Endourology and Stones Single-session Supine Bilateral Percutaneous Nephrolithotomy Silvia Proietti, Giuseppe Sortino, Antonella Giannantoni, Mario Sofer, Roberto Peschechera, Lorenzo Giuseppe Luciani, Giuseppe Morgia, and Guido Giusti OBJECTIVE METHODS
RESULTS
CONCLUSION
To evaluate the effectiveness and safety of supine bilateral percutaneous nephrolithotomy (BPCNL) performed in the same session in patients affected with bilateral renal calculi. We retrospectively identified patients with bilateral renal stones with diameters >2 cm for each side, who had been treated with supine BPCNL in the same session, from November 2006 to April 2014. We reviewed demographic and stone characteristics, intraoperative and perioperative outcomes, and complications related to the procedure adopted. The stone size was calculated by measuring the maximum stone diameter by computed tomography scan. Stone-free rate was defined as clinically insignificant when residual fragments of 2 mm were detected by computed tomography scan. Twenty-five patients were included in the study; the mean age was 51.9 11.4 years; the mean maximum stone diameter per renal unit was 3.1 0.8 cm. Statistical significant differences in creatinine serum levels were detected at day 1 postoperatively compared with the baseline (P .05). The primary stone-free rate was 80%; ancillary procedures were performed in 3 of 25 patients (12%). Grade I complications occurred in 3 patients (12%), grade II in 4 patients (16%), and grade IIIA in 1 patient (4%). Supine BPCNL performed in the same session is a safe and effective procedure in patients affected with bilateral renal calculi. On the other hand, it is still a very challenging operation, and consequently, it should be performed only by experienced surgeons in a tertiary center. UROLOGY 85: 304e310, 2015. 2015 Elsevier Inc.
A
ccording to both American Urological Association and European Association of Urology guidelines, percutaneous nephrolithotomy (PCNL) is considered the first-line treatment for renal stones >2 cm.1,2 The first PCNL was described by Fernstrom and Johansson3 in 1976, and since then, this surgical approach has undergone significant changes with the purpose of minimizing both invasivity and morbidity together with improving outcomes. The remarkable progress achieved in surgical techniques and equipment have improved the efficacy and reduced operative time and complications, expanding the treatment options for complicated stone patients such as those with bilateral Financial Disclosure: Guido Giusti is a paid consultant for Boston Scientific, Cook Medical, Porges Coloplast Division, and Karl Storz. The remaining authors declare that they have no relevant financial interests. From the Stone Center at Department of Urology, Humanitas Clinical and Research Center, Rozzano, MI, Italy; the Department of Urology, Policlinico Hospital, University of Catania, Catania, Italy; the Department of Surgical and Biochemical Science, Urologic and Andrologic Clinic, University of Perugia, Perugia, Italy; the Division of Endourology, Sourasky Medical Center, Tel-Aviv University, Tel-Aviv, Israel; and the Department of Urology, Santa Chiara Hospital, Trento, Italy Address correspondence to: Guido Giusti, M.D., Stone Center at Department of Urology, Humanitas Clinical and Research Center, Rozzano, Milano 20089, Italy. E-mail: [email protected] Submitted: July 7, 2014, accepted (with revisions): October 14, 2014
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calculi.4 Historically, patients with bilateral large stone burdens have always been a therapeutic challenge to the urologist. Traditionally, these patients had been treated with staged procedures, to avoid the increased morbidity of bilateral kidney surgery and to prevent injury to or infection of both renal units together. Nowadays, bilateral PCNL (BPCNL) performed in the same operative session is considered, in high-volume centers and experienced hands, to be a well-tolerated, safe, and effective procedure for these patients, able to avoid the risk of a second anesthesia, and to decrease morbidity and length of hospitalization.5-8 However, the removal of large and/or complex bilateral renal stones still represents a difficult task for urologists. As a consequence, there are few studies on this challenging issue and, most importantly, to date, none have described single-session BPCNL in the supine position. The aim of this study was to evaluate the effectiveness and safety of supine single-session BPCNL in patients affected with bilateral renal calculi.
METHODS We retrospectively identified patients with bilateral renal stones with diameters of >2 cm for each side, who had been treated http://dx.doi.org/10.1016/j.urology.2014.10.036 0090-4295/15
with supine BPCNL performed in the same session, from November 2006 to April 2014. Routine preoperative workup included the following: medical history, physical examination, blood samples analysis, urine and urine culture, unenhanced computed tomography (CT) scan. One day, 1 week, and 1 month after the procedure, blood samples analysis was obtained. Estimated glomerular filtration rate was calculated. Before asking for informed consent from all the patients, we also informed and offered staged metachronous PCNL as an alternative treatment option. We also clearly specified that, in case of opting for an approach performed in the same session, the contralateral side would not be attempted in the event of long operative time and/or complications occurring in the first side. All the surgical procedures were carried out by a single surgeon (G.G.). Initially, the more symptomatic side was treated. We reviewed demographic and stone characteristics, intraoperative and perioperative outcomes, and complications related to the procedure adopted. Operative time was calculated from the time of cystoscope insertion to the completion of skin suture in the second side. The Clinical Research Office of the Endourological Society validation of Clavien score for PCNL complications was used.9 The stone size was calculated by measuring the maximum stone diameter by CT scan. Stone-free rate (SFR) was defined as clinically insignificant when residual fragments of 2 mm were detected by CT scan. In case of significant residual stone, the patient was scheduled for a second-look procedure, second-look PCNL, or flexible ureteroscopy depending on the dimensions of fragments.
Technique Under general anesthesia, patients are positioned in classical supine decubitus position, according to personal modification of the classical Valdivia position: the patient is placed with the side of interest at the edge of the table, with a small jelly bolster under and all along the flank to obtain a mild rotation not exceeding an angle of 15 -20 (Fig. 1). The ipsilateral arm is adequately protected and left lying over the thorax avoiding any stretch of brachial plexus; the legs are kept open and straight according to the Galdakao position.10 The inferior edge of the 12th rib, the iliac crest, and the posterior axillary line are marked on the patient’s skin. A retrograde ureteral occlusion balloon catheter is placed over the guidewire on the first side, and after retrograde pyelography, carefully inflated at the level of the ureteropelvic junction. Puncture is carried out under solely fluoroscopic control. Once access is gained, hydrophilic guidewire is passed through the ureter and down to the bladder for its stabilization. Subsequently, balloon dilation is performed and an Amplatz working sheath is placed, ranging between 24 and 30 Fr according to the dimensions of stones and targeted calices features (Ultraxx 24 Fr; Cook Medical, Bloomington, IL; NephroMax 30 Fr; Boston Scientific, Natick, MA). Ultrasonic lithotripsy is carried out through rigid nephroscopy. Stone fragments are then removed using a zero-tip disposable basket (N-Perc; Cook Medical, Bloomington, IL). A final flexible nephroscopy is always carried out to confirm stone-free status. Stone clearance is also confirmed by fluoroscopy. At the end of the procedure, antegrade stenting is accomplished under fluoroscopic guidance and a 10-Fr nephrostomy tube is positioned only in case of major bleeding, major perforation of the collecting system, or residual stones suitable for the second-look PCNL. Otherwise, the procedure ends in a UROLOGY 85 (2), 2015
Figure 1. Supine percutaneous nephrolithotomy position with a small jelly bolster under and along the flank. (Color version available online.) Table 1. Demographic and stone characteristics of patients (n ¼ 25)
Gender, n (%) Male Female Age (mean SD), y BMI (mean SD), kg/m2 ASA score (mean SD) Maximum stone diameter per renal unit (mean SD), cm Hounsfield units (mean SD)
16 (64) 9 (36) 51.9 11.4 25.8 2.1 2.5 0.7 3.1 0.8 1100 280
ASA, American Society of Anesthesiologists; BMI, body mass index; SD, standard deviation.
tubeless fashion. Only in cases where the first-side surgery has been without complications, we proceed with the second side. In this case, the patient is placed in a specular supine position, and the same surgical technique is adopted for the second side. At the end of the procedure, an 18-Fr Foley catheter is left in place overnight.
