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Does percutaneous nephrolithotomy in children cause significant renal scarring?
Journal of Pediatric Urology (2007) 3, 36e39
Does percutaneous nephrolithotomy in children cause significant renal scarring? Lubna Samad, Samia Qureshi, Zafar Zaidi* Division of Urology, The Kidney Centre Postgraduate Training Institute, 197 Rafiqui Shaheed Road, Karachi 75530, Pakistan Received 21 September 2005; accepted 7 February 2006 Available online 5 April 2006
KEYWORDS Percutaneous nephrolithotomy; 99m Tc-DMSA; Focal renal damage; Renal calculi
Abstract Objective: To determine the frequency of renal parenchymal damage following percutaneous nephrolithotomy (PCNL) in children. Patients and methods: Fifty-six children undergoing PCNL in 60 renal units between January 2000 and December 2004 were included in this prospective study, and were subjected to postoperative technetium-99m dimercaptosuccinic acid (99mTc-DMSA). Using a standard questionnaire, demographics, number, size and location of stones, procedure details, outcome as indicated by clearance with PCNL alone or additional procedures, and follow up were documented. Presence of focal renal damage and its association with the PCNL tract were examined. Results: Out of 60 renal units, cortical defects on 99mTc-DMSA scan were seen in 10 renal units (17%). In three of these kidneys, the site of focal defect corresponded to the access site for tract formation during PCNL. Two additional kidneys had scarring at multiple sites, one of which corresponded to the access site during PCNL. In the remaining five kidneys no association between focal renal damage and nephrostomy tract site could be ascertained. No association was seen between renal damage and the size of nephroscope used during PCNL. Conclusion: There exists a risk of focal damage to renal parenchyma from the formation of the nephrostomy tract. In our series, focal damage was seen in 5% of patients; this may be an overestimate since preoperative 99mTc-DMSA scans were not available for our patients. Meticulous technique is important combined with a smaller nephroscope to minimize renal damage. Long-term follow up of such children is required to assess how many are left with permanent renal scars. ª 2006 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
Introduction * Corresponding author. Tel.: þ92 21 5661000x253; fax: þ92 21 5661040. E-mail address: [email protected] (Z. Zaidi).
Since the introduction of percutaneous nephrolithotomy (PCNL) for treatment of renal stones in
1477-5131/$30 ª 2006 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jpurol.2006.02.001
Percutaneous nephrolithotomy in children adults in 1976 and subsequently in children in 1985, this technique has been used increasingly frequently. There have been concerns about possible renal parenchymal damage secondary to the formation of the nephrosotomy tract, especially in a growing child. Moreover, in developing countries where urolithiasis has assumed epidemic proportions, children often develop recurrent stones and may require multiple procedures. It is therefore important to establish that the kidney does not incur significant damage as a result of this procedure.
Patients and methods A prospective study was designed in which children undergoing PCNL at our institute were subjected to a postoperative technetium-99m DMSA (99mTcDMSA) scan. Fifty-six children undergoing PCNL in 60 renal units between January 2000 and December 2004 were included in the study. Using a standard questionnaire, demographics, number, size and location of stones, procedure details, outcome as indicated by clearance with PCNL alone or additional procedures, and follow up were documented. Before PCNL all children were reviewed in the outpatient clinic. IVU was performed in all children with normal renal function. A decision for PCNL was taken if the stone burden was judged to be too large to clear with lithotripsy alone. The sum of the longest axis of each stone indicated the approximate stone burden [1]. All procedures were performed by a single surgeon (ZZ) with the patient under general anaesthesia with an endotracheal tube. PCNL puncture was done under fluoroscopic guidance, with the patient in the prone position as described earlier [2]. After discharge, the child was initially seen in the clinic after 1 week, and then 4e6 weeks later with a 99mTcDMSA scan.
