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Successful Percutaneous Nephrolithotomy in Children: Multicenter Study on Current Status of its Use, Efficacy and Complications Using Clavien Classification
Successful Percutaneous Nephrolithotomy in Children: Multicenter Study on Current Status of its Use, Efficacy and Complications Using Clavien Classification Selcuk Guven,* Okan Istanbulluoglu, Umit Gul, Ahmet Ozturk, Hüseyin Celik, Cem Aygün, Umit Ozdemir, Bulent Ozturk, Hakan Ozkardes and Mehmet Kilinc From the Departments of Urology, Selcuk University Meram Medical School (SG, AO, UO, MK) and Baskent University Medical School, Konya (OI, BO), Adana (UG) and Ankara (HC, CA, HO), Hospitals, Turkey
Purpose: In this multicenter study we aimed to evaluate the efficacy and safety of percutaneous nephrolithotomy in children with respect to different features and using the Clavien classification system. Materials and Methods: Percutaneous nephrolithotomies performed in children at 3 urology departments between March 2006 and May 2010 were included in the study. Results are presented for complex/simple renal stones, tubeless/totally tubeless percutaneous nephrolithotomy, simultaneous bilateral percutaneous nephrolithotomy, instrument size and age groups. Patients were divided into 3 distinct groups, infants and toddlers (3 years or younger, group 1), preschool children (4 to 7 years, group 2) and school children (8 to 16 years, group 3). Perioperative complications are presented according to the modified Clavien classification system. Results: A total of 140 percutaneous nephrolithotomies were performed in 130 patients (41.5% female, mean age 10.17 years). There were 23, 25 and 92 renal units in groups 1, 2 and 3, respectively. Pediatric instruments were used in 60 renal units and adult-sized instruments in 80. General assessment of complications showed Clavien grade I complications in 17 patients, II in 4, IIIa in 11 and IIIb in 7. There were no grade IV or V complications. Conclusions: Percutaneous nephrolithotomy can be applied safely in children of varying ages, even infants. Complications, as assessed with Clavien classification, are comparable to those seen in adults provided there is enough experience with the technique.
Abbreviations and Acronyms Hb ⫽ hemoglobin PNL ⫽ percutaneous nephrolithotomy SBPNL ⫽ simultaneous bilateral percutaneous nephrolithotomy SWL ⫽ shock wave lithotripsy Submitted for publication August 14, 2010. * Correspondence: Department of Urology, Selcuk University Meram Medical School, 42080 Akyokus, Konya, Turkey (telephone: 0090-533-2516339; FAX: 0090-332-2236181; e-mail: selcukguven@ selcuk.edu.tr).
Key Words: comparative study; kidney calculi; nephrostomy, percutaneous; postoperative complications; urologic surgical procedures TECHNOLOGICAL advances and refinements in technique have facilitated the successful application of percutaneous nephrolithotomy in the pediatric population. As a result, percutaneous nephrolithotomy has now replaced open surgery for large stone burdens in children.1–4 However, our knowledge about percutaneous nephrolithotomy in children is deficient compared to that in adults. Multicenter studies about percutaneous
nephrolithotomy outcomes in children with respect to different techniques, instrumentation size and different age groups are lacking. Although adult PNL complications have been evaluated in depth using a classification system,5–7 there has been no such evaluation regarding PNL practices in children. The definition of surgical complications and a widely accepted ranking system to classify the
0022-5347/11/1854-1419/0 THE JOURNAL OF UROLOGY® © 2011 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION
Vol. 185, 1419-1424, April 2011 Printed in U.S.A. DOI:10.1016/j.juro.2010.11.055
AND
RESEARCH, INC.
www.jurology.com
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PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
surgical outcomes are of utmost importance.8 To present an objective, simple, reliable and reproducible means of reporting negative events postoperatively, the Clavien classification system was proposed.9,10 This system has been proved valid and applicable worldwide in many fields of surgery, including some urological interventions. It is essential to take advantage of an accepted classification system for PNL applications in children. In this multicenter study we aimed to evaluate the efficacy and safety of PNL in children with respect to different features and using the Clavien classification system.
stance was flushed through the ureteral catheter, and the kidney was punctured under fluoroscopic guidance. At center 1 dilation of the nephrostomy tract was performed using an Amplatz sheath measuring up to 20Fr, with a 17Fr Storz® nephroscope being used in 49 patients. In 6 patients renal access was achieved using an 18 gauge needle and guidewire and 8Fr stylet (Amplatz type graduated renal dilator set) sent via the guidewire, and consequently minimally invasive PNL was performed through a 14Fr ureteral access sheath. A 10Fr pediatric cystoscope was used during the procedure. Stones were fragmented with a pneumatic lithotripter and extracted by grasper or triceps forceps in patients who underwent minimally invasive PNL. At centers 2 and 3 adult-sized instrumentation was used in all patients. The tract was dilated and a 28Fr Amplatz sheath was positioned. Next, a 26Fr rigid Storz nephroscope was used, and stones were fragmented with a pneumatic lithotripter and extracted by grasper. While tubeless or totally tubeless PNL was applied in selected patients at centers 1 and 2, center 3 opted for standard PNL in all patients. The technique used for tubeless and totally tubeless PNL has been described previously.11,12 To evaluate the efficacy and safety of PNL according to different age groups, patients were categorized into 3 groups, infants and toddlers (3 years old or younger, group 1), preschool children (4 to 7 years old, group 2) and school children (8 to 16 years old, group 3).
MATERIALS AND METHODS We evaluated PNL applications in children performed at 3 urology departments (Selcuk University Meram Medical School— center 1, Baskent University Konya Hospital— center 2, Baskent University Adana Hospital— center 3) with a comparable high level of experience with technique. Patient data were collected from retrospective hospital records. Patient characteristics, number and location of access points, blood loss, hospitalization time, stone burden, stone clearance and complications were recorded. Indication for PNL was based on size and type of stone. Stones less than 20 mm were treated first with SWL. If SWL failed, PNL was applied. Perioperative complications were compared according to modified Clavien classification system.10 Unlike the modified Clavien classification system reported by Tefekli et al for adult PNL,7 in this study blood transfusion was accepted as grade IIIa instead of grade II. Similarly prolonged extravasation requiring percutaneous drainage or Double-J® stent insertion was accepted as grade IIIb, as these procedures require heavy sedation or general anesthesia in children.
Statistical Analysis Compliance with normal distribution of data was analyzed. Student’s t test was used for comparison of the normally distributed variables between groups, MannWhitney U test for nonnormally distributed data, chisquare test for analysis of categorical variables and Kruskal-Wallis test for multiple group comparisons. The related descriptive statistics, test values and corresponding p values are presented in tables 1 to 3.
