Hyung K Park md, Department of Urology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. Email: firstname.lastname@example.org
Objective: To evaluate the long-term outcome of secondary endopyelotomy after failed primary intervention for uretero-pelvic junction (UPJ) obstruction and to assess the effect of preoperative parameters on treatment outcome.
Methods: Twenty patients (13 men, seven women; mean age 30.7 years) who underwent secondary endopyelotomy after the failure of a primary intervention for the treatment of congenital UPJ obstruction were included in this retrospective analysis. Mean interval from primary treatment to secondary endopyelotomy was 27.2 months (range 3–123 months). The diagnosis of failure of the primary treatment was based on symptoms and the results of imaging studies. Treatment success was defined as symptomatic relief with either stable or improved renal function and improved wash-out shown on diuretic renogram or excretory urography.
Results: Mean follow-up was 47.2 months (range 6.2–138.8 months). Success rates were as follows: overall, 70%; after primary dismembered pyeloplasty, 66.7%; after primary endopyelotomy, 57.1%; after primary balloon dilatation, 100%. Kaplan-Meier estimates of success were 64.4% at 5 years. Six patients in whom the procedure failed at a mean of 13.8 months (range 4–33 months) were treated with open pyeloplasty (four patients), simple nephrectomy (one), and a repeat endopyelotomy (one). Grade 4 hydronephrosis and significant obstruction occurred more often in the failure group.
Conclusions: Endopyelotomy is an acceptable minimally invasive secondary treatment option for UPJ obstruction. Preoperative severe hydronephrosis and the presence of a significant obstruction seem to be risk factors for the failure of a secondary endopyelotomy.
Treatment methods for an obstruction of the ureteropelvic junction (UPJ) have evolved rapidly during the past two decades. In addition to classic open pyeloplasty, which is associated with a success rate ranging from 90% to 95%,1,2 endopyelotomy has been used regularly and effectively because it has an acceptable success rate of 72–88% and it is a relatively less invasive procedure.2–6 Laparoscopic pyeloplasty, which has a success rate comparable to that of open pyeloplasty, has also become a widely accepted treatment option over the last decade.7,8 However, it is very difficult for clinicians to determine additional therapy when those primary treatments have failed. Although in many studies the success rates of open salvage procedures performed in patients who had experienced a failed primary intervention are reported to exceed 90%, those open surgeries have been associated with increased patient morbidity and with intraoperative difficulty caused by peripelvic scarring and adhesion.9,10
Although secondary endopyelotomy has a success rate lower than that achieved with open operative intervention, it offers the advantages of requiring a relatively brief hospital stay, enabling the patients' early return to prehospitalization activities, and requiring less surgical skill.11,12 We assessed the long-term results of endopyelotomy as a secondary procedure after a failed primary intervention for a UPJ obstruction and identified the factors that had an effect on the success of treatment.
At our institute from March 1994 to June 2005, 23 consecutive patients underwent endopyelotomy for the failure of a prior open or laparoscopic pyeloplasty or endourologic treatment (antegrade or retrograde endopyelotomy, balloon dilatation). Only patients who underwent endopyelotomy after the failure of a primary treatment for congenital UPJ obstruction were included in the study. Excluded from the study were a patient who underwent the procedure because of renal tuberculosis, a patient who underwent renal transplantation 13 months after the procedure because of pre-existing azotemia that made assessing the results of a secondary endopyelotomy impossible, and a patient with a UPJ obstruction and a ureterovesical obstruction caused by a prior ureterolithiasis. Twenty patients (13 men and seven women; mean age, 30.7 years; age range 16–53 years) were enrolled in this study, and the data of those patients were analyzed retrospectively. The primary treatment methods were open dismembered pyeloplasy in six patients, laparoscopic dismembered pyeloplasty in three, balloon dilatation in four, and endopyelotomy (four antegrade and three retrograde) in seven patients. The mean interval from the primary treatment to the secondary endopyelotomy was 27.2 months (median 15.0 months; range 3–123 months). The diagnosis of the failure of the primary treatment was based on symptoms and the results of imaging studies such as intravenous urography (IVU), renal ultrasonography (US), nuclear renography (mercaptoacetyltriglycine [MAG]-3 scan), retrograde pyelography (RGP), or computerized tomography (CT) in some patients. Our decision to perform secondary endopyelotomy was based on the UPJ anatomy, stricture length, comorbid conditions, and patient preference. Patients' preoperative characteristics are shown in Table 1. The extent of hydronephrosis was graded according to the Society for Fetal Urology system.13 A significant obstruction was diagnosed in patients with a delayed renogram with MAG-3 washout times of longer than 20 min. The assessment of preoperative renal function was based on the split function of the treated kidney on MAG-3 scan. Renal function was defined as follows: more than 40%, good; 25% to 40%, moderate; and less than 25%, poor. All patients had a focal stricture of less than 2 cm on preoperative imaging studies, and the presence or absence of a crossing vessel was not routinely evaluated because few patients were evaluated with CT. Preoperative imaging studies showed that none of our patients had a high insertion of the UPJ.
