Commentary

The evolution of minimally invasive renal surgery has been remarkable over the past 20 years, from the initial pioneering work of Clayman et al in 1991 to the current era of robotic surgical intervention.¹ The use of single-port access surgery has gained attention over the past five years as a cosmetically superior operation to the standard laparoscopic approach and with comparable outcome and results. Although this may be true for simple ablative renal procedures the verdict is still not in for more advanced procedures where surgical time (warm ischemia) is of the essence and reconstruction may be required.

Live donor nephrectomy requires the donor surgeon to demonstrate the highest standard of surgical skills, harvest a quality kidney and achieve excellent transplant allograft outcomes. Any live donor nephrectomy surgical procedure will not be accepted if recipient graft function is compromised. Furthermore, complications to the donor or recipient must be few and certainly comparable to the historical gold standard—the open surgical approach.

Although there was considerable controversy with the advent of laparoscopic live donor nephrectomy in 1995², this procedure should now be considered the gold standard, as currently over 85% of transplant centers in the U.S. offer laparoscopic donor nephrectomy. The postoperative advantages of the laparoscopic approach has increased living kidney donation by 53%.

Surgeons now employing laparoendoscopic single site surgery (LESS) should be commended and encouraged to further develop this technique. However, I continue to have significant skepticism about its application to live donor nephrectomy. To date, comparative studies have been predominantly retrospective and relatively small, other than that of Afaneh et al, which compared 50 cases of LESS versus 50 cases of standard laparoscopy.³ Other than that study, the warm ischemia time (WIT) has been longer with the LESS approach. Further, even with LESS surgery, a small incision (6–7 cm) is still required to extract the kidney specimen for transplantation.

When one lists the potential benefits of LESS donor nephrectomy it has been demonstrated that cosmesis is improved, and postoperative pain and recovery “may be” improved. The disadvantages of LESS surgery which need to be overcome are poor triangulation with instrument clashing, compromised visualization, longer OR time and a significant learning curve. Can this all translate into suboptimal patient outcomes?

I give great credit and encouragement to the pioneers of LESS who are forging ahead with this technique and honestly comparing it to the standard laparoscopic donor nephrectomy. To quote some of these authors themselves:

“LESS surgery remains an investigational urological procedure. At this point the benefits of LESS procedure appear limited to superior cosmesis and a small improvement in convalescence. It is likely that any demonstrated benefit from LESS procedures will be small compared to proven benefits of conventional laparoscopy over open surgery.”⁴

“LESS donor nephrectomy is a technically feasible procedure; however, the issue of prolonged warm ischemia needs to be resolved. The status of the procedure needs to be defined with the currently ongoing randomized study at our center. LESS surgery has definitely a steep learning curve …”⁵

“In the donors' opinion, in our study, there were no differences in the quality of life, body image, and cosmesis following either standard or LESS donor nephrectomy.”⁶

I believe that LESS surgery should continue to be pursued primarily as an important intermediary stepping stone to robotic-assisted LESS surgery. In my opinion, the robot will allow us to overcome many of the technical difficulties that LESS users currently encounter. Cost is an important issue and perhaps material for another Survey Section editorial in future months.

References

1. Clayman, RV, Kavoussi LR, Soper NJ et al. Laparoscopic nephrectomy: initial case report. J Urol 1991;146:278–82.

2. Ratner LE, Ciseck LJ, Moore RG et al. Laparoscopic live donor nephrectomy. Transplantation 1995;60;1047–9.

3. Afaneh C, Aull MJ, Gimenez E et al. Comparison of laparoendoscopic single-site donor nephrectomy and conventional laparoscopic donor nephrectomy: donor and recipient outcomes. Urology 2011;78:1332–7.

4. Wang GJ, Afaneh C, Aull M, et al. Laparoendoscopic single-site live donor nephrectomy: single institution report of initial 100 cases. J Urol 2011;186:2333–7.

5. Ganpule AP, Sharma R, Kurien A et al. Laparoendoscopic single-site surgery in urology: a single centre experience. J Minim Access Surg 2012;8:79–84.

6. Kurien A, Rajapurkar S, Sinha L et al. First prize: Standard laparoscopic donor nephrectomy versus laparoendoscopic single-site donor nephrectomy: a randomized comparative study. J Endourol 2011;25:365–70.

Howard N. Winfield, MD

Commentary

What are the limitations of ureteroscopy for stones? Is there an upper limit to the amount of stone we can treat ureteroscopically? Typically, we think of the need for removing volume of stone percutaneously to successfully render patients with large stone burdens stone-free. However, the holmium laser does effectively remove a volume of stone during treatment through a photo-thermal “ablation.” The authors of this manuscript report their experience ureteroscopically treating patients with stones over 2 cm in maximum diameter. These stones were located in either the proximal ureter or intrarenal collecting system. They treated 145 patients over an 11-year period. They excluded patients with refractory urinary tract infections, suspected struvite stones, and pyonephrosis found at the first ureteroscopy. If the patients required subsequent secondary ureteroscopic treatment in a short period of time, they were kept in the hospital and underwent irrigation of their intrarenal collecting system using a ureteral catheter and ureteral stent.

Overall, 55% of patients required a second-look ureteroscopy, and two required a third ureteroscopy, for an average of 1.6 procedures per stone burden. Overall stone clearance (stone-free or a single fragment of less than 4 mm diameter) was 87%. The highest stone clearance rate was for proximal ureteral stones (97%) and renal pelvic stones (94%). However, even the stone clearance rate for partial staghorn calculi (81%) was quite good. Although percutaneous treatment should be considered the standard of care for these large stones, the success rates reported here rival that of percutaneous treatment, and the complication rate (minor complications in 3.5%) is significantly lower. The authors also performed inpatient intrarenal irrigation via ureteral catheters between the first and second treatments in some patients. Some had their second ureteroscopy weeks later. In my practice, when treating a large stone burden ureteroscopically, I will re-image the patient 4–6 weeks later, and perform an additional ureteroscopy if necessary. However, if there is significant benefit to keeping them in the hospital and performing intrarenal irrigation, I would certainly do this routinely. The authors suggest that stone clearance is improved in patients who undergo irrigation. Is irrigation after ureteroscopy worthy of a clinical trial? The authors are to be congratulated for pushing the boundaries of ureteroscopy for stones. Although we may still consider PCNL the standard of care for large stones of the upper urinary tract, these results should encourage us to offer ureteroscopic treatment to more than just those patients in whom medical comorbidities make PCNL too dangerous.

Michael Conlin, MD

Ureteroscopic management of chronic unilateral hematuria: a single-center experience over 22 years. Araki M, Uehara S, Sasaki K, Monden K, Tsugawa M, Watanabe T, Monga M, Nasu Y, Kumon H, Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.

PLoS One 2012;7:e36729.

Objective: To analyze the short and long term safety and efficacy of ureteroscopic evaluation and management of chronic unilateral hematuria.

