Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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Title Page

Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report Arvind K. Shah, MD,1,# Kewei Xu, MD, PhD,1,# Hao Liu, MD,1 Hai Huang, MD, PhD,1 Tianxin Lin, MD, PhD,1 Liangkuan Bi, MD, PhD,1 Han Jinli, MD, PhD,1 Xinxiang Fan, MD, PhD,1 Rujan Shrestha, MBBS,2 Jian Huang, MD, PhD,1 1

Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China 2

Sun Yat-sen University, North Campus, Guangzhou, China

#

These authours contributed equally to this study

Address correspondence to: Jian Huang, MD, PhD Department of Urology Sun Yat-sen Memorial Hospital Sun Yat-sen University, 107 West Yanjiang Road Guangzhou 510210 China E-mail: [email protected]

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Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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Main Text

Abstract Introduction:

Miniatured

percutaneous

nephrolithotomy

(PCNL)

techniques

like

micro-percutaneous

nephrolithotomy (micro-perc) and Ultramini PCNL (UMP) are usually indicated for renal stones sized 2cm, however, requirement of greater retreatment rate to reach a satisfactory SFR, steep learning curve and the high cost has been its major concern.6, 7 This makes PCNL to be a choice of treatment for even smaller calculi in many centers.8 Trauma to renal parenchyma and bleeding is associated with the tract size. 9 To minimize tract associated complications, various researchers have introduced smaller sized tract PCNL like mini-percutaneous nephrolithotomy (miniperc),10 micro-percutaneous nephrolithotomy (microperc)11 and ultra-mini percutaneous nephrolithotomy (UMP)12. However, due to the decreased size of the scopes and sheath, the operating time as well as the potential chances of elevated intrapelvic pressure during the procedure is increased. 11, 13, 14 This limits the procedure for small-size stones and increase the possibility of systemic absorption of irrigation fluid containing bacteria or endotoxins, contributing to postoperative fever or even a sepsis. In this research work, we evaluate the outcome of UMP through a 13-Fr percutaneous tract in semi-supine combined lithotomy position to treat 2-3 cm renal stone and simultaneously use retrograde ureteral access sheath to improve irrigation and maintain low intrapelvic pressure during the procedure. Methods and materials Design and settings During April 2013 to January 2014, we performed the procedure on 22 renal stone cases with stone sized 2-3cm. All procedures were performed at our center by a single experienced surgeon (Kewei Xu). Informed consents were signed by all enrolled patients. Preoperative evaluation of patients included blood and urine routine tests, coagulation profile, urine culture and imaging series including KUB, intravenous urography, ultrasonography and/or CT scan. Patients with positive urine culture were managed with appropriate antibiotics before PCNL. Stone size was calculated by measuring the longest diameter on preoperating imaging. The procedures were performed with the UMP set (Schölly Fiberoptics GmbH, Denzlingen, Germany) which includes (i) an ultra-thin telescope, 1 mm in diameter with a 0°view and a resolution of 17 000 pixels (ii) a 6-F inner sheath (iii) an outer 13-F sheath (Fig. 1). The outer sheath has a tube of 3 F welded to its inner wall and finally connected to a port outside. This port is used to inject saline during removal of stone fragments. The scope is fitted into the inner sheath and the sheath has separate ports for irrigation and laser fibre (Fig. 2b).

Operative technique With epidural anesthesia, patients were placed in semi-supine combined lithotomy position with operating side elevated at 45˚. The ipsilateral leg was fully extended while the other was flexed thus allowing simultaneous retrograde approach throughout the procedure (Fig. 1a). A 8/9.8 Fr Wolf semirigid ureteroscope (Richard Wolf, Germany) was used to confirm the ureter was free of stones or strictures, a 0.032-inch (0.81-mm) nitinol guidewire (OptiMed Medizinische Insturmente GmbH, Germany) was placed into the renal pelvis and, along the guidewire, a 3

Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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4 9.5/11.5Fr (Flexor - Cook) Ureteral access sheath (UAS) was positioned possibly close to renal pelvis. 50ml saline was irrigated through the UAS obturator to dilate the renal collecting system facilitating puncture in non hydronephrotic kidney. Initial puncture into the dominant calyx was made with an 18-gauge coaxial needle under US-guidance through a needle guide system attached to 3.5-MHz probe (Aloka Ultrasound System, Japan). A successful puncture was confirmed by the efflux of irrigation fluid through the puncture needle, a guidewire was then introduced through needle sheath into pelvicalyceal system. 10Fr and 14Fr fascial dilators were then sequentially used to dilate muscle and fascial layers. The UMP outer sheath was placed into the target calyx along the guidewire. Nephroscopy was done with the UMP nephroscope and a peristaltic pump was used to irrigate saline. 200-μholium laser fibre (Lumenis GmbH, Germany) with energy output of 0.8-1.5 J at 10-15Hz was then used to disintegrate stones into fragments 2-3mm. The fragments were actively flushed out of the collecting system by creating an eddy flow of the irrigation fluid around the fragments either by irrigating through the scope and removing the scope rapidly out of the sheath or by manually injecting saline through the side-port of the outer sheath after removing the nephroscope. The retrograde ureteral sheath served as an outflow tract for irrigation fluid as well as removal of stone fragments. After endoscopic and US confirmation of no detectable stone fragments, a double-J stent was placed anterogradely or retrogradely and a 8F nephrostomy tube was placed into the collecting system and fixed. A 5F open-ended ureteral catheter was inserted intraoperatively into the renal collecting system retrogradely via UAS and connected to the IBP channel of anesthesia patient monitor with a baroreceptor to monitor the real-time renal pelvic pressure (Fig. 1c). The nephrostomy tube was removed within 24hours and the urinary catheter was removed 48 hours postoperatively. Blood loss was calculated as the change in Hb concentration between preoperative and 24h postoperative complete blood count. KUB was obtained after 24-48 hours to access initial stone clearance. A residual stone of size ≤ 4mm was considered ‘stone free’. Double-J stent in stone-free patients was removed at 2-4 weeks. In patients with residual fragments the auxiliary procedures were planned at 4 week follow-up depending upon the size and location of residual fragments detected in repeated KUB. Results All 22 cases were successfully completed through a single 13F access tract with patient positioned in 45°semisupine combined lithotomy position. The patient demographics and perioperative data are listed in Table 1. The retrograde 9.5/11.5 Fr UAS could be positioned without difficulty and no patients required balloon or coaxial dilation of the distal ureter. All punctures were US-guided and the mean tract creation time was less than 3 minutes. RIRS was simultaneously used for removal of stones (>4mm) inaccessible through the primary nephroscopy tract in two cases. The operative time was longer (maximum 112 minutes) in cases with hard stones and multiple caliceal stones requiring simultaneous RIRS. The mean hemoglobin drop was 1.2±0.3 (range 0.5-2.2) g/dL and no patient required blood transfusion or embolization treatment. In this series, 18/22(81.8%) of patients underwent solo UMP and 20/22(90.9%) underwent UMP associated with simultaneous RIRS had no residual calculi. In two (9.1%) cases with residual fragments one underwent second UMP procedure after 2 weeks of the initial UMP session and the other one needed ESWL.

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Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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5 Fever (T>38.5 ℃)occurred once on the first postoperative day in one (4.5 %) case treated with combined RIRS and had a slightly longer operative time (110 minutes), it responded well with antibiotic treatment. Clinically insignificant hematuria lasting for more than postoperative 48 hours was seen in 2(9.0%) cases which were managed conservatively. No other complications like urosepsis, pneumothorax, injury to adjacent organs, or urine extravasation occurred. Chemical analysis revealed pure calcium oxalate in three patients, pure calcium phosphate in two, a mixture of calcium oxalate and calcium phosphate in five, pure uric acid in one, and struvite in one.The remaining 10 patients had various other mixtures of stone types.

