ENDOPYELOTOMY FAILURE IS ASSOCIATED WITH REDUCED TRANSFORMING GROWTH FACTOR-beta

Management of benign ureteral strictures in the endoscopic era

BACKGROUND AND PURPOSE

During the past decade, endoscopic management has emerged as the first-line treatment of benign ureteral strictures. We reviewed our experience with the management of benign ureteral strictures to determine the success rate of endoscopic surgery in a contemporary series and assessed the viability of surgical reimplantation in the modern era.

PATIENTS AND METHODS

We identified 75 patients with a diagnosis of ureteral stricture between 2000 and 2005 via electronic medical records search and excluded those with completely obliterated, external compressive, malignant, or ureteroenteric strictures, ureteropelvic junction obstruction, and those with follow-up less than 2 months.

RESULTS

Thirty-four patients who were treated endoscopically (balloon dilation and/or holmium laser endoureterotomy) were identified. Mean stricture length in each patient was 1.6 +/- 1 cm (range 0.5-4 cm), and the mean number of procedures per patient was 1.7 +/- 0.8. Endoscopic success was achieved in 29 (85%), while 5 (15%) patients experienced endoscopic management failure and ultimately needed ureteral reimplantation. When comparing the endoscopically treated and reimplant groups, there was no significant difference in mean stricture length (1.38 +/- 1.13 vs 2 +/- 1.1 cm, P = 0.14), yet mean number of procedures performed (1.41 +/- 0.85 vs 3.6 +/- 1.5; P = 0.002) reached statistical significance. There were no clinical or radiographic signs of obstruction in 100% of patients who received endoscopic therapy only and 100% of patients who needed open surgical management at a mean follow-up of 25.2 +/- 19.3 and 7.7 +/- 3.2 months, respectively.

CONCLUSIONS

Endoscopic surgery is clearly a successful primary treatment modality in the management of benign ureteral strictures with minimal morbidity. In the modern era of endoscopic surgery, however, ureteral reimplantation remains a viable option in treating the small subset of patients with benign ureteral strictures for whom endoscopic management fails.

Smooth-muscle regeneration after electrosurgical endopyelotomy in a porcine model as confirmed by electron microscopy

BACKGROUND AND PURPOSE

Endopyelotomy is the preferred treatment for ureteropelvic junction (UPJ) obstruction because of its short operating time, limited morbidity, fast recovery, and reasonable efficacy. We used tissue and immunohistochemistry staining and electron microscopy to look at the muscle regeneration following an endopyelotomy incision in a porcine model.

MATERIALS AND METHODS

Bilateral electrosurgical endopyelotomy was performed in six domestic pigs with placement of 7F 20-cm Percuflex double-J stents for up to 4 weeks, and urinary tracts were harvested at 3 or 5 months. Specimen evaluation included tissue staining with hematoxylin-eosin, Masson's trichrome, and Verhoeff's iodine and Van Gieson solution; histochemical staining for smooth-muscle actin, desmin and myosin staining, and electron microscopy. Each specimen was assigned a "healing" score of 0 (normal) 1 (slight changes), 2 (mild changes), or 3 (severe changes). The fibrosis score was based on six factors: muscle layer fibrosis, lamina propria fibrosis, amount of granulation tissue present, new deposits of collagen, fibrosis in the periureteral fat, and presence of myofibroblasts. The muscles were characterized with immunohistochemistry and electron microscopy.

RESULTS

At both 3 and 5 months, the urothelium was healed, and the lamina propria was healed with focal loss. By 3 months, smooth-muscle bundles bridged the defect, and by 5 months, the whole defect was covered. Smooth muscle cells were evident by electron microscopy by 3 months, and actin and myosin could be detected by immunohistochemistry. Desmin-positive cells accounted for 50% of the population at 3 months and 40% at 5 months. The regenerated smooth-muscle bundles were oriented in different directions and intermingled with fibrous tissue. They could be distinguished easily from normal ureter under the microscope.

CONCLUSION

Verifiable, functional smooth-muscle bundles bridge the endopyelotomy defect by 3 months, as confirmed by immunohistochemistry staining and electron microscopy.

Ureteroscopic endoureterotomy

OBJECTIVE

To highlight the current status of ureteroscopic endoureterotomy (UE) by reporting extensive experience with the endoscopic management of ureteric strictures, with special emphasis on factors determining success, and by reviewing publications on the minimally invasive management of ureteric strictures.