Statistical Analysis. Statistical analysis was performed with GraphPad Prism, version 6.0, for Mac (GraphPad, Prism Software Inc). Normality testing (the D’Agostino-Pearson test) was performed to determine whether data were sampled from a Gaussian distribution. One-way analysis of variance was performed to compare serum creatinine levels. Statistically significant difference was considered for P .05. First postoperative day vs first postoperative week; P value .05.
Table 3. Intraoperative and postoperative outcomes Operative time (both sides; mean SD), min 120 45.4 Hemoglobin drop (mean SD), g/dL 2.1 0.5 Length of hospital stay (mean SD), d 3.6 1.8 Primary SFR, n (%) 20/25 (80) Need of ancillary procedures, n (%) 3/25 (12) (1 PCNL and 2 fURS) Nephrostomy tube placement, n (%) Bilateral tubeless 19/25 (76) Monolateral tubeless 4/25 (16) Complications, grade, n (%) Grade I 3 (12) (postoperative pain managed by opioid) Grade II 4 (16) (fever managed by antibiotics in the ward) Grade IIIA 1 (4) (hydrothorax managed by intercostal draining under local anesthesia) fURS, flexible ureteroscopy; PCNL, percutaneous nephrolithotomy; SFR, stone-free rate; other abbreviation as in Table 1.
with the baseline (P .05; Table 2). No significant difference in the estimated glomerular filtration rate was observed between the baseline and 1 month postoperatively (80.9 20 vs 80.2 23; P >.05). Overall, average operative time was 120 45.4 minutes; primary SFR was 80%; and 3 of 25 patients (12%) needed ancillary procedures, 1 and 2 patients underwent second-look PCNL and flexible ureteroscopy, respectively. Bilateral tubeless procedures were performed in 19 of 25 cases (76%) and monolateral tubeless procedures in 4 of 25 patients (16%). Grade I, II, and IIIA complications were recorded in 3 (12%), 4 (16%), and 1 (4%) patient (Table 3).
COMMENT Urolithiasis is a common disease with a lifetime risk of stone formation in the western world as high as 12% in men and 6% in women.11 Furthermore, kidney stone disease incidence and prevalence are increasing, and, similarly, the overall incidence of bilateral renal stones is not negligible, being reported to range from 10.7% to 26% in patients with metabolic abnormalities.12 As a consequence, patients with bilateral renal stones are not anecdotal as in the past and represent a cumbersome challenge to endourologists. To date, there are already some studies that have reported the safety and effectiveness of prone BPCNL performed in the same operative session.5-8 Desai et al6 reported a series of 45 prone BPCNLs with a mean operative time of 107 43 minutes achieving a 306
remarkable 95% SFR. Of note, blood loss and creatinine serum level changes were negligible after 48 hours. Holman et al5 showed in their series of 198 patients of single-session BPCNL, a primary SFR of 90%; no significant change in serum creatinine levels in 77% of patients after 2-3 days postoperatively; and in 11% of patients, there was a significant transient increase in serum creatinine levels that return to normal within a mean of 5 days. As far as PCNL is concerned, Wang et al8 compared staged and synchronous tubeless PCNL for bilateral staghorn calculi in a randomized controlled study: the SFR was 71.4% and 72%, respectively, with no difference with regard to changes in serum creatinine levels, hemoglobin levels, buprenorphine dosage, and complication rate. Length of stay (3.62 vs 6.37 days), analgesic requirement, direct cost, and return to normal activities were lower in simultaneous bilateral tubeless PCNL. The primary SFR in this study was 80%, and it correlates well with data reported in the literature.8 Three patients (12%) required second ancillary procedures; the rate of complications was low (grade I, 12%; grade II, 16%; and grade IIIA, 4%); only 1 patient reported a major complication due to unilateral hydrothorax during a supracostal access requiring pleural drainage under local anesthesia. No other severe complications occurred, and in particular, none of these complications could be attributed to the procedure being done bilaterally. The most frequent complication was fever (16%) that was always managed by antibiotics; none of them evolved into septic shock syndrome nor required an intensive care unit stay. UROLOGY 85 (2), 2015
Postoperative fever, pyelonephritis, and sepsis are common complications of PCNL. The most common risk factors associated with post-PCNL infection are bacteriuria, stone size, and operative time.13 As a matter of fact, it is mandatory to treat patients having a positive urine culture result before the procedure on the basis of bacterial sensitivities; despite this, sometimes the bacterial colonization of stones and preoperative obstruction of parts of the collecting system that blocks the drainage of infected material make it impossible to obtain a sterilization of the urine before PCNL.14 Moreover, like in all other endoscopic procedures, during PCNL, high intrarenal pressure may develop favoring pyelotubular, pyelolymphatic, and pyelovenous backflow of the bacteria into the blood.15 This is a factor in favor of the supine BPCNL: usually the collecting system is not distended during percutaneous manipulation in the supine position due to parallel or downward orientation of the Amplatz sheath allowing for both spontaneous fragments evacuation and containment of pressure’s peak of intrarenal pressure, reducing the risk of fluid absorption.1,16 Regarding renal function, in our study, the serum creatinine levels, not negligibly changed only on the first postoperative day that returned to normal levels within 1 week, remained stable even after 1 month. This finding is rather expectable because of course performing bilateral renal surgery at the same session may cause a temporary renal “stupor” with consequent early transient renal function impairment. Sharifiaghdas et al showed that the urinary level of b2-microglobulin, which is considered an early marker of tubular injury, increases in the first postoperative day after PCNL, returning at normal levels within 1 week.17 This temporary renal damage, which remains hidden in unilateral case because of the supplementary activity of the contralateral kidney, is what probably determines this is not a negligible early increase of creatinine level in our patients. Nevertheless, it is of utmost importance to stress that this mild impairment is absolutely temporary without any clinical sequelae already after 1 week and definitely after 1 month. Nevertheless, we point out that none of our patients was treated for problems related to impaired renal function. Moreover, several recent reports demonstrated that, once proper patients’ selection and a watchful procedure’s execution are carried out, bilateral endourologic procedures performed in the same session are both effective and safe with acute renal failure anecdotal.6-8 The present study is the first to report on BPCNL in the supine position performed in the same session. Although PCNL has been traditionally performed in the prone position for >2 decades, the enthusiasm for this innovative position generated a robust literature that made European Association of Urology to include it in its last version guidelines for urolithiasis acknowledging that supine PCNL is equally effective compared with the prone PCNL.2
