ENDOUROLOGY AND STONE DISEASE Comparison of Success Rate in Complete Supine Versus Semi Supine Percutaneous Nephrolithotomy: (The first pilot study in randomized clinical trial) Siavash Falahatkar, Ali Ghasemi, Keivan Gholamjani Moghaddam, Samaneh Esmaeili*, Ehsan Kazemnezhad, Seyednaser Seyed Esmaeili, Reza Motiee Purpose: To compare outcomes and complications of percutaneous nephrolithotomy (PCNL) in the complete supine versus semi supine position in order to select the best position. Materials and Methods: In this clinical trial, between July 2011 and May 2014, a total of 44 patients who pre- sented for PCNL were prospectively enrolled and randomly divided into 2 groups [complete supine (n=22), and semi supine (n = 22)]. The results in both positions were compared regarding the complexity and outcomes. Stone free rate was considered as a main target of the study. However, it was the first study to focus on overlapping the vertebral density during the access. Results: The two groups were comparable in age, gender, body mass index, and preoperative glomerular filtration rate, hemoglobin and creatinine. The mean operative time was significantly shorter for complete supine versus semi supine (36.68 ± 14.12 min versus 47.50 ± 16.45 min, P = .024). At the angle of 0˚, overlapping with the spine occurred in 7 patients (31.8%) in semi supine group and just in 1 patient (4.5%) in complete supine group. Also, overlapping with the edge of bed occurred in 10 cases (45.5%) of complete supine and 1 (4.5%) of semi supine; the differences were statistically significant (P = .023, P = .002, respectively). No significant difference was found between the two groups in terms of stone free rate and complications. Conclusion: Although, we had to convert two cases from semi supine into the complete supine position but we have demonstrated that PCNL in both positions is safe, effective and suitable for the patients. The stone free rate was similar in both groups. But the complete supine position is associated with a significantly shorter postoperative hospital stay and operative time, which may improve ease and safety of PCNL for patients. Key words: complexity; fluoroscopy; operative time; percutaneous nephrolithotomy; supine; stone free rate. INTRODUCTION Percutaneous nephrolithotomy (PCNL) is considered the treatment of choice for most renal stones, es- pecially for large, complex and staghorn calculi. This technique has long been performed in the prone posi- tion. But recently, there have been many reports about PCNL in the supine position and complete supine po- sition.(1-4) Supine position in PCNL is a strong alternative to prone position and is commonly performed in various mod- ification, including the Valdivia, Galdakao-modified Valdivia, modified supine, semi supine and complete supine PCNL (csPCNL).(1,5) The supine position as compared to the prone position has numerous advantages such as convenience for pa- tient and surgeon during surgery, low pressure in pyelo- calyceal system thus decreasing the migration of resid- ual stones, evacuation of stone fragments, not exposing the surgeon hands to x-ray(6), rapid access to air way that is important in morbidly obese patients(5), possibil- ity to perform coincidental the PCNL and ureteroscopy for treatment complex stones(1,5,7-13), and less bleeding (5,14-15), however this method is not familiar to most of the endourologists yet and is neglected by most urolo- gists.(2,16-17) Some controversial reasons for less trends of urologist to use supine position despite its benefits include: un- familiar and insufficient training for PCNL in supine position in most educational institutions, reducing the pressure in the collecting system and collapsing the pyelocalyceal system and therefore decreasing operat- ing field(11), anteromedial kidney displacement during accessing(18), and overlapping the stone with vertebra in semi supine position.