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ENDOPYELOTOMY
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UREEROPELVIC JUNCTION OBSTRUCTION
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ENDOPYELOTOMY Prognostic Factors and Patient Selection Paul J. Van Cangh, MD, and Sylvain Nesa, MD
For many years, open surgery has been the optimal therapy for ureteropelvic junction (UPJ) obstruction. Of the existing operations, dismembered pyeloplasty remains the gold standard. Percutaneous techniques were developed in the early 1980s for the treatment of nephrolithiasis. Their intrinsic advantage of minimal invasiveness were rapidly perceived and applied to the management of UPJ obstruction. In 1983, several reports of endoscopic management appeared in the literature, including percutaneous pyeloplasty, pyelolysis, endopyelotomy, and endoureteropyelotomy.* The basic principle of these procedures is a full-thickness incision of the narrow segment followed by prolonged stenting and drainage to allow regeneration of an adequate caliber ureter around the stent. This concept was first described in 1903 by the French urologist Joachin Albarran (ur6t6rotomie externe) and was popularized by Davis in 1943 as an open procedure (intubated ureterotomy). Although confirmed by experimental and clinical data, this pioneer work remained underexploited in the treatment of UPJ obstruction because of the excellent results of standard open pyeloplasty. The devel*The term endoureterupyelotomy was coined to underscore the importance of a combined ureteropelvic incision; use of the term endopyelotoniy is restrictive to the renal pelvis (pyelon).
opment of minimally invasive endourologic techniques revived interest in the intubated ureterotomy, which could now be performed percutaneously. With continuing progress in endourology, refined techniques were developed in an attempt to further reduce operative morbidity, such as retrograde approaches under direct endoscopic visualization and indirect fluoroscopic The success rate for such procedures ranges from 50% to 95% and remains inferior to that with open pyeloplasty.8,29, 38 Success seems to depend more on patient selection factors than on the type of operation, thereby underscoring the importance of the determination of prognostic factors. This article reviews the factors important in patient selection that influence the outcome of endourologic procedures on the UPJ. RISK FACTORS Length of Stricture Long avascular strictures, total obliteration of the UPJ, and severe periureteral fibrosis are clear contraindications to endourologic procedures. Patients with these features should be treated by open repair whenever possible. Although isolated cases have been managed successfully, overall results have, in general, been unsatisfactory.7,21. 32. 34. 38,40. 41. 42. 50
From the Department of Urology, University of Louvain Medical School, Brussels (PJVC); and Division of Urology, Mont Godinne University Clinics (SN), Yvoir, Belgium
UROLOGIC CLINICS OF NORTH AMERICA
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Degree of Hydronephrosis
tion of the involved kidney has been systematically assessed only recently or in selected cases, and its influence cannot be dissociated from that of the degree of hydronephrosis.
Endourologic procedures can only address intrinsic factors of obstruction and cannot correct extrinsic factors or reduce the size of a massively dilated renal pelvis. Initial experience suggested that a large size of the renal pelvis had a negative influence on the results of endopyel~tomy.~, A subsequent careful analysis of prognostic factors confirmed that the degree of hydronephrosis was of statistical significance when combined with the presence or absence of crossing vessels. In the presence of crossing vessels, the risk for failure was more than tripled by high-grade versus low-grade hydronephr~sis.~' The final success rate decreased from 81% to 54% when high-grade hydronephrosis was present.s2In a recent review of 401 percutaneous antegrade endopyelotomies performed at a single institution, the overall success rate was 85%. High-grade hydronephrosis as well as poor renal function were significant causes of failure. Patients with massive hydronephrosis had a 50% success rate compared with a 96% rate for those with moderate hydronephrosis.lx
TYPE OF OBSTRUCTION Primary Versus Secondary UPJ Obstruction Initially, only secondary cases of UPJ obstruction were considered ideally suited for endopyelotomy. The endourologic procedure avoided a potentially difficult open operative reintervention. Further experience revealed that primary cases of UPJ obstruction could be treated endoscopically and commendable success rates achieved. Published results, stratified by the type of UPJ obstruction (primary versus secondary) are summarized in Tables 1 and 2 for antegrade and retrograde techniques, respectively. In most recent series, secondary cases of UPJ obstruction have responded slightly better to antegrade endop yelotomy. A cumulative success rate of 84% has been achieved in comparison with a 79% rate for primary obstruction.
Renal Function Renal function is a significant prognostic factor. A high risk of failure has been reported when the function of the affected kidney is greatly impaired.I8,25, 32, 39 Unfortunately, the isolated impact of this factor is difficult to assess, because no prospective data have been collected. In most series, preoperative func-
TYPE OF PROCEDURE Antegrade Versus Retrograde Endoureteropyelotomy The success rate of endopyelotomy seems to be independent of the approach used to
Table 1. RESULTS OF ANTEGRADE ENDO(URETER0)PYELOTOMY IN ADULTS ACCORDING TO TYPE OF UPJ OBSTRUCTION
Study
Type UPJ' I II
+
No.
Percent Primary
Percent Success Total
I
II
FOIIOW-UP (months)
~
Kuenkel and KorIh, 199028 Cuzin et al, 1992 Meretyk et al, 199233 Perez et al, 19924' Kletscher et al, 1995'7 Van Cangh et al, 199652 Combe et al, 1996 l 3 Gupta et al, 1997'* j4
TOTAL
143
63
81 23
44 12
17 50
7 39
123
100
49
37
40 1 887
235 537
'Type of UPJ obstruction: I (primary)
+
+ 80 + 37
44
76
81
73
12 (643)
+
11
54 52
84 78
86 75
81 91
37 (mean) 22 (2-39)
+
10 11
41 78
88 88
86 90
90 82
14 (4-40) 12 (4-74)
81
71
68
83
62 (6-153)
48
78
75
84
16 (3-36)
59 61
85 81
82 79
89 84
51 (6-144)
+
+ 23 + 12 + 166 + 350
II (secondary)
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Table 2. RESULTS OF RETROGRADE ENDO(URETER0)PYELOTOMY TECHNIQUES IN ADULTS ACCORDING TO TYPE OF UPJ OBSTRUCTION
Technique Retrograde ureterorenoscopy lnglis and Tolley, 198622 Meretyk et al, 199233 Chowdhury and Kerogbon, 1992” Thomas et al, 199648
No.
