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Percutaneous nephrolithotomy in treatment of large stones within horseshoe kidneys
ADULT UROLOGY
PERCUTANEOUS NEPHROLITHOTOMY IN TREATMENT OF LARGE STONES WITHIN HORSESHOE KIDNEYS AHMED A. SHOKEIR, AHMED R. EL-NAHAS, AHMED M. SHOMA, IBRAHIM ERAKY, MAHMOUD EL-KENAWY, ALAA MOKHTAR, AND HAMDY EL-KAPPANY
ABSTRACT Objectives. To present our experience with percutaneous nephrolithotomy (PCNL) in the treatment of large stones within horseshoe kidneys. Methods. The study included 34 patients with 45 stone-bearing horseshoe kidneys treated by PCNL in one center. The indications for PCNL were large stone burden (greater than 2 cm) in 10 kidneys (22.2%), multiple complex stones in 22 (48.9%), staghorn stones in 3 (6.7%), and failed extracorporeal shock wave lithotripsy (ESWL) in 10 kidneys (22.2%). All PCNL procedures were performed in a standard one-session technique with fluoroscopic guidance. Procedures were evaluated for intraoperative and postoperative complications, use of auxiliary procedures (second-look PCNL, ureteroscopy, and ESWL), and length of hospital stay. Moreover, the stone-free rate was calculated at discharge from the hospital and 3 months later. In addition, we assessed the need for secondary intervention during a mean follow-up of 75 ⫾ 16 months (range 6 to 108). Results. The stone burden ranged from 264 to 2408 mm2 (mean 664 ⫾ 153). Access to the horseshoe kidneys was supracostal in 10 (22.2%) and subcostal in 35 kidneys (77.8%). A single tract was used in 37 (82%), and two tracts were created in the remaining 8 kidneys (18%). Major complications were seen in six PCNL procedures (13.3%) and included significant hematuria requiring blood transfusion in three, septicemia in one, ureteral obstruction in one, and colonic injury in one. All complications were successfully treated. Auxiliary procedures were required in 12 patients (35.3%) and included ureteroscopy in 1, second-look PCNL in 3, and ESWL to fragment residual caliceal stones in 8 patients. The mean hospital stay was 4 ⫾ 1.9 days (range 3 to 12). The stone-free rate was 82% at discharge and 89% at 3 months. During the course of follow-up, 19 patients (56%) developed stone recurrence and were successfully treated with ESWL in 8 and PCNL in 11. Conclusions. PCNL is a safe and effective procedure in the treatment of large stones within horseshoe kidneys. UROLOGY 64: 426–429, 2004. © 2004 Elsevier Inc.
H
orseshoe kidney is the most common of all renal fusion anomalies, with a prevalence of 0.25% in the general population.1 Although most horseshoe kidneys are asymptomatic, urolithiasis and ureteropelvic junction obstruction represent the most common complications requiring surgical intervention.2 The incidence of stone formation in the horseshoe kidney has been reported to be 20%.1,3,4 From the Urology and Nephrology Center, Mansoura University, Mansoura, Egypt Reprint requests: Ahmed A. Shokeir, M.D., Ph.D., Urology and Nephrology Center, Mansoura University, Mansoura 35516, Egypt Submitted: March 1, 2004, accepted (with revisions): April 16, 2004
426
© 2004 ELSEVIER INC. ALL RIGHTS RESERVED
Various treatment modalities have been used to treat stones in a horseshoe kidney, including extracorporeal shock wave lithotripsy (ESWL), ureteroscopy, percutaneous nephrolithotomy (PCNL), and open surgery. Although adequate fragmentation can be achieved by ESWL in stone-bearing horseshoe kidneys, the anatomic abnormalities prevent fragment passage in a substantial number of patients.5 The overall stone-free rate has been only 53% (range 50% to 79%).4,6 –9 Ureteroscopic approaches are challenging and not universally recommended.10 The use of PCNL in the treatment of stones in horseshoe kidneys has received little attention in published reports. Most of the previous investigators reported on small series, and the overall number of patients hardly exceeded 0090-4295/04/$30.00 doi:10.1016/j.urology.2004.04.018
TABLE I. Indications for PCNL in 45 stone-bearing horseshoe kidneys Indication
Patients (n)
Large stone burden (⬎2 cm) Complex multiple stones Staghorn stones Failed ESWL
10 22 3 10
(22.2) (48.9) (6.7) (22.2)
KEY: PCNL ⫽ percutaneous nephrolithotomy; ESWL ⫽ extracorporeal shock wave lithotripsy. Data in parentheses are percentages.