Methods: We retrospectively reviewed patients with chronic unilateral hematuria from 1987 to 2008. The distal to middle ureter was evaluated with a semi-rigid ureteroscope without a guidewire. Subsequently, the flexible ureteroscope was advanced into the upper ureter to the renal pelvis using a low-pressure automated irrigant system (Uromat™). Lesions identified ureteroscopically were treated with diathermy fulguration.

Results: One hundred and four (56 male, 48 female) patients were identified, with a median age of 37 (14–80) years and median follow-up of 139 (34–277) months. The median preoperative duration of gross hematuria was 5 (1–144) months. Endoscopic findings included 61 (56%) minute venous rupture (MVR; a venous bleeding without clear abnormalities), 21 (20%) hemangioma (vascular tumor-like structure), 3 (3%) varix (tortuous vein), 1 (1%) calculus and 18 (17%) no lesions. The incidence of “no lesions” was less in the recent 12 years (9%) than the first 10 years (27%), while the incidence of MVR increased from 40 to 66% (p < 0.05). All patients were treated endoscopically. Immediate success rate was 96% (100% in the recent 12 years). Long-term recurrent gross hematuria rate was 7%. Six resolved spontaneously and only 1 required ureteroscopy, revealing a different bleeding site.

Conclusion: Ureteroscopy and diathermy fulguration is highly useful for evaluation and treatment of chronic unilateral hematuria. Sophisticated technique and improved instrumentation contributes to a better outcome.

DOI: 10.1371/journal.pone.0036729

Commentary

The treatment of benign essential hematuria has been completely revolutionized by the introduction of ureteroscopy. In the past, these patients were treated with partial or even complete nephrectomy. However, since the advent of flexible ureteroscopy, these patients can be treated in a minimally invasive fashion. This is a nice series of 104 patients treated ureteroscopically for chronic (or benign essential) hematuria, over a 22-year period. All had true “essential” hematuria, a diagnosis by exclusion. There were more patients whose hematuria was from the left side rather than the right (67 versus 37). The authors used a “no-touch” technique, minimizing the use of a guidewire and limiting upper urinary tract trauma that might produce confounding lesions. Any lesions identified were fulgurated with a Bugbee electrode. The most common findings were minute venous rupture in 56%, and hemangioma in 20%. Overall, their immediate success rate was 96%, and hematuria recurred in only 7% of patients.

I liked that this series took place over a 22-year period. The authors used that to their advantage, and reported an improvement over time in their ability to perform the diagnostic ureteroscopy. They compared the first 10 years to the most recent 12 years, and showed improved effectiveness, less recurrence, and fewer complications. They also demonstrated more frequent identification of the cause of hematuria over the course of their series. “No lesions” were seen in only 9% of patients treated in the last 12 years versus 29% in the first 10 years. Practical tips to improve diagnostic yield are offered by the authors, including low pressure irrigation, and aspiration (negative pressure) if no lesion is seen, as venous ruptures can be easily “sealed” when irrigating. These differences in success and complications between the early and later portions of their series documents the improvements in ureteroscopic instrumentation and techniques all our patients have benefitted from over the years. This series adds to the growing literature supporting the effectiveness of ureteroscopic evaluation and treatment of patients with benign essential hematuria.

Michael Conlin, MD

Commentary

This is a well-written paper which focuses our whether pelvi-calyceal configuration or anatomy based on Sampaio classification would affect PCNL outcome. Accounting for stone burden, the authors were able to illustrate retrospectively that stone-free rates are not affected by the pelvi-calyceal anatomy. The interesting finding is that only the number of renal perrcutaneous accesses required during PCNL is dependent on the pelvi-calyceal anatomy. The Sampaio B1 pelvi-calyceal system would need higher numbers of renal accesses when compared to the other configurations. This knowledge is useful as it may guide our preoperative patient counseling with regard to the possibility of additional renal accesses in select cases.

Michael Y.C. Wong, MBBS

Percutaneous core biopsy of small renal mass lesions: a diagnostic tool to better stratify patients for surgical intervention. Menogue SR, O'Brien BA, Brown AL, Cohen RJ, University of Notre Dame, Fremantle Tissugen Pty Ltd School of Pathology and Laboratory Medicine, University of Western Australia, Perth Uropath Pty Ltd, West Leederville, WA, Australia.

BJU Int 2012 Jul. 13 [Epub ahead of print]

Study Type - Prognosis (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Biopsy of incidentally detected small renal masses is a safe and accurate method of determining benign from malignant lesions. Renal biopsy identifies over one quarter of cases as benign; however, one in five biopsy procedures results in insufficient material for a diagnosis. The study contributes an additional 268 renal biopsy cases to the literature and further assesses the accuracy of biopsy and its ability to reduce the number of patients undergoing radical surgery for benign lesions. The results of lesions managed conservatively with follow-up are also presented. Furthermore, the study identifies an improved diagnostic trend for needle core biopsies over the period.

Objectives: To further validate the safety and diagnostic accuracy of percutaneous core biopsy in small renal masses ([SRMs] ≤4 cm) in response to the rising prevalence of renal ‘incidentalomas.’ To determine the value of percutaneous core biopsy in its ability to influence the choice of intervention or surveillance for the management of SRMs.

Patients and Methods: We collected data on the incidence of benign, malignant and non-diagnostic samples from 268 SRM (clinical T1a) biopsies performed at our institution between 1998 and 2009. The diagnostic accuracy of biopsy in small renal lesions was examined in cases proceeding to nephrectomy. Follow-up on the remaining non-surgical cases was performed.

Results: SRMs (≤4 cm, clinical T1a) constituted 59% of all renal lesions diagnosed; 80% of these biopsies were diagnostic and 20% were non-diagnostic. Of the diagnostic samples, 74% were malignant and 26% were benign. Thirty-three percent (17 of the initial 52) non-diagnostic samples underwent re-biopsy, with 94% yielding a histological diagnosis on repeat sampling. Fifty-eight percent of our diagnostic masses underwent nephrectomy, returning a renal biopsy accuracy rate of 100% for identifying lesions as benign or malignant. Of the 98 observed masses, 49% were benign, 28% malignant and 23% were non-diagnostic. In 63% of these cases, size remained stable in the follow-up period.

Conclusions: Percutaneous core biopsy continues to provide an accurate and safe tool for preoperative tissue diagnosis of SRMs and should be offered to patients before considering surgical intervention. With regard to both benign and malignant T1a renal lesions, in select patient groups, those electing to undergo observation may expect favourable short- to medium-term outcomes.

© 2012 The Authors. BJU International © 2012 BJU International.

DOI: 10.1111/j.1464-410X.2012.11384.x.