Table 1. Baseline characteristics of study population
Based on the Society for Fetal Urology system.
Delayed renogram with T1/2 > 20 min on mercaptoacetyltriglycine (MAG)-3 scan.
Mean age in years (range)
Right/left side (No.)
Previous operative method
Open dismembered pyeloplasty
Laparoscopic dismembered pyeloplasty
Mean time to secondary endopyelotomy (months) (range)
A retrograde secondary endopyelotomy was performed in all patients except one who underwent a combined antegrade and retrograde endopyelotomy. The endopyelotomy incision was extended to the depth of peripelvic and periureteral fat either laterally or post-erolaterally with a cold knife (n = 4), a Ho:YAG laser (n = 13), or a hook electrode (n = 3). Initially, retrograde endopyelotomy was performed with an 11.5-Fr ureteroresectoscope with a cold knife or a hook electorode after passive dilatation with double-pigtail ureteral stent for 2 weeks. After June 2000, a 6.9-Fr to 7.5-Fr semirigid ureteroscope was primarily used with the Ho:YAG laser.
After the endopyelotomy incision had been made, a 14-Fr/7-Fr endopyeolotmy stent or a 6-Fr or 7-Fr double-pigtail ureteral stent was inserted, and a Foley catheter was positioned in the bladder and was left for 48 h. The endopyelotomy or ureteral stent was left in place for 6–8 weeks after surgery. IVU, US and MAG-3 scan and/or RGP in some patients were performed 3, 6, and 12 months after the procedure and then once yearly. Success was defined as the resolution of symptoms associated with either stable or improved renal function and improved washout from the renal pelvis (i.e. a half-time of less than 20 min) shown on MAG-3 scan or IVU, respectively.
We investigated the long-term success rate according to primary treatment and also examined the effects of preoperative parameters such as stent duration, primary treatment method, operative time, mean interval from the primary treatment to the secondary endopyelotomy, the degree of preoperative obstruction, relative renal function, and the degree of hydronephrosis on treatment success. In addition, we evaluated perioperative parameters including hospital stay and complications.
Statistical analyses were performed using the SPSS 11.5 software package. All data are expressed as the mean ± the standard deviation. The Kaplan-Meier survival analysis was used to estimate the long-term probability of success. The comparative analysis between groups was performed with the Mann–Whitney U-test for continuous data and the χ2 test for categorical data. A two-sided P-value < 0.05 was statistically significant.
The overall success rate was 70% (14 out of 20 patients) with a mean follow-up of 47.2 months (median, 32.4 months; range 6.2–138.8 months). The success rates estimated with the Kaplan-Meier method were 90.0% at 6 months, 85.0% at 12 months, 79.7% at 18 months, 73.6% at 24 months, 64.4% at 3 years, and 64.4% at 5 years (Fig. 1). The success rates according to the primary treatment were 66.7% (four of six patients) in the open pyeloplasty group at a mean follow-up of 47.1 months, 66.7% (2/3) in the laparoscopic pyeloplasty group at a mean follow-up of 20.5 months, 100% (4/4) in the balloon dilatation group at a mean follow-up of 61.0 months, and 57.1% (4/7) in the endopyelotomy group at a mean follow-up of 50.7 months.
When the success rates were analyzed in terms of preoperative hydronephrosis, renal function, and the degree of obstruction, the degree of hydronephrosis and the presence of a significant obstruction had a negative effect on the treatment success, but the relative renal function had no effect on the success (hydronephrosis: ≤grade 3, 88.9% [8/9]vs grade 4, 54.5% [6/11]; the presence vs absence of significant obstruction: 57.1% [8/14]vs 100% [6/6]; relative renal function: poor, 66.7% [2/3]vs moderate, 100% [4/4]vs good, 61.5% [8/13]). The success rates according to the surgical method were 25% (1/4) for a cold knife, 76.9% (10/13) for a Ho:YAG laser, and 100% (3/3) for a hook electrode, respectively.