(18) Because of many advantages of supine PCNL, we be- lieve the conflict between supine and prone will termi- nate in the coming years but the next question will re- main as to which kind of supine is appropriate? In the present clinical trial we compared outcomes and complications of PCNL in the complete supine position versus the semi supine position to choose a better posi- tion for patients. MATERIALS AND METHODS In this clinical trial, 44 patients were enrolled. In all patients informed consent was taken and then patients were randomly allocated to two groups using random block method (ratio 2:2) from July 2012 to May 2014. Urology Research Center, School of Medicine, Guilan University of Medical Sciences. *Correspondence: Urology Research Center, School of Medicine, Guilan University of Medical Sciences E mail: samaneh_815@yahoo.com. Received July 2017 & Accepted Endourology and Stone Diseases 3000 All patients underwent semi and complete supine PCNL by an expert surgeon. Group A (22 patients) underwent complete supine po- sition and group B (22 patients) underwent semi supine position (Figure 1). Included patients were at least 12 years of age, had single or multiple stones in the upper urinary tract (calyx, the pelvis, upper ureter) with stone burden ≥ 2 cm, lower calyx stones with stone burden ≥ 1.5 cm, SWL-resistant stones ≥ 1 cm. Excluded pa- tients were those with uncontrolled coagulopathy, preg- nancy, history of immunosuppression, renal anomalies and untreated UTI (urinary tract infection), upper uri- nary tract stones with the stone burden ≤ 2 cm, lower calyx stones with stone burden ≤1.5 cm and complete staghorn stones. All PCNLs were performed under fluoroscopic guid- ance in subcostal access method by a single surgeon who had previous experience of PCNL in the complete supine and semi supine position and general anesthesia was used for all the patients. In complete supine posi- tion, patients were located near the edge of the bed, but elevation on the flank and changes in lower limb did not occur. Lower limbs were in full extension and up- per limbs were in abduction and extension, as the same technique that the authors described in 2008.(1) In semi supine position, by a 3-liter saline bag, 20-30 degrees elevating on the ipsilateral flank was created, but the position of upper and lower limbs was similar to com- Table 1. Demographics of the patients Characteristics Complete Supine group (N=22) Semi Supine group (N=22) P-Value Gender (%) Male 8 (36.4) 10 (45.5) 0.380 Female 14 (63.6) 12 (54.5) Mean age ± SD (year) 52.59 ± 11.77 47.55 ± 12.92 0.183 Mean BMI ± SD 27.41 ± 4.11 27.07 ± 5.18 0.812 Previous intervention ESWL Yes 7 (31.8) 6 (27.3) 0.500 No 15 (68.2) 16 (72.7) Open/PCNL Yes 9 (40.9) 5 (22.7) 0.166 No 13 (59.1) 17 (77.3) Stone number (%) Single 8 (36.4) 9 (40.9) 0.500 Multiple 14 (63.6) 13 (59.1) Stone location (%) Only One Calyx 6 (27.3) 2 (9.1) Only Pelvis 4 (18.2) 3 (13.6) 4 (18.2) Only Upper Ureter 0 (0.0) 1 (4.5) Multiple Locations 11 (50.0) 12 (54.5) Staghorn 1 (4.5) 4 (18.2) Complex stone (%) Yes 12 (54.5) 16 (72.7) 0.147 No 10 (45.5) 6 (27.3) Opacity (%) Radiopaque 21 (99.5) 22 (100.0) 0.500 Radiolucent 1 (4.5) 0 (0.0) Hydronephrosis (%) Yes 16 (72.7) 19 (86.4) 0.228 No 6 (27.3) 3 (13.6) Stone burden ±SD 35.41 ± 10.89 34.23 ± 9.93 0.709 csPCNL vs. semi supine PCNL-Falahatkar et al. Vol 14 No 02 March-April 2017 3001 plete supine position. (Figure 2) In all PCNLs, the puncture was done between middle and posterior axillary line with an 18 gauge needle in subcostal position. On the base of our previous expe- riences and other studies this area is safe to enter the kidney.(2,7,13,19) Fluoroscopy was used for intraoperative monitoring as well as pneumatic method for lithotripsy. One shot di- lation was done to dilate (first by 9 Fr dilator and then 28 Fr Amplatz dilator) and 30 Fr Amplatz sheath was used. Nephrostography was applied before finishing the surgery to diagnose residual stones and extravasation. In the end, all patients in both groups were tubeless. GFR was estimated by the MDRD formula. Hemo- globin and creatinine were assessed the day before surgery and 6 and 24 hours after surgery, respectively. Blood transfusion was administered when hemoglobin dropped to less than 10. Stone free status was consid- ered as residual stone less than 4 mm. The stone free rate was main target of study to compare the feasibility of semi supine and csPCNL. Other out- comes and complications were measured as a second endpoint of the study. The assessment of outcomes and complications was done by a blind analyzer. Independent t-test and in