I
Device Rigid Rigid and flexible Rigid
Diathermy hook Electrocautery Cold knife
100 79 83
4 and 12 17 (4-36) 4-1 8
>90
15 (7-36)
+ II
2 19 12
0+2 16 + 3 -
49
40
+9
Rigid
Cold knife and electrocautery
23 27 29 52
+5 +5 + 19
Balloon Balloon Balloon Balloon
Cutting Cutting Cutting Cutting
Balloon Balloon Balloon
Disruption Disruption Disruption
Cutting balloon Nadler et al, 199635 28 Faerber et al, 199715 32 Gelet et al, 1997” (44)38 Preminger et al, 199742 66 Balloon dilatation Kadir et al, 198223 1 OFlynn et al, 198939 31 McClinton et al, 199331 42
+ 14
0+1 29 + 2 33 + 9
Percent Success
Length of Follow-up (months)
Cutting Mechanism
81 (78,100) 33 (24-43) 14 (3-28) 87 76 (68,84) 12 (3-39) 77 (72,100) 8 (1-18) 100 68 80
6 10 (3-30) 18 (3-48)
‘20 Patients via antegrade approach
perform the procedure. Results of contemporary series of retrograde endopyelotomy are summarized in Table 2 and compare favorably with the results of percutaneous procedures (Table 1).No difference has been noted in the success of procedures performed under direct ureterorenoscopic approach versus those performed with indirect fluoroscopic control. Although simple dilation of the UPJ does not seem to be sufficient, at least in adults, some evidence suggests that for secondary UPJ strictures, acceptable results can be obtained with endoballoon rupture as well as with Acucise (Applied Urology, Laguna Hills, CA)2end~pyelotomy.~~ With antegrade endopyelotomy, the invagination technique and the classical percutaneous technique have similar success rates.I3 Likewise, the type of incisional device does not significantly influence the outcome. Similar results are obtained with laser incision, cold and hot knifes, and semilunar or hook knives (Table 2). The type of stent and the experience of the surgeon (once the operative technique has been mastered) also do not influence the outcome.l8,s]
years when the Acucise balloon has been used, especially in the absence of crossing vessel^.^, 29 Preliminary experience with younger children is now being reported again showing encouraging results.s, 24, 46 In one study of a small series, simple balloon dilation appeared to be sufficient, and disruption of the UPJ may not be required as it is in However, no long-term follow-up is available in this setting. Currently, the role of endopyelotomy remains unclear in children, and open pyeloplasty is still the preferred procedure owing to its consistently superior results, especially in primary cases. In secondary cases of UPJ obstruction, such as failures of open pyeloplasty, endopyelotomy can be safe and effective. With further refinements and miniaturization of equipment, it may ultimately become a preferred option.16,24 In elderly patients, endopyelotomy offers results comparable with those in the adult group.20,27 Not surprisingly, neither the sex of the patient nor the side of the obstruction influences the outcome.’8,28
AGE AND SEX OF THE PATIENT AND THE SIDE OF OBSTRUCTION
CROSSING VESSELS
The pediatric experience has taken longer to accumulate than the data in adults, and only limited and selected series are available for review (Table 3). Recently, good results have been obtained in children older than 4
The significance of vessels crossing the UPJ remains a matter of debate, and their role in the pathogenesis of the obstruction as well as their influence on the results of various endourologic procedures is controversial.10, 34, 51, s2 An extensive historical review ad-
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Table 3. RESULTS OF ENDO(URETER0)PYELOTOMY IN CHILDREN Technique
No.
Retrograde dilatation Tan et al, 199547 10 Acucise endopyelotorny Bolton et al, 19946 2 Bogaert et al, 19965 8 Percutaneous endopyelotomy Towbin et al, 198749 3 Kavoussi et al, 199124 4 (17)13 Tan et al, 199346 Netto et al, 1996% 9 Figenshau et al, 199616 17
I
+ II
10
+0 +0
2 7
+
1
+0 +4 +3 +3 8+9
3 0 14 6
Mean Age (range) 16 rno (3 mo-9.5 yr)
Percent Success 70
Mean Follow-up, (range) Months 22 (4-25)
4and6yr 9 yr (4-15)
100 718
11 and 12 15 (2-32)
11, 13, 18yr 6.5 wks-5.5 yr 4rno-16yr 6 yr (2 rno-15 yr) 3mo-17yr
(213) 67 100 (58) 77 83 62, 100
10 and 27 18-23 15 (3-36) 30 (18-56) 45 (16-110)
dressing these issues has been published recently.5z Crossing vessels have been shown to have a statistically significant negative influence on the outcome of endoureteropyelotomy by the authors and their colleag~es.~~ In a prospective study enrolling 87 consecutive patients presenting with symptomatic UPJ obstruction between 1986 and 1989, 67 adults underwent a preoperative angiographic study, and endoureteropyelotomy was performed regardless of the results. In 26 of 67 patients (39'/0), vessels were demonstrated in close contact with the site of the obstruction. The presence of crossing vessels reduced the final success rate from 86% to 42%. The degree of hydronephrosis was also a negative factor but was of lesser significance. The influence of the combination of both factors on final outcome was highly significant, with a 95% success rate attained when there was no crossing vessel and only a moderate degree of hydronephrosis compared with a 39% success rate when a crossing vessel was associated with high-grade hydronephrosis (odds ratio, 28.29; 95% confidence interval, 24.91 to 31.66; P < 0.001). The authors subsequently reported on the preoperative vascular anatomy in 86 patients with a follow-up extending more than 12 years (mean, 6.5 years).5zThe importance of the previously mentioned prognostic factors was confirmed. The success rate decreased to 33% and 82% with and without crossing vessels, respectively (Table 4). Crossing vessels were present in 18% of successful cases in comparison with 67% of failures. Moreover, significant size of crossing vessels was demonstrated in 15 of 18 (83%) patients undergoing secondary open pyeloplasty for endopyelotomy failure; concomitant highgrade hydronephrosis was present in 13 instances.s2
Other reports have also noted a negative influence of crossing vessels on the success of endourologic management of UPJ obstruction, although without statistical e~idence.~, I", 41 Bogaert and co-workers5reported a high success rate of retrograde endopyelotomy in children but stated that open surgery remained the standard, particularly when crossing vessels were identified preoperatively. Their only failure occurred in a patient with a crossing lower pole vessel.s Bagley and coworkers* reported a lower success rate when crossing vessels were detected preoperatively by endoluminal ultrasound. Cohen and coworkersl2found that one of two unexplained failures after Acucise endopyelotomy occurred in patients with a crossing vessel. Figenshau and colleagues16reported a similar experience with percutaneous endopyelotomy in children, and Lim and Walkerz9identified crossing vessels in two of three recurrent UPJ obstructions after pyeloplasty in children. At Washington University, Wolf and
Table 4. SUCCESS RATE OF ENDOURETEROPYELOTOMY ACCORDING TO PROGNOSTIC FACTORS: VESSEL CROSSING UPJ AND DEGREE OF HYDRONEPHROSIS
Risk Factors
Percent Success
Vessel absent and low-grade hydronephrosis Vessel absent Low-grade hydronephrosis Vessel absent and high-grade hydronephrosis High-grade hydronephrosis Vessel absent and low-grade hydronephrosis Vessel present Vessel present and high-grade hydronephrosis
90 82 81 74 54 43 33 30
Data from Van Cangh PJ, Nesa S,Galeon M. et al: Vessels around the uteropelvic junction: Significance and imaging by conventional radiology. J Endourol 10:111-119, 1996.
