlexX, R. Wolf, Viper and the Olympus, URF-P5) offer significantly increased scope performance, with deflection angles of above 250°. As reported in various publications, loss of deflection with the use of tipless nitinol baskets is not much of an issue in this newer generation However, the idea offers fascinating potential for the future and deserves further investigation and improvement of the scope performance.

Thorsten Bach, M.D., and Maurice S. Michel, M.D., Ph.D.

Histotripsy of the prostate: dose effects in a chronic canine model. Hall TL, Hempel CR, Wojno K, Xu Z, Cain CA. Roberts WW. Department of Urology, University of Michigan, Ann Arbor, MI.

Urology 2009;74:932–937.

Objectives: To develop the technique of histotripsy ultrasound therapy as a noninvasive treatment for benign prostatic hyperplasia and to examine the histotripsy dose-tissue response effect over time to provide an insight for treatment optimization. We have previously demonstrated the feasibility of prostate histotripsy fractionation in a canine model.

Methods: Various doses of histotripsy were applied transabdominally to the prostates of 20 canine subjects. Treated prostates were then harvested at interval time points from 0 to 28 days and assessed for histologic treatment response.

Results: The lowest dose applied was found to produce only scattered cellular disruption and necrosis, whereas higher doses produced more significant regions of tissue effect that resulted in sufficient fractionation of tissue so the material could be voided with urination. Urethral tissue was more resistant to the lower histotripsy doses than was parenchymal tissue. Treatment of the urethra at the lowest doses appeared to heal, with minimal long-term sequelae.

Conclusions: Histotripsy was effective at fractionating parenchymal and urethral tissue in the prostate, in the presence of a sufficient dose. Further development of this technique could lead to a noninvasive method for debulking the prostate to relieve symptoms associated with benign prostatic hyperplasia.

DOI: 10.1016/j.urology.2009.03.049

Commentary

Benign prostatic obstruction remains one of the most frequent diagnoses in daily urological practice and surgical therapy is required in a high percentage of patients. TURP and open simple prostatectomy were considered gold-standard for the last decades, but incur significant morbidity. This may lead to less tolerability in older patients, especially if relevant co-morbidities exist. Therefore, minimally invasive therapy for benign prostatic obstruction is still a major issue.

Hall and colleagues report their experience of an ultrasound-based, non-invasive treatment modality for benign prostatic obstruction and examine the dose-tissue effect in this so-called histotripsy. Histotripsy was applied to 20 canine prostates in a transabdominal model, the prostates were harvested, and histological changes were evaluated. The authors showed that with sufficient treatment doses immediate tissue fractionation and drainage of the treated prostatic tissue can be achieved. Urethral tissue seems to be more resistant to histotripsy than prostatic tissue.

The in vitro feasibility of histotripsy has been shown by this group previously, so dose finding studies seem to be the next essential step. As the authors have demonstrated, histotripsy applied at sufficient dose levels seems to have the ability to create a relevant prostatic cavity in the canine model. Considering the non-invasive character of this treatment modality, there may be a high potential for the treatment of human BPO in the future. However, despite the promising data from the canine model, there are still various questions to evaluate before histotripsy may be an option in a human setting. Which energy level will be needed to achieve a cavity in the human prostate? Will the transabdominal setting of energy delivery be sufficient in human males? How can it be guaranteed that the sphincter region is not also treated during histotripsy? Although there seems to be a long way to go, the technique is definitely very interesting and promising and deserves close observation in the future.

Thorsten Bach, M.D., and Maurice S. Michel, M.D., Ph.D.

Commentary

The question is always asked but seldom answered: “how do we best train surgeons to perform cutting edge techniques, especially once they are beyond their residencies or fellowships?” Recently, this question has been quite relevant in robotic urological procedures. If a surgeon is adept or even expert at open radical prostatectomy, what price is paid by those patients on the robotic learning curve of the surgeon? If deemed necessary to embark on the learning curve, how can the price be minimized?

The researchers at the University of Minnesota studied a new type of teaching method for postgraduate urologists. Surgeons desirous of gaining competency in robotic prostatectomy first completed the standard robotic training course. They were then required to assist tableside for expert surgeons at the university center for 4 to 5 cases. The trainees were then encouraged to take on increasing responsibility of the console surgeon tasks. In all, 9 trainees participated in the program. At most recent follow-up, all 9 surgeons were independently performing cases with a total of 447 cases completed. By survey, the participants felt that the program was ‘effective’ or ‘very effective.’ This innovative model for training is certainly rather time-consuming for the proctors. However, this dedication and foresight on the part of the proctors is likely incredibly appreciated by the trainees, as evidenced by the high take rate and high satisfaction ratings. The patients in these learning curves are also likely very grateful.