case of non-normality the Mann-Whitney test were used to csPCNL vs. semi supine PCNL-Falahatkar et al. Table 2. Intraoperative and postoperative parameters in 2 groups. Characteristics Complete Supine group (N=22) Semi Supine group (N=22) P-Value Access calyx (%) Upper 4 (18.2) 0 (0.0) Middle 6 (27.3) 6 (27.3) 0.102 Lower 12 (54.5) 16 (72.7) Kidney displacement with 18 gauge needle (mm) 9.55 ± 4.36 10.50 ± 4.51 0.480 Kidney displacement with 9Fr amplatz dilator (mm) 15.14 ± 4.88 17.27 ± 5.40 0.176 Kidney displacement with 28Fr amplatz dilator (mm) 20.05 ± 4.86 22.59 ± 7.51 0.191 FST (Fluoroscopic Screening Time) (second) 86.76 ± 47.42 110.23 ± 49.67 0.121 Access time (second) 133.55 ± 129.37 133.41 ± 175.18 0.707 Operation time (minutes) 36.68 ± 14.12 47.50 ± 16.45 0.024 Post Cr ±SD (mg/dL)* 1.13 ± 0.49 0.979 ± 0.19 0.179 Post GFR ±SD (%)* 73.61 ± 23.07 80.52 ± 19.94 0.294 Post Hb ±SD (mg/dL)* 12.62 ± .94 12.97 ± 1.59 0.512 Postoperative Hospital stay (days) 1.91 ± 1.23 2.27 ± 0.703 0.057 Stone free rate Yes / No 19 (86.4) / 3 (13.6) 18 (81.8) / 4 (18.2) 0.500 Changing the position 0(0.0) 2(10.0%) 0.221 Tubeless ** 22 22 - Feasibility to get the access 22 22 - * Post: Post-operative ** Without nephrostomy tube Characteristics Complete Supine group (N=22) Semi Supine group (N=22) P-Value Complication (%) Yes 4 (18.2) 2 (9.1) 0.332 No 18 (81.8) 20 (90.9) Clavien classification Grade 0 18 (81.8) 20 (90.9) Grade 1 1 (4.5) 1 (4.5) 0.697 Grade 2 2 (9.1) 1 (4.5) Grade 3 1 (4.5) 0 (0.0) Table 3: Complications in 2 groups Endourology and Stone Diseases 3002 compare quantitative variables between the two groups, and for qualitative variables, Chi-Square test or Fish- er exact test was used. Data were analyzed using SPSS software version 19. The criterion for statistical signifi- cance was set to P < 0.05 for all comparisons. The institutional review board and ethical committee of Guilan University of Medical Sciences approved the pro- tocol of this study. The trial was registered at www.irct. ir with registration number IRCT201405041853N10. RESULT Twenty two patients underwent complete supine and another twenty two patients underwent semi supine PCNL. The preoperative parameters of the patients were comparable in both groups, with no statistically significant difference (P > .05). (Table 1) No differences in the history of previous intervention such as ESWL (Extra Shock Wave Lithotripsy), open surgery and PCNL were found between groups. The demographic data of patients and characteristics of the stones are presented in Table 1. We were able to obtain access in all patients of the two groups. The mean operative time in complete supine group was 36.68 ± 14.12 minutes that in comparison to semi supine group 47.50 ± 16.45 was significantly lower (P = .024). Also, hospitalization after operation in complete supine group was lower than semi supine group (1.91±1.23, 2.27 ± 0.703 days, respectively). Al- though there was an obvious difference between semi and csPCNL, it was not statistically significant (P = .057). Although, shorter time was found toward fluoroscopic screening time in the complete supine group (86.76 ± 47.42 seconds for the complete supine versus 110.23 ± 49.67 seconds for the semi supine), the difference was not statistically significant (P = .121). Stone free status was achieved in 19 patients (86.4%) in complete supine group and in 18 (81.8%) patients in semi supine group, that was nor statistically significant (P = .500). During the last minutes of the operation in two semi supine cases we had to convert the position into the complete supine to achieve the better stone free rate be- cause of wider space for nephroscop maneuver and lack of vertebral density interfering in csPCNL. The main intraoperative and postoperative parameters are sum- marized in Table 2. Four patients in complete supine group and 2 patients in semi supine group had complications. Four patients experienced complications in complete supine group: gross hematuria in 1 patient, hemoglobin drop requiring transfusion in 1 patient, gross hematuria and hemoglo- bin drop requiring transfusion in 1 patient had been re- ported and 1 patient had all of these complications plus urinary retention with clots. In semi supine group, fever was observed in 1 