The time to failure of six secondary endopyelotomies ranged from 4 to 33 months (mean, 13.8 months). Of the six failures, three occurred within 1 year after surgery, two occurred between 1 and 2 years, and one occurred between 2 and 3 years. Those failures were managed with a salvage treatment consisting of open pyeloplasty, simple nephrectomy, further endourologic treatment, or a combination of those therapies (Table 2).
Table 2. Six failures of secondary endopyelotomy and their salvage treatment
Relative renal function (%)
Time to failure (months)
One balloon dilatation and one endopyelotomy
Simple nephrectomy due to severe fibrosis
Two endopyelotomies and one open pyeloplasty
There was no difference in preoperative parameters between the groups in whom secondary endopyelotomy succeeded or failed, except that grade 4 hydronephrosis and significant obstruction were more often observed in the failed-treatment group (Table 3).
Table 3. Comparison of clinical and perioperative parameters between the groups in whom secondary endopyelotomy succeeded or failed
Success group (n = 14)
Failure group (n = 6)
Dismembered group, open pyeloplasty or laparoscopic pyeloplasty; endourologic treatment group, balloon dilatation or endopyelotomy.
Delayed renogram with T1/2 > 20 min on mercaptoacetyltriglycine (MAG)-3 scan.
The mean hospital stay after secondary endopyelotomy was 4.7 days (range 3–10 days). However, most patients were discharged 3–5 days after surgery, except for two patients who underwent preoperative percutaneous nephrostomy drainage and were discharged on postoperative days 8 and 10, respectively, after the percutaneous tube had been removed.
Secondary endopyelotomy resulted in few complications. There were no hematomas at the surgical site, no bleeding that required selective embolization occurred, and no ileus associated with fluid extravasation developed. Only one of the patients exhibited prolonged gross hematuria after catheter removal on postoperative day 2 and underwent re-catheterization and manual bladder irrigation. Another patient exhibited a transient fever on postoperative day 1. After conservative management, those two patients were discharged on postoperative days 7 and 4, respectively.
Since it was introduced,14,15 endopyelotomy has been used for the treatment of UPJ obstruction after a failed primary intervention. In those cases, the success rate of secondary endopyelotomy has ranged from 37% to 88%.11,1216–18 We found an overall success rate of 70% with a mean follow-up of 4 years after secondary endopyelotomy. In addition, we found a trend toward a higher success rate in patients who had undergone a previous dismembered open or laparoscopic pyeloplasty (66.7%) than in patients who had been treated with an endopyelotomy (57.1%), a finding that is consistent with those in previous reports.11,16 All patients in whom previous balloon dilatation had failed were successfully treated with endopyelotomy. We believe that the success rate of 100% after endopyelotomy in those cases was due to a minimal obstruction.
Although several earlier studies have evaluated the results of secondary endopyelotomy after a failed primary treatment for a UPJ obstruction, some of those reports11,1718 were based on a relatively brief follow-up. When compared with other studies, the follow-up of our study cohort was as long as 11.6 years (mean, 4 years), and 70% of the patients (14 of 20) were monitored for longer than 3 years. Two studies evaluating the long-term outcome of endopyelotomy after the failure of open pyeloplasty reported a success rate ranging from 71.4%16 in one of those reports to 87.5%12 in the second with a mean follow-up of 47.7 and 88.5 months, respectively. From this study, we also found a success rate of 66.7% with secondary endopyelotomy after the failure of an open pyeloplasty, although that success rate was slightly lower than those of previous reports.
In our study, we found an acceptable success rate of 57.1% for the endourologic salvage of a failed primary endopyelotomy, although Ng et al. reported a much lower success rate (37.5%).16 Those authors thought that their unacceptably low success rate might be due to a strict definition of success involving both symptomatic relief and radiologic resolution of obstruction and a long-term follow-up (mean follow-up, 4 years) compared with other studies. Although the definition of success and the follow-up in our study were similar to those in the study by Ng et al.,16 our results from secondary endopyelotomy for failed primary endopyelotomy were better than theirs. In our opinion, institutional differences in the success rates of secondary endopyelotomy result from differences in preoperative characteristics related to UPJ obstruction, such as stricture length, renal function, degree of hydronephrosis, the presence or absence of crossing vessels, and the surgeon's technique. Because the technique and the concept of endopyelotomy have been established today by many investigators,19,20 we think that the technical differences among surgeons are minimal. Instead, the differences in success rates from institute to institute may be due to differences in patients' preoperative characteristics. In our opinion, the results of our study, which show an acceptable success rate for endopyelotomy in managing both failed open pyeloplasty and failed endopyelotomy, reflect the importance of selecting patients who are candidates for salvage endopyelotomy.