David I. Lee, M.D.

Training, credentialing, proctoring and medicolegal risks of robotic urological surgery: recommendations of the society of urologic robotic surgeons. Zorn KC, Gautam G, Shalhav AL, Clayman RV, Ahlering TE, Albala DM, Lee DI, Sundaram CP, Matin SF, Castle EP, Winfield HN, Gettman MT, Lee BR, Thomas R, Patel VR, Leveillee RJ, Wong C, Badlani GH, Rha KH, Eggener SE, Wiklund P, Mottrie A, Atug F, Kural AR, Joseph JV; Members of the Society of Urologic Robotic Surgeons. Section of Urology, Department of Surgery, University of Chicago Medical Center, Chicago, IL.

J Urol 2009;182:1126–1132.

Purpose: With the exponential growth of robotic urological surgery, particularly with robot assisted radical prostatectomy, guidelines for safe initiation of this technology are a necessity. Currently no standardized credentialing system exists to our knowledge to evaluate surgeon competency and safety with robotic urological surgery performance. Although proctoring is a modality by which such competency can be evaluated, other training tools and guidelines are needed to ensure that the requisite knowledge and technical skills to perform this procedure have been acquired. We evaluated the current status of proctoring and credentialing in other surgical specialties to discuss and recommend its application and implementation specifically for robot assisted radical prostatectomy.

Materials and Methods: We reviewed the literature on safety and medicolegal implications of proctoring and the safe introduction of surgical procedures to develop recommendations for robot assisted radical prostatectomy proctoring and credentialing.

Results: Proctoring is an essential mechanism for robot assisted radical prostatectomy institutional credentialing and should be a prerequisite for granting unrestricted privileges on the robot. This should be differentiated from preceptoring, wherein the expert is directly involved in hands-on training. Advanced technology has opened new avenues for long-distance observation through teleproctoring. Although the medicolegal implications of an active surgical intervention by a proctor are not clearly defined, the role as an observer should grant immunity from malpractice liability.

Conclusions: The implementation of guidelines and proctoring recommendations is necessary to protect surgeons, proctors, institutions and, above all, the patients who are associated with the institutional introduction of a robot assisted radical prostatectomy program. With no current guidelines we anticipate this article will serve as a catalyst of interorganizational discussion to initiate regulatory oversight of surgeon certification and proctorship.

DOI: 10.1016/j.juro.2009.05.042

Commentary

In the same vein, a recent publication worth review discussed the current state of training, credentialing, and proctoring for robotic urological surgery. This article addresses the current issues and the bottom line that seems to prevail is that there is limited specialized support for surgeons who are interested in learning robotic surgery. The role of proctors cannot be appreciated enough in aiding other surgeons who are early in their experience. However, tools such as simulators and remote presence proctoring are worthy ideas but not yet ready for prime time. Unfortunately, as these issues continue to be fleshed out, we all suffer a toll in regard to the learning curve.

What then is the answer? As we work together to create and refine treatments, this type of energy must also be placed into the work of developing training and simulation. Computing power will soon be fast enough to effectively model tissue deformation. CT and MRI images will provide the basic blueprint of our bodies so that a specific surgery will be able to be simulated. However, who bears the brunt of the cost in both time and money to develop these tools that are, in reality, both priceless and cost prohibitive? As surgeons who perform these procedures, we need to be at the forefront, pushing and advocating for these issues in the current times of health reform. Otherwise, we may all pay a truly steep price.

David I. Lee, M.D.

Commentary

As prostate cancer is multifocal, there are concerns about untreated residual disease if applying subtotal prostate ablation with cryoablation or high-intensity focused ultrasound. However, investigators have reported that the dominant tumor within the prostate could determine the cancer-specific outcomes.^1,2 The highlighted article from the MD Anderson Cancer Center group assessed the simulated outcomes for the totality of prostate cancer eradication in radical prostatectomy specimens from men with a unilaterally positive prostate biopsy, treated by subtotal prostate ablation. When the authors examined 180 such radical prostatectomy specimens to characterize each tumor focus, contralateral cancer was present in 149 (83%).

This paper is important because computerized analysis was performed to find out whether all the recognized cancer foci in the 180 radical prostatectomy specimens were located within or outside the zone treated with subtotal prostate ablation. However, it should be noted that the simulated outcome is subject to the important hypothesis that targeted energies can achieve total cell death within the targeted treatment zone and also that such energy has no additional effects beyond that zone. Even so, it is impressive that the hockey-stick template encompassed all dominant tumors, and that the hemiprostate or the hockey-stick template would have successfully treated all clinically significant prostate tumors in 64% and 81% of patients, respectively.