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Supine position certainly offers some advantages over prone PCNL: easier, quicker, and safer patient positioning in terms of nervous system protection, better cardiovascular management, and airways control18; more comfort for the surgeon who can operate sitting down; lower radiation exposure over the surgeon’s hands; and better drainage through a downward-oriented Amplatz sheath facilitating both spontaneous evacuation of stone fragments and lower intrarenal pressure. Moreover, a combination of antegrade and retrograde approaches is definitely easier and more effective.10,19 On the other hand, some drawbacks do exist compared with the prone approach. These include hypermobility of the kidney, reduced window of puncture, and longer percutaneous tract with consequent limitation in rigid nephroscope manipulation.20 Nevertheless, supine percutaneous surgeons, by becoming more familiar with this position, have already developed tips and tricks to overcome them encouraging extensive use of flexible scopes both antegrade and retrograde so that the aforementioned advantages are not significantly outweighed by these limitations. Currently, there is a general consensus that the greatest concern for use of the supine position by urologists, that is, the risk of colonic injury, was overestimated. Hopper et al back in 1987 demonstrated in an elegant study, performed with CT scan, that the colon becomes retrorenal in 1.8% and 10% of cases in the supine and prone positions, respectively21; therefore, the risk of colon injury is actually greater in the prone than in the supine position. In our study, colon injuries never occurred. In addition, our modification of the traditional supine Valdivia position22 obtained by placing only 1 small bolster completely hidden under the flank of the patient allows for a minor rotation of the patient to an angle of only 15 -20 so that a bigger area for puncture is achieved with better radiologic visibility of the kidney, which in this way lies lateral to the spine. Moreover, this position facilitates the nephroscope’s manipulation preventing any kind of conflict between the scope itself and the usual big bolster (3-L saline bag) in between the patient and the operating bed. Another advantage of the supine position is that the procedure takes a shorter operative time than the prone position23 because turning the patient upside down is not required. Certainly, one may argue that in the case of synchronous BPCNL, the advantage of supine position in terms of operative time is outweighed by the necessity of changing position and draping between one side and the other: nevertheless, in this study, the total operative time (120 45.4 minutes) is comparable with those reported in the literature for prone BPCNL.7,8 Moreover, Liu et al in a systematic review and metaanalysis reported that both PCNL positions appeared to be equivalent with regard to the SFR (P ¼ .59), complication rate (P ¼ .72), transfusion need (P ¼ .07), and fever rate (P ¼ .09). In brief, it has been
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demonstrated that the supine position is as effective and safe as the prone PCNL.24 If synchronous BPCNL and staged PCNL are compared, even though in this study economic aspects were not analyzed, in literature, it has been reported that cost analysis highlights an economic advantage toward the synchronous bilateral procedure. These cost savings can be significant if some variables are evaluated, such as cumulative hospital stay, room and anesthesia time, preoperative and postoperative laboratory analysis, use of equipment and disposable instruments, drugs administration, and postoperative imaging.25 This excludes consideration of social cost, however. It is rather intuitive that time to return to normal activities is much shorter in the case of the bilateral procedure. It should be stressed that, in the period of current financial constraints, provided that clinical safety and outcomes are guaranteed, social cost containment is something that a doctor should always be aware of. However, in contrast to the facts presented, cost reimbursements for synchronous BPCNL are inconsistent and are not adjusted to the complexity of the procedure and the real social cost saving provided. This issue might become a disincentive to perform a simultaneous procedure and might influence the surgical attitude of the urologist facing such a very delicate procedure that is insufficiently remunerated.26 Although surgeons are generally conscious of the resource context in which they operate, there is potential for conflict with the ethical choice we have followed here by selecting BPCNL as the ideal solution for a patient, although less remunerative for the hospital. In addition, we tried to further contain costs by pursuing tubeless BPCNL whenever possible because it has been demonstrated that costs are significantly reduced if a tubeless procedure is performed because of the decreased expenses associated with a shorter hospital stay.27 In fact, Giusti et al27 reported a statistically significant difference between tubeless and standard PCNL in terms of hospitalization (2.2 vs 5.3 days) as well as a reduction in the amount of analgesics, postoperative patients’ discomfort, and convalescence. As a consequence, in this study, 76% of procedures were bilaterally tubeless, 16% unilateral tubeless, and the rest were bilateral standard PCNL reducing hospital stay to a very short period of time (3.6 1.8 days). Of note, all patients who required opioid analgesics underwent nephrostomy tube placement after PCNL according to the general understanding that pain related to PCNL is basically related to the presence and the diameter of the nephrostomy tube rather than to the diameter of the tract [30].28,29 Moreover, several reports have shown the safety of a tubeless procedure compared with standard PCNL demonstrating that the placement of a nephrostomy tube at the end of PCNL is more due to habit than to clinical necessity27 and, as such, also bilateral procedures may benefit from this innovative version of PCNL. 308
Our study certainly presents some limitations: it is a purely retrospective study with a small cohort of patients, and a comparison group is missing; however, to our best knowledge, it is the first study in the literature that describes single-session BPCNL in the supine position showing all the advantages of this procedure.
CONCLUSION Bearing in mind all the limitations due to the small size and to the pure retrospective nature of this study, our results demonstrate that supine BPCNL performed in the same session is effective and safe in patients affected with bilateral renal calculi. On the other hand, it is still a very challenging operation, and consequently, it should be performed only by experienced surgeons in a tertiary center. References 1. Preminger GM, Assimos DG, Lingeman JE, et al. Chapter 1: AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations. J Urol. 2005;173:1991-2000. 2. T€urk C, Knoll T, Petrik A, et al. EAU Guidelines on Urolithiasis. 2014. 3. Fernstrom I, Johansson B. Percutaneous pyelolithotomy: a new extraction technique. Scand J Urol Nephrol. 1976;10:257-259. 4. Armitage JN. Editorial comment from Dr Armitage to tubeless simultaneous bilateral percutaneous nephrolithotomy: safety, feasibility and efficacy in an Indian setting. Int J Urol. 2014;21:502-503. 5. Holman E, Salah MA, Toth C. Comparison of 150 simultaneous bilateral and 300 unilateral percutaneous nephrolithotomies. J Endourol. 2002;16:33-36. 6. Desai M, Grover R, Manohar T, et al. Simultaneous bilateral percutaneous nephrolithotomy: a single-center experience. J Endourol. 2007;21:508-514. 7. Pillai S, Mishra D, Sharma P, et al. Tubeless simultaneous bilateral percutaneous nephrolithotomy: safety, feasibility and efficacy in an Indian setting. Int J Urol. 2014;2:497-502. 8. Wang CJ, Chang CH, Huang SW. Simultaneous bilateral tubeless percutaneous nephrolithotomy of staghorn stones: a prospective randomized controlled study. Urol Res. 2011;39:289-294. 9. de la Rosette JJ, Opondo D, Daels FP, et al; on behalf of the CROES PCNL Study Group. Categorisation of complications and validation of the Clavien score for percutaneous nephrolithotomy. Eur Urol. 2012;62:246-250. 10. Ibarluzea G, Scoffone CM, Cracco CM, et al. Supine Valdivia and modified lithotomy position for simultaneous anterograde and retrograde endourological access. BJU Int. 2007 Jul;100:233-236. 11. Stamatelou KK, Francis ME, Jones CA, et al. Time trends in reported prevalence of kidney stones in the United States: 1976-1994. Kidney Int. 2003;63:1817-1823. 12. Sreenevasan G. Bilateral renal calculi. Ann R Coll Surg Engl. 1974; 55:3-12. 13. Kreydin EI, Eisner BH. Risk factors for sepsis after percutaneous renal stone surgery. Nat Rev Urol. 2013;10:598-605. 14. Charton M, Vallancien G, Veillon B, et al. Urinary tract infection in percutaneous surgery for renal calculi. J Urol. 1986;135:15-17. 15. Stenberg A, Bohman SO, Morsing P, et al. Back-leak of pelvic urine to the bloodstream. Acta Physiol Scand. 1988;134:223-234. 16. Kukreja RA, Desai MR, Sabnis RB, et al. Fluid absorption during percutaneous nephrolithotomy: does it matter? J Endourol. 2002;16: 221-224. 17. Sharifiaghdas F, Kashi AH, Eshratkhah R. Evaluating percutaneous nephrolithotomy-induced kidney damage by measuring urinary concentrations of b2-microglobulin. Urol J. 2011;8:277-282.