Commentary

This is an excellent paper which raises the age-old question of how to approach a solid small renal mass of <4 cm. The authors adopted an approach to perform percutaneous renal biopsy based on their clinical experience of 268 cases. They argue that the downside of chronic renal insufficiency due to radical intervention^1–3 and a reduction in quality of life due to nephron-sparing intervention⁴ causes them to adopt a less aggressive strategy of performing a percutaneous renal biopsy up-front. They further argue that the ability to identify histological evidence of more aggressive disease (high Fuhrman grade or infiltrative growth pattern) allows more tailored decision-making in the management of their patients.^5,6

The fact remains that there is an unacceptable percentage of non-diagnosis on percutaneous renal biopsy in 20% of their cases, resulting in a diagnostic dilemma. The authors argue that with experience, this rate drops to an acceptable 14% later in their series. Coupled with a low complication rate of <1% and an inability to demonstrate tumor seeding should result in a wider use of percutaneous renal biopsy to assess solid renal tumors <4 cm in size. Further studies are required to validate this position.

References

1. Huang WC, Levey AS, Serio AM et al. Chronic kidney disease after nephrectomy in patients with renal cortical tumours: a retrospective cohort study. Lancet Oncol 2006;7:735–40

2. Novick AC, Campbell SC, Leveillee RJ et al. Guideline for management of the clinical stage 1 renal mass. Linthicum, MD: American Urological Association, 2009.

3. Go AS, Chertow GM, Fan D et al. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. N Engl J Med 2004;351:1296–305.

4. Van Poppel H. Efficacy and safety of nephron-sparing surgery. Int J Urol 2010;17:314–26.

5. Neuzillet Y, Lechevallier E, Andre M et al. Accuracy and clinical role of fine needle percutaneous biopsy with computerize tomography guidance of small (less than 4cm) renal masses. J Urol 2004;171:1802–5.

6. Volpe A, Mattar K, Finelli A et al. Contemporary results of percutaneous biopsy of 100 small renal masses: a single center experience. J Urol 2008; 80: 2333–7.

Michael Y.C. Wong, MBBS

Extracorporeal Shock Wave

Treatment of ureteral and renal stones: a systematic review and meta-analysis of randomized, controlled trials. Matlaga BR, Jansen JP, Meckley LM, Byrne TW, Lingeman JE, The James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, MD.

J Urol 2012;188:130-7.

Purpose: We compared the clinical outcomes of patients with ureteral or renal stones treated with ureteroscopy, shock wave lithotripsy using HM3 (Dornier^®) and nonHM3 lithotripters, and percutaneous nephrolithotomy.

Materials and Methods: A systematic literature search identified 6, 4 and 3 randomized, controlled trials of treatment of distal and proximal ureteral stones, and renal stones, respectively, published between 1995 and 2010. Overall stone-free, re-treatment and complication rates were calculated by meta-analytical techniques.

Results: Based on the randomized, controlled trials evaluated the treatment of distal ureteral stones with semirigid ureteroscopy showed a 55% greater probability (pooled RR 1.55, 95% CI 1.13–2.56) of stone-free status at the initial assessment than treatment with shock wave lithotripsy. Patients treated with semirigid ureteroscopy were also less likely to require re-treatment than those treated with shock wave lithotripsy (nonHM3) (RR 0.14, 95% CI 0.08–0.23). The risk of complications was no different between the 2 modalities. Only 2 of the 4 randomized, controlled trials identified for proximal ureteral stones evaluated flexible ureteroscopy and each focused specifically on the treatment of stones 1.5 cm or greater, limiting their clinical relevance. The degree of heterogeneity among the studies evaluating renal stones was so great that it precluded any meaningful comparison.

Conclusions: Semirigid ureteroscopy is more efficacious than shock wave lithotripsy for distal ureteral stones. To our knowledge there are no relevant randomized, controlled trials of flexible ureteroscopy treatment of proximal ureteral calculi of a size commonly noted in the clinical setting. Collectively the comparative effectiveness of ureteroscopy and shock wave lithotripsy for proximal ureteral and renal calculi is poorly characterized with no meaningful published studies.

Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

DOI: 10.1016/j.juro.2012.02.2569

Transurethral Procedures

Holmium laser enucleation versus photoselective vaporization for prostatic adenoma greater than 60 ml: preliminary results of a prospective, randomized clinical trial. Elmansy H, Baazeem A, Kotb A, Badawy H, Riad E, Emran A, Elhilali M, Department of Urology, McGill University, Montreal, Quebec, Canada.

J Urol 2012;188:216–21.

Purpose: To our knowledge we report the first single center, prospective, randomized study comparing holmium laser enucleation and high performance GreenLight™ prostate photoselective vaporization as surgical treatment of prostatic adenomas greater than 60 ml.

Materials and Methods: A total of 80 patients with a large prostatic adenoma were randomly assigned to surgical treatment with holmium laser enucleation or photoselective vaporization. International Prostate Symptom Score, International Index of Erectile Function-15, maximum flow rate, post-void residual urine, serum prostate specific antigen and transrectal ultrasound volume were recorded.

Results: Patient baseline characteristics were similar for holmium laser enucleation and photoselective vaporization. Operative time and catheter removal time were almost equal in the 2 groups (p = 0.7 and 0.2, respectively). Eight vaporization cases were converted to transurethral prostate resection or holmium laser enucleation intraoperatively due to bleeding. A significantly higher maximum flow rate and lower post-void residual urine were noted in holmium laser cases during the entire followup (at 1 year each p = 0.02). However, no significant difference in International Prostate Symptom Score, quality of life or International Index of Erectile Function-15 was detected. Prostate volume and serum PSA decreased 78% and 88% in the holmium laser group, and 52% and 60% in the vaporization group, respectively.

Conclusions: Holmium laser enucleation and photoselective vaporization are effective for lower urinary tract symptoms due to a large prostatic adenoma. Early subjective functional results (maximum flow rate and post-void residual urine) of holmium laser enucleation appear to be superior to those of photoselective vaporization. In our hands cases intended to be treated with photoselective vaporization were at 22% risk of conversion to another modality. This could reflect our determination to vaporize to the capsule in all vaporization cases.

Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

DOI: 10.1016/j.juro.2012.02.2576

Commentary

This is the one of the few randomized trials comparing two “laser” technologies for prostatectomy. However, it should be noted that what is really being compared are two variations of prostatectomy. One is an enucleation-based technique which is less of a laser procedure than a scope-based enucleation, requiring the laser for hemostasis and cutting, a scope tip for enucleation and a morcellator for extracting tissue, versus a pure vaporization technique. It is well known that the holmium enucleation (HoLEP) technique is a challenging and technically difficult procedure that, in the hands of experienced surgeons, has superior outcomes, comparable to TURP and open prostatectomy, and that vaporization, whether electrosurgical or laser-based, is generally not as efficient at removing large amounts of tissue but is certainly much easier to apply. As such, conversions are generally due to impatience with vaporization techniques as well as selection of a less than ideal patient with a large gland. With these known differences, the results obtained in this study are not unexpected, especially with older technology vaporization systems with less power applied to larger glands.