References

1. Villers A, McNeal JE, Freiha FS, Stamey TA. Multiple cancers in the prostate. Morphologic features of clinically recognized versus incidental tumors. Cancer 1992;70:2313–2318.

2. Noguchi M, Stamey TA, McNeal JE, Nolley R. Prognostic factors for mutifocal prostate cancer in radical prostatectomy specimens: lack of significance of secondary cancer. J Urol 2003;170:459–463.

Osamu Ukimura, M.D., Ph.D.

Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI. Rouvière O, Girouin N, Glas L, Ben Cheikh A, Gelet A, Mège-Lechevallier F, Rabilloud M, Chapelon JY, Lyonnet D, Hospices Civils de Lyon. Department of Urinary and Vascular Radiology, Hôpital, Edouard Herriot, Lyon, France.

Eur Radiol 2009; Aug 19. [Epub ahead of print]

The objective was to evaluate T2-weighted (T2w) and dynamic contrast-enhanced (DCE) MRI in detecting local cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. Fifty-nine patients with biochemical recurrence after prostate HIFU ablation underwent T2-weighted and DCE MRI before transrectal biopsy. For each patient, biopsies were performed by two operators: operator 1 (blinded to MR results) performed random and colour Doppler-guided biopsies (“routine biopsies”); operator 2 obtained up to three cores per suspicious lesion on MRI (“targeted biopsies”). Seventy-seven suspicious lesions were detected on DCE images (n = 52), T2w images (n = 2) or both (n = 23). Forty patients and 41 MR lesions were positive at biopsy. Of the 36 remaining MR lesions, 20 contained viable benign glands. Targeted biopsy detected more cancers than routine biopsy (36 versus 27 patients, p = 0.0523). The mean percentages of positive cores per patient and of tumour invasion of the cores were significantly higher for targeted biopsies (p < 0.0001). The odds ratios of the probability of finding viable cancer and viable prostate tissue (benign or malignant) at targeted versus routine biopsy were respectively 3.35 (95% CI 3.05–3.64) and 1.38 (95% CI 1.13–1.63). MRI combining T2-weighted and DCE images is a promising method for guiding post-HIFU biopsy towards areas containing recurrent cancer and viable prostate tissue.

Commentary

This study describes improved biopsy-proven detection of local cancer recurrences after prostate HIFU ablation using targeted biopsies directed by MRI, especially by dynamic contrast-enhanced (DCE) MRI. When using only routine random biopsy without MRI targeted biopsy, the recurrent cancer would be missed in 13 of 59 patients (22%). Although the long-term oncologic efficacy of an ablative procedure has yet to mature, it is clear that prostatic ablative procedures, including HIFU and cryosurgery, have the clear advantages of their minimal invasiveness and also their repeatable nature in cases of incomplete treatment or in cases with local recurrence. The recent emerging technology of DCE MRI has been reported as a promising imaging modality in visualizing cancer foci in patients with biochemical recurrence after external beam radiation therapy^1,2 and/or HIFU.³ The combination of a new appropriate use of follow-up PSA value⁴ and the best use of imaging modality is an essential issue in order to establish standard care for such an ablative procedure. This study provides an important conjunction of HIFU prostate ablation with its post-therapeutic follow-up imaging modality to determine the indication of repeated HIFU and the exact targeting location to be re-treated. In this study, DCE MRI-visualized areas are proved to contain more residual viable prostate tissue, confirmed by targeted biopsy.

References

1. Rouvière O, Valette O, Grivolat S, Colin-Pangaud C, Bouvier R, Chapelon JY, Gelet A, Lyonnet D. Recurrent prostate cancer after external beam radiotherapy: value of contrast-enhanced dynamic MRI in localizing intraprostatic tumor–correlation with biopsy findings. Urology 2004;63:922–927.

2. Haider MA, Chung P, Sweet J, Toi A, Jhaveri K, Ménard C, Warde P, Trachtenberg J, Lockwood G, Milosevic M. Dynamic contrast-enhanced magnetic resonance imaging for localization of recurrent prostate cancer after external beam radiotherapy. Int J Radiat Oncol Biol Phys 2008;70:425–430.

3. Kim CK, Park BK, Lee HM, Kim SS, Kim E. MRI techniques for prediction of local tumor progression after high-intensity focused ultrasonic ablation of prostate cancer. AJR Am J Roentgenol 2008;190:1180–1186.

4. Blana A, Brown SC, Chaussy C, Conti GN, eastham JA, Ganzer R, Murat FJ, Pasticier G, Rebillard X, Rewcastle JC, Robertson CN, Thuroff S, Ward JF. High-intensity focused ultrasound for prostate cancer: comparative definitions of biochemical failure. BJU Int 2009;104:1058–1062.

Osamu Ukimura, M.D., Ph.D.