Results
37 preoperatively; this had normalized or improved in each of these children after the procedure. During the procedure, access was gained and clearance achieved through a single puncture in 58 renal units (97%), with an upper, mid and lower calyceal tract in 12, 1 and 45 renal units, respectively. Two tracts each were required in two children. A 17-F Storz nephroscope was used in 45 children (75%) and a 26-F Storz nephroscope in 15 children (25%). A 99mTc-DMSA scan was performed at a median time of 1 month after the procedure (mean 3.6 months, range 1e34 months). Four children had undergone a 99mTc-DMSA scan preoperatively; none of them had evidence of renal damage on either the pre- or postoperative scans. Focal defects were identified in 10 renal units (17%), and their details are shown in Table 1. One child had undergone bilateral PCNL and focal defects were demonstrated in both renal units. In this group, only one child had impaired renal function, which improved in the postoperative period. Of the 10 children with focal renal defects on 99m Tc-DMSA scan, four had undergone ESWL for residual stones after PCNL. In three children, the site of residual stone was different from the site of defect. In the fourth case, defects were seen in both upper and lower poles, whereas the puncture site as well as residual stone targeted for Table 1 Renal units demonstrating scarring on 99m Tc-DMSA scan Serial Scarring site Access Scope UTIa Scar due to tract no. on 99mTcsite for size formation DMSA PCNL (F) 1
Upper pole
2
Upper pole
3
Lower pole
4
7
Upper þ lower pole Upper þ lower pole Patchy scarring Upper pole
8
Lower pole
9
Upper pole
10
Upper pole
5
Fifty-two children undergoing unilateral PCNL and four children undergoing bilateral PCNL were included. Mean age was 7.7 years (range 1.1e16 years). PCNL was performed on 35 right and 25 left kidneys. Mean stone burden was 23.8 mm. Fifteen children (27%) had a history of documented UTI prior to surgery. Five children had a history of stone disease in the past: one child each underwent a cystolithotomy, ipsilateral ureterolithotomy, ipsilateral pyelolithotomy, while two children passed stones spontaneously. Five children had impaired renal function (serum creatinine >1 mEq/l)
6
a
Upper pole Upper pole Lower pole Lower pole Lower pole Lower pole Lower pole Upper pole Lower pole Lower pole
History of documented UTI.
17
Yes
Possible
17
No
Possible
17
Yes
Possible
17
No
Unlikely
26
Yes
Unlikely
17
Yes
No
17
No
No
26
No
No
17
No
No
17
Yes
No
38 ESWL were in the lower calyx. Hence, renal damage cannot be attributable to ESWL after PCNL.
Discussion The application of nephrostomy tracts for therapeutic purposes has led to the increasing use of larger bore tracts. While this has resulted in great benefits by providing minimally invasive methods of dealing with common problems, there have been concerns voiced about the possibility of long-term renal damage as a result of tract formation. The size and type of dilator used may play a role in the development of renal damage. Clayman et al. [3] attempted to duplicate the standard nephrostomy technique in porcine models, using either semi-rigid dilatation to 24 F, or balloon dilatation to 36 F. Detailed histopathological studies performed 6 weeks after the procedure found nephrostomy tracts in these kidneys to be healed to a fine scar, with renal damage averaging 0.15% of the total cortical surface. In another series [4], standard (30-F) versus mini (11-F) PCNL was compared in animal models and found to have no difference in resultant scar formation. Wilson et al. [5] compared the renal damage incurred with four different methods of treatment of stone disease in animal models. Pathologic and biochemical sequelae of open pyelotomy, nephrotomy, lithotripsy and percutaneous nephrostomy were studied. No significant effect on renal function was found 1 month after the procedure in all four groups; however, significantly greater scarring was seen in the percutaneous nephrostomy group (1.53 0.4%) than in the other groups. Even then, the parenchyma affected was less than 2% of the total renal volume. In comparison, ESWL has been shown to cause renal loss of less than 1% of the total cortical surface [6]. The use of 99m Tc-DMSA scans to assess parenchymal damage in children following ESWL was initially reported by Lottman et al. [7]. The authors demonstrated ESWL to be a safe modality with no permanent sequelae in children. Renal parenchymal injury, as evidenced by enzyme markers and 99mTc-DMSA scan, may occur in the early period following ESWL but has been shown to be reversible with time. In our practice, we use PCNL either as a monotherapy or with one or more sessions of ESWL to achieve complete stone clearance. In our series of 60 renal units, focal parenchymal defects were seen in 10 kidneys. When comparing site of focal defect with site of tract formation, correlation was seen in five renal units. Of these, two renal units had focal damage on isotope scans