100.1,11–14 The largest series in English published studies included only 24 patients. However, this number was collected from the databases of three large institutions during a 10-year period. We present our experience with 45 PCNL procedures in 34 patients with stone-bearing horseshoe kidneys. To the best of our knowledge, the present study is the largest single-institution study of the English published studies. MATERIAL AND METHODS Between January 1995 and June 2003, 34 consecutive patients with unilateral or bilateral stones in horseshoe kidneys were treated with PCNL. Of the 34 patients, 30 were males and 4 were 4 females (mean age 41.6⫾ 10 years, range 11 to 61). Eleven patients had bilateral renal stones; therefore, the number of kidneys treated by PCNL was 45. The leading symptoms were recurrent flank pain and/or hematuria in 20 (59%) and recurrent urinary tract infection in 14 patients (41%). The indications for PCNL in the 45 kidneys are given in Table I. In addition to routine history taking and clinical examination, the investigations included plain abdominal x-ray (KUB) and gray-scale ultrasonography. Excretory urography was performed if the serum creatinine was less than 2 mg/dL. If the stones were radiolucent, faintly opaque, or difficult to localize by the previous methods, noncontrast spiral computed tomography (CT) was performed. The stone burden was determined by multiplying the stone length by the width in millimeters, squared, as measured on the preoperative KUB or excretory urography in cases with radiolucent stones. Urine specimens were obtained for culture. Chemical analysis of the stones was performed in 20 patients. All PCNL procedures were performed by the urology team in a standard one-session technique with fluoroscopic guidance. Procedures were assessed for cutaneous access of the tract (supracostal or subcostal), renal access location (upper, middle, or lower calices), and the number of tracts. In all patients, ultrasound and/or pneumatic disintegration was used, together with mechanical extraction of stone fragments. A rigid nephroscope was used in all patients. Residual stone fragments were assessed at completion of the PCNL procedures by KUB and intraoperative nephrostography. The procedures were also evaluated for blood loss and intraoperative complications. After completing the PCNL procedure, a nephrostomy tube was placed and routinely removed 2 to 4 days postoperatively. Additional studies, including postoperative nephrostography or spiral CT, were not routinely performed. Auxiliary procedures, including second-look PCNL, ureteroscopy, and ESWL, were also recorded. The hospital stay was calculated, and outcomes regarding postoperative complications and UROLOGY 64 (3), 2004
TABLE II. Access to 45 stone-bearing horseshoe kidneys Access Site
Kidneys (n)
Cutaneous Subcostal Supracostal Renal Upper calix Middle calix Upper ⫹ middle calices Upper ⫹ lower calices Middle ⫹ lower calices
35 (77.8) 10 (22.2) 21 17 6 1 1
(46.7) (37.8) (13.3) (2.2) (7.2)
Data in parentheses are percentages.
stone-free rates were examined. Complications were characterized as major if they required additional intervention or resulted in a prolonged hospital stay or minor if they could be conservatively managed with no additional intervention. Blood loss was considered significant if blood transfusion was required. All patients were seen 3 months after treatment and at least once annually during a mean follow-up of 75 ⫾ 16 months (range 6 to 108). At each visit, KUB and ultrasonography were performed; excretory urography was performed if stone recurrence was diagnosed. Noncontrast spiral CT was used in the follow-up of patients with lucent or faintly opaque stones.
RESULTS Of the 45 horseshoe kidneys, the stones were located in the renal pelvis in 13 (28.9%), calices in 17 (37.8%), and both in 15 kidneys (33.3%). The stone burden ranged from 264 to 2408 mm2 (mean 664 ⫾ 153). The left kidney was affected in 13 (38.2%), the right in 10 (29.4%), and both kidneys in 11 patients (32.4%). Access to the horseshoe kidneys was supracostal in 10 and subcostal in 35. A single tract was used in 37 kidneys (82%), and two tracts were created in the remaining 8 (18%). A detailed description of the access to the horseshoe kidneys is given in Table II. A radiologic profile of a PCNL procedure in a stone-bearing right horseshoe kidney in an 11year-old boy is shown in Figure 1. Major complications were seen in six PCNL procedures (13.3%) and included significant hematuria requiring blood transfusion in three, septicemia in one, ureteral obstruction by stone fragments in one, and colonic injury in one. Angioembolization was necessary to control bleeding in 1 of the 3 patients requiring a transfusion. The ureteral stone fragments were pushed up to the kidney and retrieved using a second-look PCNL. The colonic injury was found by nephrostography after PCNL. The patient was treated by withdrawal of the nephrostomy tube and temporary placement of a double-J ureteral stent with no untoward longterm sequelae. To identify the cause of this colonic injury, the patient underwent an additional CT 427
FIGURE 1. Radiologic profile of PCNL procedure in 11-year-old boy with large stone in right horseshoe kidney (prone position). (A) Preoperative plain abdominal radiograph showing large radiopaque calculus shadow in right kidney region. (B) Upper caliceal puncture under retrograde ureterogram. Filling defect of stone is evident in pelvis.