Discussion Tract size is associated with renal parenchyma injury and hence the blood loss which is one of the most worrisome complication of PCNL.9 Recent technical development has allowed smaller tract PCNL for non-bulky stones. Various researchers have reported the ‘Mini-PCNL’ technique through tract size ranging from 11F-20F to be feasible and demonstrated reduced bleeding, hospital stay and postoperative analgesics requirement when compared with standard PCNL.8, 10, 15-17 However, Giusti and colleagues13 found a 13F tract lead to limited irrigation flow and required more extensive stone fragmentation, leading to prolonged operative time. Recently introduced single-step micro-perc through a 4.85F tract and holium laser lithotripsy has been appreciated by researchers for its high SFR of 82-93%, lower invasiveness and faster recovery. However, the inability to completely remove the stone fragments, low visibility even with minimal hemorrhage, and limited maneuverability seems to have limited it for small sized stones. Elevated intrarenal pelvic pressure due to the small sheath size and fluid intravasation has been its other concern.11, 18, 19 UMP uses a special 6 Fr Mininephroscope to perform PCNL through a 11–13 Fr metallic sheath. The early studies have shown minimal complication rate, a high stone-free rate and a very low auxiliary procedure rate; however, it is best for treating stones 30 mm Hg to cause fever due to backflow.14 In the research by Dogan et al. found 21% (17/81) of the patients had a postoperative fever and suggested the absorption of perfusion fluid to be a high risk factor.24 Urologists must be conscious of the potential fluid extravasation and absorption and attempt to prevent elevated intrarenal pressures during PCNL, especially when the collecting system contains infected urine or an infected calculus and in small tract PCNL where the operative time tends to be longer and the interspace for fluid drainage is limited. Researchers have mentioned the significance of UAS in improving drainage and decreasing intrarenal pressure during ex vivo percutaneous nephroscopy, 25 and as well facilitate removal of stone fragments during ESWL.26 During our study we found that the use of UAS efficiently facilitated irrigant drainage and maintained low intrarenal pressure (5-10mmHg) throughout the procedure even with high-pressure irrigation using a peristaltic pump. The improved irrigation flow rendered good visualization and facilitated rapid removal of stone fragments through the access sheath. UAS also allowed flexible ureteroscopy in two cases for managing stones in calices beyond the reach of the percutaneous access tract. This increased the stone clearance and lowered the chances of haemorrhage due to excessive torquing of the tract. Additionally, an access sheath allowed passive elimination of small stone fragments throughout the procedure (Fig. 1d). The routine use of UAS during flexible ureteroscopy has been found safe and beneficial for better visibility, lowering of intrapelvic pressure and improving the stone clearance. Lallas et al.

27

evaluating ureteral blood flow

found a minimal decrease of 25% below baseline with 10/12F UAS compared to the other larger sized and suggested that UAS can induce transient ureteral ischemia and promote an acute inflammatory response, however, it 6

Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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7 seldom causes ischemic necrosis. Delvecchio and colleagues 28 in their retrospective study did not find any evidence of ureteral stricture attributable to use of UAS. All the procedures in our study were completed in 45°semi-supine combined lithotomy position which is similar to the Galdakao-modified supine Valdivia (GMSV) position.29 Compared to the conventional prone position, this position eliminates the need of intraoperative change in patient position, provides a more comfortable position for patient, allows better patient monitoring for anesthesiologist and simultaneous retrograde access was possible when required.29 As the access tract is horizontal, it contributes in maintaining low intrapelvic pressure and the stone fragments can be easily flushed out. The other advantage of this position is the comfortable sitting position for the surgeon during the stone management.30 The ultrasound guidance avoids the radiation hazard for both patient and operative team and prevents injury to the visceral organs.9 The limitation of the study includes a nonrandomized controlled nature of the study. It was a prospective experimental case control designed study. Further studies of a randomized controlled nature on larger number of patients, with stone size less than 2cm and 2-3cm, may provide us a valid conclusion with meaningful statistical power. Conclusion Implementation of Ultra-mini percutaneous nephrolithotomy for the treatment of renal stones 2 - 3cm is feasible and safe. The procedure is less invasive and has faster recovery period. Intraoperative retrograde ureteral sheath allows possibility of simultaneous RIRS, decrease intrapelvic pressure and facilitates removal of stone fragments.

