Efficacy of Endopyelotomy in Patients with Secondary Ureteropelvic Junction Obstruction

Introduction

I t has been more than 20 years since the first successful series that involved percutaneous endopyelotomy and the management of ureteropelvic junction obstruction (UPJO) from failed open pyeloplasty, previous instrumentation/trauma, or history of stone disease has been reported. ¹ Since then, the landscape in the management of UPJO has evolved farther away from open surgical pyeloplasty to the development of more minimally invasive techniques, including laparoscopic surgery and antegrade/retrograde endopyelotomy, both of which have been shown to decrease hospital stay and postoperative pain when compared with open surgery. ^{2 –4}

Whereas laparoscopic pyeloplasty has become the procedure of choice for congenital UPJO associated with crossing vessels, secondary UPJO, although with varying definitions, is usually not associated with crossing vessels. The success rates for endopyelotomy with respect to secondary UPJO as a consequence of failed primary intervention have ranged from 59% to 70% ^5,6 ; however, there is a paucity of data in the literature focusing on outcomes and etiology of secondary UPJO beyond that of just failed primary repair. This study was designed to elucidate the etiology of secondary UPJO and compare the success rates of endopyelotomy for secondary UJPO vs primary obstruction.

Patients and Methods

Between May 1997 and September 2009, 157 endopyelotomies (antegrade and retrograde) were performed by a single surgeon at our institution. Preoperatively, the diagnosis of UPJO was made by symptoms in conjunction with radiographic imaging—ie, intravenous urography (IVU), CT, ultrasonography, retrograde pyelography, or diuretic nuclear renal scintigraphy. It is the practice of the operating surgeon at our institution to perform CT angiograms on all patients before they are offered endopyelotomy. Only patients with no evidence of crossing vessels were offered endopyelotomy; as such, none of the 157 patients operated on for UPJO had crossing vessels. Primary UPJO was defined as a congenital obstruction without a history of renal surgery. Secondary UPJO was defined as: (1) formation of anastomotic strictures after dismembered pyeloplasty; (2) de novo formation after surgery to the kidney or the ureter; (3) de novo formation after stone disease; and (4) de novo idiopathic formation.

Of the 157 endopyelotomies, 117 (74.5%) were performed for primary UPJO. There were 41 (25.5%) endopyelomoties for secondary UPJO. These 41 patients were evaluated in this study, with all demographic and follow-up data reviewed in a retrospective fashion. Based on preoperative radiographic imaging, hydronephrosis was stratified as grade 1 (mild), grade 2 (moderate), grade 3 (severe), and grade 4 (massive). Renal function was considered good, moderate, or poor if the kidney contributed greater than 40%, 25% to 40%, or less than 25% of the total function, respectively.

Of the 41 patients, 38 patients underwent an antegrade percutaneous endopyelotomy, and the remaining 3 patients underwent retrograde endopyelotomy. This was determined by individual patient anatomy, concurrent medical comorbidities, and patient preference. Our technique first involves cystoscopy, retrograde pyelography, and ureteral catheterization. Once the patient is in the prone position, an upper pole or midpolar calix is chosen for gaining percutaneous access. The nephrostomy tract is then dilated to 30F with a balloon device, allowing placement of an Amplatz sheath through the nephrostomy. Nephroscopy is then performed with a Storz 26F continuous flow nephroscope. The UPJ is carefully inspected to rule out the presence of any pulsating crossing vessels. It must be noted that we did not expect to find any obstructing crossing vessels in this study population, because secondary UPJO would obviate the existence of such vessels; however, transposition of vessels could still allow their presence in the vicinity of the UJPO.

Using a hook knife, scissors, or a cutting balloon, a full thickness incision to the depth of peripelvic/periureteral fat is made truly lateral at the UPJO. Balloon dilation of the UPJO was also used in one patient. After incision, the area is observed for any significant bleeding. At completion of the procedure, a 6F multilength double pigtail ureteral stent is positioned, followed by placement of a 20F nephrostomy tube.

Postoperative objective success was evaluated by CT, intravenous pyelography (IVP), or diuretic renal scintigraphy at 1month after stent removal, and 6 months and 1 year after the procedure. All patients had at least one radiographic evaluation following stent removal. Success was defined as decreased hydronephrosis and improvement in flow of contrast from renal pelvis through ureter or absence of obstruction via CT, IVU, or diuretic scintigraphy, in addition to symptomatic improvement and/or improvement in quality of life.