We performed endopyelotomy as a secondary procedure with several clinical considerations, including stricture length, renal function, and UPJ anatomy. All patients in our study had a short segment stricture (<2 cm), and 85% (17/20) of the patients had moderate-to-good renal function. Moreover, no patients had a high insertion of the UPJ. Another important consideration was the patient's treatment preference. During the study, all three patients in whom laparoscopic pyeloplasty failed had chosen endopyelotomy as salvage treatment because of its less invasive nature and low complication rate. Of those three patients, 66.7% (2/3) were successfully treated. Varkarakis et al.21 also reported that most patients select endoscopic management after a failed primary laparoscopic pyeloplasty and that in their study, the success rate of secondary endopyelotomy was 85.7% (6/7) with a mean follow-up of 25.5 months.
During the same study period, secondary open pyeloplasty was performed in six patients who had failed five primary endopyelotomies and one open pyeloplasty. Meanwhile, laparoscopic pyeloplasty was not performed as a secondary procedure for UPJ obstruction because at the time of the study we were on the learning curve of this new technique. Our indications for secondary open pyeloplasty included a relatively long segment stricture, combined UPJ abnormality, which was confirmed after primary surgery, and cases in which endourologic salvage treatments were thought to be unsuitable based on the surgeon's judgment. In contrast to the secondary endopyelotomy group, two of the six patients had strictures longer than 2 cm and two had combined abnormalities such as UPJ polyp and abnormal cluster of blood vessels with UPJ obstruction. Despite these preoperative unfavorable characteristics, all patients were successfully treated with secondary pyeloplasty. From this study, we confirmed that open pyeloplasty is a very effective salvage treatment and that it is superior to secondary endopyelotomy, these findings being consistent with those of the other report.22 However, our practice, namely, less common use of secondary pyeloplasty during the same period, indicates that it is a more technically demanding and more invasive procedure than secondary endopyelotomy, from the point of view of both the surgeons and our patients.
Many studies have analyzed the effect of various preoperative factors on the success of endopyelotomy.12,2324 Like other authors, we found that grade 4 hydronephrosis and the presence of a significant obstruction had a negative effect on the success of secondary endopyelotomy with marginal statistical significance. We think that marginal statistical significance of those two factors may be due to the small sample size. However, our study showed that preoperative renal function had no effect on treatment outcomes. In our study, two of three patients with poor preoperative renal function (15% in one patient and 18% in the other) were successfully treated with secondary endopyelotomy. Our study results suggest that poor preoperative renal function is not an absolute contraindication for endopyelotomy. We believe that secondary endopyelotomy could result in a good treatment outcome, even in some patients with relatively poor renal function. Because we did not identify crossing vessels in all cases before performing secondary endopyelotomy, we do not know its effect on treatment outcome. However, the effect of crossing vessels in endopyelotomy is still controversial, and their mere presence is not a contraindication for endopyelotomy.5,2526 In our study cohort, the incidence of crossing vessels in patients who underwent primary open or laparoscopic pyeloplasty was 33.3% (3/9).
Our study confirmed the excellent postoperative safety and the minimal invasiveness of secondary endopyelotomy. There were no major procedure-related complications, and the mean hospital stay after endopyelotomy was significantly shorter (4.7 days vs 8.4 days) than that required after open pyeloplasty at our institute. Secondary endopyelotomy is a treatment option with an excellent safety profile, and it offers a reasonable expectation of success in properly selected patients.
Several potential limitations of our study need to be addressed, the first of which is its retrospective nature. We did not differentiate extrinsic from intrinsic causes of obstruction. Thus our acceptable success rate for secondary endopyelotomy after primary endourologic failure may have been based on the selection of patients who had a small number of extrinsic obstructions, such as aberrant vessels or periureteral bands. However, we believe that the cause of obstruction does not determine the success of endopyelotomy but is merely one of the many factors that affect treatment outcomes. In addition, our study was based on a small sample size because it was a single-center study. However, all consecutive patients in whom primary treatment for a UPJ obstruction failed were included, and our results were based on the long-term follow-up of those patients.
Secondary endopyelotomy is an acceptable and relatively less invasive treatment for failed primary endopyelotomy or failed primary pyeloplasty (open or laparoscopic) performed to treat a UPJ obstruction. Preoperative severe hydronephrosis and the presence of a significant obstruction seem to be risk factors for the failure of secondary endopyelotomy.