Conflict of interest: None

Abbreviations used PCNL= Percutaneous nephrolithotomy MPCNL= Mini percutaneous nephrolithotomy UMP= Ultra-mini percutaneous nephrolithotomy SFR= Stone free rate SWL= Shock wave lithotripsy RIRS= Retrograde intrarenal surgery UAS= Ureteral access sheath KUB= Kidney ureter bladder (X-ray) 7

Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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References:

1. Albala DM, Assimos DG, Clayman RV, et al. Lower pole I: a prospective randomized trial of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy for lower pole nephrolithiasis-initial results. J Urol. 2001 Dec;166(6):2072-80. PubMed PMID: 11696709. 2. Osman M, Wendt-Nordahl G, Heger K, Michel MS, Alken P, Knoll T. Percutaneous nephrolithotomy with ultrasonography-guided renal access: experience from over 300 cases. BJU Int. 2005 Oct;96(6):875-8. PubMed PMID: 16153221. 3. de la Rosette JJ, Opondo D, Daels FP, et al. Categorisation of complications and validation of the Clavien score for percutaneous nephrolithotomy. Eur Urol. 2012 Aug;62(2):24655. PubMed PMID: 22487016. 4. Michel MS, Trojan L, Rassweiler JJ. Complications in percutaneous nephrolithotomy. Eur Urol. 2007 Apr;51(4):899-906; discussion PubMed PMID: 17095141. 5. Elbahnasy AM, Shalhav AL, Hoenig DM, et al. Lower caliceal stone clearance after shock wave lithotripsy or ureteroscopy: the impact of lower pole radiographic anatomy. J Urol. 1998 Mar;159(3):676-82. PubMed PMID: 9474124. 6. Aboumarzouk OM, Monga M, Kata SG, Traxer O, Somani BK. Flexible ureteroscopy and laser lithotripsy for stones >2 cm: a systematic review and meta-analysis. J Endourol. 2012 Oct;26(10):1257-63. PubMed PMID: 22642568. 7. Hyams ES, Shah O. Percutaneous nephrostolithotomy versus flexible ureteroscopy/holmium laser lithotripsy: cost and outcome analysis. J Urol. 2009 Sep;182(3):1012-7. PubMed PMID: 19616804. 8. Nagele U, Schilling D, Sievert KD, Stenzl A, Kuczyk M. Management of lower-pole stones of 0.8 to 1.5 cm maximal diameter by the minimally invasive percutaneous approach. J Endourol. 2008 Sep;22(9):1851-3; discussion 7. PubMed PMID: 18811465. 9. Kukreja R, Desai M, Patel S, Bapat S, Desai M. Factors affecting blood loss during percutaneous nephrolithotomy: prospective study. J Endourol. 2004 Oct;18(8):715-22. PubMed PMID: 15659890. 10. Jackman SV, Docimo SG, Cadeddu JA, Bishoff JT, Kavoussi LR, Jarrett TW. The "miniperc" technique: a less invasive alternative to percutaneous nephrolithotomy. World J Urol. 1998;16(6):371-4. PubMed PMID: 9870281. 11. Desai MR, Sharma R, Mishra S, Sabnis RB, Stief C, Bader M. Single-step percutaneous nephrolithotomy (microperc): the initial clinical report. J Urol. 2011 Jul;186(1):140-5. PubMed PMID: 21575966. 12. Desai J, Solanki R. Ultra-mini percutaneous nephrolithotomy (UMP): one more armamentarium. BJU Int. 2013 Nov;112(7):1046-9. PubMed PMID: 23841665. 13. Giusti G, Piccinelli A, Taverna G, et al. Miniperc? No, thank you! Eur Urol. 2007 Mar;51(3):810-4; discussion 5. PubMed PMID: 16938385. 14. Zhong W, Zeng G, Wu K, Li X, Chen W, Yang H. Does a smaller tract in percutaneous nephrolithotomy contribute to high renal pelvic pressure and postoperative fever? J Endourol. 2008 Sep;22(9):2147-51. PubMed PMID: 18811571. 15. Chan DY, Jarrett TW. Mini-percutaneous nephrolithotomy. J Endourol. 2000 Apr;14(3):269-72; discussion 72-3. PubMed PMID: 10795617. 16. Lahme S, Bichler KH, Strohmaier WL, Gotz T. Minimally invasive PCNL in patients with renal pelvic and calyceal stones. Eur Urol. 2001 Dec;40(6):619-24. PubMed PMID: 11805407. 17. Monga M, Oglevie S. Minipercutaneous nephorlithotomy. J Endourol. 2000 Jun;14(5):419-21. PubMed PMID: 10958563. 8

Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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9 18. Piskin MM, Guven S, Kilinc M, Arslan M, Goger E, Ozturk A. Preliminary, favorable experience with microperc in kidney and bladder stones. J Endourol. 2012 Nov;26(11):1443-7. PubMed PMID: 23036099. 19. Tepeler A, Armagan A, Sancaktutar AA, et al. The role of microperc in the treatment of symptomatic lower pole renal calculi. J Endourol. 2013 Jan;27(1):13-8. PubMed PMID: 22873714. 20. Desai J, Zeng G, Zhao Z, Zhong W, Chen W, Wu W. A novel technique of ultra-minipercutaneous nephrolithotomy: introduction and an initial experience for treatment of upper urinary calculi less than 2 cm. Biomed Res Int. 2013;2013:490793. PubMed PMID: 23984372. Pubmed Central PMCID: 3741699. 21. Kukreja RA, Desai MR, Sabnis RB, Patel SH. Fluid absorption during percutaneous nephrolithotomy: does it matter? J Endourol. 2002 May;16(4):221-4. PubMed PMID: 12042103. 22. Stenberg A, Bohman SO, Morsing P, Muller-Suur C, Olsen L, Persson AE. Back-leak of pelvic urine to the bloodstream. Acta Physiol Scand. 1988 Oct;134(2):223-34. PubMed PMID: 3227945. 23. Wang J, Zhou DQ, He M, et al. Effects of renal pelvic high-pressure perfusion on nephrons in a porcine pyonephrosis model. Exp Ther Med. 2013 May;5(5):1389-92. PubMed PMID: 23737886. Pubmed Central PMCID: 3671845. 24. Dogan HS, Sahin A, Cetinkaya Y, Akdogan B, Ozden E, Kendi S. Antibiotic prophylaxis in percutaneous nephrolithotomy: prospective study in 81 patients. J Endourol. 2002 Nov;16(9):649-53. PubMed PMID: 12490017. 25. Landman J, Venkatesh R, Ragab M, et al. Comparison of intrarenal pressure and irrigant flow during percutaneous nephroscopy with an indwelling ureteral catheter, ureteral occlusion balloon, and ureteral access sheath. Urology. 2002 Oct;60(4):584-7. PubMed PMID: 12385911. 26. Okeke Z, Lam JS, Gupta M. Use of a ureteral access sheath to facilitate removal of large stone burden during extracorporeal shock wave lithotripsy. Urology. 2004 Mar;63(3):574-6. PubMed PMID: 15028463. 27. Lallas CD, Auge BK, Raj GV, Santa-Cruz R, Madden JF, Preminger GM. Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement. J Endourol. 2002 Oct;16(8):583-90. PubMed PMID: 12470467. 28. Delvecchio FC, Auge BK, Brizuela RM, et al. Assessment of stricture formation with the ureteral access sheath. Urology. 2003 Mar;61(3):518-22; discussion 22. PubMed PMID: 12639636. 29. 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(1):233-6. PubMed PMID: 17552975. 30. Xu KW, Huang J, Guo ZH, et al. Percutaneous nephrolithotomy in semisupine position: a modified approach for renal calculus. Urol Res. 2011 Dec;39(6):467-75. PubMed PMID: 21336573.