Surgical Technique At all centers the procedure started with the patient in the lithotomy position with rigid cystoscopy (10Fr) performed to place a ureteral catheter. The patient was then placed in a prone position. A mixture of saline and opaque sub-
RESULTS A total of 130 patients (41.5% female) younger than 17 years (mean 10.17) underwent 140 PNL proce-
Table 1. Comparison of surgical groups by modified Clavien classification
No. pts No. renal units Mean yrs pt age (range) No. single access Mean mm stone size (range) Mean mins operative time (range) Mean gm/dl Hb decrease (range) No. residual stones initially (%) Mean days hospitalization (range) No. complications No. Clavien grade: I II IIIa IIIb
Standard PNL
Tubeless PNL
Totally Tubeless PNL
Overall
p Value
102 111 10.57 (0.4–16) 95 27.10 (10–60) 97.80 (40–240) 1.24 (0–6.1) 22 (19.8) 2.84 (1–15) 36
14 15 9.14 (1–16) 12 23.61 (10–35) 63.75 (30–75) 1.05 (0–1) 1 (7) 4.02 (1–7) 1
14 14 9.02 (0.75–14) 14 21.2 (10–30) 58.07 (30–75) 0.89 (0–1) 1 (7) 3.12 (1–6) 2
130 140 10.28 (0.4–16) 121 26.28 (10–60) 88.67 (30–240) 1.18 (0–6.1) 24 (17.1) 3 (1–15) 39 (27.9%)
— — — — 0.001 ⬍0.001 0.13 0.80 0.50 0.76
16 2 11 7
1
— — — —
2
17 4 11 7
(12.1%) (2.9%) (7.9%) (5%)
— — — —
PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
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Table 2. Comparison of patient groups by modified Clavien classification Stones
No. pts No. renal units Mean yrs pt age (range) No. single access Mean mm stone size (range) Mean mins operative time (range) Mean gm/dl Hb decrease (range) No. residual stones initially (%) Mean days hospitalization (range) No. complications No. Clavien grade: I II IIIa IIIb
Instrument Size
Simple
Complex
Overall
89 96 10.11 (0.4–16) 96 21.25 (10–42)
41 44 10.5 (0.75–16) 25 35.56 (15–60)
83.05 (30–240)
100.92 (35–240)
1.09 (0–4.1) 7 2.88 16
(7) (1–15) (17%)
7 2 5 2
1.39
(1–6.1)
23
Pediatric
Adult
130 140 10.28 (0.4–16) 121 26.28 (10–60)
0.66 0.20 ⬍0.001
54 60 11.42 (0.4–16) 55 26.31 (12–42)
88.67 (30–240)
0.12
80
1.18 (0–6.1)
0.01
24
(17.1)
⬍0.001
(1–15)
3
(1–15)
0.12
(52%)
39
(27.9%)
0.71
16
17 4 11 7
(12.1%) (2.9%) (7.9%) (5%)
0.51 — — —
12 2 -1 -1
10 2 6 5
(30–150)
0.71 (0–2.2)
(39)
17 3.25
p Value
11 3.05
(18) (1–15)
p Value
SBPNL
76 80 10.45 (1.75–16) 67 26.02 (10–60)
0.76 0.07 0.85
6 12 6.06 (0.75–16) 6* 19.5 (11–22)
93.59 (30–240)
0.67
88.3 (55–120)
1.53 13
(0–6.1)
⬍0.001
0.7
(0–1.1)
(16)
0.86
1
(1–15)
0.78
3.8
(2–5)
23
0.52
1
(8%)
5 2 10 6
0.39 — — —
1
2.96
(8)
— — —
* Single access was used per side.
(grade IIIb). In 1 patient as the tip of the Double-J catheter was placed outside the collecting system, the emerging perirenal collection was corrected with replacement of the Double-J catheter (grade IIIb). Lastly in 1 patient a pseudoaneurysm was treated with angioembolization (grade IIIb). Complex renal stones consisted of complete or partial staghorn stones, those with a large bulk and those involving more than 1 calyx, the upper ureter or both.13,14 Among 41 patients (44 renal units) with complex renal stones single access was adequate for retrieval of stones in 25. Mean hemoglobin decrease was 1.39 gm/dl (range 1 to 6.1) in patients with complex renal stones. Blood transfusion was necessary in 8 patients (19.5%). Complete clearance was achieved with a single treatment in 27 renal units (61.4%). Of 17 renal units with residual stone clear-
dures for renal stones between March 2006 and May 2010. A total of 54 patients were treated at center 1, 43 at center 2 and 33 at center 3. Single access was sufficient in 121 procedures. However, in 18 interventions 2 accesses and in 1 intervention 3 accesses were necessary. Patient and stone characteristics, perioperative and postoperative data, complications and stone clearance are outlined in table 2. There were no Clavien grade IV or V complications. Fever occurred postoperatively in 21 patients. In 17 of these patients fever resolved with antipyretic therapy (grade I), while in 4 patients with infections additional antibiotics were needed (grade II). A total of 11 patients required blood transfusions (grade IIIa). In 5 patients postoperative extravasations occurred requiring percutaneous drainage Table 3. Comparison of groups by age
No. pts No. renal units Mean age (yrs) Mean stone size (mm) Mean operative time (mins) Mean Hb decrease (gm/dl) No. residual stone monotherapy (%) Mean hospital days No. complications No. Clavien grade: I II IIIa IIIb
3 Yrs or Younger
4–7 Yrs
8–16 Yrs
Overall
p Value
20 23 2.02 23.73 57.50 0.52 3 (13) 2.5 4
20 25 6.34 25.62 89.62 0.51 6 (24) 3 7
90 92 12.80 26.81 96.50 0.93 15 (16) 3.11 28
130 140 10.28 (range 0.4–16) 26.28 (range 12–60) 88.67 (range 30–150) 1.18 (range 0–6.1) 24 (17.1) 3 (range 1–15) 39 (27.9%)
⬍0.00 0.13 ⬍0.00 0.98 0.05 0.39 0.65
2 2 — —
5 1 1 —
10 1 10 7
17 4 11 7
(12.1%) (2.9%) (7.9%) (5%)
— — — —
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ance was achieved in 2 after a second look PNL, in 4 after SWL, and in 1 after SWL and repeat PNL (final stone clearance 77.2%). Of 140 renal units 29 were managed by tubeless PNL. A total of 14 procedures were tubeless and stentless (totally tubeless). In the tubeless group mean operative time was 63.75 minutes (range 30 to 75) and mean stone burden was 23.61 mm (10 to 35). In the totally tubeless group mean operative time was 58.07 minutes (range 30 to 75) and mean stone burden was 21.2 mm (10 to 30). In both groups the mean operative time was shorter than with the standard technique (table 1, p ⬍0.001) and no patient required blood transfusion. All patients except 2 (1 in each group) were stone-free. Stone clearance was achieved in these patients after SWL and conversion to open surgery was not required. In 3 patients fever was noted on postoperative day 2. Two of these patients (totally tubeless group) recovered with administration of antibiotics. Pediatric instrumentation was used in 60 renal units (including minimally invasive PNL in 6) and adult-sized instrumentation was used in 80 renal units. Pediatric PNL instruments were used at center 1, while adult instruments were used at centers 2 and 3. The success rates with the 2 instrumentation techniques were comparable (p ⫽ 0.86). However, postoperative Hb reduction was greater in children who underwent PNL with adult-sized instruments (p ⬍0.00, table 2). A comparison of the centers demonstrated similar stone characteristics and complications. Mean ⫾ SD operative time was longer at center 3 (129.7 ⫾ 45.3 minutes) compared to centers 1 (80.0 ⫾ 35.2) and 2 (65.8 ⫾ 29.3, p ⫽ 0.001). Hb reduction at center 1, which used pediatric instruments, was lower than that recorded at the other 2 centers (0.71 and 1.53, p ⬍0.001, table 2). Of 12 children who presented with bilateral renal calculi only 6 were considered appropriate candidates for SBPNL.15 Among the remaining 6 children 4 children were treated using staged PNL. In 1 patient PNL was applied on 1 side and SWL on the other. In the remaining patient the 5 mm stone in the right kidney passed during followup. Only 1 access was used per side in all patients. Perioperative complications were grade II to V, and no patient required a blood transfusion (table 2). Except for the patient with complex renal stones, all patients were stone-free after intervention and none required conversion to open surgery. In the patient with complex renal stones the 8 mm residual stone was retrieved during the second session of PNL. There were 23, 25 and 92 renal units in groups 1, 2 and 3, respectively. Stone clearance was complete in 87%, 76% and 83.6% of patients. Complications, stone clearance, Hb reduction and hospitalization did not differ between the groups. However, opera-