PATIENTS AND METHODS

The study comprised 50 patients (mean age 53 years, range 18-85, equal sex distribution) with ureteric strictures of varying causes; all had their stricture treated endoscopically. The follow-up was 0.5-9 years; 10 patients with recurrent strictures had two ipsilateral stents placed to try to improve the outcome, and eight patients with completely obliterating strictures were treated by ureteroscopic re-canalization.

RESULTS

The site of stricture had no bearing on the eventual outcome. Patients with uretero-enteric and malignant strictures did not fare so well. The most important predictor of failure was the length of the stricture, with failure in all seven patients with strictures of > 2 cm. In the 10 patients treated with two ipsilateral stents, eight were successful, which was very promising considering that these patients had recalcitrant strictures and placing one stent had previously failed. The overall success rate was 74%.

CONCLUSION

UE has become the procedure of choice for the initial management of ureteric strictures. Simple balloon dilatation is also effective in certain situations. The characteristics of the stricture often govern the eventual outcome. In properly selected cases success rates of approximately 75% can be expected.

Comprehensive evaluation of ureteral healing after electrosurgical endopyelotomy in a porcine model: original report and review of the literature

PURPOSE

Endopyelotomy (EP) has yet to equal the success achieved with open dismembered pyeloplasty. To understand better the ureteral response to EP we performed a timed histopathological evaluation of the porcine ureter after Acucise (Applied Medical, Rancho Santa Margarita, California) EP.

MATERIALS AND METHODS

In 28 domestic pigs bilateral Acucise EPs were performed and bilateral 7Fr stents were placed. The kidneys, ureters and bladder were harvested after EP at 0, 1, 2, 3, 6, 12 and 18 hours, 1, 3 and 5 days, and 1, 2, 4 and 8 weeks. The stents were removed after 4 weeks. The healing area of the ureter was sectioned. Half was fixed in formalin 10%, stained and evaluated by light microscopy. The other half was frozen and reverse transcriptase-polymerase chain reaction was performed to measure steady state levels of epidermal growth factor, transforming growth factor (TGF)-alpha, TGF-beta 1, TGF-beta 2, TGF-beta 3, keratinocyte growth factor, vascular endothelial growth factor, insulin-like growth factor, platelet derived growth factor, collagen type 1, integrin and fibronectin transcript expression. Immunohistochemistry for actin, desmin and myosin expression was completed. The same studies were applied to the mid portion of the unoperated ureter.

RESULTS

Initial sealing of the ureterotomy defect was by blood clot and periureteral fat. Complete healing of the mucosa was observed at 2 weeks in animals without an associated urinoma. However, in no case did the muscle layer bridge the whole circumference of the ureter despite followup out to 8 weeks. In the operated ureter elevated expression of keratinocyte growth factor, vascular endothelial growth factor, TGF-alpha, TGF-beta 1, TGF-beta 3 and integrin was detected 2 hours after the operation and sustained for 7 to 14 days after the procedure. Immunohistochemistry revealed that most presumed myocytes seen in the defect were actually myofibroblasts. Persistent urinoma formation beyond the first few days appeared to slow the healing process.

CONCLUSIONS

Urothelium regenerated rapidly over an iatrogenic ureteral defect despite the absence of a lamina propria. Muscle cell coverage failed to occur completely at 8 weeks. In the initial 8 weeks of the healing process myofibroblasts appear to be prevalent. A persistent urinoma negatively impacts the healing process.

Update On Minimally Invasive Management of Ureteral Strictures

PURPOSE

To review the role of minimally invasive management in ureteral stricture disease.

MATERIALS AND METHODS

A literature search was performed on the MEDLINE database through 2002 concerning endoscopic treatment of patients with ureteral strictures.

RESULTS

Many endourologic methods are available for ureteral strictures. Ureteral dilation may be accomplished in most cases, with various rates of success depending on stricture etiology, location, and length. Endoureterotomy also leads to long-term patency in properly selected cases and appears to be superior to dilation alone.

CONCLUSIONS

Significant advances in technique and technology have improved our ability to treat ureteral strictures without the need for open surgery in most patients.

Impact of hydronephrosis and renal function on treatment outcome: antegrade versus retrograde endopyelotomy

OBJECTIVES

To compare, in a single-surgeon, single-institution study, the efficacy of antegrade and retrograde endopyelotomy in terms of success rate and morbidity and to identify which risk factors affect treatment outcomes.