study with contrast, which revealed a retrorenal position of the descending colon. Auxiliary procedures were required in 12 patients (35.3%), including ureteroscopy in 1, second-look PCNL in 3, and ESWL to fragment residual caliceal stones in 8 patients. The mean hospital stay was 4 ⫾ 1.9 days (range 3 to 12). The stone-free rate was 82% at discharge and 89% at 3 months. Stone-free status was defined as the complete absence of stones or the presence of peripheral, small (less than 4 mm) stone fragments after primary and auxiliary procedures. Stone analysis was available in 20 patients and revealed calcium oxalate in 10 (50%), struvite stones in 4 (20%), and mixed stones in 6 (30%). During the course of follow-up, 19 patients (56%) developed stone recurrence and were successfully treated by ESWL in 8 and PCNL in 11. COMMENT Yohannes and Smith2 have recently provided a comprehensive literature review of the different 428
endourologic approaches in the management of stones secondary to a horseshoe kidney using Medline. Small stones are best managed by ESWL, and stones that have failed management by ESWL or that are larger than 2 cm are best managed percutaneously. Ureteroscopy or ESWL is associated with a greater residual stone rate than the percutaneous approach. Nevertheless, the conclusions regarding the safety and effectiveness of PCNL in the treatment of stones in horseshoe kidneys were based on a limited number of studies containing a small number of patients.1,11–14 The present study provides the results of this line of therapy in a relatively large number of patients treated in one center. With percutaneous renal surgery in horseshoe kidneys, two main factors differ from the normal renal anatomy: the blood supply and the orientation of the collecting system. In an anatomic and radiologic study, Janetschek and Kunzel15 have shown that all blood vessels, except for some to the isthmus, enter the kidney from its ventromedial aspect, and percutaneous access is obtained only on the opposite, far from the major arteries. The dorsal arteries to the isthmus are protected by the spine and are situated away from the nephrostomy tract. The risk of arterial bleeding is, therefore, not greater than in a normal kidney.15 In a horseshoe kidney, most of the calices point either dorsomedially or dorsolaterally. The calices to the isthmus lie within a coronal plane and point medially. Access to the calices in the isthmus is gained across the pelvis. The anatomic situation results in a lower and more medial position of the nephrostomy tract, whose orientation is more or less dorsoventral.15 The good clearance rate with a low incidence of complications shown by the present study demonstrates that the access is adequate and safe for percutaneous surgery within the collecting system of the horseshoe kidney. Upper pole access was used in 62% of patients in the present study. The percentage of upper pole access in previous studies ranged from 64% to 81%.1,13,14 It allows access to the upper pole calices, renal pelvis, lower pole calices, pelviureteral junction, and proximal ureter. Furthermore, upper pole access can decrease blood loss, because the long axis of the nephroscope is aligned with the long axis of the kidney, thereby minimizing nephroscope torque on renal tissue during manipulation.1 Nevertheless, upper pole access will result in an unusually long tract, and the instruments may not reach the lower and medial calices. This problem is exacerbated in obese patients, but it can be overcome using long, rigid nephroscopes or flexible ones. Notably, even though a flexible nephroscope was not used in the present study, we achieved a stoneUROLOGY 64 (3), 2004
free rate as good as other investigators. Most experts would, however, contend that flexible nephroscopy is a vital part of rendering patients stone free during PCNL in standard cases and, in particular, for stones in anomalous kidneys. In a recent study, a flexible nephroscope was used in 84% of patients who underwent PCNL for stones in horseshoe kidneys.1 In patients with normal renal anatomy, upper pole access often requires a supracostal approach, which may result in intrathoracic complications.16 In patients with a horseshoe kidney, upper pole percutaneous access is often essential and is relatively safe owing to the inferior displacement of the kidneys away from the pleura. Violation of the pleural cavity is decreased because a supracostal approach is less likely.1 None of our patients with an upper pole nephrostomy tract in a horseshoe kidney developed pneumothorax, and a rate of only 6% was reported by Raj et al.1 