L. Samad et al. at multiple sites, raising the possibility that focal defects could be due to other factors, e.g. infection. Thus, in only three cases (5%) could renal damage possibly be attributed to nephrostomy tract formation. This could be an overestimation, since pre-operative 99mTc-DMSA was not performed in this series, and two out of these three children had previous documented UTI. The non-availability of pre-operative isotope scans is a limitation of our study. However, Mor et al. [8] reported unchanged differential function and no evidence of significant scarring in all but one of 17 children in their series, and that one child had recurrent UTI and multiple PCNL procedures over a period of several years. All procedures in this series were performed using an adult Amplatz sheath. The authors contend that use of paediatric instruments, gentle technique and a single tract minimize the complication of renal parenchymal damage even further. Although animal models have not shown greater scar formation with the use of adult-sized instruments for paediatric PCNL, we still prefer to use a 17-F scope whenever possible, especially in smaller children and in children with a limited stone burden. The smaller scope allows for easier navigation within the pelvicalyceal system, with the urothelium less liable to sustain traumatic injury. Possible changes in renal function as an indicator of renal damage have also been studied. Mayo et al. [9] found no significant change in creatinine clearance and no evidence of cortical scarring as seen on 99mTc-DMSA scans in 17 renal units before and after PCNL. Moreover, where infected stones were present, a significant improvement in function was seen. In another series comparing pre- and post-PCNL DMSA scans in 33 renal units, the authors concluded that there was no significant effect on renal function, even with creation of more than one nephrostomy tract [10]. Dawaba et al. [11] performed 99mTc-DMSA scans to detect renal scarring and 99mTc-DTPA scans to determine selective glomerular filtration rates following PCNL in 65 children (72 renal units). There was no evidence of renal scarring in any renal unit, and stabilization or improvement of selective glomerular filtration rate in all but four renal units. Three of these four units showed improvement over time. These authors dilated the tract up to 30 F in older children in this series. ESWL and PCNL were found to be equally safe in a series of patients with impaired renal function [12]. Liou and Streem, in their review of adult patients undergoing ESWL, PCNL or a combination of both [13], found no deterioration of renal function even at long-term follow up in all three treatment groups. In our series, four out of 10 children with
Percutaneous nephrolithotomy in children focal defects on 99mTc-DMSA scan had required ESWL following PCNL. In all four cases the site of damage was not consistent with the site of residual stone. The use of ESWL either in isolation or in conjunction with PCNL appears to be safe in children. In our series, the median time to postoperative isotope scans was 1 month after PCNL. Since a large majority of our patient population comes from distant rural settings, we have advocated early isotope scans to improve compliance. Hence, we describe focal parenchymal defects as these may not necessarily evolve with time into permanent scars. Interestingly, all three children with isotope scan changes possibly attributable to nephrostomy tract formation had their 99mTc-DMSA scans done between 4 and 6 months.
Conclusion With increasing experience, PCNL in children is becoming safer and more effective. A careful approach and meticulous attention to detail helps limits the trauma sustained by the kidney. Our study shows that frequency of damage to renal parenchyma from nephrostomy tract formation is as low as 5%. However, long-term follow up is necessary in young children to assess renal growth and function.
References 1 Wolf JS, Clayman RV. Percutaneous nephrolithotomy: what is its role in 1997? Urol Clin North Am 1997;24:43e58.