METHODS

The results were retrospectively reviewed for 88 patients with ureteropelvic junction obstruction treated with endopyelotomy. Antegrade endopyelotomy was performed with a hook knife, scissors, or cutting balloon device. Retrograde endopyelotomy was performed with a cutting balloon device. Objective results were based on intravenous urogram and/or diuretic nuclear renal scan findings, and subjective results were based on direct patient query and questionnaire.

RESULTS

Ninety-three endopyelotomy procedures, 64 antegrade and 29 retrograde, were performed. The mean follow-up was 37.0 months (range 5 to 76). The overall success rates between antegrade and retrograde endopyelotomy (81.3% versus 75.9%) were not statistically different (P = 0.553). Patients with massive hydronephrosis and poor initial renal function were less likely to have successful endopyelotomy. Antegrade endopyelotomy, however, was more successful than retrograde endopyelotomy in patients with massive hydronephrosis (66.7% versus 20.0%; P = 0.046). The average operative time for antegrade and retrograde endopyelotomy was 93.9 and 32.7 minutes (P <0.001), respectively. The average length of hospital stay after antegrade and retrograde endopyelotomy was 3.20 and 0.14 nights (P <0.001), respectively.

CONCLUSIONS

Both antegrade and retrograde endopyelotomy are effective treatments for ureteropelvic junction obstruction associated with minimal morbidity. Antegrade endopyelotomy appears to be more successful in patients with high-grade hydronephrosis. Retrograde endopyelotomy results in a shorter hospital stay, a shorter operative time, and less postoperative pain.

Potential role for the nuclear transcription factor NF-kappa B in the pathogenesis of ureteropelvic junction obstruction

BACKGROUND AND PURPOSE

In an effort to better understand the pathophysiology of ureteropelvic junction (UPJ) obstruction and to determine possible predisposing factors for endopyelotomy failures, we compared the activation of the nuclear factor NF-kappa B and proinflammatory cytokines in patients who failed endopyelotomy and post-primary pyeloplasty patients. We hypothesized that an imbalance toward proinflammatory cytokines may promote fibrosis prior to and after endopyelotomy in patients with severe hydronephrosis.

PATIENTS AND METHODS

The charts of patients who underwent open pyeloplasty at our institution were reviewed. Group I was the control group, consisting of 10 patients who had undergone radical nephrectomy for renal-cell carcinoma without involvement of the renal pelvis. Group II was the endopyelotomy failure group and included 11 patients over the age of 15 years treated for symptomatic UPJ obstruction. Group III included six patients who underwent primary pyeloplasty. Paraffin-embedded blocks of UPJ segments from each of these patients were obtained, and immunohistochemical detection of NF-kappa B activation, interleukin (IL)-6, and hypoxia-inducing factor (HIF) was performed. As an in-vitro model, activation of NF-kappa B and cytokine gene expression were also monitored in human bladder T24 urothelial cells 24 hours after exposure to hypoxia (1% O(2)) in the presence and absence of NF-kappa B inhibitor. The activation of NF-kappa B was determined by immunocytochemical analysis, whereas cytokine gene expression was measured using reverse transcriptase-polymerase chain reaction.

RESULTS

Immunoreactivity to NF-kappa B was observed in the nuclei of the urothelium and muscle layer in all patients in group II. Such immunostaining suggests increased nuclear translocation and activation of this transcription factor. Those patients with increased expression of NF-kappa B demonstrated increases in IL-6 expression as well. Hypoxia-inducing factor was identified in all the tissue samples tested in group II. Stimulation of the human urothelial cells by hypoxia, known to activate NF-kappa B, resulted in an increase in the levels of IL-1 and IL-6 transcripts compared with hypoxia-exposed cells in the presence of NF-kappa B inhibitors.

CONCLUSIONS

The NF-kappa B factor was upregulated and proinflammatory cytokines were activated in patients with UPJ obstruction who failed endopyelotomy. Proinflammatory cytokines upregulated by this nuclear factor can result in fibrosis and affect healing after endopyelotomy. Hypoxia appears to activate this nuclear factor. Further studies correlating the degree of hydronephrosis with the activation of HIF are necessary to clarify the role of severe hydronephrosis and its management in UPJ obstruction.