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18. Edgcombe H, Carter K, Yarrow S. Anaesthesia in the prone position. Br J Anaesth. 2008;100:165-183. 19. Scoffone CM, Cracco CM, Cossu M, et al. Endoscopic combined intrarenal surgery in Galdakao-modified supine Valdivia position: a new standard for percutaneous nephrolithotomy? Eur Urol. 2008;54: 1393-1403. 20. Duty B, Waingakar N, Okhunov Z, et al. Anatomical variation between the prone, supine and supine oblique positions on computed tomography: implications for percutaneous nephrolithotomy access. Urology. 2012;79:67-71. 21. Hopper KD, Sherman JL, Luethke JM, et al. The retrorenal colon in the supine and prone patient. Radiology. 1987;162:443-446. 22. Valdivia Urıa JG, Valle Gerhold J, Lopez Lopez JA, et al. Technique and complications of percutaneous nephroscopy: experience with 557 patients in the supine position. J Urol. 1998;160:19751978. 23. De Sio M, Autorino R, Quarto G, et al. Modified supine versus prone position in percutaneous nephrolithotomy for renal stones treatable with a single percutaneous access: a prospective randomized trial. Eur Urol. 2008;54:196-202. 24. Liu L, Zheng S, Xu Y, et al. Systematic review and meta-analysis of percutaneous nephrolithotomy for patients in the supine versus prone position. J Endourol. 2010;24:1941-1946. 25. Bagrodia A, Raman JD, Bensalah K, et al. Synchronous bilateral percutaneous nephrostolithotomy: analysis of clinical outcomes, cost and surgeon reimbursement. J Urol. 2009;181:149-153. 26. Bagrodia A, Gupta A, Raman JD, et al. Predictors of cost and clinical outcomes of percutaneous nephrostolithotomy. J Urol. 2009;182:586-590. 27. Giusti G, Piccinelli A, Maugeri O, et al. Percutaneous nephrolithotomy: tubeless or not tubeless. Urol Res. 2009;37:153-158. 28. Pietrow PK, Auge BK, Lallas CD, et al. Pain after percutaneous nephrolithotomy: impact of nephrostomy tube size. J Endourol. 2003;17:411-414. 29. Desai MR, Kukreja RA, Desai MM, et al. A prospective randomized comparison of type of nephrostomy drainage following percutaneous nephrostolithotomy: large bore versus small bore versus tubeless. J Urol. 2004;172:565-567.
EDITORIAL COMMENT One of the more contentious issues in the world of percutaneous nephrolithotomy (PNL) during the past few years has been supine vs prone positioning. Each approach has its relative advantages and disadvantages, many of which are enumerated by the authors1 in the present article. This study1 will not serve to settle this debate and declare a victor. What it does do, although, is introduce the concept of performing bilateral PNL in the same setting through a supine approach. In the authors’1 experience, they undertook this procedure in a series of patients and claim excellent results. Although the series is small, the results do objectively suggest a relative safety of this approach. However, the usual caveats to such a series apply as follows: patient selection, surgeon experience, and institutional volume. Nonetheless, for surgeons who do routinely perform supine PNL, the same session bilateral procedure may be considered for select patients. I do not believe that this approach offers meaningful advantages over a similar procedure performed in the prone position but certainly merits consideration for those facile in the supine protocol. Brian R. Matlaga, M.D., M.P.H., James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, MD
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Reference 1. Proietti S, Sortino G, Antonella G. Single-session supine bilateral percutaneous nephrolithotomy. Urology. 2015;85:304-310.
http://dx.doi.org/10.1016/j.urology.2014.10.037 UROLOGY 85: 309, 2015. 2015 Elsevier Inc.
REPLY In 1976, Fernstrom and Johansson1 revolutionized the surgical approach to urolithiasis by introducing percutaneous nephrolithotomy (PCNL) in the prone position. That position was considered the only possible way because, at that time, pioneers of endourology estimated that there was a high risk of puncturing the colon. Since then, this surgical approach has continued to evolve to improve the stone-free rate while reducing the invasiveness and morbidity of the procedure. Already in 1990, Valdivia Uria was able to demonstrate that this risk was overestimated, reporting encouraging results of the supine PCNL2 starting from the concept that a retrorenal colon is present only in 1.9% of the cases in the supine position and up to 10% in the prone.3 Despite this, the supine position did not take over for years not because it was not effective and safe but because prone PCNL was already established with optimal outcomes in the hands of the vast majority of urologists worldwide. Urolithiasis that involves both renal units in 10.7%-26% of cases has become an intriguing challenge for endourologists who, in selected patients, may be keen to treat bilateral renal stones in the same operative session. Prone simultaneous bilateral PCNL (SBPCNL), although not largely widespread, has been shown to be safe and effective.4 For the first time, our study reported the good outcomes of SBPCNL in the supine position showing high stone-free rate and low complication rate5. In the last decade, supine PCNL has become increasingly widespread in Latin Europe and many surgeons, including the authors of the present study, have shifted completely to this new approach, abandoning progressively the prone position. Our study was carried out, not to directly contribute to the debate between the prone and supine positions, but to report our experience on supine SBPCNL providing evidence on the success rate in this position even in the difficult clinical setting in which the prone approach is supposed to be clearly superior. In practice, an increased familiarity with the supine PCNL results in surgeons becoming uncomfortable returning to the prone position to perform, for example, bilateral procedures, even considering the advantage of a single position and draping of the patient for both sides. Concerns that the supine SBPCNL could be considered not worthwhile and time-consuming compared with the prone position in this clinical scenario were unfounded, and we listed a series of advantages of the supine approach. Nevertheless, SBPCNL, both supine and prone positions, is still a very challenging surgery, and consequently, it should be performed by experienced endourologists in high-volume centers. It should be performed on well-selected patients to achieve good results with acceptable complication rates. In reality, the assessment of whether the prone or supine SBPCNL provides the best results is only initiating; only forthcoming, randomized, multicenter studies comparing these procedures may discern the best procedure.
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Guido Giusti, M.D., and Silvia Proietti, M.D., F.E.B.U, Stone Center at Department of Urology, Humanitas Clinical and Research Center, Rozzano, Milan, Italy
References 1. Fernstrom I, Johansson B. Percutaneous pyelolithotomy: a new extraction technique. Scand J Urol Nephrol. 1976;10:257-259. 2. Valdivia Urıa JG, Valle Gerhold J, Lopez Lopez JA, et al. Technique and complications of percutaneous nephroscopy: experience with 557 patients in the supine position. J Urol. 1998;160:1975-1978.
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3. Hopper KD, Sherman JL, Luethke JM, et al. The retrorenal colon in the supine and prone patient. Radiology. 1987;162:443-446. 4. Desai M, Grover R, Manohar T, et al. Simultaneous bilateral percutaneous nephrolithotomy: a single-center experience. J Endourol. 2007; 21:508-514. 5. Proietti S, Sortino G, Antonella G. Single-session supine bilateral percutaneous nephrolithotomy. Urology. 2015;85:304-310.
http://dx.doi.org/10.1016/j.urology.2014.10.038 UROLOGY 85: 309e310, 2015. 2015 Elsevier Inc.