39 2 Mahmud M, Zaidi Z. Percutaneous nephrolithotomy in children before school age: experience of a Pakistani centre. BJU Int 2004;94:1352e4. 3 Clayman RV, Elbers J, Miller RP, et al. Percutaneous nephrostomy: assessment of renal damage associated with semirigid (24F) and balloon (36F) dilatation. J Urol 1987;138: 203e6. 4 Traxer O, Smith III TG, Pearle MS, et al. Renal parenchymal injury after standard and mini percutaneous nephrostolithotomy. J Urol 2001;165:1693e5. 5 Wilson WT, Husmann DA, Morris JS, et al. A comparison of the bioeffects of four different modes of stone therapy on renal function and morphology. J Urol 1993;150:1267e70. 6 Gunasekaran S, Donovan JM, Chvapil M, et al. Effects of extracorporeal shock wave lithotripsy on the structure and function of rabbit kidney. J Urol 1989;141:1250. 7 Lottmann HB, Archambaud F, Hellal B, et al. 99m Technetium-dimercaptosuccininc acid renal scan in the evaluation of potential long-term renal parenchymal damage associated with extracorporeal shock wave lithotripsy in children. J Urol 1998;159:521e4. 8 Mor Y, Elmasry YET, Kellett MJ, et al. The role of percutaneous nephrolithotomy in the management of pediatric renal calculi. J Urol 1997;158:1319e21. 9 Mayo ME, Krieger JN, Rudd TG. Effect of percutaneous nephrostolithotomy on renal function. J Urol 1985;133:167e9. 10 Eshghi M, Schiff RG, Smith AD. Renal effects of percutaneous stone removal. J Urol 1988;140:950e3. 11 Dawaba MS, Shokeir AA, Hafez AT, et al. Percutaneous nephrolithotomy in children: early and late anatomical and functional results. J Urol 2004;172:1078e81. 12 Chandhoke PS, Albala DM, Clayman RV. Long-term comparison of renal function in patients with solitary kidneys and/or moderate renal insufficiency undergoing extracorporeal shock wave lithotripsy or percutaneous nephrolithotomy. J Urol 1992;147:1226e30. 13 Liou LS, Streem SB. Long-term renal functional effects of shock wave lithotripsy, percutaneous nephrolithotomy and combination therapy: a comparative study of patients with solitary kidney. J Urol 2001;166:36e7.
Does percutaneous nephrolithotomy in children cause significant renal scarring? Lubna Samad, Samia Qureshi, Zafar Zaidi* Division of Urology, The Kidney Centre Postgraduate Training Institute, 197 Rafiqui Shaheed Road, Karachi 75530, Pakistan Received 21 September 2005; accepted 7 February 2006 Available online 5 April 2006
KEYWORDS Percutaneous nephrolithotomy; 99m Tc-DMSA; Focal renal damage; Renal calculi
Abstract Objective: To determine the frequency of renal parenchymal damage following percutaneous nephrolithotomy (PCNL) in children. Patients and methods: Fifty-six children undergoing PCNL in 60 renal units between January 2000 and December 2004 were included in this prospective study, and were subjected to postoperative technetium-99m dimercaptosuccinic acid (99mTc-DMSA). Using a standard questionnaire, demographics, number, size and location of stones, procedure details, outcome as indicated by clearance with PCNL alone or additional procedures, and follow up were documented. Presence of focal renal damage and its association with the PCNL tract were examined. Results: Out of 60 renal units, cortical defects on 99mTc-DMSA scan were seen in 10 renal units (17%). In three of these kidneys, the site of focal defect corresponded to the access site for tract formation during PCNL. Two additional kidneys had scarring at multiple sites, one of which corresponded to the access site during PCNL. In the remaining five kidneys no association between focal renal damage and nephrostomy tract site could be ascertained. No association was seen between renal damage and the size of nephroscope used during PCNL. Conclusion: There exists a risk of focal damage to renal parenchyma from the formation of the nephrostomy tract. In our series, focal damage was seen in 5% of patients; this may be an overestimate since preoperative 99mTc-DMSA scans were not available for our patients. Meticulous technique is important combined with a smaller nephroscope to minimize renal damage. Long-term follow up of such children is required to assess how many are left with permanent renal scars. ª 2006 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
Introduction * Corresponding author. Tel.: þ92 21 5661000x253; fax: þ92 21 5661040. E-mail address: [email protected] (Z. Zaidi).