tive time was longer in groups 2 and 3 compared to group 1 (table 3).
DISCUSSION A unique and broadly accepted classification system could be helpful for monitoring and reporting outcomes in PNL.5–7,16,17 In this study the modified version of the Clavien classification system for adult PNL was considered appropriate for PNL complications in children after some slight adjustments. Comparison of the prevalent complications classified according to Clavien system at the 3 clinics in our study revealed similar percentages. Overall, complications in adult PNL according to Clavien classification were reported as 43.8% by de la Rosette et al6 and 29.2% by Tefekli et al.7 In our series the overall complication rate was 29.1%. Although the degree of some complications was increased in children compared to adults, a significant portion of the complications (43.5%) were grade I. This finding can be attributed to the fact that interventions were performed by physicians with extensive experience in adults who had completed the PNL learning curve and were more meticulous with pediatric cases. In addition, PNL interventions may be easier in children than adults due to their smaller structures. Further light can be shed on this issue by prospective studies comparing the complications emerging in adults and children following PNL. Although many adult studies have confirmed the efficacy and safety of tubeless PNL,18,19 there are limited studies evaluating the use of totally tubeless or tubeless PNL in children.11,12,20 In the present study tubeless PNL was applied in 29 renal units and totally tubeless PNL in 14. In patients who underwent totally tubeless and tubeless PNL mean operative times were shorter than with the standard technique (p ⬍0.001). Based on our results, the latest forms of PNL (tubeless and totally tubeless) are also safe and effective in children, provided patients are selected properly and the surgeon performing the procedure has the necessary experience. In the present study post-PNL residual stone formation in patients with simple renal stones was significantly less than in patients with complex stones (p ⬍0.001). The outcomes of the stone-free rates and transfusion rates were comparable to former PNL series of patients with complex renal stones.13,14,21 Hb reduction in patients with simple stones who underwent PNL was significantly less than in patients with complex stones (p ⫽ 0.01). While the complication rate according to Clavien classification system was higher in complex stones (53.3%) than simple stones (17.5%), the difference was not statistically significant. Children with bilateral kidney stones are generally treated with staged PNL. Reports of SBPNL in
PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
children are scarce.22,23 Our results are comparable to these prior studies. With appropriate patient selection criteria the main advantages of SBPNL are reduced psychological stress, 1 cystoscopy and anesthesia, less medication, and a shorter hospital stay and convalescence with considerable savings in cost. We did not encounter grade II to V complications in these patients. In previous studies there has been no general agreement regarding instrument sizes as related to complications and success rates. The smaller caliber percutaneous tract and nephroscope are considered to be less injurious to the kidney, decreasing dilation and tortuosity, important considerations in preventing bleeding and renal trauma.24 –26 However, there are also studies claiming that adult equipment in PNL is compatible for use in infants and toddlers.27 The PNL techniques and instrumentation in the present study differed since the results of 3 centers were evaluated. The success rates with pediatric and adult-sized instruments were comparable, although mean postoperative Hb reduction and blood transfusion rate were higher in the adult-sized instrumentation group. Unlike previous reports,26,28 we divided patients into 3 distinct groups, infants and toddlers, preschool children and school children. While PNL application and technique are similar between adolescents and adults, infants and toddlers are considered a distinct group since they require greater surgical skill and caution. As the number of PNL applied renal units in infants was relatively small, their numbers were combined with the data regarding toddlers. The results were comparable between the groups in many of the parameters. Although complications and Clavien score were higher in school children compared to
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younger children, the difference was not statistically significant (p ⫽ 0.68). However, mean operative times were significantly shorter for infants and toddlers than for older children. As stated earlier, this may stem from the fact that the smaller structures in children require greater surgical skill and precision. Hence PNL interventions were performed by more experienced surgeons in this group. A comparison of the centers showed that while stone characteristics and complications were not different, operative time at center 3 was longer than at centers 1 and 2 (p ⫽ 0.001). Hb reduction at center 1, where pediatric instruments were used, was lower than that of the other 2 centers (p ⬍0.001). The long operative time seen at center 3 might be due to the preference of the surgeons at centers 1 and 2 for tubeless or totally tubeless PNL. The low Hb reduction at center 1 may stem from the use of pediatric instruments. A limitation of the present study is the comparison of the moderate-sized series of 3 centers. There are some obvious differences in techniques, including the size of the access tract, size of scopes and the performance of tubeless procedures, which would likely influence the complication rates if the cohort number were larger.