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RESULTS
CONCLUSION
To evaluate the effectiveness and safety of supine bilateral percutaneous nephrolithotomy (BPCNL) performed in the same session in patients affected with bilateral renal calculi. We retrospectively identified patients with bilateral renal stones with diameters >2 cm for each side, who had been treated with supine BPCNL in the same session, from November 2006 to April 2014. We reviewed demographic and stone characteristics, intraoperative and perioperative outcomes, and complications related to the procedure adopted. The stone size was calculated by measuring the maximum stone diameter by computed tomography scan. Stone-free rate was defined as clinically insignificant when residual fragments of 2 mm were detected by computed tomography scan. Twenty-five patients were included in the study; the mean age was 51.9 11.4 years; the mean maximum stone diameter per renal unit was 3.1 0.8 cm. Statistical significant differences in creatinine serum levels were detected at day 1 postoperatively compared with the baseline (P .05). The primary stone-free rate was 80%; ancillary procedures were performed in 3 of 25 patients (12%). Grade I complications occurred in 3 patients (12%), grade II in 4 patients (16%), and grade IIIA in 1 patient (4%). Supine BPCNL performed in the same session is a safe and effective procedure in patients affected with bilateral renal calculi. On the other hand, it is still a very challenging operation, and consequently, it should be performed only by experienced surgeons in a tertiary center. UROLOGY 85: 304e310, 2015. 2015 Elsevier Inc.
A
ccording to both American Urological Association and European Association of Urology guidelines, percutaneous nephrolithotomy (PCNL) is considered the first-line treatment for renal stones >2 cm.1,2 The first PCNL was described by Fernstrom and Johansson3 in 1976, and since then, this surgical approach has undergone significant changes with the purpose of minimizing both invasivity and morbidity together with improving outcomes. The remarkable progress achieved in surgical techniques and equipment have improved the efficacy and reduced operative time and complications, expanding the treatment options for complicated stone patients such as those with bilateral Financial Disclosure: Guido Giusti is a paid consultant for Boston Scientific, Cook Medical, Porges Coloplast Division, and Karl Storz. The remaining authors declare that they have no relevant financial interests. From the Stone Center at Department of Urology, Humanitas Clinical and Research Center, Rozzano, MI, Italy; the Department of Urology, Policlinico Hospital, University of Catania, Catania, Italy; the Department of Surgical and Biochemical Science, Urologic and Andrologic Clinic, University of Perugia, Perugia, Italy; the Division of Endourology, Sourasky Medical Center, Tel-Aviv University, Tel-Aviv, Israel; and the Department of Urology, Santa Chiara Hospital, Trento, Italy Address correspondence to: Guido Giusti, M.D., Stone Center at Department of Urology, Humanitas Clinical and Research Center, Rozzano, Milano 20089, Italy. E-mail: [email protected] Submitted: July 7, 2014, accepted (with revisions): October 14, 2014
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calculi.4 Historically, patients with bilateral large stone burdens have always been a therapeutic challenge to the urologist. Traditionally, these patients had been treated with staged procedures, to avoid the increased morbidity of bilateral kidney surgery and to prevent injury to or infection of both renal units together. Nowadays, bilateral PCNL (BPCNL) performed in the same operative session is considered, in high-volume centers and experienced hands, to be a well-tolerated, safe, and effective procedure for these patients, able to avoid the risk of a second anesthesia, and to decrease morbidity and length of hospitalization.5-8 However, the removal of large and/or complex bilateral renal stones still represents a difficult task for urologists. As a consequence, there are few studies on this challenging issue and, most importantly, to date, none have described single-session BPCNL in the supine position. The aim of this study was to evaluate the effectiveness and safety of supine single-session BPCNL in patients affected with bilateral renal calculi.
METHODS We retrospectively identified patients with bilateral renal stones with diameters of >2 cm for each side, who had been treated http://dx.doi.org/10.1016/j.urology.2014.10.036 0090-4295/15
with supine BPCNL performed in the same session, from November 2006 to April 2014. Routine preoperative workup included the following: medical history, physical examination, blood samples analysis, urine and urine culture, unenhanced computed tomography (CT) scan. One day, 1 week, and 1 month after the procedure, blood samples analysis was obtained. Estimated glomerular filtration rate was calculated. Before asking for informed consent from all the patients, we also informed and offered staged metachronous PCNL as an alternative treatment option. We also clearly specified that, in case of opting for an approach performed in the same session, the contralateral side would not be attempted in the event of long operative time and/or complications occurring in the first side. All the surgical procedures were carried out by a single surgeon (G.G.). Initially, the more symptomatic side was treated. We reviewed demographic and stone characteristics, intraoperative and perioperative outcomes, and complications related to the procedure adopted. Operative time was calculated from the time of cystoscope insertion to the completion of skin suture in the second side. The Clinical Research Office of the Endourological Society validation of Clavien score for PCNL complications was used.9 The stone size was calculated by measuring the maximum stone diameter by CT scan. Stone-free rate (SFR) was defined as clinically insignificant when residual fragments of 2 mm were detected by CT scan. In case of significant residual stone, the patient was scheduled for a second-look procedure, second-look PCNL, or flexible ureteroscopy depending on the dimensions of fragments.
Technique Under general anesthesia, patients are positioned in classical supine decubitus position, according to personal modification of the classical Valdivia position: the patient is placed with the side of interest at the edge of the table, with a small jelly bolster under and all along the flank to obtain a mild rotation not exceeding an angle of 15 -20 (Fig. 1). The ipsilateral arm is adequately protected and left lying over the thorax avoiding any stretch of brachial plexus; the legs are kept open and straight according to the Galdakao position.10 The inferior edge of the 12th rib, the iliac crest, and the posterior axillary line are marked on the patient’s skin. A retrograde ureteral occlusion balloon catheter is placed over the guidewire on the first side, and after retrograde pyelography, carefully inflated at the level of the ureteropelvic junction. Puncture is carried out under solely fluoroscopic control. Once access is gained, hydrophilic guidewire is passed through the ureter and down to the bladder for its stabilization. Subsequently, balloon dilation is performed and an Amplatz working sheath is placed, ranging between 24 and 30 Fr according to the dimensions of stones and targeted calices features (Ultraxx 24 Fr; Cook Medical, Bloomington, IL; NephroMax 30 Fr; Boston Scientific, Natick, MA). Ultrasonic lithotripsy is carried out through rigid nephroscopy. Stone fragments are then removed using a zero-tip disposable basket (N-Perc; Cook Medical, Bloomington, IL). A final flexible nephroscopy is always carried out to confirm stone-free status. Stone clearance is also confirmed by fluoroscopy. At the end of the procedure, antegrade stenting is accomplished under fluoroscopic guidance and a 10-Fr nephrostomy tube is positioned only in case of major bleeding, major perforation of the collecting system, or residual stones suitable for the second-look PCNL. Otherwise, the procedure ends in a UROLOGY 85 (2), 2015
Figure 1. Supine percutaneous nephrolithotomy position with a small jelly bolster under and along the flank. (Color version available online.) Table 1. Demographic and stone characteristics of patients (n ¼ 25)
Gender, n (%) Male Female Age (mean SD), y BMI (mean SD), kg/m2 ASA score (mean SD) Maximum stone diameter per renal unit (mean SD), cm Hounsfield units (mean SD)
16 (64) 9 (36) 51.9 11.4 25.8 2.1 2.5 0.7 3.1 0.8 1100 280
ASA, American Society of Anesthesiologists; BMI, body mass index; SD, standard deviation.
tubeless fashion. Only in cases where the first-side surgery has been without complications, we proceed with the second side. In this case, the patient is placed in a specular supine position, and the same surgical technique is adopted for the second side. At the end of the procedure, an 18-Fr Foley catheter is left in place overnight.