While this study may meet Level 1 evidence-based criteria by its randomized, prospective study design, bias is inherent since this single center is well known for its expertise with HoLEP, especially with large prostates. As such, a simple vaporization technique in a large prostate will be predisposed to conversion due to known data about length of time to vaporize a large prostate with any laser technology and familiarity with the another laser procedure by its study surgeons that is superior in their hands. Thus, a 22% conversion rate and a more complete resection via PSA data is not surprising. What is highly unusual is the high rate of bleeding requiring conversion to TURP or holmium. That is not the experience of most since by its nature, pure vaporization is hemostatic. However, like all procedures, it still requires end-user skill to obtain hemostasis, and this may reflect a tendency to use a comfortable and familiar technique that is known to obtain hemostasis. Additionally, with conversion to a procedure that has a higher rate of bleeding, it is not clear that all the blood loss is due to the primary prostatectomy procedure.

In the end, it is important to note that there are many options for prostatectomy and the surgeon will select the technique he or she is most comfortable performing with the best result and outcome. Thus, at this center and in this study, HoLEP appears to be the procedure of choice and is expertly performed over others.

Alexis Te, MD

Photoselective vaporisation of the prostate using 80-w and 120-w laser versus transurethral resection of the prostate for benign prostatic hyperplasia: a systematic review with meta-analysis from 2002 to 2012. Thangasamy IA, Chalasani V, Bachmann A, Woo HH, Department of Surgery, Hornsby Ku-Ring-Gai Hospital, Sydney, Australia.

Eur Urol 2012;62:315-23.

Context: Photoselective vaporisation (PVP) of the prostate is being used increasingly to treat symptomatic benign prostatic hyperplasia, due to the associated lower morbidity. Holmium laser enucleation of the prostate was considered to be the treatment with the highest evidence; however, evidence for PVP has dramatically increased recently.

Objective: To conduct a systematic review and meta-analysis of level 1 evidence studies to determine the effectiveness of PVP versus transurethral resection of the prostate (TURP) for surgical treatment of benign prostatic hyperplasia. Outcomes reviewed included perioperative data, complications, and functional outcomes.

Evidence Acquisition: Biomedical databases from 2002 to 2012 and American Urological Association and European Association of Urology conference proceedings from 2007 to 2011 were searched. Trials were included if they were randomised controlled trials, had PVP as the intervention, and TURP as control. Meta-analysis was performed using a random effects model.

Evidence Synthesis: Nine trials were identified with 448 patients undergoing PVP (80W in five trials and 120W in four trials) and 441 undergoing TURP. Catheterisation time and length of stay were shorter in the PVP group by 1.91 d (95% confidence interval [CI], 1.47-2.35; p < 0.00001) and 2.13 d (95% CI, 1.78–2.48; p < 0.00001), respectively. Operation time was shorter in the TURP group by 19.64min (95% CI, 9.05–30.23; p = 0.0003). Blood transfusion was significantly less likely in the PVP group (risk ratio: 0.16; 95% CI, 0.05–0.53; p = 0.003). There were no significant differences between PVP and TURP when comparing other complications. Regarding functional outcomes, six studies found no difference between PVP and TURP, two favoured TURP, and one favoured PVP.

Conclusions: Perioperative outcomes of catheterisation time and length of hospital stay were shorter with PVP, whereas operative time was longer with PVP. Postoperative complications of blood transfusion and clot retention were significantly less likely with PVP; no difference was noted in other complications. Overall, no difference was noted in intermediate-term functional outcomes.

Copyright © 2012 European Association of Urology. Published by Elsevier B.V. All rights reserved.

DOI: 10.1016/j.eururo.2012.04.051

Commentary

Since 2001, the 532 nm high powered laser system has been commercially available for laser prostatectomy. This procedure is commonly performed with a specific laser vaporization technique suited to the 532 nm high power laser, and is well known by many monikers including photoselective vaporization (PVP) as well as KTP, LBO and the trade name Greenlight. The first commercial version was an 80W quasicontinuous KTP-based 532 nm laser system and was effective in prostate glands averaging about 50 g in an early multicenter study. However, with larger prostates, vaporization efficiency was less than ideal. As a result, the technology evolved to higher powered laser systems that were diode-based with dual delivery power, one for vaporization and the other for coagulation. With higher power and more efficient vaporization, hemostasis is less, and techniques and technology to achieve hemostasis have developed over time. Over the last decade, the 532 nm laser systems have become popular and easily adopted by many practicing urologists for ease of use and good efficacy and safety outcomes, so that many consider this a viable, competitive alternative to replace standard monopolar TURP. As a result, a quickly growing body of published data have developed. This meta-analysis of the two most recent commercial versions of the 532 nm high power laser system for prostatectomy is consistent with the general experience and previously published data of many, demonstrating competitive efficacy to TURP with improved safety profiles and less bleeding requiring transfusion, less dilutional hyponatremia events, and shorter hospital and catheter times. While not noted in this study, the bulk of the published safety experience resides with the initial 80W laser system. However, this is not surprising since more power results in better vaporization efficiency at the expense of hemostasis. Thus, it is important to realize that not all procedures require 80W power and that one should select the appropriate power that balances hemostasis. Too much coagulation results in unwanted prolonged dysuria against superior vaporization efficiency and increases the risk of bleeding. With the greater power 80W laser system, power flexibility is the advantage.

Alexis Te, MD

Examining the ‘gold standard’: a comparative critical analysis of three consecutive decades of monopolar transurethral resection of the prostate (TURP) outcomes. Mayer EK, Kroeze SG, Chopra S, Bottle A, Patel A, Department of Urology, St Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK Department of Urology, University Medical Center Utrecht, Utrecht, the Netherlands Department of Urology, St Vincent's Hospital, Sydney, Australia Division of Epidemiology, Public Health and Primary Care, Imperial College London, London, UK.

BJU Int 2012 Apr. 30 [Epub ahead of print]