CONCLUSIONS Based on our results, PNL can be applied safely in children of varying ages, even infants. Complications are comparable to those observed in adults or even less provided there is adequate experience with the technique. Use of a common grading system in emerging complications will facilitate better comparison of the literature and results obtained from different centers.
REFERENCES 1. Mahmud M and Zaidi Z: Percutaneous nephrolithotomy in children before school age: experience of a Pakistani centre. BJU Int 2004; 94: 1352. 2. Schuster TK, Smaldone MC, Averch TD et al: Percutaneous nephrolithotomy in children. J Endourol 2009; 23: 1699. 3. Smaldone MC, Corcoran AT, Docimo SG et al: Endourological management of pediatric stone disease: present status. J Urol 2009; 181: 17.
6. de la Rosette JJ, Zuazu JR, Tsakiris P et al: Prognostic factors and percutaneous nephrolithotomy morbidity: a multivariate analysis of a contemporary series using the Clavien classification. J Urol 2008; 180: 2489.
10. Dindo D, Demartines N and Clavien PA: Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004; 240: 205.
7. Tefekli A, Ali Karadag M, Tepeler K et al: Classification of percutaneous nephrolithotomy complications using the modified Clavien grading system: looking for a standard. Eur Urol 2008; 53: 184.
11. Khairy Salem H, Morsi HA, Omran A et al: Tubeless percutaneous nephrolithotomy in children. J Pediatr Urol 2007; 3: 235.
4. Smaldone MC, Docimo SG and Ost MC: Contemporary surgical management of pediatric urolithiasis. Urol Clin North Am 2010; 37: 253.
8. Clavien PA, Barkun J, de Oliveira ML et al: The Clavien-Dindo classification of surgical complications: five-year experience. Ann Surg 2009; 250: 187.
5. Skolarikos A and de la Rosette J: Prevention and treatment of complications following percutaneous nephrolithotomy. Curr Opin Urol 2008; 18: 229.
9. Clavien PA, Sanabria JR and Strasberg SM: Proposed classification of complications of surgery with examples of utility in cholecystectomy. Surgery 1992; 111: 518.
12. Ozturk A, Guven S, Kilinc M et al: Totally tubeless percutaneous nephrolithotomy: is it safe and effective in preschool children? J Endourol 2010; Epub ahead of print. 13. Ozden E, Sahin A, Tan B et al: Percutaneous renal surgery in children with complex stones. J Pediatr Urol 2008; 4: 295. 14. Desai MR, Kukreja RA, Patel SH et al: Percutaneous nephrolithotomy for complex pediatric renal calculus disease. J Endourol 2004; 18: 24e7.
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15. Ugras MY, Gedik E, Gunes A et al: Some criteria to attempt second side safely in planned bilateral simultaneous percutaneous nephrolithotomy. Urology 2008; 72: 996.
20. Bogris S and Papatsoris AG: Status quo of percutaneous nephrolithotomy in children. Urol Res 2010; 38: 1.
16. Zuazu JR, Hruza M, Rassweiler JJ et al: The Clavien classification system to optimize the documentation of PNL morbidity. Arch Ital Urol Androl 2010; 82: 20.
21. Gonen M, Turunc T, Ozturk B et al: Outcome of percutaneous nephrolithotomy in children having complex stones. Urol Int 2009; 83: 416.
17. Michel MS, Trojan L and Rassweiler JJ: Complications in percutaneous nephrolithotomy. Eur Urol 2007; 51: 899.
22. Salah MA, Tallai B, Holman E et al: Simultaneous bilateral percutaneous nephrolithotomy in children. BJU Int 2005; 95: 137.
18. Istanbulluoglu MO, Ozturk B, Cicek T et al: Bilateral simultaneous totally tubeless percutaneous nephrolithotomy: preliminary report of six cases. J Endourol 2009; 23: 1255.
23. Samad L, Aquil S and Zaidi Z: Paediatric percutaneous nephrolithotomy: setting new frontiers. BJU Int 2006; 97: 359.
19. Zilberman DE, Lipkin ME, de la Rosette JJ et al: Tubeless percutaneous nephrolithotomy—the new standard of care? J Urol 2010; 184: 1261.
24. Zeren S, Satar N, Bayazit Y et al: Percutaneous nephrolithotomy in the management of pediatric renal calculi. J Endourol 2002; 16: 75.
25. Bilen CY, Kocak B, Kitirci G et al: Percutaneous nephrolithotomy in children: lessons learned in 5 years at a single institution. J Urol 2007; 177: 1867. 26. Unsal A, Resorlu B, Kara C et al: Safety and efficacy of percutaneous nephrolithotomy in infants, preschool age, and older children with different sizes of instruments. Urology 2010; 76: 247. 27. Kroovand RL: Pediatric urolithiasis. Urol Clin North Am 1997; 24: 173. 28. Jackman SV, Hedican SP, Peters CA et al: Percutaneous nephrolithotomy in infants and preschool age children: experience with a new technique. Urology 1998; 52: 697.
EDITORIAL COMMENTS The evolution of the treatment of pediatric nephrolithiasis has permitted techniques previously exclusive to adults to be transferred to the pediatric arena. The continued theme in this series and the literature is that adult-sized instruments have a significant impact on overall blood loss. Every effort should be made to use appropriately sized equipment for the pediatric patient to eliminate this potential morbidity. The authors are to be commended for using an objective validated measurement of the morbidities in their patients with the Clavien-Dindo clas-
sification. Future clinical reports on adoption and implementation of new surgical techniques should strive to incorporate such measurements. With the recent health care reform in the United States, assessment of outcomes and quality for pediatric urology diagnoses and procedures may become the norm rather than the exception.1 Nicholas M. Holmes Division of Pediatric Urology University of California San Diego San Diego, California
REFERENCE 1. Raval MV, Dillon PW, Bruny JL et al: American College of Surgeons national surgical quality improvement program pediatric: a phase 1 report. J Am Coll Surg 2011; 212: 1.
The application by the authors of a modified Clavien classification is a useful way to standardize postPNL complications, and clearly illustrates that PNL can be safely performed in children, an issue that is becoming more relevant as stone incidence in this population increases. However, there is an array of literature citing increased morbidity of transfused patients that supports more judicious transfusion rates than what the authors present.1 They do not delineate indications for transfusion, but if transfusion had been restricted to patients with signs of anemia/hypovolemia, the study would likely further
illustrate the safety of appropriately performed pediatric PNL. The authors also performed totally tubeless PNL, a novel concept, in a small subset of patients. The results are intriguing, although this procedure is normally only done in cases with a low risk of complications. Further study is needed before widespread application of this technique is adopted.