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co-workers" observed that all four patients treated with laparoscopic pyeloplasty after failed endoureteropyelotomy had vessels crossing the UPJ. Similar findings were reported by Faerber and c o - ~ o r k e r s 'with ~ Acucise endopyelotomy. Three of four failures reoperated on using open pyeloplasty had vessels crossing the UPJ. Faerber and colleagues therefore recommended spiral CT to identify crossing vessels preoperatively and the selection of another form of therapy when they are present.15 Although some impact of crossing vessels on outcome is not disputed, the relative importance of this effect remains a matter of debate. In a recently published series of 401 percutaneous antegrade endopyelotomies, there were 60 failures. A total of 54 patients were explored, and crossing vessels were found to be present in 13 (24%) of the cases.'* It was concluded that obstructing crossing vessels were potential factors of failure in 4% of endopyelotomies, and that their preoperative identification was not indicated.l8 The difference between the authors' findings and the data reported in the series just cited is perhaps best explained by patient selection. The data reported by the authors are based on the prospective recruitment of all patients presenting with symptomatic UPJ obstruction during the study period; endoureteropyelotomy was performed regardless of the results of the preoperative evaluation for crossing vessels.'O Also, in the authors' series, more than 80% of patients had a primary type of UPJ obstruction with a higher likelihood of crossing vessels in contrast to the majority of other series in which approximately half of the cases were primary in origin. Some investigators maintain that crossing vessels are present around the UPJ in as many as 71% of kidneys; therefore, they must not be detrimental to the success of the procedure." However, such data have been obtained from anatomic studies on normal kidneys and show the vascular anatomy at the normal UPJ. This may not be relevant to the actual crossing of the UPJ in clear-cut hydronephrosis secondary to UPJ obstruction. In fact, the literature on surgical pyeloplasty is replete with accurate illustrations relevant to UPJ obstruction and confirms the authors' findings at surgery in patients with failed endoureteropyelotomy..',37 The reported incidence of late failures or recurrences is diverse. Some investigators
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have found that failures occur early, and that late failures or recurrences are distinctly uncommon.1n, 34 However, a higher incidence of late failures or recurrences was noted in the authors' series.52Seven of the 18 failures occurred after 1 year; and one occurred 6 years postoperatively.The possibility that this might be the result of inadequate follow-up is unlikely, because all patients were observed according to a strict study protocol. Interestingly, the cases of late failure were very similar to the well-known entity of intermittent hydronephrosis in which a crossing vessel is often pre~ent.'~ In 15 of the 18 failures treated by open pyeloplasty, a crossing vessel was found. Clearly, long-term success can be achieved in the presence of crossing vessels. In those instances, the authors believe that the operation succeeds in correcting both the intrinsic and the extrinsic factors of obstruction. The functional patency of the UPJ is reestablished, and the crossing vessels become somewhat fixed in a silent nonobstructing position. In recurrences, perhaps either or both outcomes are insufficient, or the quality of the hypotonic renal pelvic musculature is inadequate and thereby irreparable. Even with limited diuresis, the renal pelvis balloons out and protrudes through the vascular window, making recurrence inevitable. Vessels crossing the UPJ influence not only the outcome of endopyelotomy but act as a potential source of complications. Vascular complications of endoureteropyelotomy can be significant. Although possibly underreported in the literature, they remain an important concern to urologists.6, Although such complications are rare in the experience of some surgeons, this may reflect their expertise in technique as well as patient selection.% Complications can nevertheless occur and are acknowledged as potentially serious.' Careful visual inspection of the operative site to direct the incision away from pulsating vessels is strongly advocated with direct visual endourologic approaches, and is indeed a recognized advantage of endoscopic versus fluoroscopic techniques.% Reported vascular complications have been summarized elsewhere.52 Malden and cow o r k e r ~described ~~ an arteriovenous fistula complicating antegrade endopyelotomy, and Brooks and colleaguess reported the need to transfuse 4 of 22 (18%) of their patients undergoing endopyelotomy. Cohen,I2 Streemf and Wagner% and their colleagues have de-
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scribed significant bleeding from direct vascular injury after retrograde endopyelotomy. Cohen acknowledged a 10% to 15% risk of bleeding from crossing vessels and suggested that full patient evaluation is warranted.I2 Gelet and co-w~rkers'~ reported two cases of significant bleeding after 44 Acucise procedures, one of which resulted from an arteriovenous fistula from a crossing vessel. The authors believe that such data are of sufficient importance to justify preoperative documentation of crossing vessels and the selection of an alternative approach when they are found (especially when they are asso44, 55 ciated with high-grade hydronephrosis).26, By following these guidelines, hemorrhagic complications have all but disappeared, and success rates have dramatically increased.2,3, 26 Quillin and c o - ~ o r k e r reported s~~ the absence of failures in patients without crossing vessels documented by spiral CT angiography. Fig-
ures 1 to 3 are representative views of preoperative spiral CT in a patient with primary UPJ obstruction and bilateral crossing vessels. The documentation of crossing vessels preoperatively has the additional benefit of improving postoperative follow-up planning, as the risk of long-term recurrence increases when crossing vessels are present. Furthermore, some diagnostic techniques (e.g., angiography, spiral CT) are able to detect vessels crossing the contralateral UPJ, which ultimately may prove advantageous because UPJ obstruction can be bilateral in as many as 10% of cases (Figs. 1 and 3). CONCLUSIONS
Endoureteropyelotomy has not gained universal acceptance in the urologic community, in part, because of a 10% to 30% inferior
Figure 1. Three-dimensional reconstruction of renal vasculature obtained from spiral CT imaging (Figures 1-3 from same patient with primaly UPJ obstruction). Bilateral lower polar vessels and their relation to the UPJ are accurately demonstrated.
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287
References
Figure 2. Polar artery and accessory inferior polar vein crossing posteriorly to the UPJ (same patient as in Figure 1).
success rate and the fear of vascular complications.” 51, 52 Identification of prognostic risk factors for failure and complications is therefore of primary importance. The length of the stricture, the level of renal function, and the grade of hydronephrosis are generally accepted prognostic factors. Additionally, in the authors’ experience, crossing vessels have a major role and, in association with the grade of hydronephrosis, are major predictive factors of outcome. Endoureteropyelotomy represents a significant advance in the management of UPJ obstruction but should not be offered indiscriminately. The goal is to characterize prognostic factors fully in an attempt to achieve better case selection. Crossing vessels significantly impact on the overall success and complication rates, and their presence should therefore be documented. In this regard, it is encouraging that several recent series in which these recommendations have been followed report a success rate equivalent to that for the gold standard of dismembered pyeloplasty, that is, close to loo%, as well as the absence of vascular complication^.^, 26, 43
Figure 3. Accessory artery and vein demonstrated on a frontal reconstruction (same patient as in Figure 1).