Statistical Analysis. Statistical analysis was performed with GraphPad Prism, version 6.0, for Mac (GraphPad, Prism Software Inc). Normality testing (the D’Agostino-Pearson test) was performed to determine whether data were sampled from a Gaussian distribution. One-way analysis of variance was performed to compare serum creatinine levels. Statistically significant difference was considered for P .05. First postoperative day vs first postoperative week; P value .05.
Table 3. Intraoperative and postoperative outcomes Operative time (both sides; mean SD), min 120 45.4 Hemoglobin drop (mean SD), g/dL 2.1 0.5 Length of hospital stay (mean SD), d 3.6 1.8 Primary SFR, n (%) 20/25 (80) Need of ancillary procedures, n (%) 3/25 (12) (1 PCNL and 2 fURS) Nephrostomy tube placement, n (%) Bilateral tubeless 19/25 (76) Monolateral tubeless 4/25 (16) Complications, grade, n (%) Grade I 3 (12) (postoperative pain managed by opioid) Grade II 4 (16) (fever managed by antibiotics in the ward) Grade IIIA 1 (4) (hydrothorax managed by intercostal draining under local anesthesia) fURS, flexible ureteroscopy; PCNL, percutaneous nephrolithotomy; SFR, stone-free rate; other abbreviation as in Table 1.
with the baseline (P .05; Table 2). No significant difference in the estimated glomerular filtration rate was observed between the baseline and 1 month postoperatively (80.9 20 vs 80.2 23; P >.05). Overall, average operative time was 120 45.4 minutes; primary SFR was 80%; and 3 of 25 patients (12%) needed ancillary procedures, 1 and 2 patients underwent second-look PCNL and flexible ureteroscopy, respectively. Bilateral tubeless procedures were performed in 19 of 25 cases (76%) and monolateral tubeless procedures in 4 of 25 patients (16%). Grade I, II, and IIIA complications were recorded in 3 (12%), 4 (16%), and 1 (4%) patient (Table 3).
COMMENT Urolithiasis is a common disease with a lifetime risk of stone formation in the western world as high as 12% in men and 6% in women.11 Furthermore, kidney stone disease incidence and prevalence are increasing, and, similarly, the overall incidence of bilateral renal stones is not negligible, being reported to range from 10.7% to 26% in patients with metabolic abnormalities.12 As a consequence, patients with bilateral renal stones are not anecdotal as in the past and represent a cumbersome challenge to endourologists. To date, there are already some studies that have reported the safety and effectiveness of prone BPCNL performed in the same operative session.5-8 Desai et al6 reported a series of 45 prone BPCNLs with a mean operative time of 107 43 minutes achieving a 306
remarkable 95% SFR. Of note, blood loss and creatinine serum level changes were negligible after 48 hours. Holman et al5 showed in their series of 198 patients of single-session BPCNL, a primary SFR of 90%; no significant change in serum creatinine levels in 77% of patients after 2-3 days postoperatively; and in 11% of patients, there was a significant transient increase in serum creatinine levels that return to normal within a mean of 5 days. As far as PCNL is concerned, Wang et al8 compared staged and synchronous tubeless PCNL for bilateral staghorn calculi in a randomized controlled study: the SFR was 71.4% and 72%, respectively, with no difference with regard to changes in serum creatinine levels, hemoglobin levels, buprenorphine dosage, and complication rate. Length of stay (3.62 vs 6.37 days), analgesic requirement, direct cost, and return to normal activities were lower in simultaneous bilateral tubeless PCNL. The primary SFR in this study was 80%, and it correlates well with data reported in the literature.8 Three patients (12%) required second ancillary procedures; the rate of complications was low (grade I, 12%; grade II, 16%; and grade IIIA, 4%); only 1 patient reported a major complication due to unilateral hydrothorax during a supracostal access requiring pleural drainage under local anesthesia. No other severe complications occurred, and in particular, none of these complications could be attributed to the procedure being done bilaterally. The most frequent complication was fever (16%) that was always managed by antibiotics; none of them evolved into septic shock syndrome nor required an intensive care unit stay. UROLOGY 85 (2), 2015
Postoperative fever, pyelonephritis, and sepsis are common complications of PCNL. The most common risk factors associated with post-PCNL infection are bacteriuria, stone size, and operative time.13 As a matter of fact, it is mandatory to treat patients having a positive urine culture result before the procedure on the basis of bacterial sensitivities; despite this, sometimes the bacterial colonization of stones and preoperative obstruction of parts of the collecting system that blocks the drainage of infected material make it impossible to obtain a sterilization of the urine before PCNL.14 Moreover, like in all other endoscopic procedures, during PCNL, high intrarenal pressure may develop favoring pyelotubular, pyelolymphatic, and pyelovenous backflow of the bacteria into the blood.15 This is a factor in favor of the supine BPCNL: usually the collecting system is not distended during percutaneous manipulation in the supine position due to parallel or downward orientation of the Amplatz sheath allowing for both spontaneous fragments evacuation and containment of pressure’s peak of intrarenal pressure, reducing the risk of fluid absorption.1,16 Regarding renal function, in our study, the serum creatinine levels, not negligibly changed only on the first postoperative day that returned to normal levels within 1 week, remained stable even after 1 month. This finding is rather expectable because of course performing bilateral renal surgery at the same session may cause a temporary renal “stupor” with consequent early transient renal function impairment. Sharifiaghdas et al showed that the urinary level of b2-microglobulin, which is considered an early marker of tubular injury, increases in the first postoperative day after PCNL, returning at normal levels within 1 week.17 This temporary renal damage, which remains hidden in unilateral case because of the supplementary activity of the contralateral kidney, is what probably determines this is not a negligible early increase of creatinine level in our patients. Nevertheless, it is of utmost importance to stress that this mild impairment is absolutely temporary without any clinical sequelae already after 1 week and definitely after 1 month. Nevertheless, we point out that none of our patients was treated for problems related to impaired renal function. Moreover, several recent reports demonstrated that, once proper patients’ selection and a watchful procedure’s execution are carried out, bilateral endourologic procedures performed in the same session are both effective and safe with acute renal failure anecdotal.6-8 The present study is the first to report on BPCNL in the supine position performed in the same session. Although PCNL has been traditionally performed in the prone position for >2 decades, the enthusiasm for this innovative position generated a robust literature that made European Association of Urology to include it in its last version guidelines for urolithiasis acknowledging that supine PCNL is equally effective compared with the prone PCNL.2