REFERENCE 1. Pape A, Stein P, Horn O et al: Clinical evidence of blood transfusion effectiveness. Blood Transfus 2009; 7: 250.
S. Scott Sparks Department of Urology and Pediatrics George Washington University Washington, DC
Purpose: In this multicenter study we aimed to evaluate the efficacy and safety of percutaneous nephrolithotomy in children with respect to different features and using the Clavien classification system. Materials and Methods: Percutaneous nephrolithotomies performed in children at 3 urology departments between March 2006 and May 2010 were included in the study. Results are presented for complex/simple renal stones, tubeless/totally tubeless percutaneous nephrolithotomy, simultaneous bilateral percutaneous nephrolithotomy, instrument size and age groups. Patients were divided into 3 distinct groups, infants and toddlers (3 years or younger, group 1), preschool children (4 to 7 years, group 2) and school children (8 to 16 years, group 3). Perioperative complications are presented according to the modified Clavien classification system. Results: A total of 140 percutaneous nephrolithotomies were performed in 130 patients (41.5% female, mean age 10.17 years). There were 23, 25 and 92 renal units in groups 1, 2 and 3, respectively. Pediatric instruments were used in 60 renal units and adult-sized instruments in 80. General assessment of complications showed Clavien grade I complications in 17 patients, II in 4, IIIa in 11 and IIIb in 7. There were no grade IV or V complications. Conclusions: Percutaneous nephrolithotomy can be applied safely in children of varying ages, even infants. Complications, as assessed with Clavien classification, are comparable to those seen in adults provided there is enough experience with the technique.
Abbreviations and Acronyms Hb ⫽ hemoglobin PNL ⫽ percutaneous nephrolithotomy SBPNL ⫽ simultaneous bilateral percutaneous nephrolithotomy SWL ⫽ shock wave lithotripsy Submitted for publication August 14, 2010. * Correspondence: Department of Urology, Selcuk University Meram Medical School, 42080 Akyokus, Konya, Turkey (telephone: 0090-533-2516339; FAX: 0090-332-2236181; e-mail: selcukguven@ selcuk.edu.tr).
Key Words: comparative study; kidney calculi; nephrostomy, percutaneous; postoperative complications; urologic surgical procedures TECHNOLOGICAL advances and refinements in technique have facilitated the successful application of percutaneous nephrolithotomy in the pediatric population. As a result, percutaneous nephrolithotomy has now replaced open surgery for large stone burdens in children.1–4 However, our knowledge about percutaneous nephrolithotomy in children is deficient compared to that in adults. Multicenter studies about percutaneous
nephrolithotomy outcomes in children with respect to different techniques, instrumentation size and different age groups are lacking. Although adult PNL complications have been evaluated in depth using a classification system,5–7 there has been no such evaluation regarding PNL practices in children. The definition of surgical complications and a widely accepted ranking system to classify the
0022-5347/11/1854-1419/0 THE JOURNAL OF UROLOGY® © 2011 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION
Vol. 185, 1419-1424, April 2011 Printed in U.S.A. DOI:10.1016/j.juro.2010.11.055
AND
RESEARCH, INC.
www.jurology.com
1419
1420
PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
surgical outcomes are of utmost importance.8 To present an objective, simple, reliable and reproducible means of reporting negative events postoperatively, the Clavien classification system was proposed.9,10 This system has been proved valid and applicable worldwide in many fields of surgery, including some urological interventions. It is essential to take advantage of an accepted classification system for PNL applications in children. In this multicenter study we aimed to evaluate the efficacy and safety of PNL in children with respect to different features and using the Clavien classification system.
stance was flushed through the ureteral catheter, and the kidney was punctured under fluoroscopic guidance. At center 1 dilation of the nephrostomy tract was performed using an Amplatz sheath measuring up to 20Fr, with a 17Fr Storz® nephroscope being used in 49 patients. In 6 patients renal access was achieved using an 18 gauge needle and guidewire and 8Fr stylet (Amplatz type graduated renal dilator set) sent via the guidewire, and consequently minimally invasive PNL was performed through a 14Fr ureteral access sheath. A 10Fr pediatric cystoscope was used during the procedure. Stones were fragmented with a pneumatic lithotripter and extracted by grasper or triceps forceps in patients who underwent minimally invasive PNL. At centers 2 and 3 adult-sized instrumentation was used in all patients. The tract was dilated and a 28Fr Amplatz sheath was positioned. Next, a 26Fr rigid Storz nephroscope was used, and stones were fragmented with a pneumatic lithotripter and extracted by grasper. While tubeless or totally tubeless PNL was applied in selected patients at centers 1 and 2, center 3 opted for standard PNL in all patients. The technique used for tubeless and totally tubeless PNL has been described previously.11,12 To evaluate the efficacy and safety of PNL according to different age groups, patients were categorized into 3 groups, infants and toddlers (3 years old or younger, group 1), preschool children (4 to 7 years old, group 2) and school children (8 to 16 years old, group 3).
MATERIALS AND METHODS We evaluated PNL applications in children performed at 3 urology departments (Selcuk University Meram Medical School— center 1, Baskent University Konya Hospital— center 2, Baskent University Adana Hospital— center 3) with a comparable high level of experience with technique. Patient data were collected from retrospective hospital records. Patient characteristics, number and location of access points, blood loss, hospitalization time, stone burden, stone clearance and complications were recorded. Indication for PNL was based on size and type of stone. Stones less than 20 mm were treated first with SWL. If SWL failed, PNL was applied. Perioperative complications were compared according to modified Clavien classification system.10 Unlike the modified Clavien classification system reported by Tefekli et al for adult PNL,7 in this study blood transfusion was accepted as grade IIIa instead of grade II. Similarly prolonged extravasation requiring percutaneous drainage or Double-J® stent insertion was accepted as grade IIIb, as these procedures require heavy sedation or general anesthesia in children.
Statistical Analysis Compliance with normal distribution of data was analyzed. Student’s t test was used for comparison of the normally distributed variables between groups, MannWhitney U test for nonnormally distributed data, chisquare test for analysis of categorical variables and Kruskal-Wallis test for multiple group comparisons. The related descriptive statistics, test values and corresponding p values are presented in tables 1 to 3.