1. Badlani G, Karlin G, Smith A D Complications of endopyelotomy: Analysis in a series of 64 patients. J Urol 140:473-475, 1988 2. Bagley DH, Liu JB, Goldberg BB, et al: Endopyelotomy: Importance of crossing vessels demonstrated by endoluminal ultrasonography. J Endourol 9:465467, 1995 3. Bagley DH, Conlin MJ, Liu JB: Device for intraluminal incision guided by endoluminal ultrasonography. J Endourol 10:421-423, 1996 4. Bamett JS, Stephens F D The role of the lower segment vessel in the aetiology of hydronephrosis. Aust N Z J Surg 31:201-213, 1962 5. Bogaert GA, Kogan BA, Mevorach RA, et al: Efficacy of retrograde endopyelotomy in children. J Urol 156:734-737, 1996 6. Bolton DM, Bogaert GA, Mevorach RA, et al: Pediatric ureteropelvic junction obstruction treated with retrograde endopyelotomy. Urology 44:609413, 1994 7. Brannen GE, Bush WH, Lewis GP: Endopyelotomy for primary repair of ureteropelvic junction obstruction. J Urol 13999-32, 1988 8. Brooks JD, Kavoussi LR, Preminger GM, et a1 Comparison of open and endourologic approaches to the obstructed ureteropelvic junction. Urology 46:791795, 1995 9. Bush WH, Brannen GE, Lewis GP: Ureteropelvic junction obstruction: Treatment with percutaneous endopyelotomy. Radiology 171:535-538, 1989 10. Cassis A, Brannen GE, Bush WH, et al: Endopyelotomy: Review of results and complications. J Urol 146:1492-1495, 1991 11. Chowdhury SD, Kerogbon J: Rigid ureteroscopic endopyelotomy without external drainage. J Endourol 6:357-360, 1992 12. Cohen TD, Gross MB, Preminger GM: Long-term follow-up of Acucise incision of ureteropelvic junction obstruction and ureteral strictures. Urology 47317-323, 1996 13. Combe M, Gelet A, Abdelrahim AF, et al: Ureteropelvic invagination procedure for endopyelotomy (Gelet technique): Results of 51 consecutive cases. J Endourol 1015S157, 1996 14. Cuzin B, Abbar M, Dawahra M, et al: 100 Endopyelotomies percutanees: Techniques, indication, resultats. Prog Urol 2559-569, 1992 15. Faerber GJ, Richardson TD, Farah N, et al: Retrograde treatment of ureteropelvic junction obstruction using the ureteral cutting balloon catheter. J Urol 157454-458,1997 16. Figenshau RS, Clayman RV, Colberg JW, et al: Pediatric endopyelotomy: The Washington University experience. J Urol 156:2025-2030, 1996 17. Gelet A, Combe M, Ramackers JM: Endopyelotomy with the Acucise cutting balloon: Early clinical experience. Eur Urol 31:389-393, 1997 18. Gupta M, Tuncay OL, Smith A: Open surgical exploration after failed endopyelotomy: A 12-year experience. J Urol 157161S1619, 1997 19. Hoffer FA, Lebowitz RL: Intermittent hydronephrosis: A unique feature of ureteropelvic junction obstruction caused by a crossing renal vessel. Radiology 156:655-658, 1985 20. Horgan JD, Maidenberg MJ, Smith A D Endopyelotomy in the elderly. J Urol 150:1107-1109, 1993 21. Hulbert JC, Hunter D, Castaneda-Zuniga W: Classification of techniques for the reconstruction of ac-
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quired strictures in the region of the ureteropelvic junction. J Urol 140:46&472, 1988 22. lnglis JA, Tolley DA: Ureteroscopic pyelolysis for pelvi-ureteric junction obstruction. Br J Urol 58:250252, 1986 23. Kadir S, White RI, Engel R: Balloon dilatation of a ureteropelvic junction obstruction. Radiology 143:263-264, 1982 24. Kavoussi LR, Meretyk S, Dierks SM, et al: Endopyelotomy for secondary ureteropelvic junction obstruction in children. J Urol 145:345-349, 1991 25. Kavoussi LR, Albala DM, Clayman R Outcome of secondary open surgical procedure in patients who failed primary endopyelotomy. Br J Urol 72:157-160, 1993 26. Keely FX, Bagley DH, Kulp-Hughe D, et al: Laparoscopic division of crossing vessels at the ureteropelvic junction. J Endourol 10:163-168, 1996 27. Kletscher BA, Segura JW, Leroy AJ, et al: Percutaneous antegrade endoscopic pyelotomy: Review of 50 consecuti\re cases. J Urol 153:701-704, 1995 28. Kuenkel M, Korth K: Endopyelotomy: Long-term follow-up of 143 patients. J Endourol 4:109-115, 1990 29. Lim DJ, Walker RD: Management of the failed pyeloplasty. J Urol 156:738-740, 1996 30. Malden ES, Picus D, Clayman RV Arteriovenous fistula complicating endopyelotomy. J Urol 148:15201523, 1992 31. McClinton S, Steyn JH, Hussey JK: Retrograde balloon dilatation for pelviureteric junction obstruction. Br J Urol 71:152-155, 1993 32. Meretyk S, Meretyk I, Kavoussi LR, et al: Ureteronephroscopic vs. antegrade endopyelotomy for treatment of ureteropelvic junction obstruction. J Endourol 45141, 1990 33. Meretyk 1, Meretyk S, Clayman RV Endopyelotomy: Comparison of ureteroscopic retrograde and antegrade percutaneous techniques. J Urol 148:775-783, 1992 34. Motola JA, Badlani GH, Smith AD: Results of 212 consecutive endopyelotomies: An 8-year follow up. J Urol 149:453-456, 1993 35. Nadler RB, Rao GS, Pearle MS, et al: Acucise endopyelotomy: Assessment of long term durability. J Urol 1S6:1094-1097, 1996 36. Nakada SY, Soble JJ, Gardner SM, et al: Comparison of Acucise endopyelotomy and endoballoon rupture for management of secondary proximal ureteral stricture in the porcine model. J Endourol 10311-318, 1996 37. Nesbit RM: Diagnosis of intermittent hydronephrosis: Importance of pyelography during episodes of pain. J Urol 75:767-771, 1956 38. Netto NR, Ikari 0, Esteves SC, et al: Antegrade endopyelotomy for pelviureteric junction obstruction in children. Br J Urol 78:607-612, 1996
39. O'Flynn K, Mc Kelvic G, Steyn J: Endoballoon rupture and stenting for pelvi-ureteric junction obstruction technique and early results. Br J Urol 64:572574, 1989 40. Ono Y, Hashimato J, Ohshima S: Percutaneous endoscopic surgery for obstructive disease in the upper urinary tract-preliminary report. Sen J Urol81:12471251, 1990 41. Perez LM, Friedman RM, Carson CC: Endoureteropyelotomy in adults. Urology 39:71-76, 1992 42. Preminger GM, Clayman RV, Nakada SY, et al: A multicenter clinical trial investigating the use of a fluoroscopically controlled cutting balloon catheter for the management of ureteral and ureteropelvic junction obstruction. J Urol 1571625-1629,1997 43. Quillin SP, Brink JA, Heiken JP, et al: Helical (spiral) CT angiography for identification of crossing vessels at the ureteropelvic junction. AJR Am J Roentgenol 166:1125-1130, 1996 44. Sampaio FJ, Favorito LA: Ureteropelvic junction ste nosis: Vascular anatomical background for endopyelotomy. J Urol 150:1787-1791, 1993 45. Streem SB, Geisinger MA: Prevention and manage ment of hemorrhage associated with cautery wire balloon incision of ureteropelvic junction obstruction. J Urol 153:1904-1906, 1995 46. Tan HL, Najmaldin A, Webb DR: Endopyelotomy for pelvi-ureteric junction obstruction in children. Eur Urol 24:84-88, 1993 47. Tan HL, Roberts JP, Grattan-Smith D Retrograde balloon dilatation of ureteropelvic obstruction in infants and children: Early results. Urology 46:89-91,1995 48. Thomas R, Monga M, Klein EW: Ureteroscopic retrograde endopyelotomy for management of ureteropelvic junction obstruction. J Endourol 10:141-145,1996 49. Towbin RB, Wacksman J, Ball W S Percutaneous pyeloplasty in children: Experience in three patients. Radiology 163:381-384, 1987 SO. Van Cangh PJ, Jorion JL, Wese FX, et al: Endoureteropyelotomy: Percutaneous treatment of ureteropelvic junction obstruction. J Urol 141:1317-1322,1989 51. Van Cangh PJ, Wilmart JF, Opsomer RJ, et a1 Longterm results and late recurrence after endoureteropyelotomy: A critical analysis of prognostic factors. J Urol 151:934-937, 1994 52. Van Cangh PJ, Nesa S, Galeon M, et al: Vessels around the ureteropelvic junction: Significance and imaging by conventional radiology. J Endourol 10:111-119, 1996 53. Van Cangh PJ, Nesa S: Endoureteropyelotomy. Atlas Urol Clin North Am 443-58, 1996 54. Wagner JR, D'Agostino R, Babayan RK: Renal arterioureteral hemorrhage: A complication of Acucise endopyelotomy. Urology 48:139-141, 1996 55. Wolf JS, Siege1 CL, Brink JA, et al: Imaging for URteropelvic junction obstruction in adults. J Endourol 10:93-104, 1996
Address reprints requests to Paul J. Van Cangh, MD Professor and Chairman Department of Urology University of Louvain Medical School St Luc University Clinics 10 Avenue Hippocrate 1200 Brussels BELGIUM
UREEROPELVIC JUNCTION OBSTRUCTION
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ENDOPYELOTOMY Prognostic Factors and Patient Selection Paul J. Van Cangh, MD, and Sylvain Nesa, MD
For many years, open surgery has been the optimal therapy for ureteropelvic junction (UPJ) obstruction. Of the existing operations, dismembered pyeloplasty remains the gold standard. Percutaneous techniques were developed in the early 1980s for the treatment of nephrolithiasis. Their intrinsic advantage of minimal invasiveness were rapidly perceived and applied to the management of UPJ obstruction. In 1983, several reports of endoscopic management appeared in the literature, including percutaneous pyeloplasty, pyelolysis, endopyelotomy, and endoureteropyelotomy.* The basic principle of these procedures is a full-thickness incision of the narrow segment followed by prolonged stenting and drainage to allow regeneration of an adequate caliber ureter around the stent. This concept was first described in 1903 by the French urologist Joachin Albarran (ur6t6rotomie externe) and was popularized by Davis in 1943 as an open procedure (intubated ureterotomy). Although confirmed by experimental and clinical data, this pioneer work remained underexploited in the treatment of UPJ obstruction because of the excellent results of standard open pyeloplasty. The devel*The term endoureterupyelotomy was coined to underscore the importance of a combined ureteropelvic incision; use of the term endopyelotoniy is restrictive to the renal pelvis (pyelon).
opment of minimally invasive endourologic techniques revived interest in the intubated ureterotomy, which could now be performed percutaneously. With continuing progress in endourology, refined techniques were developed in an attempt to further reduce operative morbidity, such as retrograde approaches under direct endoscopic visualization and indirect fluoroscopic The success rate for such procedures ranges from 50% to 95% and remains inferior to that with open pyeloplasty.8,29, 38 Success seems to depend more on patient selection factors than on the type of operation, thereby underscoring the importance of the determination of prognostic factors. This article reviews the factors important in patient selection that influence the outcome of endourologic procedures on the UPJ. RISK FACTORS Length of Stricture Long avascular strictures, total obliteration of the UPJ, and severe periureteral fibrosis are clear contraindications to endourologic procedures. Patients with these features should be treated by open repair whenever possible. Although isolated cases have been managed successfully, overall results have, in general, been unsatisfactory.7,21. 32. 34. 38,40. 41. 42. 50
From the Department of Urology, University of Louvain Medical School, Brussels (PJVC); and Division of Urology, Mont Godinne University Clinics (SN), Yvoir, Belgium
UROLOGIC CLINICS OF NORTH AMERICA
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Degree of Hydronephrosis
tion of the involved kidney has been systematically assessed only recently or in selected cases, and its influence cannot be dissociated from that of the degree of hydronephrosis.
Endourologic procedures can only address intrinsic factors of obstruction and cannot correct extrinsic factors or reduce the size of a massively dilated renal pelvis. Initial experience suggested that a large size of the renal pelvis had a negative influence on the results of endopyel~tomy.~, A subsequent careful analysis of prognostic factors confirmed that the degree of hydronephrosis was of statistical significance when combined with the presence or absence of crossing vessels. In the presence of crossing vessels, the risk for failure was more than tripled by high-grade versus low-grade hydronephr~sis.~' The final success rate decreased from 81% to 54% when high-grade hydronephrosis was present.s2In a recent review of 401 percutaneous antegrade endopyelotomies performed at a single institution, the overall success rate was 85%. High-grade hydronephrosis as well as poor renal function were significant causes of failure. Patients with massive hydronephrosis had a 50% success rate compared with a 96% rate for those with moderate hydronephrosis.lx
TYPE OF OBSTRUCTION Primary Versus Secondary UPJ Obstruction Initially, only secondary cases of UPJ obstruction were considered ideally suited for endopyelotomy. The endourologic procedure avoided a potentially difficult open operative reintervention. Further experience revealed that primary cases of UPJ obstruction could be treated endoscopically and commendable success rates achieved. Published results, stratified by the type of UPJ obstruction (primary versus secondary) are summarized in Tables 1 and 2 for antegrade and retrograde techniques, respectively. In most recent series, secondary cases of UPJ obstruction have responded slightly better to antegrade endop yelotomy. A cumulative success rate of 84% has been achieved in comparison with a 79% rate for primary obstruction.