What's known on the subject? and What does the study add? Transurethral resection of the prostate (TURP) remains the dominant and definitive treatment for lower urinary tract symptoms due to benign prostatic hyperplasia (LUTS-BPH), but the widespread use of medical therapies (particularly monotherapies) for rapid symptom improvement has meant that the most common indication for TURP has shifted to moderate-severe medical therapy refractory LUTS to, coupled with abnormal objective parameters, or when complications arise. Patients undergoing TURP as part of contemporary randomised controlled trials are not older but have a larger preoperative prostate volume and reduced major morbidity compared with large cohort studies from successive past eras. Delayed surgery because of prolonged medical monotherapy may explain a higher reported failure to void rate, possibly because of negative impact on detrusor function from unrelieved obstruction. This study examined contemporary TURP for significant changes, specifically regarding prostate size, operative parameters, and outcomes, compared with two preceding decades. Electronic databases PubMed, EMBASE & Cochrane collaboration were searched for English literature on prospective randomized controlled trials, published between 1997 and 2007 using keywords “transurethral resection” and “prostate.” Monopolar TURP (M-TURP) cohort data of each study were selectively pooled for analysis, weighting studies according to patient numbers. Where possible, pooled post-operative outcomes data were compared with two large cohort landmark studies of successive preceding decades. A total of 3470 patients from 67 studies were included. Mean patient age (67 years) was unchanged, while mean pre-operative prostate volume of 47.6 g was greater than previously reported. Mean resected prostate tissue (25.8 g) with a resection time of 38.5 minutes suggested improved resection efficiency. A statistically significantly reduced transfusion rate and increased urinary tract infection (UTI) rate were reported. Hospital stay (3.6 days) and initial catheterisation duration (2.5 days) were similar, but post-operative urinary retention rate was slightly higher (6.8%). Contemporary RCTs of M-TURP showed larger prostate volume, and reduced major morbidity, compared with large cohort studies from successive past eras. The higher reported failure to void rate, may possibly reflect worse detrusor function at time of TURP. Delaying surgery by prolonged medical monotherapy may compound this. Trials methodology in this area requires quality improvement and standardisation in future.

© 2012 The Authors. BJU International. © 2012 BJU International.

DOI: 10.1111/j.1464-410X.2012.11119.x.

Commentary

This is an interesting study attempting to analyze trends of monopolar TURP over succeeding decades. Overall, there is an improved efficacy and safety trend that probably reflects the refinement in technique and technology with monopolar TURP including improved preoperative selection and preparation, and improved perioperative management and postoperative care. This has resulted in the ability to treat larger prostates more safely. However, I would disagree that higher reported rates of failure to void reflects worse detrusor function due to medical therapy. Rather, if the mean resected volume has not changed much with larger preoperative prostate volumes, does it not reflect the reality that inadequate resection is the etiology in the failure to void? It would make sense since limiting the time of resection to less than 45 minutes is still a keystone parameter to a monopolar TURP, even in large prostates, in order to reduce major morbidities like bleeding requiring transfusions, and dilutional hyponatremia syndrome.

Alexis Te, MD

Commentary

Patients subjected to malabsorptive bariatric surgery such as Roux-en-Y gastric bypass or biliopancreatic diversion and duodenal switch are at risk for development of calcium oxalate kidney stones. Hyperoxaluria is a major risk factor. Patients subjected to restrictive procedures such as gastric banding have been reported not to be at stone risk. Pang et al found that urinary oxalate excretion did not decrease after consumption of a normal calcium and low oxalate diet. However, the supersaturation of calcium oxalate decreased during this intervention, most likely due to increased urine volume and citrate excretion. The take-home message is that while dietary modifications should be enacted in this patient cohort, other measures will be needed to reduce oxalate excretion, including more aggressive utilization of calcium supplementation, probiotic therapy and perhaps enzyme preparations that can metabolize oxalate when they become available for clinical use.

Dean G. Assimos, MD

Surgery for primary hyperparathyroidism: are the consensus guidelines being followed? Yeh MW, Wiseman JE, Ituarte PH, Pasternak JD, Hwang RS, Wu B, Liu IL, Haigh PI, Division of General Surgery, UCLA David Geffen School of Medicine, Los Angeles, CA.

Ann Surg 2012;25):1179-83.

Objective: To determine parathyroidectomy (PTx) rates in patients who satisfy the consensus guidelines for surgical treatment of primary hyperparathyroidism (PHPT).

Background: Surgery for PHPT is recommended for all symptomatic patients and select asymptomatic patients meeting established consensus criteria. Adherence to the consensus guidelines has not been examined systematically, because of inadequate information regarding patients managed nonoperatively.

Methods: All nonuremic patients with PHPT during the period 1995–2008 were identified using the Kaiser Permanente-Southern California laboratory database, encompassing 3.5 million individuals annually. Multivariate logistic regression was used to examine predictors of PTx.

Results: We found 3388 patients with PHPT, of whom 265 (8%) were symptomatic (nephrolithiasis). Nephrolithiasis was predictive of PTx (OR 2.94 vs asymptomatic), with 51% of symptomatic patients undergoing surgery. Among asymptomatic patients, the proportion meeting consensus criteria was 39% during the early period (1995–2002) and 51% during the late period (2003–2008). The PTx rate for these patients exceeded that for asymptomatic patients not meeting consensus criteria but remained low (early 44% vs 19%, P < 0.0001; late 39% vs 16%, P < 0.0001). The following individual criteria were predictive of PTx: calcium > 11.5 mg/dL (OR 2.27), hypercalciuria (OR 3.28, P < 0.0001), and age < 50 years (OR 1.54, P < 0.0001). However, the absolute PTx rates associated with satisfaction of these criteria were in the 50% range. Bone density scores did not influence likelihood of PTx and renal impairment predicted against PTx (OR 0.35, P < 0.0001).

Conclusions: The consensus guidelines regarding PHPT have not been followed in our study population. PTx appears to be underutilized in both asymptomatic and symptomatic patients.

DOI: 10.1097/SLA.0b013e31824dad7d

Commentary

Primary hyperparathyroidism is associated with the development of both calcium oxalate and calcium phosphate stones. Approximately 20% of individuals afflicted with this disorder develop stones and surgical removal of the affected gland(s) will generally result in significant attenuation of stone activity. The diagnosis of primary hyperparathyroidism may be subtle. It should be suspected in patients with high normal serum calcium with an inappropriately high serum parathyroid level (high normal range). Our surgical colleagues sometimes need to be coaxed to proceed with surgical correction of this problem as evidenced by this article.

Dean G. Assimos, MD

Commentary

Since the recent recommendation of the United States Preventive Task Force (USPSTF) against prostate cancer screening, the urology community has been challenged to defend the accusations of overdiagnosis and overtreatment of clinically insignificant prostate cancer. Several articles have encouraged fewer prostate biopsies and less aggressive diagnostic schemes to prevent the problems of overdiagnosis and overtreatment. The current article, however, takes a completely different view of the problem with current prostate cancer diagnosis practices and examines the problem of underdiagnosis and undertreatment of clinically significant prostate cancer.

Lecornet et al evaluated how well different prostate biopsy strategies performed at detecting clinically significant prostate cancer using computer simulation in cystoprostatectomy cases with cancer. Ninety-six prostates containing cancer were digitally reconstructed from 3 mm whole mount slices. Biopsy simulations incorporating various degrees of random localization error were performed using the prostate computer model. Two different definitions of clinically significant prostate cancer were employed to determine detection rate. Definition 1 was Gleason score ≥7, and/or lesion volume ≥0.5 mL. Definition 2 was Gleason score ≥7, and/or lesion volume ≥0.2 mL.