Since the introduction of percutaneous nephrolithotomy (PCNL) for treatment of renal stones in
1477-5131/$30 ª 2006 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jpurol.2006.02.001
Percutaneous nephrolithotomy in children adults in 1976 and subsequently in children in 1985, this technique has been used increasingly frequently. There have been concerns about possible renal parenchymal damage secondary to the formation of the nephrosotomy tract, especially in a growing child. Moreover, in developing countries where urolithiasis has assumed epidemic proportions, children often develop recurrent stones and may require multiple procedures. It is therefore important to establish that the kidney does not incur significant damage as a result of this procedure.
Patients and methods A prospective study was designed in which children undergoing PCNL at our institute were subjected to a postoperative technetium-99m DMSA (99mTcDMSA) scan. Fifty-six children undergoing PCNL in 60 renal units between January 2000 and December 2004 were included in the study. Using a standard questionnaire, demographics, number, size and location of stones, procedure details, outcome as indicated by clearance with PCNL alone or additional procedures, and follow up were documented. Before PCNL all children were reviewed in the outpatient clinic. IVU was performed in all children with normal renal function. A decision for PCNL was taken if the stone burden was judged to be too large to clear with lithotripsy alone. The sum of the longest axis of each stone indicated the approximate stone burden [1]. All procedures were performed by a single surgeon (ZZ) with the patient under general anaesthesia with an endotracheal tube. PCNL puncture was done under fluoroscopic guidance, with the patient in the prone position as described earlier [2]. After discharge, the child was initially seen in the clinic after 1 week, and then 4e6 weeks later with a 99mTcDMSA scan.
Results
37 preoperatively; this had normalized or improved in each of these children after the procedure. During the procedure, access was gained and clearance achieved through a single puncture in 58 renal units (97%), with an upper, mid and lower calyceal tract in 12, 1 and 45 renal units, respectively. Two tracts each were required in two children. A 17-F Storz nephroscope was used in 45 children (75%) and a 26-F Storz nephroscope in 15 children (25%). A 99mTc-DMSA scan was performed at a median time of 1 month after the procedure (mean 3.6 months, range 1e34 months). Four children had undergone a 99mTc-DMSA scan preoperatively; none of them had evidence of renal damage on either the pre- or postoperative scans. Focal defects were identified in 10 renal units (17%), and their details are shown in Table 1. One child had undergone bilateral PCNL and focal defects were demonstrated in both renal units. In this group, only one child had impaired renal function, which improved in the postoperative period. Of the 10 children with focal renal defects on 99m Tc-DMSA scan, four had undergone ESWL for residual stones after PCNL. In three children, the site of residual stone was different from the site of defect. In the fourth case, defects were seen in both upper and lower poles, whereas the puncture site as well as residual stone targeted for Table 1 Renal units demonstrating scarring on 99m Tc-DMSA scan Serial Scarring site Access Scope UTIa Scar due to tract no. on 99mTcsite for size formation DMSA PCNL (F) 1
Upper pole
2
Upper pole
3
Lower pole
4
7
Upper þ lower pole Upper þ lower pole Patchy scarring Upper pole
8
Lower pole
9
Upper pole
10
Upper pole
5
Fifty-two children undergoing unilateral PCNL and four children undergoing bilateral PCNL were included. Mean age was 7.7 years (range 1.1e16 years). PCNL was performed on 35 right and 25 left kidneys. Mean stone burden was 23.8 mm. Fifteen children (27%) had a history of documented UTI prior to surgery. Five children had a history of stone disease in the past: one child each underwent a cystolithotomy, ipsilateral ureterolithotomy, ipsilateral pyelolithotomy, while two children passed stones spontaneously. Five children had impaired renal function (serum creatinine >1 mEq/l)
6
a
Upper pole Upper pole Lower pole Lower pole Lower pole Lower pole Lower pole Upper pole Lower pole Lower pole
History of documented UTI.