The Fisher exact test was used to compare categorical variables. A P value of less than 0.05 was considered to be significant. All statistical analysis was performed using STATA 11.0 (Stata Corp).

Results

The patient demographic and perioperative data are summarized in Table 1. A total of 41 patients underwent endopyelotomy for secondary UPJO, and of these, 38 (92.7%) patients underwent antegrade endopyelotomy with the remaining 3 (7.3%) patients undergoing retrograde repair of their secondary UPJO. The mean age of the study population was 50.3 (2–82), which included four pediatric patients (ages 2–12). Stone disease was found to be associated in 44.1% of patients.

Factors that have been associated with endopyelotomy failure include the presence of crossing vessels, the degree of hydronephrosis, and the function of the affected kidney. The preoperative degree of hydronephrosis and renal function was evaluated for each patient (Table 1). In patients with available data, there was a relatively equal distribution of poor (7), moderate (4), good (5) renal function; however, with respect to degree of hydronephrosis, the majority of patients presented with either severe or massive hydronephrosis (23). Of the six failures, four (66.7%) patients had findings of massive hydronephrosis, as compared with 40% in patients who had successful outcomes after endopyelotomy (P = 0.38). Success rates stratified by degree of hydronephrosis were 100% for mild, 85.7% for moderate, 91.7% for severe, and 77.8% for massive.

With respect to the etiology for the development of secondary UPJO, the majority of patients had some history of surgical intervention that involved the urinary tract before the development of their UPJO. Fourteen (34.2%) of patients had a previous open or laparoscopic repair for congenital UPJO. A total of 20 (48.9%) patients had the development of iatrogenic secondary UPJO from previous surgery that involved the urinary tract. These included nine (22.0%) patients having had open renal surgery, and another nine (22.0%) patients with a history of undergoing percutaneous renal surgery. Two (4.9%) patients had a history of ureteroscopy before development of a stricture. In patients with no previous surgery, two (4.9%) patients were found to have a history of impacted stones at the UPJ. In both instances, the strictures were discovered at the time of percutaneous nephrolithotomy and managed with an antegrade endopyelotomy. Both patients had a severe fibrotic reaction secondary to an impacted stone at the UPJ.

A total of five patients were found to have secondary UPJO without any previous history of stone disease, obstruction, or previous direct trauma. These idiopathic cases all had normal renal imaging and function before the development of UPJ stricture. Secondary UPJO developed in three patients after they had been treated with systemic chemotherapy for breast carcinoma. One patient did have a history of a Whipple procedure before the development of stricture; however, no correlation could be made linking the procedure to the development of the stricture. The fourth patient had a history of renal cysts in the affected kidney; however, previous imaging did not reveal any evidence of previous obstruction. Distribution of the etiology of secondary UPJO is listed on Table 2.

Of the total 157 endopyelotomies that were performed during the study period, overall 127 succeeded for a success rate of 81% (Table 3.). Of these 157 cases, 116 (74%) represented treatment for primary UPJO with a success rate of 79.3%. The overall success rate for patients undergoing endopyelotomy for secondary UPJO in this series was 83.5% (35/41). All three retrograde endopyelotomies for secondary UPJO were successful. The success rate in cases of secondary UPJO after a previous dismembered pyeloplasty was 61.5% compared with 97.1% in all other cases (P = 0.01).

Of the six patients in whom antegrade endopyelotomy failed, three (50%) were pediatric patients, ages 2, 2, and 5 years, respectively (Table 4). Five (80%) had either a previous open/laparoscopic dismembered pyeloplasty, with one (20%) patient having had a repair of an UPJ avulsion. The mean time to failure after endopyelotomy was 3.7 months (range 1–6 mos). All pediatric failures were managed with open pyeloplasty.

Discussion

As the drive for successful minimally invasive techniques continues, the role of endopyelotomy has been called into question. In our study, we specifically evaluated the role of endopyelotomy with respect to the management of secondary UPJO. Our success rate of 83.5% was comparable to previous published results for patients who have undergone endopyelotomy for both primary and secondary UPJO. ^{1,6 –11} Hoenig and associates ⁸ reported a series describing the etiology of secondary UPJO and endopyelotomy success. In that series of 35 total patients (24 failed open pyeloplasty and 11 failed endopyelotomy), failed open pyeloplasty was associated with a higher subjective (88% vs 71%) and objective (71% vs 55%) success rate than those in whom previous endopyelotomies had failed.