Renal Function Renal function is a significant prognostic factor. A high risk of failure has been reported when the function of the affected kidney is greatly impaired.I8,25, 32, 39 Unfortunately, the isolated impact of this factor is difficult to assess, because no prospective data have been collected. In most series, preoperative func-
TYPE OF PROCEDURE Antegrade Versus Retrograde Endoureteropyelotomy The success rate of endopyelotomy seems to be independent of the approach used to
Table 1. RESULTS OF ANTEGRADE ENDO(URETER0)PYELOTOMY IN ADULTS ACCORDING TO TYPE OF UPJ OBSTRUCTION
Study
Type UPJ' I II
+
No.
Percent Primary
Percent Success Total
I
II
FOIIOW-UP (months)
~
Kuenkel and KorIh, 199028 Cuzin et al, 1992 Meretyk et al, 199233 Perez et al, 19924' Kletscher et al, 1995'7 Van Cangh et al, 199652 Combe et al, 1996 l 3 Gupta et al, 1997'* j4
TOTAL
143
63
81 23
44 12
17 50
7 39
123
100
49
37
40 1 887
235 537
'Type of UPJ obstruction: I (primary)
+
+ 80 + 37
44
76
81
73
12 (643)
+
11
54 52
84 78
86 75
81 91
37 (mean) 22 (2-39)
+
10 11
41 78
88 88
86 90
90 82
14 (4-40) 12 (4-74)
81
71
68
83
62 (6-153)
48
78
75
84
16 (3-36)
59 61
85 81
82 79
89 84
51 (6-144)
+
+ 23 + 12 + 166 + 350
II (secondary)
ENDOPYELOTOMY
283
Table 2. RESULTS OF RETROGRADE ENDO(URETER0)PYELOTOMY TECHNIQUES IN ADULTS ACCORDING TO TYPE OF UPJ OBSTRUCTION
Technique Retrograde ureterorenoscopy lnglis and Tolley, 198622 Meretyk et al, 199233 Chowdhury and Kerogbon, 1992” Thomas et al, 199648
No.
I
Device Rigid Rigid and flexible Rigid
Diathermy hook Electrocautery Cold knife
100 79 83
4 and 12 17 (4-36) 4-1 8
>90
15 (7-36)
+ II
2 19 12
0+2 16 + 3 -
49
40
+9
Rigid
Cold knife and electrocautery
23 27 29 52
+5 +5 + 19
Balloon Balloon Balloon Balloon
Cutting Cutting Cutting Cutting
Balloon Balloon Balloon
Disruption Disruption Disruption
Cutting balloon Nadler et al, 199635 28 Faerber et al, 199715 32 Gelet et al, 1997” (44)38 Preminger et al, 199742 66 Balloon dilatation Kadir et al, 198223 1 OFlynn et al, 198939 31 McClinton et al, 199331 42
+ 14
0+1 29 + 2 33 + 9
Percent Success
Length of Follow-up (months)
Cutting Mechanism
81 (78,100) 33 (24-43) 14 (3-28) 87 76 (68,84) 12 (3-39) 77 (72,100) 8 (1-18) 100 68 80
6 10 (3-30) 18 (3-48)
‘20 Patients via antegrade approach
perform the procedure. Results of contemporary series of retrograde endopyelotomy are summarized in Table 2 and compare favorably with the results of percutaneous procedures (Table 1).No difference has been noted in the success of procedures performed under direct ureterorenoscopic approach versus those performed with indirect fluoroscopic control. Although simple dilation of the UPJ does not seem to be sufficient, at least in adults, some evidence suggests that for secondary UPJ strictures, acceptable results can be obtained with endoballoon rupture as well as with Acucise (Applied Urology, Laguna Hills, CA)2end~pyelotomy.~~ With antegrade endopyelotomy, the invagination technique and the classical percutaneous technique have similar success rates.I3 Likewise, the type of incisional device does not significantly influence the outcome. Similar results are obtained with laser incision, cold and hot knifes, and semilunar or hook knives (Table 2). The type of stent and the experience of the surgeon (once the operative technique has been mastered) also do not influence the outcome.l8,s]
years when the Acucise balloon has been used, especially in the absence of crossing vessel^.^, 29 Preliminary experience with younger children is now being reported again showing encouraging results.s, 24, 46 In one study of a small series, simple balloon dilation appeared to be sufficient, and disruption of the UPJ may not be required as it is in However, no long-term follow-up is available in this setting. Currently, the role of endopyelotomy remains unclear in children, and open pyeloplasty is still the preferred procedure owing to its consistently superior results, especially in primary cases. In secondary cases of UPJ obstruction, such as failures of open pyeloplasty, endopyelotomy can be safe and effective. With further refinements and miniaturization of equipment, it may ultimately become a preferred option.16,24 In elderly patients, endopyelotomy offers results comparable with those in the adult group.20,27 Not surprisingly, neither the sex of the patient nor the side of the obstruction influences the outcome.’8,28
AGE AND SEX OF THE PATIENT AND THE SIDE OF OBSTRUCTION
CROSSING VESSELS
The pediatric experience has taken longer to accumulate than the data in adults, and only limited and selected series are available for review (Table 3). Recently, good results have been obtained in children older than 4
The significance of vessels crossing the UPJ remains a matter of debate, and their role in the pathogenesis of the obstruction as well as their influence on the results of various endourologic procedures is controversial.10, 34, 51, s2 An extensive historical review ad-
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Table 3. RESULTS OF ENDO(URETER0)PYELOTOMY IN CHILDREN Technique
No.