patient and another patient experi- enced hemoglobin drop requiring transfusion. In complete supine group, 3 patients (13.6%) received blood transfusions and 1 patient (4.5%) underwent flu- ids treatment. In semi supine group, 1 patient (4.5%) was treated conservatively and 1 patient (4.5%) was treated with blood transfusions. No significant differ- ences between patients in the two groups were observed for complications (P = .332). The complications on the base of Clavien categories (grades 1, 2 and 3) in both groups are shown in Table 3. Overlapping with the spine at the angle of 0˚ occurred in 7 patients (31.8%) in semi supine group and just in 1 patient (4.5%) in complete supine group, which was statistically significant (P = .023). Two patients in both groups had overlapping with the spine at the angle of 30˚. There was significant difference in the overlap- ping with the edge of the bed at the angle of 0˚ in two groups (10 patients (45.5%) in group A versus 1 patient (4.5%) in group B; P=.002). No patient in both groups had overlapping with the edge of the bed at the angle of 30˚. (Table 4) DISCUSSION For many years, PCNL was performed in the prone po- sition. Studies have shown that the supine position is as effective and safe as prone position in PCNL. (6,13,14,20) Although, the stone free rates, and rates of complica- tions and transfusion of both methods are equivalent to each other(19,21) but supine position does not harbor Table 4: Overlapping with the spine and the edge of the bed at the angle of 0 and 30 degrees in 2 groups Characteristics Complete Supine group (N=22) Semi Supine group (N=22) P-Value Overlapping with the spine at the angle of 0˚ (%) Yes 1 (4.5) 7 (31.8) 0.023 No 21 (95.5) 15 (68.2) Overlapping with the spine at the angle of 30˚ (%) Yes 2 (9.1) 2 (9.1) 0.697 No 20 (90.1) 20 (90.1) Overlapping with the edge of the bed at the angle of 0˚ (%) Yes 10 (45.5) 1 (4.5) 0.002 No 12 (54.5) 21 (95.5) Overlapping with the edge of the bed at the angle of 30˚ (%) Yes 0 0 - No csPCNL vs. semi supine PCNL-Falahatkar et al. Vol 14 No 02 March-April 2017 3003 some disadvantages of prone position such as necessity to reposition the patient after ureteral catheter insertion, increased risk of pulmonary and anesthetic complica- tions, risk of colonic, central and and peripheral nerv- ous system injuries.(6,7,13,14,18,20,22,23) The supine position offers several technical advantages for the surgeon such as evacuation of stone fragments, shorter operation time, feasibility to do cystoscopy or ureteroscopy coincidentally, less patient handling, sit- ing position for the surgeon, easier access to the airway, feasibility to get the access to the upper calyces, and etc. Today, supine position is being performed in var- ious safe and effective types such as: Valdivia, Galda- kao-modified Valdivia, and modified supine, semi su- pine and complete supine.(1,5-6) Our results showed that there were no significantly dif- ference between the two study groups in terms of sex, age, body mass index, diabetes and preoperative glo- merular filtration rate, creatinine and hemoglobin. Tubeless PCNL was found a safe and effective proce- dure with reduced postoperative hospital stay and pain even for staghorn stone and more ease and comfort to the patient.(24-26) Tubeless PCNL had similar results in csPCNL compared to the prone position(10,24) so, this method was performed for all patients in this study. We were able to get access in all patients of two groups in this study, this confirms that PCNL in complete and semi supine position is feasible as other studies men- tioned.(1,2,6) In our study, history of SWL and history of open neph- rolithotomy or PCNL were evaluated but no significant differences was found between the two studied groups (P = .500, P = .166). Therefore, these factors could have little influence on the outcomes. In another study Figure 2: A: semi supine position, B: csPCNL position csPCNL vs. semi supine PCNL-Falahatkar et al. Figure 1: Flow diagram of the study. Endourology and Stone Diseases 3004 in 2011 by Falahatkar et al., previous open surgery had no effect on kidney stone free rate and complications after the complete supine PCNL.