The 17.6% major complication rate in our series compares favorably with rates of previous studies that ranged between 12.5% and 42%.1,11–14 Bleeding is the most common complication and could be markedly reduced by proper planning of the percutaneous access to the horseshoe kidney, as previously described. The initial stone-free rate of our study (82%) is also comparable to the results of previous ones, with rates ranging from 72% to 87.5%.1,11–14 Significant effort should be made to render patients stone free before discharge from the hospital by the initial use of a long rigid nephroscope and secondlook PCNL whenever indicated. The mean stone burden of the present series (664 mm2) is relatively large compared with that in previous studies. The average stone burden of the largest previous series was 448 mm2.1 Despite the large stone burden of the present and previous studies, PCNL has proved safe and effective. Nevertheless, the usefulness of other lines of treatment, including ESWL and ureteroscopy, need to be compared with the results of PCNL in prospective, randomized, multi-institutional trials. Colonic injury occurred in one of our patients and has also been reported by others.17 This could be explained by the posterolateral or retrorenal colonic positions sometimes associated with horseshoe kidneys and other fusion anomalies. The posterior position of the colon results from a defect in the normal development of the lateroconal fascia combined with the mechanical absence of the kidney from its normal position. Therefore, the horseshoe kidney is predisposed to a posterolaterally displaced colon or retrorenal colon.18 Some inves-
UROLOGY 64 (3), 2004
tigators recommend CT with contrast before PCNL in patients with horseshoe kidneys to avoid colonic injury.18 Management of such cases is usually successful through withdrawal of the nephrostomy tube, temporary fixation of a ureteral stent, parenteral antibiotics, stopping of oral feeding for a few days, and anal dilation.19 REFERENCES 1. Raj GN, Auge BK, Weizer AZ, et al: Percutaneous management of calculi within horseshoe kidneys. J Urol 170: 48 – 51, 2003. 2. Yohannes A, and Smith AD: The endourological management of complications associated with horseshoe kidney. J Urol 168: 5–8, 2002. 3. Evans WP, and Resnick MI: Horseshoe kidney and urolithiasis. J Urol 125: 620 –621, 1981. 4. Pitts WR, and Muecke EC: Horseshoe kidney: a 40-year experience. J Urol 113: 743–746, 1975. 5. Kirkali Z, Esen AA, and Mungan MU: Effectiveness of extracorporeal shockwave lithotripsy in the management of stone-bearing horseshoe kidneys. J Endourol 10: 13–15, 1996. 6. Baskin LS, Floth A, and Stoller ML: The horseshoe kidney: therapeutic considerations with urolithiasis. J Endourol 3: 51–54, 1989. 7. Serrate R, Regue R, Prats J, et al: ESWL as the treatment for lithiasis in horseshoe kidney. Eur Urol 20: 122–125, 1991. 8. Clayman RV: Effectiveness of extracorporeal shockwave lithotripsy in the management of stone-bearing horseshoe kidneys. J Urol 160: 1949, 1998. 9. Gallucci M, Vincenzoni A, Schettini M, et al: Extracorporeal shock wave lithotripsy in ureteral and kidney malformations. Urol Int 66: 61–65, 2001. 10. Andreoni C, Portis AJ, and Clayman RV: Retrograde renal pelvic access sheath to facilitate flexible ureteroscopic lithotripsy for the treatment of urolithiasis in a horseshoe kidney. J Urol 164: 1290 –1291, 2000. 11. Jones DJ, Wickham JEA, and Kellett MJ: Percutaneous nephrolithotomy for calculi in horseshoe kidneys. J Urol 145: 481–483, 1991. 12. Lampel A, Hohenfellner M, Schultz-Lampel D, et al: Urolithiasis in horseshoe kidneys: therapeutic management. Urology 47: 182–186, 1996. 13. Al-Otaibi K, and Hosking DH: Percutaneous stone removal in horseshoe kidneys. J Urol 162: 674 –677, 1999. 14. Lingeman JE, and Saw KC: Percutaneous operative procedures in horseshoe kidneys (abstract). J Urol 161(suppl): 371, 1999. 15. Janetschek G, and Kunzel KH: Percutaneous nephrolithotomy in horseshoe kidneys: applied anatomy and clinical experience. Br J Urol 62: 117–122, 1988. 16. Munver R, Delvecchio FC, Newman GE, et al: Critical analysis of supracostal access for percutaneous renal surgery. J Urol 166: 1242–1246, 2001. 17. Barbaric ZL: Percutaneous nephrostomy for urinary tract obstruction. AJR Am J Roentgenol 143: 803–805, 1984. 18. Skoog SJ, Reed MD, Gaudier FA Jr, et al: The posterolateral and the retrorenal colon: implication in percutaneous stone extraction. J Urol 134: 110 –112, 1985. 19. El-Kenawy MR, El-Kappany HA, El-Diasty TA, et al: Percutaneous nephrolithotripsy for renal stones in 1000 patients. Br J Urol 69: 470 –475, 1992.