Abbreviations used PCNL= Percutaneous nephrolithotomy MPCNL= Mini percutaneous nephrolithotomy 9

Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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UMP= Ultra-mini percutaneous nephrolithotomy

SFR= Stone free rate

SWL= Shock wave lithotripsy

RIRS= Retrograde intrarenal surgery

UAS= Ureteral access sheath

KUB= Kidney ureter bladder (X-ray)

Legends for figures

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Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof. Page 11 of 13

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Fig. 1. The UMP set: telescope, inner sheath, outer sheath and obturator.

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Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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Fig. 2. (a) Semi-supine combined lithotomy position; ( b) Intraoperative view during lithotripsycomfortable sitting position for surgeon; (c) Intraoperative measurement of intrarenal pressure; (d) Drainage of irrigant and removal of stone fragments through UAS.

Table 1: Patient demographics and perioperative data Patient no. Mean ±SD age, yrs (range) Gender, Male/female, no. BMI ±SD, Kg/M2 (range) Stone location , no. Renal pelvis Upper calyx Middle calyx Lower calyx Proximal ureter Multiple calices Mean stone burden, mm (range) Degree of hydronephrosis Nil/ Mild/ Moderate/ Severe No. positive preoperative urine culture No. medical comorbidity Hypertension Diabetes Solitary kidney Renal intervention history, no. Open surgery/ ESWL/ PCNL Calyx punctured, no. Upper calyx

22 49.1±11.2(22-73) 14/8 25.1±3.2 (21.9-29.3) 12 1 1 3 2 3 26.6±4.7(21-32) 14/7/1/0 None 3 2 1 2/3/2 5 12

Journal of Endourology Implementation of Ultra-mini percutaneous nephrolithotomy for treatment of 2 - 3cm kidney stone: a preliminary report (doi: 10.1089/end.2015.0171) This article has been peer-reviewed and accepted for publication, but has yet to undergo copyediting and proof correction. The final published version may differ from this proof.

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13 Middle calyx 13 Lower calyx 4 No. of tracts Single Tract size 13Fr, n 22 UMP+RIRS 2 * Mean tract creation time ±SD, min (range) 2.2±0.6 (2.1-2.9) £ Mean operation Time ±SD, min (range) 85.7±18.0 (47-112) Mean hemoglobin drop (ΔHb) ±SD, g/dL (range) 1.2±0.3 (0.5-2.2) Solo UMP primary stone-free rate, no. (%) 18/22(81.8) UMP+RIRS primary stone-free rate, no. (%) 20/22(90.9) Postoperative hospital stay, d (range) 3.1±1.8 (2-5) Auxiliary treatment, no. Second UMP 1 ESWL 1 RIRS 0 Stone-free rate after auxiliary treatment, no.(%) 22/22(100.0) Post-operative complications, no.(%) Fever 1 (4.5%) Collecting system perforation 0 Clinically insignificant hematuria 2 (9.0%) Urine leakage 0 Transfusion 0 Pneumothorax 0 Colon injury 0 SD: standard deviation; BMI:body mass index; ESWL: extracorporeal shock wave lithotripsy; PCNL:percutaneous lithotomy *Tract creation time was the time puncture to successful placement of UMP sheath; £Operation time was the time from cystoscopy to placement of nephrostomy tube.

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Implementation of Ultramini Percutaneous Nephrolithotomy for Treatment of 2-3 cm Kidney Stones: A Preliminary Report.

Miniatured percutaneous nephrolithotomy (PCNL) techniques such as micro-PCNL (microperc) and ultramini-PCNL (UMP) are usually indicated for renal ston...
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