(27) Yuruk et al. found that PCNL after failed ESWL is safe and successful but it makes the procedure more difficult with prolonged operative time and fluoroscopic screening time.(28) Also, in 2014 Khorrami et al. reported that PCNL can be per- formed in patients with one or more open stone surgery history successfully without further complications.(29) We believe the history of open nephrolithotomy can make the access more difficult. The reasons of this dif- ficulty is the existence of fibrosis and previous sutures along the access pathway. Mean access time and operative time were 133.55 ± 129.37 seconds and 36.68 ± 14.12 minutes in com- plete supine group, and 133.41±175.18 seconds and 47.50±16.45 minutes in semi supine group. There was no significant difference in the access time (P=.707) but the duration of operative time was significantly higher in semi supine group (P = .024). The longer operative time in semi supine position could be related to some factors such as less number of pa- tients, the duration that needed to prepare the position and because of the less experience of the surgeon in this position. Mean operative time was reported 11.52 ± 44.5 min- utes(2) in the studies of Xu et al., 123.5 ± 51.2min by Honzek et al.(30) 162.1 minutes by Neto et al.(17) and 65 minutes by Rana et al.(26). In two previous studies by Falahatkar et al. the mean operative time of complete supine group were reported 74.7 ± 25.1 minutes and 95.14 ± 26.57 minutes.(1,10) Although, two meta-analysis have shown the superior- ity of supine PCNL regarding operative time(19,21) but we should mentioned the operative time can be affected by several factors including the position of the patient, stone characteristic, surgeon’s experience, migration of stone toward upper calyx and etc. Stone free rate is one of the most important outcomes of PCNL that is measured by researchers in all stud- ies of this field to evaluates the success rate. Stone free rate has been reported in different studies ranges from 70.2% to 89% for supine position.(2,5,7,13,26) We believe that the stone free rate like other outcomes can be affected by several factors such as: stone charac- teristic, and also the experience of the surgeon. In two meta-analysis stone free rate in supine position was found the same as prone position [(82.4% in the supine position versus 82.1% in the prone position) (19), (83.5% in the supine position versus 81.6% in the prone position) (21)] but a meta-analysis in 2014 found significantly lower stone-free rate in the supine position (72.9%) compared to prone position (77.3%).(4) In this study the stone free rate was 86.4% (19/22) in csPCNL versus 81.8% (18/22) in semi supine group but this difference was not statistically significant (P = .500). The cushion under the patient in some cases of semi supine precluded to have a complete look to calices, as we mentioned it was a difficulty of semi supine position that would need to remove the cushion and consequent- ly to change the position to csPCNL. Hospital stay after surgery was 1.91±1.23 day in com- plete supine, and 2.27 ± 0.703 days in semi supine. No statistically significant difference was observed be- tween the two groups (P = .057). In comparison with other studies such as Honzek et al. (3.4 ± 1.9 days)(30), Steele et al.(3 days)(22), Neto et al. (4.5 days)(17), Falahat- kar et al. (3.7 days)(6), Rana et al. (2 days)(12) and Pan et al. (7.63 ± 2.39 days)(8) duration of hospitalization after surgery in our study was shorter in both groups. Although, hospital stay of patients depends on some factors such as bleeding, fever, infection, pain and dis- comfort, trauma to others organs and etc, but we believe the policy of the surgeon has an important role in this matter, because nowadays surgeons trend to discharge the patients sooner. According to an article previously published by the authors, the kidney displacement was measured with transparent graph paper (covered in 5 × 5 mm squares) during accessing to target calyx with 18 gauge needle, and dilation by 9 and 28 Fr amplatz dilators.(18) The mean kidney displacements were respectively 9.55 ± 4.36, 15.14 ± 4.88 and 20.05 ± 4.86 mm in the complete supine group and 10.50 ± 4.51 , 17.27 ± 5.40 and 22.59 ± 7.51 mm semi supine group that was not statistically significant (P = .191 , .176 and 480 respectively). In Shoma et al. study, anteromedial kidney displacement in the supine PCNL was more than prone PCNL (11% versus 0%).