In short, a 12-core standard TRUS biopsy missed 47% of lesions ≥0.5 mL and 79% of those 0.2 to 0.5 mL. A 14-core “optimal biopsy” included 2 more transition zone biopsies but still missed 36% of lesions ≥0.5 mL and 65% of those 0.2 to 0.5 mL. A template prostate mapping biopsy scheme (median 48 cores spaced 5 mm apart on a grid) missed no 0.5 mL lesions and only 7% of 0.2 to 0.5 mL lesions.

It goes without saying that our current biopsy strategies perform extremely poorly based on this computer simulated study of clinically significant prostate cancer. The computer simulation performs an ideal biopsy (which would be difficult to recreate in clinical practice), so these numbers are a best-case scenario on the standard prostate biopsy performance. The computer simulation was based on a series of prostates that would reflect a typical screened population and it was extremely well designed and executed.

The authors are not recommending that we change to template prostate mapping for all prostate biopsies. Proposing that patients receive anywhere from 16 to 152 biopsies (based on prostate size and configuration) is not clinically nor economically feasible. It does, however, highlight the need for better biopsies schemes or techniques, and the authors suggest the possibility of utilizing MRI guided biopsies. I am not sure that is the answer either, but we do need to rethink the way we currently perform biopsies in order to avoid both overdiagnosing insignificant cancer and/or underdiagnosing clinically significant cancer.

David A. Duchene, MD

In vitro comparison of prototype magnetic tool with conventional nitinol basket for ureteroscopic retrieval of stone fragments rendered paramagnetic with iron oxide microparticles. Tan YK, McLeroy SL, Faddegon S, Olweny E, Fernandez R, Beardsley H, Gnade B, Park S, Pearle MS, Cadeddu JA, University of Texas Southwestern Medical Center at Dallas, Dallas, TX.

J Urol 2012;188:648-52.

Purpose: We developed a prototype magnetic tool for ureteroscopic extraction of magnetized stone particles. We compared its efficiency for retrieving magnetized calcium oxalate monohydrate stone particles with that of a conventional nitinol basket from the pelvi-collecting system of a bench top ureteroscopic simulator.

Materials and Methods: Iron oxide microparticles were successfully bound to 1 to 1.5, 1.5 to 2 and 2 to 2.5 mm human calcium oxalate monohydrate stones. Several coated fragments of each size were implanted in the collecting system of a bench top ureteroscopic simulator. Five-minute timed stone extraction trials were performed for each fragment size using a back loaded 8Fr magnetic tool mounted on a 0.038-inch guidewire or a conventional basket. The median number of fragments retrieved per timed trial was compared for the magnetic tool vs the basket using the Mann-Whitney U test.

Results: For 1 to 1.5 mm fragments the median number retrieved within 5 minutes was significantly higher for the prototype magnetic tool than for the nitinol basket (9.5 vs 3.5, p = 0.03). For 1.5 to 2 mm fragments the magnetic tool was more efficient but the difference in the number of fragments retrieved was not statistically significant (9.5 vs 4.5, p = 0.19). For 2 to 2.5 mm fragments there was no difference between the instruments in the number retrieved (6 per group, p = 1.0).

Conclusions: The prototype magnetic tool improved the efficiency of retrieving stone particles rendered paramagnetic that were less than 2 mm but showed no advantage for larger fragments. This system has the potential to decrease the number of small retained fragments after ureteroscopic lithotripsy.

Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

DOI: 10.1016/j.juro.2012.03.118

Commentary

Small “insignificant” residual stones after surgical nephrolithiasis management have been shown to usually not be “insignificant.”¹ The goal of stone surgery is complete stone removal. During ureteroscopic management of kidney stones, however, urologists often leave small fragments and “dust” to pass after surgery. Often the remaining fragments are too small to efficiently basket with standard ninitol baskets. What else can we utilize to truly render patients stone-free?

Tan and colleagues have previously explored the novel use of peptide and polymer coated iron oxide paramagnetic microparticles that bind to calcium stones, allowing for the extraction of small stone fragments with magnetic tools.² The group has also reported successful magnetic fragment retrieval from a bladder model with a 8 Fr magnetic tool.³ Now the authors have developed a prototype magnetic tool for ureteroscopic extraction of magnetized stone particles to create a more clinically useful application of the technology.

Iron oxide microparticles were successfully bound to 1 to 1.5, 1.5 to 2, and 2 to 2.5 mm human calcium oxalate monohydrate stones. The fragments were placed in a bench top ureteroscopic simulator and five-minute timed stone extraction trials were performed for each fragment size using a back-load 8 Fr magnetic tool mounted on a 0.038 inch guidewire or a conventional ninitol basket. For 1 to 1.5 mm fragments the median number retrieved within 5 minutes was significantly higher for the prototype magnetic tool than for the ninitol basket. The magnetic tool was also more efficient in 1.5 to 2 mm fragments, but not to a statistically significant degree. No difference existed for 2 to 2.5 mm fragments.

The authors showed that the prototype magnetic tool could greatly improve efficiency of retrieving stone particles rendered paramagnetic that were <2 mm in size. These are the exact stones that are often left behind to pass as “dust” that may clump together and/or act as a nidus for future stone development. The magnetic tool approach has the added advantage of removing several fragments in a single passage, and not risking ureteral injury as the stones readily decouple with resistance.

Several hurdles still exist prior to this technology becoming clinically available. The authors are still refining and improving the microparticle binding to calcium oxalate stones with better efficacy and less incubation time. The microparticle density per stone also needs to be increased to increase magnetic strength and coupling, especially for larger fragments. However, this unique and exciting technology continues to improve and move toward clinical applications.

References

1. Raman JD, Bagrodia A, Gupta A, et al. Natural history of residual fragments following percutaneous nephrostolithotomy. J Urol 2009;181:1163–68.

2. Mir SA, Best SL, McLeroy S, et al. Novel stone-magnetizing microparticles: in vitro toxicity and biologic functionality analysis. J Endourol 2011;25:1203–7.

3. Tracy CR, McLeroy SL, Best SL, et al. Rendering stone fragments paramagnetic with iron-oxide microparticles improves the efficiency and effectiveness of endoscopic stone fragment retrieval. Urology 2010;76:1266.e10-4.

David A. Duchene, MD

Commentary

There have been numerous publications in the literature describing different levels of nerve-sparing during robot-assisted laparoscopic radical prostatectomy (RARP). At present, the nomenclature for nerve-sparing during RARP is not standardized. Nonetheless, most robotic surgeons who perform RARP note extrafascial (wide), interfascial, or intrafascial nerve-sparing. The indications and degree of nerve-sparing generally depend on the preoperative prostate biopsy, PSA, and preoperative imaging such as endorectal coil MRI, but considerable variability exists among surgeons.