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Supine position certainly offers some advantages over prone PCNL: easier, quicker, and safer patient positioning in terms of nervous system protection, better cardiovascular management, and airways control18; more comfort for the surgeon who can operate sitting down; lower radiation exposure over the surgeon’s hands; and better drainage through a downward-oriented Amplatz sheath facilitating both spontaneous evacuation of stone fragments and lower intrarenal pressure. Moreover, a combination of antegrade and retrograde approaches is definitely easier and more effective.10,19 On the other hand, some drawbacks do exist compared with the prone approach. These include hypermobility of the kidney, reduced window of puncture, and longer percutaneous tract with consequent limitation in rigid nephroscope manipulation.20 Nevertheless, supine percutaneous surgeons, by becoming more familiar with this position, have already developed tips and tricks to overcome them encouraging extensive use of flexible scopes both antegrade and retrograde so that the aforementioned advantages are not significantly outweighed by these limitations. Currently, there is a general consensus that the greatest concern for use of the supine position by urologists, that is, the risk of colonic injury, was overestimated. Hopper et al back in 1987 demonstrated in an elegant study, performed with CT scan, that the colon becomes retrorenal in 1.8% and 10% of cases in the supine and prone positions, respectively21; therefore, the risk of colon injury is actually greater in the prone than in the supine position. In our study, colon injuries never occurred. In addition, our modification of the traditional supine Valdivia position22 obtained by placing only 1 small bolster completely hidden under the flank of the patient allows for a minor rotation of the patient to an angle of only 15 -20 so that a bigger area for puncture is achieved with better radiologic visibility of the kidney, which in this way lies lateral to the spine. Moreover, this position facilitates the nephroscope’s manipulation preventing any kind of conflict between the scope itself and the usual big bolster (3-L saline bag) in between the patient and the operating bed. Another advantage of the supine position is that the procedure takes a shorter operative time than the prone position23 because turning the patient upside down is not required. Certainly, one may argue that in the case of synchronous BPCNL, the advantage of supine position in terms of operative time is outweighed by the necessity of changing position and draping between one side and the other: nevertheless, in this study, the total operative time (120 45.4 minutes) is comparable with those reported in the literature for prone BPCNL.7,8 Moreover, Liu et al in a systematic review and metaanalysis reported that both PCNL positions appeared to be equivalent with regard to the SFR (P ¼ .59), complication rate (P ¼ .72), transfusion need (P ¼ .07), and fever rate (P ¼ .09). In brief, it has been
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demonstrated that the supine position is as effective and safe as the prone PCNL.24 If synchronous BPCNL and staged PCNL are compared, even though in this study economic aspects were not analyzed, in literature, it has been reported that cost analysis highlights an economic advantage toward the synchronous bilateral procedure. These cost savings can be significant if some variables are evaluated, such as cumulative hospital stay, room and anesthesia time, preoperative and postoperative laboratory analysis, use of equipment and disposable instruments, drugs administration, and postoperative imaging.25 This excludes consideration of social cost, however. It is rather intuitive that time to return to normal activities is much shorter in the case of the bilateral procedure. It should be stressed that, in the period of current financial constraints, provided that clinical safety and outcomes are guaranteed, social cost containment is something that a doctor should always be aware of. However, in contrast to the facts presented, cost reimbursements for synchronous BPCNL are inconsistent and are not adjusted to the complexity of the procedure and the real social cost saving provided. This issue might become a disincentive to perform a simultaneous procedure and might influence the surgical attitude of the urologist facing such a very delicate procedure that is insufficiently remunerated.26 Although surgeons are generally conscious of the resource context in which they operate, there is potential for conflict with the ethical choice we have followed here by selecting BPCNL as the ideal solution for a patient, although less remunerative for the hospital. In addition, we tried to further contain costs by pursuing tubeless BPCNL whenever possible because it has been demonstrated that costs are significantly reduced if a tubeless procedure is performed because of the decreased expenses associated with a shorter hospital stay.27 In fact, Giusti et al27 reported a statistically significant difference between tubeless and standard PCNL in terms of hospitalization (2.2 vs 5.3 days) as well as a reduction in the amount of analgesics, postoperative patients’ discomfort, and convalescence. As a consequence, in this study, 76% of procedures were bilaterally tubeless, 16% unilateral tubeless, and the rest were bilateral standard PCNL reducing hospital stay to a very short period of time (3.6 1.8 days). Of note, all patients who required opioid analgesics underwent nephrostomy tube placement after PCNL according to the general understanding that pain related to PCNL is basically related to the presence and the diameter of the nephrostomy tube rather than to the diameter of the tract [30].28,29 Moreover, several reports have shown the safety of a tubeless procedure compared with standard PCNL demonstrating that the placement of a nephrostomy tube at the end of PCNL is more due to habit than to clinical necessity27 and, as such, also bilateral procedures may benefit from this innovative version of PCNL. 308
Our study certainly presents some limitations: it is a purely retrospective study with a small cohort of patients, and a comparison group is missing; however, to our best knowledge, it is the first study in the literature that describes single-session BPCNL in the supine position showing all the advantages of this procedure.
CONCLUSION Bearing in mind all the limitations due to the small size and to the pure retrospective nature of this study, our results demonstrate that supine BPCNL performed in the same session is effective and safe in patients affected with bilateral renal calculi. On the other hand, it is still a very challenging operation, and consequently, it should be performed only by experienced surgeons in a tertiary center. References 1. Preminger GM, Assimos DG, Lingeman JE, et al. Chapter 1: AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations. J Urol. 2005;173:1991-2000. 2. T€urk C, Knoll T, Petrik A, et al. EAU Guidelines on Urolithiasis. 2014. 3. Fernstrom I, Johansson B. Percutaneous pyelolithotomy: a new extraction technique. Scand J Urol Nephrol. 1976;10:257-259. 4. Armitage JN. Editorial comment from Dr Armitage to tubeless simultaneous bilateral percutaneous nephrolithotomy: safety, feasibility and efficacy in an Indian setting. Int J Urol. 2014;21:502-503. 5. Holman E, Salah MA, Toth C. Comparison of 150 simultaneous bilateral and 300 unilateral percutaneous nephrolithotomies. J Endourol. 2002;16:33-36. 6. Desai M, Grover R, Manohar T, et al. Simultaneous bilateral percutaneous nephrolithotomy: a single-center experience. J Endourol. 2007;21:508-514. 7. Pillai S, Mishra D, Sharma P, et al. Tubeless simultaneous bilateral percutaneous nephrolithotomy: safety, feasibility and efficacy in an Indian setting. Int J Urol. 2014;2:497-502. 8. Wang CJ, Chang CH, Huang SW. Simultaneous bilateral tubeless percutaneous nephrolithotomy of staghorn stones: a prospective randomized controlled study. Urol Res. 2011;39:289-294. 9. de la Rosette JJ, Opondo D, Daels FP, et al; on behalf of the CROES PCNL Study Group. Categorisation of complications and validation of the Clavien score for percutaneous nephrolithotomy. Eur Urol. 2012;62:246-250. 10. Ibarluzea G, Scoffone CM, Cracco CM, et al. Supine Valdivia and modified lithotomy position for simultaneous anterograde and retrograde endourological access. BJU Int. 2007 Jul;100:233-236. 11. Stamatelou KK, Francis ME, Jones CA, et al. Time trends in reported prevalence of kidney stones in the United States: 1976-1994. Kidney Int. 2003;63:1817-1823. 12. Sreenevasan G. Bilateral renal calculi. Ann R Coll Surg Engl. 1974; 55:3-12. 13. Kreydin EI, Eisner BH. Risk factors for sepsis after percutaneous renal stone surgery. Nat Rev Urol. 2013;10:598-605. 14. Charton M, Vallancien G, Veillon B, et al. Urinary tract infection in percutaneous surgery for renal calculi. J Urol. 1986;135:15-17. 15. Stenberg A, Bohman SO, Morsing P, et al. Back-leak of pelvic urine to the bloodstream. Acta Physiol Scand. 1988;134:223-234. 16. Kukreja RA, Desai MR, Sabnis RB, et al. Fluid absorption during percutaneous nephrolithotomy: does it matter? J Endourol. 2002;16: 221-224. 17. Sharifiaghdas F, Kashi AH, Eshratkhah R. Evaluating percutaneous nephrolithotomy-induced kidney damage by measuring urinary concentrations of b2-microglobulin. Urol J. 2011;8:277-282.