429
PERCUTANEOUS NEPHROLITHOTOMY IN TREATMENT OF LARGE STONES WITHIN HORSESHOE KIDNEYS AHMED A. SHOKEIR, AHMED R. EL-NAHAS, AHMED M. SHOMA, IBRAHIM ERAKY, MAHMOUD EL-KENAWY, ALAA MOKHTAR, AND HAMDY EL-KAPPANY
ABSTRACT Objectives. To present our experience with percutaneous nephrolithotomy (PCNL) in the treatment of large stones within horseshoe kidneys. Methods. The study included 34 patients with 45 stone-bearing horseshoe kidneys treated by PCNL in one center. The indications for PCNL were large stone burden (greater than 2 cm) in 10 kidneys (22.2%), multiple complex stones in 22 (48.9%), staghorn stones in 3 (6.7%), and failed extracorporeal shock wave lithotripsy (ESWL) in 10 kidneys (22.2%). All PCNL procedures were performed in a standard one-session technique with fluoroscopic guidance. Procedures were evaluated for intraoperative and postoperative complications, use of auxiliary procedures (second-look PCNL, ureteroscopy, and ESWL), and length of hospital stay. Moreover, the stone-free rate was calculated at discharge from the hospital and 3 months later. In addition, we assessed the need for secondary intervention during a mean follow-up of 75 ⫾ 16 months (range 6 to 108). Results. The stone burden ranged from 264 to 2408 mm2 (mean 664 ⫾ 153). Access to the horseshoe kidneys was supracostal in 10 (22.2%) and subcostal in 35 kidneys (77.8%). A single tract was used in 37 (82%), and two tracts were created in the remaining 8 kidneys (18%). Major complications were seen in six PCNL procedures (13.3%) and included significant hematuria requiring blood transfusion in three, septicemia in one, ureteral obstruction in one, and colonic injury in one. All complications were successfully treated. Auxiliary procedures were required in 12 patients (35.3%) and included ureteroscopy in 1, second-look PCNL in 3, and ESWL to fragment residual caliceal stones in 8 patients. The mean hospital stay was 4 ⫾ 1.9 days (range 3 to 12). The stone-free rate was 82% at discharge and 89% at 3 months. During the course of follow-up, 19 patients (56%) developed stone recurrence and were successfully treated with ESWL in 8 and PCNL in 11. Conclusions. PCNL is a safe and effective procedure in the treatment of large stones within horseshoe kidneys. UROLOGY 64: 426–429, 2004. © 2004 Elsevier Inc.
H
orseshoe kidney is the most common of all renal fusion anomalies, with a prevalence of 0.25% in the general population.1 Although most horseshoe kidneys are asymptomatic, urolithiasis and ureteropelvic junction obstruction represent the most common complications requiring surgical intervention.2 The incidence of stone formation in the horseshoe kidney has been reported to be 20%.1,3,4 From the Urology and Nephrology Center, Mansoura University, Mansoura, Egypt Reprint requests: Ahmed A. Shokeir, M.D., Ph.D., Urology and Nephrology Center, Mansoura University, Mansoura 35516, Egypt Submitted: March 1, 2004, accepted (with revisions): April 16, 2004
426
© 2004 ELSEVIER INC. ALL RIGHTS RESERVED
Various treatment modalities have been used to treat stones in a horseshoe kidney, including extracorporeal shock wave lithotripsy (ESWL), ureteroscopy, percutaneous nephrolithotomy (PCNL), and open surgery. Although adequate fragmentation can be achieved by ESWL in stone-bearing horseshoe kidneys, the anatomic abnormalities prevent fragment passage in a substantial number of patients.5 The overall stone-free rate has been only 53% (range 50% to 79%).4,6 –9 Ureteroscopic approaches are challenging and not universally recommended.10 The use of PCNL in the treatment of stones in horseshoe kidneys has received little attention in published reports. Most of the previous investigators reported on small series, and the overall number of patients hardly exceeded 0090-4295/04/$30.00 doi:10.1016/j.urology.2004.04.018
TABLE I. Indications for PCNL in 45 stone-bearing horseshoe kidneys Indication
Patients (n)
Large stone burden (⬎2 cm) Complex multiple stones Staghorn stones Failed ESWL
10 22 3 10
(22.2) (48.9) (6.7) (22.2)
KEY: PCNL ⫽ percutaneous nephrolithotomy; ESWL ⫽ extracorporeal shock wave lithotripsy. Data in parentheses are percentages.