Retrograde dilatation Tan et al, 199547 10 Acucise endopyelotorny Bolton et al, 19946 2 Bogaert et al, 19965 8 Percutaneous endopyelotomy Towbin et al, 198749 3 Kavoussi et al, 199124 4 (17)13 Tan et al, 199346 Netto et al, 1996% 9 Figenshau et al, 199616 17
I
+ II
10
+0 +0
2 7
+
1
+0 +4 +3 +3 8+9
3 0 14 6
Mean Age (range) 16 rno (3 mo-9.5 yr)
Percent Success 70
Mean Follow-up, (range) Months 22 (4-25)
4and6yr 9 yr (4-15)
100 718
11 and 12 15 (2-32)
11, 13, 18yr 6.5 wks-5.5 yr 4rno-16yr 6 yr (2 rno-15 yr) 3mo-17yr
(213) 67 100 (58) 77 83 62, 100
10 and 27 18-23 15 (3-36) 30 (18-56) 45 (16-110)
dressing these issues has been published recently.5z Crossing vessels have been shown to have a statistically significant negative influence on the outcome of endoureteropyelotomy by the authors and their colleag~es.~~ In a prospective study enrolling 87 consecutive patients presenting with symptomatic UPJ obstruction between 1986 and 1989, 67 adults underwent a preoperative angiographic study, and endoureteropyelotomy was performed regardless of the results. In 26 of 67 patients (39'/0), vessels were demonstrated in close contact with the site of the obstruction. The presence of crossing vessels reduced the final success rate from 86% to 42%. The degree of hydronephrosis was also a negative factor but was of lesser significance. The influence of the combination of both factors on final outcome was highly significant, with a 95% success rate attained when there was no crossing vessel and only a moderate degree of hydronephrosis compared with a 39% success rate when a crossing vessel was associated with high-grade hydronephrosis (odds ratio, 28.29; 95% confidence interval, 24.91 to 31.66; P < 0.001). The authors subsequently reported on the preoperative vascular anatomy in 86 patients with a follow-up extending more than 12 years (mean, 6.5 years).5zThe importance of the previously mentioned prognostic factors was confirmed. The success rate decreased to 33% and 82% with and without crossing vessels, respectively (Table 4). Crossing vessels were present in 18% of successful cases in comparison with 67% of failures. Moreover, significant size of crossing vessels was demonstrated in 15 of 18 (83%) patients undergoing secondary open pyeloplasty for endopyelotomy failure; concomitant highgrade hydronephrosis was present in 13 instances.s2
Other reports have also noted a negative influence of crossing vessels on the success of endourologic management of UPJ obstruction, although without statistical e~idence.~, I", 41 Bogaert and co-workers5reported a high success rate of retrograde endopyelotomy in children but stated that open surgery remained the standard, particularly when crossing vessels were identified preoperatively. Their only failure occurred in a patient with a crossing lower pole vessel.s Bagley and coworkers* reported a lower success rate when crossing vessels were detected preoperatively by endoluminal ultrasound. Cohen and coworkersl2found that one of two unexplained failures after Acucise endopyelotomy occurred in patients with a crossing vessel. Figenshau and colleagues16reported a similar experience with percutaneous endopyelotomy in children, and Lim and Walkerz9identified crossing vessels in two of three recurrent UPJ obstructions after pyeloplasty in children. At Washington University, Wolf and
Table 4. SUCCESS RATE OF ENDOURETEROPYELOTOMY ACCORDING TO PROGNOSTIC FACTORS: VESSEL CROSSING UPJ AND DEGREE OF HYDRONEPHROSIS
Risk Factors
Percent Success
Vessel absent and low-grade hydronephrosis Vessel absent Low-grade hydronephrosis Vessel absent and high-grade hydronephrosis High-grade hydronephrosis Vessel absent and low-grade hydronephrosis Vessel present Vessel present and high-grade hydronephrosis
90 82 81 74 54 43 33 30
Data from Van Cangh PJ, Nesa S,Galeon M. et al: Vessels around the uteropelvic junction: Significance and imaging by conventional radiology. J Endourol 10:111-119, 1996.
ENDOPYELOTOMY
co-workers" observed that all four patients treated with laparoscopic pyeloplasty after failed endoureteropyelotomy had vessels crossing the UPJ. Similar findings were reported by Faerber and c o - ~ o r k e r s 'with ~ Acucise endopyelotomy. Three of four failures reoperated on using open pyeloplasty had vessels crossing the UPJ. Faerber and colleagues therefore recommended spiral CT to identify crossing vessels preoperatively and the selection of another form of therapy when they are present.15 Although some impact of crossing vessels on outcome is not disputed, the relative importance of this effect remains a matter of debate. In a recently published series of 401 percutaneous antegrade endopyelotomies, there were 60 failures. A total of 54 patients were explored, and crossing vessels were found to be present in 13 (24%) of the cases.'* It was concluded that obstructing crossing vessels were potential factors of failure in 4% of endopyelotomies, and that their preoperative identification was not indicated.l8 The difference between the authors' findings and the data reported in the series just cited is perhaps best explained by patient selection. The data reported by the authors are based on the prospective recruitment of all patients presenting with symptomatic UPJ obstruction during the study period; endoureteropyelotomy was performed regardless of the results of the preoperative evaluation for crossing vessels.'O Also, in the authors' series, more than 80% of patients had a primary type of UPJ obstruction with a higher likelihood of crossing vessels in contrast to the majority of other series in which approximately half of the cases were primary in origin. Some investigators maintain that crossing vessels are present around the UPJ in as many as 71% of kidneys; therefore, they must not be detrimental to the success of the procedure." However, such data have been obtained from anatomic studies on normal kidneys and show the vascular anatomy at the normal UPJ. This may not be relevant to the actual crossing of the UPJ in clear-cut hydronephrosis secondary to UPJ obstruction. In fact, the literature on surgical pyeloplasty is replete with accurate illustrations relevant to UPJ obstruction and confirms the authors' findings at surgery in patients with failed endoureteropyelotomy..',37 The reported incidence of late failures or recurrences is diverse. Some investigators
285
have found that failures occur early, and that late failures or recurrences are distinctly uncommon.1n, 34 However, a higher incidence of late failures or recurrences was noted in the authors' series.52Seven of the 18 failures occurred after 1 year; and one occurred 6 years postoperatively.The possibility that this might be the result of inadequate follow-up is unlikely, because all patients were observed according to a strict study protocol. Interestingly, the cases of late failure were very similar to the well-known entity of intermittent hydronephrosis in which a crossing vessel is often pre~ent.'