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18. Edgcombe H, Carter K, Yarrow S. Anaesthesia in the prone position. Br J Anaesth. 2008;100:165-183. 19. Scoffone CM, Cracco CM, Cossu M, et al. Endoscopic combined intrarenal surgery in Galdakao-modified supine Valdivia position: a new standard for percutaneous nephrolithotomy? Eur Urol. 2008;54: 1393-1403. 20. Duty B, Waingakar N, Okhunov Z, et al. Anatomical variation between the prone, supine and supine oblique positions on computed tomography: implications for percutaneous nephrolithotomy access. Urology. 2012;79:67-71. 21. Hopper KD, Sherman JL, Luethke JM, et al. The retrorenal colon in the supine and prone patient. Radiology. 1987;162:443-446. 22. Valdivia Urıa JG, Valle Gerhold J, Lopez Lopez JA, et al. Technique and complications of percutaneous nephroscopy: experience with 557 patients in the supine position. J Urol. 1998;160:19751978. 23. De Sio M, Autorino R, Quarto G, et al. Modified supine versus prone position in percutaneous nephrolithotomy for renal stones treatable with a single percutaneous access: a prospective randomized trial. Eur Urol. 2008;54:196-202. 24. Liu L, Zheng S, Xu Y, et al. Systematic review and meta-analysis of percutaneous nephrolithotomy for patients in the supine versus prone position. J Endourol. 2010;24:1941-1946. 25. Bagrodia A, Raman JD, Bensalah K, et al. Synchronous bilateral percutaneous nephrostolithotomy: analysis of clinical outcomes, cost and surgeon reimbursement. J Urol. 2009;181:149-153. 26. Bagrodia A, Gupta A, Raman JD, et al. Predictors of cost and clinical outcomes of percutaneous nephrostolithotomy. J Urol. 2009;182:586-590. 27. Giusti G, Piccinelli A, Maugeri O, et al. Percutaneous nephrolithotomy: tubeless or not tubeless. Urol Res. 2009;37:153-158. 28. Pietrow PK, Auge BK, Lallas CD, et al. Pain after percutaneous nephrolithotomy: impact of nephrostomy tube size. J Endourol. 2003;17:411-414. 29. Desai MR, Kukreja RA, Desai MM, et al. A prospective randomized comparison of type of nephrostomy drainage following percutaneous nephrostolithotomy: large bore versus small bore versus tubeless. J Urol. 2004;172:565-567.
EDITORIAL COMMENT One of the more contentious issues in the world of percutaneous nephrolithotomy (PNL) during the past few years has been supine vs prone positioning. Each approach has its relative advantages and disadvantages, many of which are enumerated by the authors1 in the present article. This study1 will not serve to settle this debate and declare a victor. What it does do, although, is introduce the concept of performing bilateral PNL in the same setting through a supine approach. In the authors’1 experience, they undertook this procedure in a series of patients and claim excellent results. Although the series is small, the results do objectively suggest a relative safety of this approach. However, the usual caveats to such a series apply as follows: patient selection, surgeon experience, and institutional volume. Nonetheless, for surgeons who do routinely perform supine PNL, the same session bilateral procedure may be considered for select patients. I do not believe that this approach offers meaningful advantages over a similar procedure performed in the prone position but certainly merits consideration for those facile in the supine protocol. Brian R. Matlaga, M.D., M.P.H., James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, MD
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Reference 1. Proietti S, Sortino G, Antonella G. Single-session supine bilateral percutaneous nephrolithotomy. Urology. 2015;85:304-310.
http://dx.doi.org/10.1016/j.urology.2014.10.037 UROLOGY 85: 309, 2015. 2015 Elsevier Inc.
REPLY In 1976, Fernstrom and Johansson1 revolutionized the surgical approach to urolithiasis by introducing percutaneous nephrolithotomy (PCNL) in the prone position. That position was considered the only possible way because, at that time, pioneers of endourology estimated that there was a high risk of puncturing the colon. Since then, this surgical approach has continued to evolve to improve the stone-free rate while reducing the invasiveness and morbidity of the procedure. Already in 1990, Valdivia Uria was able to demonstrate that this risk was overestimated, reporting encouraging results of the supine PCNL2 starting from the concept that a retrorenal colon is present only in 1.9% of the cases in the supine position and up to 10% in the prone.3 Despite this, the supine position did not take over for years not because it was not effective and safe but because prone PCNL was already established with optimal outcomes in the hands of the vast majority of urologists worldwide. Urolithiasis that involves both renal units in 10.7%-26% of cases has become an intriguing challenge for endourologists who, in selected patients, may be keen to treat bilateral renal stones in the same operative session. Prone simultaneous bilateral PCNL (SBPCNL), although not largely widespread, has been shown to be safe and effective.4 For the first time, our study reported the good outcomes of SBPCNL in the supine position showing high stone-free rate and low complication rate5. In the last decade, supine PCNL has become increasingly widespread in Latin Europe and many surgeons, including the authors of the present study, have shifted completely to this new approach, abandoning progressively the prone position. Our study was carried out, not to directly contribute to the debate between the prone and supine positions, but to report our experience on supine SBPCNL providing evidence on the success rate in this position even in the difficult clinical setting in which the prone approach is supposed to be clearly superior. In practice, an increased familiarity with the supine PCNL results in surgeons becoming uncomfortable returning to the prone position to perform, for example, bilateral procedures, even considering the advantage of a single position and draping of the patient for both sides. Concerns that the supine SBPCNL could be considered not worthwhile and time-consuming compared with the prone position in this clinical scenario were unfounded, and we listed a series of advantages of the supine approach. Nevertheless, SBPCNL, both supine and prone positions, is still a very challenging surgery, and consequently, it should be performed by experienced endourologists in high-volume centers. It should be performed on well-selected patients to achieve good results with acceptable complication rates. In reality, the assessment of whether the prone or supine SBPCNL provides the best results is only initiating; only forthcoming, randomized, multicenter studies comparing these procedures may discern the best procedure.
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Guido Giusti, M.D., and Silvia Proietti, M.D., F.E.B.U, Stone Center at Department of Urology, Humanitas Clinical and Research Center, Rozzano, Milan, Italy
References 1. Fernstrom I, Johansson B. Percutaneous pyelolithotomy: a new extraction technique. Scand J Urol Nephrol. 1976;10:257-259. 2. Valdivia Urıa JG, Valle Gerhold J, Lopez Lopez JA, et al. Technique and complications of percutaneous nephroscopy: experience with 557 patients in the supine position. J Urol. 1998;160:1975-1978.
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3. Hopper KD, Sherman JL, Luethke JM, et al. The retrorenal colon in the supine and prone patient. Radiology. 1987;162:443-446. 4. Desai M, Grover R, Manohar T, et al. Simultaneous bilateral percutaneous nephrolithotomy: a single-center experience. J Endourol. 2007; 21:508-514. 5. Proietti S, Sortino G, Antonella G. Single-session supine bilateral percutaneous nephrolithotomy. Urology. 2015;85:304-310.
http://dx.doi.org/10.1016/j.urology.2014.10.038 UROLOGY 85: 309e310, 2015. 2015 Elsevier Inc.
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