100.1,11–14 The largest series in English published studies included only 24 patients. However, this number was collected from the databases of three large institutions during a 10-year period. We present our experience with 45 PCNL procedures in 34 patients with stone-bearing horseshoe kidneys. To the best of our knowledge, the present study is the largest single-institution study of the English published studies. MATERIAL AND METHODS Between January 1995 and June 2003, 34 consecutive patients with unilateral or bilateral stones in horseshoe kidneys were treated with PCNL. Of the 34 patients, 30 were males and 4 were 4 females (mean age 41.6⫾ 10 years, range 11 to 61). Eleven patients had bilateral renal stones; therefore, the number of kidneys treated by PCNL was 45. The leading symptoms were recurrent flank pain and/or hematuria in 20 (59%) and recurrent urinary tract infection in 14 patients (41%). The indications for PCNL in the 45 kidneys are given in Table I. In addition to routine history taking and clinical examination, the investigations included plain abdominal x-ray (KUB) and gray-scale ultrasonography. Excretory urography was performed if the serum creatinine was less than 2 mg/dL. If the stones were radiolucent, faintly opaque, or difficult to localize by the previous methods, noncontrast spiral computed tomography (CT) was performed. The stone burden was determined by multiplying the stone length by the width in millimeters, squared, as measured on the preoperative KUB or excretory urography in cases with radiolucent stones. Urine specimens were obtained for culture. Chemical analysis of the stones was performed in 20 patients. All PCNL procedures were performed by the urology team in a standard one-session technique with fluoroscopic guidance. Procedures were assessed for cutaneous access of the tract (supracostal or subcostal), renal access location (upper, middle, or lower calices), and the number of tracts. In all patients, ultrasound and/or pneumatic disintegration was used, together with mechanical extraction of stone fragments. A rigid nephroscope was used in all patients. Residual stone fragments were assessed at completion of the PCNL procedures by KUB and intraoperative nephrostography. The procedures were also evaluated for blood loss and intraoperative complications. After completing the PCNL procedure, a nephrostomy tube was placed and routinely removed 2 to 4 days postoperatively. Additional studies, including postoperative nephrostography or spiral CT, were not routinely performed. Auxiliary procedures, including second-look PCNL, ureteroscopy, and ESWL, were also recorded. The hospital stay was calculated, and outcomes regarding postoperative complications and UROLOGY 64 (3), 2004
TABLE II. Access to 45 stone-bearing horseshoe kidneys Access Site
Kidneys (n)
Cutaneous Subcostal Supracostal Renal Upper calix Middle calix Upper ⫹ middle calices Upper ⫹ lower calices Middle ⫹ lower calices
35 (77.8) 10 (22.2) 21 17 6 1 1
(46.7) (37.8) (13.3) (2.2) (7.2)
Data in parentheses are percentages.
stone-free rates were examined. Complications were characterized as major if they required additional intervention or resulted in a prolonged hospital stay or minor if they could be conservatively managed with no additional intervention. Blood loss was considered significant if blood transfusion was required. All patients were seen 3 months after treatment and at least once annually during a mean follow-up of 75 ⫾ 16 months (range 6 to 108). At each visit, KUB and ultrasonography were performed; excretory urography was performed if stone recurrence was diagnosed. Noncontrast spiral CT was used in the follow-up of patients with lucent or faintly opaque stones.
RESULTS Of the 45 horseshoe kidneys, the stones were located in the renal pelvis in 13 (28.9%), calices in 17 (37.8%), and both in 15 kidneys (33.3%). The stone burden ranged from 264 to 2408 mm2 (mean 664 ⫾ 153). The left kidney was affected in 13 (38.2%), the right in 10 (29.4%), and both kidneys in 11 patients (32.4%). Access to the horseshoe kidneys was supracostal in 10 and subcostal in 35. A single tract was used in 37 kidneys (82%), and two tracts were created in the remaining 8 (18%). A detailed description of the access to the horseshoe kidneys is given in Table II. A radiologic profile of a PCNL procedure in a stone-bearing right horseshoe kidney in an 11year-old boy is shown in Figure 1. Major complications were seen in six PCNL procedures (13.3%) and included significant hematuria requiring blood transfusion in three, septicemia in one, ureteral obstruction by stone fragments in one, and colonic injury in one. Angioembolization was necessary to control bleeding in 1 of the 3 patients requiring a transfusion. The ureteral stone fragments were pushed up to the kidney and retrieved using a second-look PCNL. The colonic injury was found by nephrostography after PCNL. The patient was treated by withdrawal of the nephrostomy tube and temporary placement of a double-J ureteral stent with no untoward longterm sequelae. To identify the cause of this colonic injury, the patient underwent an additional CT 427
FIGURE 1. Radiologic profile of PCNL procedure in 11-year-old boy with large stone in right horseshoe kidney (prone position). (A) Preoperative plain abdominal radiograph showing large radiopaque calculus shadow in right kidney region. (B) Upper caliceal puncture under retrograde ureterogram. Filling defect of stone is evident in pelvis.