Unlike Hoenig and associates, ⁸ our study excluded patients who had UJPO after a failed endopyelotomy, because we propose that this situation represents a continuing disease process and a failure of primary endopyelotomy, rather than de novo UPJ stricture formation. Our overall success rate of 83.5% is similar to that of Hoenig and associates ⁸ : 88% subjective and 71% objective success rates with endopyelotomy after failed pyeloplasty. When stratified to cases of secondary UPJO after dismembered pyeloplasty, our success rate was 61.5% compared with 97.1% in all other cases. There was no difference in the finding of severe/massive hydronephrosis in cases of pyeloplasty failure and all other causes, 74.1% vs 71.4%, respectively. Our findings suggest that stricture formation at the UPJ after failed pyeloplasty may be less amenable to endopyelotomy than from all other causes described.

The majority of patients in whom secondary UPJO developed had a history of surgical intervention within our series. Only 34.2% of patients had a history of open or laparoscopic pyeloplasty with strictures developing at the UPJ after surgical treatment on the kidney in 48.9% of patients. A total of 44.1% of patients had concomitant stone disease, with two patients having impacted stones at the UPJ, which resulted in a fibrotic reaction and subsequent UPJO. Five (16.7%) patients were deemed to have idiopathic development of obstruction, with one patient having had a previous Whipple procedure. Although there is no documented evidence of injury to the right renal pelvis, this likely represents an unrecognized iatrogenic injury. Interestingly, three patients undergoing systemic chemotherapy for the management of breast cancer had strictures develop at the UPJ. Metastatic disease has been documented from the breast to the ureter and the UPJ. ^12,13 Whether our findings represent subclinical disease with subsequent reaction to chemotherapy is unknown.

Hydronephrosis and renal function play an important role in outcomes with endopyelotomy. In a large series, Gupta and colleagues ⁷ found that high-grade hydronephrosis and poor renal function were associated with endopyelotomy failure. They also reported lower success rates of endopyelotomy with treatment of primary UPJO (82%) vs secondary UPJO (89%). ¹² One possible explanation for this is that patients in whom secondary UPJO developed are better candidates for endoscopic management, because the presence of crossing vessels is obviated. Van Cangh and coworkers, ¹⁴ who also reported an association with high-grade hydronephrosis and worse outcomes, demonstrated that the presence of a crossing vessel in conjunction with hydronephrosis significantly decreased long-term success rates compared with patients who did not have either factor present. Although 66.7% of failures in our cohort had massive hydronephrosis, 40.0% of patients with successful outcome had a similar such finding. Because of the small sample size, it is difficult to ascertain any significant conclusion with respect to hydronephrosis and outcome in patients with secondary UPJO within this series.

Our results demonstrated that 50% of all failures occurred in patients younger than 6 years old, which represents only a 25% (1/4) success rate in children with secondary UPJO who are treated with endopyelotomy. All were considered to have anastomotic strictures at the UPJ after open pyeloplasty and, similar to previously published reports, all failures occurred within 6 months. ⁷ There have been multiple series that describe the efficacy of endopyelotomy in the pediatric population with secondary UPJO. Kavoussi and associates ¹⁵ described the antegrade approach in four children all younger than age 6 with a 50% success rate. Larger series by Caoplicchio and colleagues ¹⁶ and Figenshau and coworkers ¹⁷ describe success rates of 88.9% and 100%, respectively, for children after failed open pyeloplasty. Lim and colleagues ¹⁸ found that 50% of patients with persistent UPJO after primary repair were younger than age 6 months with a reported salvage rate of 75% with repeated surgery. All three pediatric failures were successfully salvaged with open pyeloplasty in our cohort.

Conclusions

Our results demonstrate that secondary UPJO can occur as a sequelae from surgery on the kidney in addition to after laparoscopic/open pyeloplasty. We have seen that secondary UPJO can be idiopathic in origin with no significant history of direct insult to the UPJ. With an overall success rate of 83.5%, endopyelotomy is an acceptable form of management for secondary UJPO with proper selection. In this limited evaluation, however, we found that endopyelotomy is not as effective in the pediatric population (success rate of 25%), and in cases of pyeloplasty failure (success rate of 61.5%). Further corroboration of our findings is necessary to confirm these results.