In this study, the authors histologically analyzed RARP prostate specimens to try to determine if the surgeon performed the intended nerve preservation during RARP. The surgeon performing RARP, who was an experienced robotic surgeon, recorded the nerve-sparing to be wide resection, interfascial nerve-sparing, or intrafascial nerve-sparing. The uropathologist was then blinded to the type of nerve-sparing and examination of prostate specimens was performed. The fascia width was measured and recorded from several points along the prostate from the outermost prostate gland to the surgical margin. In this study, the fascia width correlated well with the surgical technique used; the fascia width was greatest for wide resection (2.24 mm) and least for intrafascial nerve-sparing (1.08 mm). The wider the nerve-sparing, the greater the pathologic surgical margin.

One unexpected finding was that for interfascial nerve-sparing, there was more variability with the fascia width on the left side of the prostate, with the left-sided fascia width being much wider than the right. The authors speculate that this may be due to potential right-handed dominance by the surgeon. Indeed, although robotic surgery allows the surgeon to more easily use the nondominant hand, it has been my observation that for RARP the vast majority of surgeons do the majority of the prostate dissection, including nerve preservation, using the dominant hand. In other words, the surgeon does not switch the robotic dissector/bipolar instrument and scissors when moving from left- to right-sided nerve-sparing.

This well-designed study is reassuring in noting that in an experienced surgeon's hands, the degree of intended nerve-sparing during RARP correlates well with the pathologic analysis. When the surgeon planned on taking the neurovascular bundles widely, the fascia width (surgical margin) was wide; on the other hand, when intrafascial nerve-sparing was performed, the margin was less. It is notable that there were unexpected differences between the right side and the left side, possibly attributable to hand dominance. For the novice RARP surgeon, it would probably be useful to review specimens with the uropathologist and confirm that nerve-sparing is being performed accurately and as intended. In addition, extreme caution and extra care should be exercised when performing nerve-sparing on the nondominant side. When positive margins occur, it would be useful for the surgeon to determine whether the area of positive margin was in the area of nerve-sparing. As further technical refinements in RARP are developed and implemented, continued collaboration between the urologist and pathologist will be useful in ensuring that maximum nerve preservation can be safely and reliably performed without jeopardizing long-term cancer control.

David S. Wang, MD

A matched comparison of perioperative outcomes of a single laparoscopic surgeon versus a multisurgeon robot-assisted cohort for partial nephrectomy. Ellison JS, Montgomery JS, Wolf JS Jr, Hafez KS, Miller DC, Weizer AZ, Department of Urology, University of Michigan, Ann Arbor, MI.

J Urol 2012;188:45-50.

Purpose: Minimally invasive nephron sparing surgery is gaining popularity for small renal masses. Few groups have evaluated robot-assisted partial nephrectomy compared to other approaches using comparable patient populations. We present a matched pair analysis of a heterogeneous group of surgeons who performed robot-assisted partial nephrectomy and a single experienced laparoscopic surgeon who performed conventional laparoscopic partial nephrectomy. Perioperative outcomes and complications were compared.

Materials and Methods: All 249 conventional laparoscopic and robot-assisted partial nephrectomy cases from January 2007 to June 2010 were reviewed from our prospectively maintained institutional database. Groups were matched 1:1 (108 matched pairs) by R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines) nephrometry score, transperitoneal vs retroperitoneal approach, patient age and hilar nature of the tumor. Statistical analysis was done to compare operative outcomes and complications.

Results: Matched analysis revealed that nephrometry score, age, gender, tumor side and American Society of Anesthesia physical status classification were similar. Operative time favored conventional laparoscopic partial nephrectomy. During the study period robot-assisted partial nephrectomy showed significant improvements in estimated blood loss and warm ischemia time compared to those of the experienced conventional laparoscopic group. Postoperative complication rates, and complication distributions by Clavien classification and type were similar for conventional laparoscopic and robot-assisted partial nephrectomy (41.7% and 35.0%, respectively).

Conclusions: Robot-assisted partial nephrectomy has a noticeable but rapid learning curve. After it is overcome the robotic procedure results in perioperative outcomes similar to those achieved with conventional laparoscopic partial nephrectomy done by an experienced surgeon. Robot-assisted partial nephrectomy likely improves surgeon and patient accessibility to minimally invasive nephron sparing surgery.

Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

DOI: 10.1016/j.juro.2012.02.2570

Commentary

Nephron sparing surgery is now considered the standard surgical treatment option for small renal masses. Partial nephrectomy can now be performed via the traditional open flank approach, laparoscopic approach, and, more recently, the robotic approach. Laparoscopic partial nephrectomy remains a technically difficult and demanding procedure, and the majority are done by surgeons who are fellowship trained and/or have considerable experience with laparoscopic renal surgery. Robotic surgery has facilitated minimally invasive partial nephrectomy and has allowed for more surgeons to perform robot-assisted laparoscopic partial nephrectomy (RAPN). It is unclear if there are any significant benefits of RAPN over conventional laparoscopic partial nephrectomy (LPN).

In this study, the authors compared a matched pair analysis of conventional laparoscopic partial nephrectomy (LPN) cases between a single highly experienced surgeon with RAPN by a heterogeneous group of surgeons with mixed experience with minimally invasive partial nephrectomy. The groups were matched by RENAL nephrometry score, patient demographics, and ASA score. Parameters analyzed included operative time, warm ischemia time, blood loss, and postoperative complications. The surgeon performing LPN had experience with over 200 cases whereas the RAPN group (five surgeons total) included all first cases performed and did not exclude the learning curve cases.

In the study, operative times and warm ischemia times were shorter in the experienced LPN group. However, when excluding zero ischemia cases, there was no difference in warm ischemia time between LPN and RAPN groups. There were no differences in complication rates, positive surgical margin rates, and overall patient morbidity between the groups. The complication rates of 41.7% (LPN) and RAPN (35.0%) are somewhat high, although all minor complications were noted and the major complication rate was low.

It is clear that RAPN allows more surgeons to perform minimally invasive partial nephrectomy given the inherent technical difficulties associated with conventional LPN. While one limitation of this study is that it is comparing one surgeon with a heterogeneous group of five surgeons, this may represent the surgeon at the academic center with greater experience with LPN versus the general urologist who is starting to incorporate robotic surgery into practice. In this study the learning curve for RPN began to plateau after 33 cases. I would certainly argue that the learning curve for traditional LPN exceeds 33 cases.

One cannot help but draw comparisons of LPN vs RAPN with traditional laparoscopic vs robotic radical retropubic prostatectomy. A decade ago, laparoscopic radical prostatectomy in the United States was limited to only a handful of academic centers, whereas robot-assisted laparoscopic radical prostatectomy is now common. Even those surgeons who previously had expertise with traditional laparoscopic radical prostatectomy now favor the robotic approach. Indeed, there are very few centers in the United States now performing traditional laparoscopic radical prostatectomy.

Currently, the benefits of RAPN over traditional LPN are unclear. Purported efforts include slightly decreased warm ischemia time, possible ability to do more complex and/or hilar tumors, less operative time, and more precise collecting system closure. Whether these benefits are clinically significant and whether the additional costs are justified remain to be determined. It is clear, however, that the robotic approach hastens the learning curve for minimally invasive partial nephrectomy and allows more surgeons to perform this operation. Ultimately, this will provide greater patient access to minimally invasive nephron sparing surgery.