study with contrast, which revealed a retrorenal position of the descending colon. Auxiliary procedures were required in 12 patients (35.3%), including ureteroscopy in 1, second-look PCNL in 3, and ESWL to fragment residual caliceal stones in 8 patients. The mean hospital stay was 4 ⫾ 1.9 days (range 3 to 12). The stone-free rate was 82% at discharge and 89% at 3 months. Stone-free status was defined as the complete absence of stones or the presence of peripheral, small (less than 4 mm) stone fragments after primary and auxiliary procedures. Stone analysis was available in 20 patients and revealed calcium oxalate in 10 (50%), struvite stones in 4 (20%), and mixed stones in 6 (30%). During the course of follow-up, 19 patients (56%) developed stone recurrence and were successfully treated by ESWL in 8 and PCNL in 11. COMMENT Yohannes and Smith2 have recently provided a comprehensive literature review of the different 428
endourologic approaches in the management of stones secondary to a horseshoe kidney using Medline. Small stones are best managed by ESWL, and stones that have failed management by ESWL or that are larger than 2 cm are best managed percutaneously. Ureteroscopy or ESWL is associated with a greater residual stone rate than the percutaneous approach. Nevertheless, the conclusions regarding the safety and effectiveness of PCNL in the treatment of stones in horseshoe kidneys were based on a limited number of studies containing a small number of patients.1,11–14 The present study provides the results of this line of therapy in a relatively large number of patients treated in one center. With percutaneous renal surgery in horseshoe kidneys, two main factors differ from the normal renal anatomy: the blood supply and the orientation of the collecting system. In an anatomic and radiologic study, Janetschek and Kunzel15 have shown that all blood vessels, except for some to the isthmus, enter the kidney from its ventromedial aspect, and percutaneous access is obtained only on the opposite, far from the major arteries. The dorsal arteries to the isthmus are protected by the spine and are situated away from the nephrostomy tract. The risk of arterial bleeding is, therefore, not greater than in a normal kidney.15 In a horseshoe kidney, most of the calices point either dorsomedially or dorsolaterally. The calices to the isthmus lie within a coronal plane and point medially. Access to the calices in the isthmus is gained across the pelvis. The anatomic situation results in a lower and more medial position of the nephrostomy tract, whose orientation is more or less dorsoventral.15 The good clearance rate with a low incidence of complications shown by the present study demonstrates that the access is adequate and safe for percutaneous surgery within the collecting system of the horseshoe kidney. Upper pole access was used in 62% of patients in the present study. The percentage of upper pole access in previous studies ranged from 64% to 81%.1,13,14 It allows access to the upper pole calices, renal pelvis, lower pole calices, pelviureteral junction, and proximal ureter. Furthermore, upper pole access can decrease blood loss, because the long axis of the nephroscope is aligned with the long axis of the kidney, thereby minimizing nephroscope torque on renal tissue during manipulation.1 Nevertheless, upper pole access will result in an unusually long tract, and the instruments may not reach the lower and medial calices. This problem is exacerbated in obese patients, but it can be overcome using long, rigid nephroscopes or flexible ones. Notably, even though a flexible nephroscope was not used in the present study, we achieved a stoneUROLOGY 64 (3), 2004
free rate as good as other investigators. Most experts would, however, contend that flexible nephroscopy is a vital part of rendering patients stone free during PCNL in standard cases and, in particular, for stones in anomalous kidneys. In a recent study, a flexible nephroscope was used in 84% of patients who underwent PCNL for stones in horseshoe kidneys.1 In patients with normal renal anatomy, upper pole access often requires a supracostal approach, which may result in intrathoracic complications.16 In patients with a horseshoe kidney, upper pole percutaneous access is often essential and is relatively safe owing to the inferior displacement of the kidneys away from the pleura. Violation of the pleural cavity is decreased because a supracostal approach is less likely.1 None of our patients with an upper pole nephrostomy tract in a horseshoe kidney developed pneumothorax, and a rate of only 6% was reported by Raj et al.1 The 17.6% major complication