Endopyelotomy failure is associated with reduced urinary transforming growth factor-beta1 levels in patients with upper urinary tract obstruction

BACKGROUND AND PURPOSE

We previously demonstrated that obstructed ureteropelvic junction (UPJ) segments from patients who had secondary pyeloplasty after endopyelotomy failure expressed transforming growth factor-beta1 (TGF-beta1) at levels significantly lower than patients who had primary pyeloplasty. In order to determine whether these differences in secreted TGF-beta1 are detectable preoperatively in the urine, the TGF-beta1 concentration of urine from patients undergoing endopyelotomy was determined and compared with that from subjects without urologic disease.

MATERIALS AND METHODS

Bladder and renal pelvic urine from the obstructed side was obtained from patients (N = 34) undergoing primary endopyelotomy for UPJ obstruction. Bladder urine was also obtained from sex- and age-matched patients (N = 26) having no evidence of urinary tract obstruction. The TGF-beta1 concentration was determined by ELISA and normalized to the creatinine concentration.

RESULTS

The bladder urine TGF-beta1 concentration was significantly (P < 0.02) higher in patients with UPJ obstruction (86.1+/-20.5 pg/mg of creatinine) than in those without obstruction (29.7+/-8.0 pg/mg creatinine). The TGF-beta1 concentration in the bladder urine of patients who underwent endopyelotomy and later returned because of UPJ obstruction (25.7+/-12.3 pg/mg of creatinine; N = 6) was not significantly different from the value in unobstructed patients but was significantly lower (P < 0.01) than in patients for whom endopyelotomy was successful (100+/-24.29 pg/mg of creatinine; N = 28). The renal pelvic urinary TGF-beta1 concentration was higher in patients for whom endopyelotomy was successful (772+/-490.1 pg/mg of creatinine) than in patients who underwent endopyelotomy and later returned because of UPJ obstruction (126.1+/-41.9 pg/mg of creatinine).

CONCLUSIONS

These data suggest that preoperative concentration of TGF-beta1 in the bladder urine of patients with UPJ obstruction who fail endopyelotomy is not significantly different from that in subjects with no urologic disease and significantly lower than in those patients for whom endopyelotomy is successful. Thus, the preoperative bladder urine concentration of TGF-beta1 may assist in selecting patients for this operation, although further investigation is necessary.

Failed endopyelotomy: low expression of TGF beta regardless of the presence or absence of crossing vessels

BACKGROUND AND OBJECTIVE

Endopyelotomy relies on Davis' intubated ureterotomy principle of healing by secondary intention and smooth-muscle regeneration. Approximately 15% of endopyelotomies fail, and the restrictured segment almost always shows evidence of reactive fibrosis with little smooth-muscle regeneration. Previous data suggests that an elevation of TGF beta in obstructed ureteropelvic junctures may be necessary for successful tissue repair following endopyelotomy. The role of crossing vessels in endopyelotomy failure is very controversial. To better understand the pathophysiology of endopyelotomy failure, the expression of transforming growth factor-beta (TBG beta) in patients with a failed endopyelotomy and crossing vessels was compared with that in patients without crossing vessels, as well as those having primary pyeloplasty or a normal ureteropelvic junction (UPJ).

MATERIALS AND METHODS

The expression of TGF beta was detected immunohistochemically in slide-mounted thin sections (4 microns) cut from paraffin-blocked adult UPJ segments obtained during primary pyeloplasty (N = 11), secondary pyeloplasty after failed endopyelotomy with documented crossing vessels (N = 10), secondary pyeloplasty after failed endopyelotomy without crossing vessels (N = 11), and normal UPJs removed during nephrectomy for purposes unrelated to obstruction (N = 11). Expression was graded on a scale of 0 to 4.

RESULTS

The combined failed endopyelotomy group had a significantly (P < 0.05) lower level of TGF beta (1.9 +/- 0.7) than did primary obstructed UPJs (2.6 +/- 0.7). The TGF beta level in the crossing vessels group (1.9 +/- 0.7) did not differ from that in the group without crossing vessels (1.8 +/- 0.7), nor did it differ from that in the group with normal UPJs (1.6 +/- 0.7). As expected, primary obstructed UPJs had a significantly higher level of TGF beta than normal ones (P < 0.02).

CONCLUSIONS

Obstructed UPJs that had failed endopyelotomy had a similarly reduced level of TGF beta whether or not crossing vessels were present. These data suggest that an elevation of TGF beta in obstructed UPJs may be necessary for successful tissue repair after endopyelotomy and that the presence of crossing vessels is probably not relevant.