Surgical Technique At all centers the procedure started with the patient in the lithotomy position with rigid cystoscopy (10Fr) performed to place a ureteral catheter. The patient was then placed in a prone position. A mixture of saline and opaque sub-
RESULTS A total of 130 patients (41.5% female) younger than 17 years (mean 10.17) underwent 140 PNL proce-
Table 1. Comparison of surgical groups by modified Clavien classification
No. pts No. renal units Mean yrs pt age (range) No. single access Mean mm stone size (range) Mean mins operative time (range) Mean gm/dl Hb decrease (range) No. residual stones initially (%) Mean days hospitalization (range) No. complications No. Clavien grade: I II IIIa IIIb
Standard PNL
Tubeless PNL
Totally Tubeless PNL
Overall
p Value
102 111 10.57 (0.4–16) 95 27.10 (10–60) 97.80 (40–240) 1.24 (0–6.1) 22 (19.8) 2.84 (1–15) 36
14 15 9.14 (1–16) 12 23.61 (10–35) 63.75 (30–75) 1.05 (0–1) 1 (7) 4.02 (1–7) 1
14 14 9.02 (0.75–14) 14 21.2 (10–30) 58.07 (30–75) 0.89 (0–1) 1 (7) 3.12 (1–6) 2
130 140 10.28 (0.4–16) 121 26.28 (10–60) 88.67 (30–240) 1.18 (0–6.1) 24 (17.1) 3 (1–15) 39 (27.9%)
— — — — 0.001 ⬍0.001 0.13 0.80 0.50 0.76
16 2 11 7
1
— — — —
2
17 4 11 7
(12.1%) (2.9%) (7.9%) (5%)
— — — —
PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
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Table 2. Comparison of patient groups by modified Clavien classification Stones
No. pts No. renal units Mean yrs pt age (range) No. single access Mean mm stone size (range) Mean mins operative time (range) Mean gm/dl Hb decrease (range) No. residual stones initially (%) Mean days hospitalization (range) No. complications No. Clavien grade: I II IIIa IIIb
Instrument Size
Simple
Complex
Overall
89 96 10.11 (0.4–16) 96 21.25 (10–42)
41 44 10.5 (0.75–16) 25 35.56 (15–60)
83.05 (30–240)
100.92 (35–240)
1.09 (0–4.1) 7 2.88 16
(7) (1–15) (17%)
7 2 5 2
1.39
(1–6.1)
23
Pediatric
Adult
130 140 10.28 (0.4–16) 121 26.28 (10–60)
0.66 0.20 ⬍0.001
54 60 11.42 (0.4–16) 55 26.31 (12–42)
88.67 (30–240)
0.12
80
1.18 (0–6.1)
0.01
24
(17.1)
⬍0.001
(1–15)
3
(1–15)
0.12
(52%)
39
(27.9%)
0.71
16
17 4 11 7
(12.1%) (2.9%) (7.9%) (5%)
0.51 — — —
12 2 -1 -1
10 2 6 5
(30–150)
0.71 (0–2.2)
(39)
17 3.25
p Value
11 3.05
(18) (1–15)
p Value
SBPNL
76 80 10.45 (1.75–16) 67 26.02 (10–60)
0.76 0.07 0.85
6 12 6.06 (0.75–16) 6* 19.5 (11–22)
93.59 (30–240)
0.67
88.3 (55–120)
1.53 13
(0–6.1)
⬍0.001
0.7
(0–1.1)
(16)
0.86
1
(1–15)
0.78
3.8
(2–5)
23
0.52
1
(8%)
5 2 10 6
0.39 — — —
1
2.96
(8)
— — —
* Single access was used per side.
(grade IIIb). In 1 patient as the tip of the Double-J catheter was placed outside the collecting system, the emerging perirenal collection was corrected with replacement of the Double-J catheter (grade IIIb). Lastly in 1 patient a pseudoaneurysm was treated with angioembolization (grade IIIb). Complex renal stones consisted of complete or partial staghorn stones, those with a large bulk and those involving more than 1 calyx, the upper ureter or both.13,14 Among 41 patients (44 renal units) with complex renal stones single access was adequate for retrieval of stones in 25. Mean hemoglobin decrease was 1.39 gm/dl (range 1 to 6.1) in patients with complex renal stones. Blood transfusion was necessary in 8 patients (19.5%). Complete clearance was achieved with a single treatment in 27 renal units (61.4%). Of 17 renal units with residual stone clear-
dures for renal stones between March 2006 and May 2010. A total of 54 patients were treated at center 1, 43 at center 2 and 33 at center 3. Single access was sufficient in 121 procedures. However, in 18 interventions 2 accesses and in 1 intervention 3 accesses were necessary. Patient and stone characteristics, perioperative and postoperative data, complications and stone clearance are outlined in table 2. There were no Clavien grade IV or V complications. Fever occurred postoperatively in 21 patients. In 17 of these patients fever resolved with antipyretic therapy (grade I), while in 4 patients with infections additional antibiotics were needed (grade II). A total of 11 patients required blood transfusions (grade IIIa). In 5 patients postoperative extravasations occurred requiring percutaneous drainage Table 3. Comparison of groups by age
No. pts No. renal units Mean age (yrs) Mean stone size (mm) Mean operative time (mins) Mean Hb decrease (gm/dl) No. residual stone monotherapy (%) Mean hospital days No. complications No. Clavien grade: I II IIIa IIIb
3 Yrs or Younger
4–7 Yrs
8–16 Yrs
Overall
p Value
20 23 2.02 23.73 57.50 0.52 3 (13) 2.5 4
20 25 6.34 25.62 89.62 0.51 6 (24) 3 7
90 92 12.80 26.81 96.50 0.93 15 (16) 3.11 28
130 140 10.28 (range 0.4–16) 26.28 (range 12–60) 88.67 (range 30–150) 1.18 (range 0–6.1) 24 (17.1) 3 (range 1–15) 39 (27.9%)
⬍0.00 0.13 ⬍0.00 0.98 0.05 0.39 0.65
2 2 — —
5 1 1 —
10 1 10 7
17 4 11 7
(12.1%) (2.9%) (7.9%) (5%)
— — — —
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PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
ance was achieved in 2 after a second look PNL, in 4 after SWL, and in 1 after SWL and repeat PNL (final stone clearance 77.2%). Of 140 renal units 29 were managed by tubeless PNL. A total of 14 procedures were tubeless and stentless (totally tubeless). In the tubeless group mean operative time was 63.75 minutes (range 30 to 75) and mean stone burden was 23.61 mm (10 to 35). In the totally tubeless group mean operative time was 58.07 minutes (range 30 to 75) and mean stone burden was 21.2 mm (10 to 30). In both groups the mean operative time was shorter than with the standard technique (table 1, p ⬍0.001) and no patient required blood transfusion. All patients except 2 (1 in each group) were stone-free. Stone clearance was achieved in these patients after SWL and conversion to open surgery was not required. In 3 patients fever was noted on postoperative day 2. Two of these patients (totally tubeless group) recovered with administration of antibiotics. Pediatric instrumentation was used in 60 renal units (including minimally invasive PNL in 6) and adult-sized instrumentation was used in 80 renal units. Pediatric PNL instruments were used at center 1, while adult instruments were used at centers 2 and 3. The success rates with the 2 instrumentation techniques were comparable (p ⫽ 0.86). However, postoperative Hb reduction was greater in children who underwent PNL with adult-sized instruments (p ⬍0.00, table 2). A comparison of the centers demonstrated similar stone characteristics and complications. Mean ⫾ SD operative time was longer at center 3 (129.7 ⫾ 45.3 minutes) compared to centers 1 (80.0 ⫾ 35.2) and 2 (65.8 ⫾ 29.3, p ⫽ 0.001). Hb reduction at center 1, which used pediatric instruments, was lower than that recorded at the other 2 centers (0.71 and 1.53, p ⬍0.001, table 2). Of 12 children who presented with bilateral renal calculi only 6 were considered appropriate candidates for SBPNL.15 Among the remaining 6 children 4 children were treated using staged PNL. In 1 patient PNL was applied on 1 side and SWL on the other. In the remaining patient the 5 mm stone in the right kidney passed during followup. Only 1 access was used per side in all patients. Perioperative complications were grade II to V, and no patient required a blood transfusion (table 2). Except for the patient with complex renal stones, all patients were stone-free after intervention and none required conversion to open surgery. In the patient with complex renal stones the 8 mm residual stone was retrieved during the second session of PNL. There were 23, 25 and 92 renal units in groups 1, 2 and 3, respectively. Stone clearance was complete in 87%, 76% and 83.6% of patients. Complications, stone clearance, Hb reduction and hospitalization did not differ between the groups. However, opera-