David S. Wang, MD

Commentary

The authors report their prospective experience with a novel bipolar radiofrequency ablation device that was recently developed in France. The probe isolates the thermal energy between two electrode rings, and has been shown in animal and ex vivo studies to produce reproducibly sized lesions, without injuring surrounding tissue. Ten consecutive patients who were undergoing laparoscopic radical or partial nephrectomy for renal tumors consented to participate. After laparoscopic exposure, the probe was placed percutaneously and then guided into the tumor with laparoscopic guidance. The specimens were then removed in standard fashion and areas of necrosis were evaluated with additional vital stains using NADH. The authors report that ablation was successful in all 10 tumors and the duration of treatment was 200 seconds. No viable cells were seen in the zones of ablation, and the mean size of the zone was 6.26 cm³ with regular borders and cylindrical shape. The area of the transition zone was 10 to 60 μm. The specific complications due to the ablation were reported. The authors concluded that this device can produce a defined, reproducible lesion with a precise transition zone and that this area of ablation was completely devitalized.

This article is interesting in several respects. It is a prospectively performed pilot evaluation of a novel therapy for renal tumors in human subjects, and it provides tissue evaluation. We also glean some safety aspects based on initial experience. I had the opportunity to test the bipolar system of an American manufacturer several years ago; while the preliminary animal studies were promising, the company did not want to pursue this indication for the kidney, and subsequently, I believe, even for the actual technology. I am thus happy to see that there is still an active interest in developing this approach. The primary advantages of a bipolar versus monopolar system are related to safety and efficacy. The electrical charge is isolated between the coils and does not travel throughout the body and out via grounding pads, precluding the serious complication of grounding pad burns associated with radiofrequency ablation. Additionally, the amount of tissue treated is defined by the actual physical location of the probes, allowing for accurate placement and reproducible and precise ablation zones. While this initial pilot study is very promising, further follow-up studies performed with post-ablation tissue to confirm success are still needed.

Surena F. Matin, MD

Placement of marker coils at biopsy: usefulness in the localization of poorly visualized renal neoplasms for subsequent CT-guided radiofrequency ablation. Pietryga JA, Beland MD, Dupuy DE, Mayo-Smith WW, Department of Diagnostic Imaging, Brown University, Providence, RI.

Radiology 2012;263:555-61.

Purpose: To determine whether placement of marking coils at biopsy of small renal neoplasms to facilitate localization at subsequent radiofrequency (RF) ablation is safe and can reduce fluoroscopy time during the ablative procedure.

Materials and Methods: This retrospective study was approved by the hospital institutional review board and was compliant with HIPAA. The requirement to obtain informed consent was waived. A search of the renal RF ablation database (235 patients) identified 23 consecutive patients who had a marking coil placed at biopsy of a renal neoplasm (coil group) and 23 patients who did not have a marking coil placed at biopsy (control group). The patients were matched for tumor characteristics, including size, parenchymal position, location in the kidney, and laterality. All patients underwent subsequent RF ablation. The authors compared computed tomographic (CT) fluoroscopy times and technical success rates between the two groups. Statistical analyses were performed by using a single-tailed paired t test for comparison of CT fluoroscopy times, a two-tailed paired t test for comparison of age and tumor size, and a single-tailed McNemar test for comparison of the technical success rate of ablation.

Results: The mean CT fluoroscopy time for the RF ablation procedure was 28 seconds ± 11.7 (standard deviation) for the coil group and 66 seconds ± 85.8 for the control group (P = .025). There was no significant difference in the technical success rates of renal RF ablation.

Conclusion: For small renal neoplasms that are poorly visualized at unenhanced CT, placement of a metallic marking coil at biopsy facilitates tumor localization, thus reducing CT fluoroscopy time and radiation dose for subsequent RF ablation procedures.

DOI: 10.1148/radiol.12111430

Commentary

This is a retrospective, matched comparison of 23 patients who had a marking coil placed at the time of biopsy of renal neoplasm, compared to 23 matched patients who did not have a coil placed. The control group was matched for multiple tumor characteristics, including size, depth and laterality. The authors had a total experience of 235 patients at the time of this publication. The authors found that the mean fluoroscopy time for the RF ablation procedure was, on average, 28 seconds for the coil group versus 66 seconds for the control group, a finding that was statistically significant. The technical success rates were similar between these two groups. The authors conclude that for small renal neoplasms that are poorly visualized at unenhanced CT, placement of a coil at the time of biopsy facilitates tumor localization with reduction of radiation dose during RF ablation.

Interesting aspects of this study are that since 2008 the authors have modified their practice to performing a biopsy first to confirm the presence of renal cell carcinoma, before proceeding with ablative therapy. This was motivated based on the knowledge that at least one-third of these lesions proved to be benign and did not require treatment. Additionally, these authors have had some reimbursement issues in these cases. This closely mirrors our own experience and current practice at M.D. Anderson Cancer Center. The rationale for the metallic coil is based on the central location of kidney tumors being a negative predictive factor for success and a known predictor of nondiagnostic biopsy, particularly when there is no renal surface distortion to help guide the biopsy needle localization. Probably due to the experience of placing fiducials in other organ sites such as the lung and prostate and for four-dimensional radiotherapy, the authors address the problem of ablating renal tumors that are difficult to target.

From a technical perspective the coil added approximately $44 to the total cost of the procedure and the decision to place it was made by the operator based on difficulty in localizing the tumor at pre-biopsy unenhanced imaging and during the biopsy. Intravenous contrast was needed in five of the 23 patients to confirm accurate localization of the needle in the mass. At least two biopsy cores were taken and the coil was deployed via a previously placed 19 gauge outer coaxial needle. One patient was lost to follow-up in the control group.

There are several strengths of this study; most notably the matching of the study group with the control group for tumor anatomic factors. The power of the study would have been improved they been matched 2 to 1, such that more control patients were available. An additional strength was that the matched control group was selected during a similar time frame, thus precluding the potential for learning curve bias. Concerns with this study include the fluoroscopy time, which could have been lengthened during biopsy because of the coil placement, thus artificially enhancing the benefit of this intervention. However, the authors evaluated this by comparing the fluoroscopy time during biopsy in the coil and control groups and these were very similar. An additional concern may be the presence of a metallic coil within the tumor and how this may interfere with probe placement and thermal diffusion kinetics. We also don't know how much better this is than using ultrasound simultaneously with CT during ablation.

This is an interesting study that may address one of the difficult aspects of ablative therapy in treating small intrarenal tumors. While the authors did not demonstrate that this led to any better treatment, this could easily have been due to a poorly powered study. However, the fact that the radiation dose was significantly reduced is significant enough. This novel procedure should warrant consideration by those performing ablative therapy programs.

Surena F. Matin, MD