(7) In 2011, Falahatkar et al. showed that the mean kidney displacement in the complete supine PCNL in stage 1 and 2 (When the 18 gauge needle and 9Fr dilator had moved the kidney) was significantly lower than prone group. This amount for stage 3 (When the 28Fr Amp- latz dilator had moved the kidney) was lower in com- plete supine group too, however it was not statistically significant.(18) There was a little study to show kidney displacement during the PCNL. However, it seems that the kidney displacement is so different in case by case and the po- sition of the patients is one of the factors that can influ- ence on kidney movement. Nevertheless, the concrete declaration in these field requisites further studies. Our results showed that there was no significant differ- ence between two groups for overlapping at the angle of 30˚ with the spine. Our study has shown that in semi supine position over- lapping of kidney with spine might be an important problem and one of the important difficulties in csP- CNL was interfering of the edge of the bed during the access that these difficulties were solved with the in- creasing of the angle of fluoroscopy. So, this simple but useful maneuver should be in the surgeon’s mind during the surgery. This study was performed in a center which has exten- sive prior experience in csPCNL. Therefore, the results cannot be simply generalized to other centers. Another limitation of this survey was the small sample size of our study. CONCLUSIONS There were some differences between csPCNL and semi supine PCNL in our study. The advantages of csP- CNL were: not using cushion, more simple position, little interference with overlapping with spin density, perhaps shorter operative time and hospital stay, evacu- ation of stone fragments, proper stone free rate, and no need to convert the position. But there were some dis- advantages for csPCNL such as: interfering of bed edge during the access, less familarity to many urologists. Although, in two cases we had to convert the position csPCNL vs. semi supine PCNL-Falahatkar et al. Vol 14 No 02 March-April 2017 3005 from the semi supine procedure to complete supine po- sition but our results have clearly shown that complete supine and semi supine PCNL were safe, feasible and also there were a little difference between them. We believe in the future the battle is among modification of supine position for PCNL. So, further prospective studies should be conducted in the future to detect the complexity and benefits of these methods. ACKNOWLEDGMENTS This study was supported by Urology Research Center, Guilan University of Medical Sciences. And also, it is adapted from the specialty thesis of Ali Ghasemi. CONFLICT OF INTEREST The authors declare that they have no competing finan- cial interests in relation to the work described. REFERENCES: 1. Falahatkar S, Moghaddam AA, Salehi M, Nikpour S, Esmaili F, Khaki N. Complete Supine Percutaneous Nephrolithotripsy Comparison with the Prone Standard Technique. J Endourol. 2008; 22: 2513-8. 2. Xu KW, Huang J, Guo ZH, Lin TX, Zhang CX, Liu H, et al. Percutaneous nephrolithotomy in semisupine position: a modified approach for renal calculus. Urol Res. 2011; 39:467-75. 3. Ibarluzea G, Scoffone CM, Cracco CM, Poggio M, Porpiglia F, Terrone C, et al. Supine Valdivia and modified lithotomy position for simultaneous anterograde and retrograde endourological access. BJU Int. 2007;100:233-6. 4. Zhang X, Xia L, Xu T,Wang X, Zhong S, Shen Z. Is the supine position superior to the prone position for percutaneous nephrolithotomy (PCNL)? Urolithiasis 2014; 42:87-93. 5. Valdivia JG, Scarpa RM, Duvdevani M, Gross AJ, Nadler RB, Nutahara K, et al. Supine versus prone position during percutaneous nephrolithotomy: a report from the Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study. J Endourol. 2011; 25:1619-25. 6. Falahatkar S, Farzan A, Allahkhah A. Is complete supine percutaneous nephrolithotripsy feasible in all patients? Urol Res. 2011; 39:99-104. 7. Shoma AM, Eraky I, El-Kenawy MR, El- Kappany HA. Percutaneous nephrolithotomy in the supine position: technical aspects and functional outcome compared with the prone technique. Urology. 