rate in our series compares favorably with rates of previous studies that ranged between 12.5% and 42%.1,11–14 Bleeding is the most common complication and could be markedly reduced by proper planning of the percutaneous access to the horseshoe kidney, as previously described. The initial stone-free rate of our study (82%) is also comparable to the results of previous ones, with rates ranging from 72% to 87.5%.1,11–14 Significant effort should be made to render patients stone free before discharge from the hospital by the initial use of a long rigid nephroscope and secondlook PCNL whenever indicated. The mean stone burden of the present series (664 mm2) is relatively large compared with that in previous studies. The average stone burden of the largest previous series was 448 mm2.1 Despite the large stone burden of the present and previous studies, PCNL has proved safe and effective. Nevertheless, the usefulness of other lines of treatment, including ESWL and ureteroscopy, need to be compared with the results of PCNL in prospective, randomized, multi-institutional trials. Colonic injury occurred in one of our patients and has also been reported by others.17 This could be explained by the posterolateral or retrorenal colonic positions sometimes associated with horseshoe kidneys and other fusion anomalies. The posterior position of the colon results from a defect in the normal development of the lateroconal fascia combined with the mechanical absence of the kidney from its normal position. Therefore, the horseshoe kidney is predisposed to a posterolaterally displaced colon or retrorenal colon.18 Some inves-
UROLOGY 64 (3), 2004
tigators recommend CT with contrast before PCNL in patients with horseshoe kidneys to avoid colonic injury.18 Management of such cases is usually successful through withdrawal of the nephrostomy tube, temporary fixation of a ureteral stent, parenteral antibiotics, stopping of oral feeding for a few days, and anal dilation.19 REFERENCES 1. Raj GN, Auge BK, Weizer AZ, et al: Percutaneous management of calculi within horseshoe kidneys. J Urol 170: 48 – 51, 2003. 2. Yohannes A, and Smith AD: The endourological management of complications associated with horseshoe kidney. J Urol 168: 5–8, 2002. 3. Evans WP, and Resnick MI: Horseshoe kidney and urolithiasis. J Urol 125: 620 –621, 1981. 4. Pitts WR, and Muecke EC: Horseshoe kidney: a 40-year experience. J Urol 113: 743–746, 1975. 5. Kirkali Z, Esen AA, and Mungan MU: Effectiveness of extracorporeal shockwave lithotripsy in the management of stone-bearing horseshoe kidneys. J Endourol 10: 13–15, 1996. 6. Baskin LS, Floth A, and Stoller ML: The horseshoe kidney: therapeutic considerations with urolithiasis. J Endourol 3: 51–54, 1989. 7. Serrate R, Regue R, Prats J, et al: ESWL as the treatment for lithiasis in horseshoe kidney. Eur Urol 20: 122–125, 1991. 8. Clayman RV: Effectiveness of extracorporeal shockwave lithotripsy in the management of stone-bearing horseshoe kidneys. J Urol 160: 1949, 1998. 9. Gallucci M, Vincenzoni A, Schettini M, et al: Extracorporeal shock wave lithotripsy in ureteral and kidney malformations. Urol Int 66: 61–65, 2001. 10. Andreoni C, Portis AJ, and Clayman RV: Retrograde renal pelvic access sheath to facilitate flexible ureteroscopic lithotripsy for the treatment of urolithiasis in a horseshoe kidney. J Urol 164: 1290 –1291, 2000. 11. Jones DJ, Wickham JEA, and Kellett MJ: Percutaneous nephrolithotomy for calculi in horseshoe kidneys. J Urol 145: 481–483, 1991. 12. Lampel A, Hohenfellner M, Schultz-Lampel D, et al: Urolithiasis in horseshoe kidneys: therapeutic management. Urology 47: 182–186, 1996. 13. Al-Otaibi K, and Hosking DH: Percutaneous stone removal in horseshoe kidneys. J Urol 162: 674 –677, 1999. 14. Lingeman JE, and Saw KC: Percutaneous operative procedures in horseshoe kidneys (abstract). J Urol 161(suppl): 371, 1999. 15. Janetschek G, and Kunzel KH: Percutaneous nephrolithotomy in horseshoe kidneys: applied anatomy and clinical experience. Br J Urol 62: 117–122, 1988. 16. Munver R, Delvecchio FC, Newman GE, et al: Critical analysis of supracostal access for percutaneous renal surgery. J Urol 166: 1242–1246, 2001. 17. Barbaric ZL: Percutaneous nephrostomy for urinary tract obstruction. AJR Am J Roentgenol 143: 803–805, 1984. 18. Skoog SJ, Reed MD, Gaudier FA Jr, et al: The posterolateral and the retrorenal colon: implication in percutaneous stone extraction. J Urol 134: 110 –112, 1985. 19. El-Kenawy MR, El-Kappany HA, El-Diasty TA, et al: Percutaneous nephrolithotripsy for renal stones in 1000 patients. Br J Urol 69: 470 –475, 1992.
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