tive time was longer in groups 2 and 3 compared to group 1 (table 3).
DISCUSSION A unique and broadly accepted classification system could be helpful for monitoring and reporting outcomes in PNL.5–7,16,17 In this study the modified version of the Clavien classification system for adult PNL was considered appropriate for PNL complications in children after some slight adjustments. Comparison of the prevalent complications classified according to Clavien system at the 3 clinics in our study revealed similar percentages. Overall, complications in adult PNL according to Clavien classification were reported as 43.8% by de la Rosette et al6 and 29.2% by Tefekli et al.7 In our series the overall complication rate was 29.1%. Although the degree of some complications was increased in children compared to adults, a significant portion of the complications (43.5%) were grade I. This finding can be attributed to the fact that interventions were performed by physicians with extensive experience in adults who had completed the PNL learning curve and were more meticulous with pediatric cases. In addition, PNL interventions may be easier in children than adults due to their smaller structures. Further light can be shed on this issue by prospective studies comparing the complications emerging in adults and children following PNL. Although many adult studies have confirmed the efficacy and safety of tubeless PNL,18,19 there are limited studies evaluating the use of totally tubeless or tubeless PNL in children.11,12,20 In the present study tubeless PNL was applied in 29 renal units and totally tubeless PNL in 14. In patients who underwent totally tubeless and tubeless PNL mean operative times were shorter than with the standard technique (p ⬍0.001). Based on our results, the latest forms of PNL (tubeless and totally tubeless) are also safe and effective in children, provided patients are selected properly and the surgeon performing the procedure has the necessary experience. In the present study post-PNL residual stone formation in patients with simple renal stones was significantly less than in patients with complex stones (p ⬍0.001). The outcomes of the stone-free rates and transfusion rates were comparable to former PNL series of patients with complex renal stones.13,14,21 Hb reduction in patients with simple stones who underwent PNL was significantly less than in patients with complex stones (p ⫽ 0.01). While the complication rate according to Clavien classification system was higher in complex stones (53.3%) than simple stones (17.5%), the difference was not statistically significant. Children with bilateral kidney stones are generally treated with staged PNL. Reports of SBPNL in
PERCUTANEOUS NEPHROLITHOTOMY IN CHILDREN
children are scarce.22,23 Our results are comparable to these prior studies. With appropriate patient selection criteria the main advantages of SBPNL are reduced psychological stress, 1 cystoscopy and anesthesia, less medication, and a shorter hospital stay and convalescence with considerable savings in cost. We did not encounter grade II to V complications in these patients. In previous studies there has been no general agreement regarding instrument sizes as related to complications and success rates. The smaller caliber percutaneous tract and nephroscope are considered to be less injurious to the kidney, decreasing dilation and tortuosity, important considerations in preventing bleeding and renal trauma.24 –26 However, there are also studies claiming that adult equipment in PNL is compatible for use in infants and toddlers.27 The PNL techniques and instrumentation in the present study differed since the results of 3 centers were evaluated. The success rates with pediatric and adult-sized instruments were comparable, although mean postoperative Hb reduction and blood transfusion rate were higher in the adult-sized instrumentation group. Unlike previous reports,26,28 we divided patients into 3 distinct groups, infants and toddlers, preschool children and school children. While PNL application and technique are similar between adolescents and adults, infants and toddlers are considered a distinct group since they require greater surgical skill and caution. As the number of PNL applied renal units in infants was relatively small, their numbers were combined with the data regarding toddlers. The results were comparable between the groups in many of the parameters. Although complications and Clavien score were higher in school children compared to
1423
younger children, the difference was not statistically significant (p ⫽ 0.68). However, mean operative times were significantly shorter for infants and toddlers than for older children. As stated earlier, this may stem from the fact that the smaller structures in children require greater surgical skill and precision. Hence PNL interventions were performed by more experienced surgeons in this group. A comparison of the centers showed that while stone characteristics and complications were not different, operative time at center 3 was longer than at centers 1 and 2 (p ⫽ 0.001). Hb reduction at center 1, where pediatric instruments were used, was lower than that of the other 2 centers (p ⬍0.001). The long operative time seen at center 3 might be due to the preference of the surgeons at centers 1 and 2 for tubeless or totally tubeless PNL. The low Hb reduction at center 1 may stem from the use of pediatric instruments. A limitation of the present study is the comparison of the moderate-sized series of 3 centers. There are some obvious differences in techniques, including the size of the access tract, size of scopes and the performance of tubeless procedures, which would likely influence the complication rates if the cohort number were larger.