17
Yes
Possible
17
No
Possible
17
Yes
Possible
17
No
Unlikely
26
Yes
Unlikely
17
Yes
No
17
No
No
26
No
No
17
No
No
17
Yes
No
38 ESWL were in the lower calyx. Hence, renal damage cannot be attributable to ESWL after PCNL.
Discussion The application of nephrostomy tracts for therapeutic purposes has led to the increasing use of larger bore tracts. While this has resulted in great benefits by providing minimally invasive methods of dealing with common problems, there have been concerns voiced about the possibility of long-term renal damage as a result of tract formation. The size and type of dilator used may play a role in the development of renal damage. Clayman et al. [3] attempted to duplicate the standard nephrostomy technique in porcine models, using either semi-rigid dilatation to 24 F, or balloon dilatation to 36 F. Detailed histopathological studies performed 6 weeks after the procedure found nephrostomy tracts in these kidneys to be healed to a fine scar, with renal damage averaging 0.15% of the total cortical surface. In another series [4], standard (30-F) versus mini (11-F) PCNL was compared in animal models and found to have no difference in resultant scar formation. Wilson et al. [5] compared the renal damage incurred with four different methods of treatment of stone disease in animal models. Pathologic and biochemical sequelae of open pyelotomy, nephrotomy, lithotripsy and percutaneous nephrostomy were studied. No significant effect on renal function was found 1 month after the procedure in all four groups; however, significantly greater scarring was seen in the percutaneous nephrostomy group (1.53 0.4%) than in the other groups. Even then, the parenchyma affected was less than 2% of the total renal volume. In comparison, ESWL has been shown to cause renal loss of less than 1% of the total cortical surface [6]. The use of 99m Tc-DMSA scans to assess parenchymal damage in children following ESWL was initially reported by Lottman et al. [7]. The authors demonstrated ESWL to be a safe modality with no permanent sequelae in children. Renal parenchymal injury, as evidenced by enzyme markers and 99mTc-DMSA scan, may occur in the early period following ESWL but has been shown to be reversible with time. In our practice, we use PCNL either as a monotherapy or with one or more sessions of ESWL to achieve complete stone clearance. In our series of 60 renal units, focal parenchymal defects were seen in 10 kidneys. When comparing site of focal defect with site of tract formation, correlation was seen in five renal units. Of these, two renal units had focal damage on isotope scans
L. Samad et al. at multiple sites, raising the possibility that focal defects could be due to other factors, e.g. infection. Thus, in only three cases (5%) could renal damage possibly be attributed to nephrostomy tract formation. This could be an overestimation, since pre-operative 99mTc-DMSA was not performed in this series, and two out of these three children had previous documented UTI. The non-availability of pre-operative isotope scans is a limitation of our study. However, Mor et al. [8] reported unchanged differential function and no evidence of significant scarring in all but one of 17 children in their series, and that one child had recurrent UTI and multiple PCNL procedures over a period of several years. All procedures in this series were performed using an adult Amplatz sheath. The authors contend that use of paediatric instruments, gentle technique and a single tract minimize the complication of renal parenchymal damage even further. Although animal models have not shown greater scar formation with the use of adult-sized instruments for paediatric PCNL, we still prefer to use a 17-F scope whenever possible, especially in smaller children and in children with a limited stone burden. The smaller scope allows for easier navigation within the pelvicalyceal system, with the urothelium less liable to sustain traumatic injury. Possible changes in renal function as an indicator of renal damage have also been studied. Mayo et al. [9] found no significant change in creatinine clearance and no evidence of cortical scarring as seen on 99mTc-DMSA scans in 17 renal units before and after PCNL. Moreover, where infected stones were present, a significant improvement in function was seen. In another series comparing pre- and post-PCNL DMSA scans in 33 renal units, the authors concluded that there was no significant effect on renal function, even with creation of more than one nephrostomy tract [10]. Dawaba et al. [11] performed 99mTc-DMSA scans to detect renal scarring and 99mTc-DTPA scans to determine selective glomerular filtration rates following PCNL in 65 children (72 renal units). There was no evidence of renal scarring in any renal unit, and stabilization or improvement of selective glomerular filtration rate in all but four renal units. Three of these four units showed improvement over time. These authors dilated the tract up to 30 F in older children in this series. ESWL and PCNL were found to be equally safe in a series of patients with impaired renal function [12]. Liou and Streem, in their review of adult patients undergoing ESWL, PCNL or a combination of both [13], found no deterioration of renal function even at long-term follow up in all three treatment groups. In our series, four out of 10 children with
Percutaneous nephrolithotomy in children focal defects on 99mTc-DMSA scan had required ESWL following PCNL. In all four cases the site of damage was not consistent with the site of residual stone. The use of ESWL either in isolation or in conjunction with PCNL appears to be safe in children. In our series, the median time to postoperative isotope scans was 1 month after PCNL. Since a large majority of our patient population comes from distant rural settings, we have advocated early isotope scans to improve compliance. Hence, we describe focal parenchymal defects as these may not necessarily evolve with time into permanent scars. Interestingly, all three children with isotope scan changes possibly attributable to nephrostomy tract formation had their 99mTc-DMSA scans done between 4 and 6 months.