~ In 15 of the 18 failures treated by open pyeloplasty, a crossing vessel was found. Clearly, long-term success can be achieved in the presence of crossing vessels. In those instances, the authors believe that the operation succeeds in correcting both the intrinsic and the extrinsic factors of obstruction. The functional patency of the UPJ is reestablished, and the crossing vessels become somewhat fixed in a silent nonobstructing position. In recurrences, perhaps either or both outcomes are insufficient, or the quality of the hypotonic renal pelvic musculature is inadequate and thereby irreparable. Even with limited diuresis, the renal pelvis balloons out and protrudes through the vascular window, making recurrence inevitable. Vessels crossing the UPJ influence not only the outcome of endopyelotomy but act as a potential source of complications. Vascular complications of endoureteropyelotomy can be significant. Although possibly underreported in the literature, they remain an important concern to urologists.6, Although such complications are rare in the experience of some surgeons, this may reflect their expertise in technique as well as patient selection.% Complications can nevertheless occur and are acknowledged as potentially serious.' Careful visual inspection of the operative site to direct the incision away from pulsating vessels is strongly advocated with direct visual endourologic approaches, and is indeed a recognized advantage of endoscopic versus fluoroscopic techniques.% Reported vascular complications have been summarized elsewhere.52 Malden and cow o r k e r ~described ~~ an arteriovenous fistula complicating antegrade endopyelotomy, and Brooks and colleaguess reported the need to transfuse 4 of 22 (18%) of their patients undergoing endopyelotomy. Cohen,I2 Streemf and Wagner% and their colleagues have de-
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VAN CANCH & NESA
scribed significant bleeding from direct vascular injury after retrograde endopyelotomy. Cohen acknowledged a 10% to 15% risk of bleeding from crossing vessels and suggested that full patient evaluation is warranted.I2 Gelet and co-w~rkers'~ reported two cases of significant bleeding after 44 Acucise procedures, one of which resulted from an arteriovenous fistula from a crossing vessel. The authors believe that such data are of sufficient importance to justify preoperative documentation of crossing vessels and the selection of an alternative approach when they are found (especially when they are asso44, 55 ciated with high-grade hydronephrosis).26, By following these guidelines, hemorrhagic complications have all but disappeared, and success rates have dramatically increased.2,3, 26 Quillin and c o - ~ o r k e r reported s~~ the absence of failures in patients without crossing vessels documented by spiral CT angiography. Fig-
ures 1 to 3 are representative views of preoperative spiral CT in a patient with primary UPJ obstruction and bilateral crossing vessels. The documentation of crossing vessels preoperatively has the additional benefit of improving postoperative follow-up planning, as the risk of long-term recurrence increases when crossing vessels are present. Furthermore, some diagnostic techniques (e.g., angiography, spiral CT) are able to detect vessels crossing the contralateral UPJ, which ultimately may prove advantageous because UPJ obstruction can be bilateral in as many as 10% of cases (Figs. 1 and 3). CONCLUSIONS
Endoureteropyelotomy has not gained universal acceptance in the urologic community, in part, because of a 10% to 30% inferior
Figure 1. Three-dimensional reconstruction of renal vasculature obtained from spiral CT imaging (Figures 1-3 from same patient with primaly UPJ obstruction). Bilateral lower polar vessels and their relation to the UPJ are accurately demonstrated.
ENDOPYELOTOMY
287
References
Figure 2. Polar artery and accessory inferior polar vein crossing posteriorly to the UPJ (same patient as in Figure 1).
success rate and the fear of vascular complications.” 51, 52 Identification of prognostic risk factors for failure and complications is therefore of primary importance. The length of the stricture, the level of renal function, and the grade of hydronephrosis are generally accepted prognostic factors. Additionally, in the authors’ experience, crossing vessels have a major role and, in association with the grade of hydronephrosis, are major predictive factors of outcome. Endoureteropyelotomy represents a significant advance in the management of UPJ obstruction but should not be offered indiscriminately. The goal is to characterize prognostic factors fully in an attempt to achieve better case selection. Crossing vessels significantly impact on the overall success and complication rates, and their presence should therefore be documented. In this regard, it is encouraging that several recent series in which these recommendations have been followed report a success rate equivalent to that for the gold standard of dismembered pyeloplasty, that is, close to loo%, as well as the absence of vascular complication^.^, 26, 43
Figure 3. Accessory artery and vein demonstrated on a frontal reconstruction (same patient as in Figure 1).
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39. O'Flynn K, Mc Kelvic G, Steyn J: Endoballoon rupture and stenting for pelvi-ureteric junction obstruction technique and early results. Br J Urol 64:572574, 1989 40. Ono Y, Hashimato J, Ohshima S: Percutaneous endoscopic surgery for obstructive disease in the upper urinary tract-preliminary report. Sen J Urol81:12471251, 1990 41. Perez LM, Friedman RM, Carson CC: Endoureteropyelotomy in adults. Urology 39:71-76, 1992 42. Preminger GM, Clayman RV, Nakada SY, et al: A multicenter clinical trial investigating the use of a fluoroscopically controlled cutting balloon catheter for the management of ureteral and ureteropelvic junction obstruction. J Urol 1571625-1629,1997 43. Quillin SP, Brink JA, Heiken JP, et al: Helical (spiral) CT angiography for identification of crossing vessels at the ureteropelvic junction. AJR Am J Roentgenol 166:1125-1130, 1996 44. Sampaio FJ, Favorito LA: Ureteropelvic junction ste nosis: Vascular anatomical background for endopyelotomy. J Urol 150:1787-1791, 1993 45. Streem SB, Geisinger MA: Prevention and manage ment of hemorrhage associated with cautery wire balloon incision of ureteropelvic junction obstruction. J Urol 153:1904-1906, 1995 46. Tan HL, Najmaldin A, Webb DR: Endopyelotomy for pelvi-ureteric junction obstruction in children. Eur Urol 24:84-88, 1993 47. Tan HL, Roberts JP, Grattan-Smith D Retrograde balloon dilatation of ureteropelvic obstruction in infants and children: Early results. Urology 46:89-91,1995 48. Thomas R, Monga M, Klein EW: Ureteroscopic retrograde endopyelotomy for management of ureteropelvic junction obstruction. J Endourol 10:141-145,1996 49. Towbin RB, Wacksman J, Ball W S Percutaneous pyeloplasty in children: Experience in three patients. Radiology 163:381-384, 1987 SO. Van Cangh PJ, Jorion JL, Wese FX, et al: Endoureteropyelotomy: Percutaneous treatment of ureteropelvic junction obstruction. J Urol 141:1317-1322,1989 51. Van Cangh PJ, Wilmart JF, Opsomer RJ, et a1 Longterm results and late recurrence after endoureteropyelotomy: A critical analysis of prognostic factors. J Urol 151:934-937, 1994 52. Van Cangh PJ, Nesa S, Galeon M, et al: Vessels around the ureteropelvic junction: Significance and imaging by conventional radiology. J Endourol 10:111-119, 1996 53. Van Cangh PJ, Nesa S: Endoureteropyelotomy. Atlas Urol Clin North Am 443-58, 1996 54. Wagner JR, D'Agostino R, Babayan RK: Renal arterioureteral hemorrhage: A complication of Acucise endopyelotomy. Urology 48:139-141, 1996 55. Wolf JS, Siege1 CL, Brink JA, et al: Imaging for URteropelvic junction obstruction in adults. J Endourol 10:93-104, 1996
Address reprints requests to Paul J. Van Cangh, MD Professor and Chairman Department of Urology University of Louvain Medical School St Luc University Clinics 10 Avenue Hippocrate 1200 Brussels BELGIUM