CONCLUSIONS Based on our results, PNL can be applied safely in children of varying ages, even infants. Complications are comparable to those observed in adults or even less provided there is adequate experience with the technique. Use of a common grading system in emerging complications will facilitate better comparison of the literature and results obtained from different centers.
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6. de la Rosette JJ, Zuazu JR, Tsakiris P et al: Prognostic factors and percutaneous nephrolithotomy morbidity: a multivariate analysis of a contemporary series using the Clavien classification. J Urol 2008; 180: 2489.
10. Dindo D, Demartines N and Clavien PA: Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004; 240: 205.
7. Tefekli A, Ali Karadag M, Tepeler K et al: Classification of percutaneous nephrolithotomy complications using the modified Clavien grading system: looking for a standard. Eur Urol 2008; 53: 184.
11. Khairy Salem H, Morsi HA, Omran A et al: Tubeless percutaneous nephrolithotomy in children. J Pediatr Urol 2007; 3: 235.
4. Smaldone MC, Docimo SG and Ost MC: Contemporary surgical management of pediatric urolithiasis. Urol Clin North Am 2010; 37: 253.
8. Clavien PA, Barkun J, de Oliveira ML et al: The Clavien-Dindo classification of surgical complications: five-year experience. Ann Surg 2009; 250: 187.
5. Skolarikos A and de la Rosette J: Prevention and treatment of complications following percutaneous nephrolithotomy. Curr Opin Urol 2008; 18: 229.
9. Clavien PA, Sanabria JR and Strasberg SM: Proposed classification of complications of surgery with examples of utility in cholecystectomy. Surgery 1992; 111: 518.
12. Ozturk A, Guven S, Kilinc M et al: Totally tubeless percutaneous nephrolithotomy: is it safe and effective in preschool children? J Endourol 2010; Epub ahead of print. 13. Ozden E, Sahin A, Tan B et al: Percutaneous renal surgery in children with complex stones. J Pediatr Urol 2008; 4: 295. 14. Desai MR, Kukreja RA, Patel SH et al: Percutaneous nephrolithotomy for complex pediatric renal calculus disease. J Endourol 2004; 18: 24e7.
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15. Ugras MY, Gedik E, Gunes A et al: Some criteria to attempt second side safely in planned bilateral simultaneous percutaneous nephrolithotomy. Urology 2008; 72: 996.
20. Bogris S and Papatsoris AG: Status quo of percutaneous nephrolithotomy in children. Urol Res 2010; 38: 1.
16. Zuazu JR, Hruza M, Rassweiler JJ et al: The Clavien classification system to optimize the documentation of PNL morbidity. Arch Ital Urol Androl 2010; 82: 20.
21. Gonen M, Turunc T, Ozturk B et al: Outcome of percutaneous nephrolithotomy in children having complex stones. Urol Int 2009; 83: 416.
17. Michel MS, Trojan L and Rassweiler JJ: Complications in percutaneous nephrolithotomy. Eur Urol 2007; 51: 899.
22. Salah MA, Tallai B, Holman E et al: Simultaneous bilateral percutaneous nephrolithotomy in children. BJU Int 2005; 95: 137.
18. Istanbulluoglu MO, Ozturk B, Cicek T et al: Bilateral simultaneous totally tubeless percutaneous nephrolithotomy: preliminary report of six cases. J Endourol 2009; 23: 1255.
23. Samad L, Aquil S and Zaidi Z: Paediatric percutaneous nephrolithotomy: setting new frontiers. BJU Int 2006; 97: 359.
19. Zilberman DE, Lipkin ME, de la Rosette JJ et al: Tubeless percutaneous nephrolithotomy—the new standard of care? J Urol 2010; 184: 1261.
24. Zeren S, Satar N, Bayazit Y et al: Percutaneous nephrolithotomy in the management of pediatric renal calculi. J Endourol 2002; 16: 75.
25. Bilen CY, Kocak B, Kitirci G et al: Percutaneous nephrolithotomy in children: lessons learned in 5 years at a single institution. J Urol 2007; 177: 1867. 26. Unsal A, Resorlu B, Kara C et al: Safety and efficacy of percutaneous nephrolithotomy in infants, preschool age, and older children with different sizes of instruments. Urology 2010; 76: 247. 27. Kroovand RL: Pediatric urolithiasis. Urol Clin North Am 1997; 24: 173. 28. Jackman SV, Hedican SP, Peters CA et al: Percutaneous nephrolithotomy in infants and preschool age children: experience with a new technique. Urology 1998; 52: 697.
EDITORIAL COMMENTS The evolution of the treatment of pediatric nephrolithiasis has permitted techniques previously exclusive to adults to be transferred to the pediatric arena. The continued theme in this series and the literature is that adult-sized instruments have a significant impact on overall blood loss. Every effort should be made to use appropriately sized equipment for the pediatric patient to eliminate this potential morbidity. The authors are to be commended for using an objective validated measurement of the morbidities in their patients with the Clavien-Dindo clas-
sification. Future clinical reports on adoption and implementation of new surgical techniques should strive to incorporate such measurements. With the recent health care reform in the United States, assessment of outcomes and quality for pediatric urology diagnoses and procedures may become the norm rather than the exception.1 Nicholas M. Holmes Division of Pediatric Urology University of California San Diego San Diego, California
REFERENCE 1. Raval MV, Dillon PW, Bruny JL et al: American College of Surgeons national surgical quality improvement program pediatric: a phase 1 report. J Am Coll Surg 2011; 212: 1.
The application by the authors of a modified Clavien classification is a useful way to standardize postPNL complications, and clearly illustrates that PNL can be safely performed in children, an issue that is becoming more relevant as stone incidence in this population increases. However, there is an array of literature citing increased morbidity of transfused patients that supports more judicious transfusion rates than what the authors present.1 They do not delineate indications for transfusion, but if transfusion had been restricted to patients with signs of anemia/hypovolemia, the study would likely further
illustrate the safety of appropriately performed pediatric PNL. The authors also performed totally tubeless PNL, a novel concept, in a small subset of patients. The results are intriguing, although this procedure is normally only done in cases with a low risk of complications. Further study is needed before widespread application of this technique is adopted.
REFERENCE 1. Pape A, Stein P, Horn O et al: Clinical evidence of blood transfusion effectiveness. Blood Transfus 2009; 7: 250.
S. Scott Sparks Department of Urology and Pediatrics George Washington University Washington, DC