Conclusion With increasing experience, PCNL in children is becoming safer and more effective. A careful approach and meticulous attention to detail helps limits the trauma sustained by the kidney. Our study shows that frequency of damage to renal parenchyma from nephrostomy tract formation is as low as 5%. However, long-term follow up is necessary in young children to assess renal growth and function.
References 1 Wolf JS, Clayman RV. Percutaneous nephrolithotomy: what is its role in 1997? Urol Clin North Am 1997;24:43e58.
39 2 Mahmud M, Zaidi Z. Percutaneous nephrolithotomy in children before school age: experience of a Pakistani centre. BJU Int 2004;94:1352e4. 3 Clayman RV, Elbers J, Miller RP, et al. Percutaneous nephrostomy: assessment of renal damage associated with semirigid (24F) and balloon (36F) dilatation. J Urol 1987;138: 203e6. 4 Traxer O, Smith III TG, Pearle MS, et al. Renal parenchymal injury after standard and mini percutaneous nephrostolithotomy. J Urol 2001;165:1693e5. 5 Wilson WT, Husmann DA, Morris JS, et al. A comparison of the bioeffects of four different modes of stone therapy on renal function and morphology. J Urol 1993;150:1267e70. 6 Gunasekaran S, Donovan JM, Chvapil M, et al. Effects of extracorporeal shock wave lithotripsy on the structure and function of rabbit kidney. J Urol 1989;141:1250. 7 Lottmann HB, Archambaud F, Hellal B, et al. 99m Technetium-dimercaptosuccininc acid renal scan in the evaluation of potential long-term renal parenchymal damage associated with extracorporeal shock wave lithotripsy in children. J Urol 1998;159:521e4. 8 Mor Y, Elmasry YET, Kellett MJ, et al. The role of percutaneous nephrolithotomy in the management of pediatric renal calculi. J Urol 1997;158:1319e21. 9 Mayo ME, Krieger JN, Rudd TG. Effect of percutaneous nephrostolithotomy on renal function. J Urol 1985;133:167e9. 10 Eshghi M, Schiff RG, Smith AD. Renal effects of percutaneous stone removal. J Urol 1988;140:950e3. 11 Dawaba MS, Shokeir AA, Hafez AT, et al. Percutaneous nephrolithotomy in children: early and late anatomical and functional results. J Urol 2004;172:1078e81. 12 Chandhoke PS, Albala DM, Clayman RV. Long-term comparison of renal function in patients with solitary kidneys and/or moderate renal insufficiency undergoing extracorporeal shock wave lithotripsy or percutaneous nephrolithotomy. J Urol 1992;147:1226e30. 13 Liou LS, Streem SB. Long-term renal functional effects of shock wave lithotripsy, percutaneous nephrolithotomy and combination therapy: a comparative study of patients with solitary kidney. J Urol 2001;166:36e7.