2002;60:388-92. 8. Pan TJ, Li GC, Ye ZQ, Wen HD, Shen GQ, Zhang JQ. Flank suspended supine position for percutaneous nephrolithotomy. Urologia. 2012;79:58-61. 9. Romero V, Akpinar H, Assimos DG. Kidney Stones: a global picture of prevalence, incidence and associated risk factors. Rev Urol. 2010; 12(2-3):e86-96. 10. Falahatkar S, Khosropanah I, Atrkar Roshan Z, Golshahi M, Emadi SA. Decreasing the complications of PNL with alternative techniques including complete supine PNL and subcostal approach. Pak J Med Sci. 2009; 25:353-58. 11. de la Rosette JJMCH, Tsakiris P, Ferrandino MN, Elsakka AM, Rioja J, Preminger GM. Beyond prone position in percutaneous nephrolithotomy: a comprehensive review. Eur Urol. 2008; 54:1262-1269. 12. Rana AM, Mithani S. Tubeless percutaneous nephrolithotomy: call of the day. J Endourol. 2007; 21:169-72. 13. De Sio M, Autorino R, Quarto G, Calabrò F, Damiano R, Giugliano F, 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. 14. Ng MT, Sun WH, Cheng CW, Chan ES. Supine position is safe and effective for percutaneous nephrolithotomy. J Endourol. 2004; 18:469-474. 15. Soucy F, Ko R, Duvdevani M, Nott L, Denstedt JD, Razvi H. Percutaneous nephrolithotomy for staghorn calculi: a single center’s experience over 15 years. J Endourol. 2009; 23:1669-73. 16. Falahatkar S, Allahkhah A, Soltanipour S. Supine percutaneous nephrolithotomy: pro. Urol J. 2011;8:257-64. 17. Neto EAC, Mitre AI, Gomes CM, Arap MA, Srougi M. Percutaneous nephrolithotripsy with the patient in a modified supine position. J Urol. 2007; 178:165-8. 18. Falahatkar S, Asgari SA, Nasseh H, Allahkhah A, Farshami FJ, Shakiba M, Esmaeili S. Kidney displacement in complete supine PCNL is lower than prone PCNL. Urol Res. 2011;39:159-64. 19. Wu P, Wang L, Wang K. Supine versus prone position in percutaneous nephrolithotomy for kidney calculi: a meta-analysis. Int Urol Nephrol. 2011;43:67-77. 20. Llanes L, Sáenz J, Gamarra M, Pérez DA, Juárez A, García C, Arroyo JM, Ibarluzea G. Reproducibility of percutaneous nephrolithotomy in the Galdakao-modified supine Valdivia position. Urolithiasis. 2013;41:333-40. 21. Liu L, Zheng S, Xu Y, Wei Q. Systematic review and meta-analysis of percutaneous nephrolithotomy for patients in the supine versus prone position. J Endourol. 2010;24:1941-6. 22. Steele D, Marshal V. Percutaneous nephrolithotomy in the supine position:a neglected approach? J Endourol. 2007; 21:1433-37. csPCNL vs. semi supine PCNL-Falahatkar et al. Endourology and Stone Diseases 3006 23. Zhou X, Gao X, Wen J, Xiao C. Clinical value of minimally invasive percutaneous nephrolithotomy in the supine position under the guidance of real-time ultrasound: report of 92 cases. Urol Res. 2008;36:111-4. 24. Falahatkar S, Khosropanah I, Roshani A, Neiroomand H, Nikpour S, Nadjafi-Semnani M, Akbarpour M. Tubeless percutaneous nephrolithotomy for staghorn stones. J Endourol. 2008;22:1447-51. 25. Jou YC, Cheng MC, Lin CT, Chen PC, Shen JH. Nephrostomy tube-free percutaneous nephrolithotomy for patients with large stones and staghorn stones. Urology. 2006;67:30- 4. 26. Rana AM, Bhojwani JP, Junejo NN, Das Bhagia S. Tubeless PNL with patient in supine position: procedure for all seasons?-- with Comprehensive Technique. Urology. 2008; 71:581-5. 27. Falahatkar S, Asli MM, Emadi SA, Enshaei A, Pourhadi H, Allahkhah A. Complete supine percutaneous nephrolithotomy (csPCNL) in patients with and without a history of stone surgery: safety and effectiveness of csPCNL. Urol Res. 2011;39:295-301. 28. Yuruk E, Tefekli A, Sari E, Karadag MA, Tepeler A, Binbay M, Muslumanoglu AY. Does previous extracorporeal shock wave lithotripsy affect the performance and outcome of percutaneous nephrolithotomy? J Urol. 2009;181:663-7. 29. Khorrami M, Hadi M, Sichani MM, Nourimahdavi K, Yazdani M, Alizadeh F, Izadpanahi MH, Tadayyon F. Percutaneous nephrolithotomy success rate and complications in patients with previous open stone surgery. Urol J. 2014;11:1557-62. 30. Hoznek A, Rode J, Ouzaid I, Faraj B, Kimuli M, de la Taille A, et al. Modified supine percutaneous nephrolithotomy for large kidney and ureteral stones: technique and results. Eur Urol. 2012;61:164-70. Vol 14 No 02 March-April 2017 3007 csPCNL vs. semi supine PCNL-Falahatkar et al.