The process of uretheral repair; a recapitulation of the splinting question

["We're going to place a ureteral stent …" : Development and use of the terms stent and splint by German-speaking urologists]

The use of eponyms has a long history in medicine. But it is a rare case that a term not associated with a procedure or an anatomical description has come into use. The terms "stent" and "splint" in German and English used as a verb and a noun are a typical example. The coronary stent was named after Charles Thomas Stent (1807-1885). Charles Theodore Dotter (1920-1985) was the one who introduced the eponym into the literature of angiography in 1983. The change in urology occurred after an article of Willard Goodwin especially in the English literature but did not come into constant use in the German language.

Morphologic changes in the canine urinary tract after ureteral reconstruction with the tunica albuginea (experimental study)

OBJECTIVES

The problem of ureteral reconstruction has not been fully solved, despite dramatic developments in surgical methods. Many attempts to repair a ureteral damage with autologous or homologous organ grafts, or with organic substitutes have not really been satisfactory. Also, attempts to use alloplastic and heteroplastic prostheses made of synthetic materials have been equally disappointing. Experimental studies, particularly in dogs, indicate great regenerative abilities of ureters when appropriate surgical techniques are used.

MATERIALS AND METHODS

In our experimental study, suitability of the tunica albuginea for reconstruction of the middle part of the ureter was investigated in 20 dogs. The dogs were divided into two groups according to a type of ureteral damage: partial (a patch graft) or complete (a tube graft). The ureteral damage was 2-3 cm long in 10 dogs and 3-3.5 cm long in the subsequent 10 dogs. Each dog underwent two operations. The first operation involved a fenestrating incision in the ureter, 23.5 cm long, so as to preserve the ureteral continuity, and then the produced injury was repaired with a patch of the tunica albuginea, with the 4 Charr catheter being inserted in the ureter. The second operation involved a complete excision of ureteral segments, 2-3.5 cm long, on the contralateral side. The excised length of the ureter was substituted with a tube graft of the tunica albuginea, also using the 4 Charr catheter. Thus, in 21 cases, a partial damage of the ureteral wall was repaired with a patch graft of the tunica albuginea. In 19 cases, a complete damage of the ureter was repaired with a tube graft of the tunica albuginea.

RESULTS

Four dogs died after the tube-graft implantation due to urinary infiltration and/or purulent inflammatory changes in the kidneys. Autopsies were performed in all the dogs after they had been put to sleep. Definitely poor results were obtained in case of the complete reconstruction of the ureteral loss with a tube graft of the tunica albuginea, 3-3.5 cm long. Within the graft area, we observed inflammatory infiltrates of varied intensity, fibrosis, cicatricial strictures or ureteral obstruction. Occasionally, necrotic foci, degenerative changes or hydronephrosis were found. In case of the reconstruction with a shorter tube graft, i.e. 2-3 cm long, similar changes were observed, however, they were less intense. Satisfactory results were obtained following the partial reconstruction of the ureteral loss with a patch graft of the tunica albuginea. In this case, we observed generally normal regeneration not only of the transitional epithelium but the muscular layer and ureteral structure as well, with full patency of the ureter preserved. The findings obtained in our study are compatible with the findings of other authors.

CONCLUSIONS

(1) The success of reconstructive procedures in the ureters can be achieved if the continuity of the ureter is preserved and the catheter is removed after 14 days. (2) The substitution of a complete ureteral loss with a tube-graft of the tunica albuginea results in necrosis of the graft and restenosis.

Anatomic and physiologic considerations in ureteroscopy

The successful and safe implementation of ureteroscopic techniques depends on considerations of anatomy and physiology. Combining knowledge of the drainage system of the kidney with its vascular supply, predictive patterns of incisions can be applied within the collecting system to safely avoid vascular injury. In addition, awareness of the variation in normal and pathologic anatomy and physiology is key to effective interventions. An appreciation of the impact of ureteroscopy on normal anatomy and physiology can prevent complications and promote improved therapeutic outcomes.

Role of acellular collagen matrix surgisis in the endoscopic management of ureteropelvic junction obstruction

PURPOSE

To investigate the role of acellular collagen matrix (Surgisis during endopyelotomy.

MATERIALS AND METHODS

Nine female pigs (25-35 kg) were enrolled in our protocol. The pigs were categorized as follows. Group I (N = 3) had endopyelotomy + insertion of SIS, Group II (N = 3) creation of UPJ stricture + endopyelotomy + insertion of SIS, and Group III (N = 3) Davis intubated ureterotomy using SIS. The contralateral side served as a control for each group (one pig in each group). In three pigs (two in Group III and one in Group II), Surgisis was treated with India ink prior to insertion at the endopyelotomy site. An endopyelotomy stent (14/8 F x 24 cm) was used to stent the ureteropelvic junction (UPJ) for 4 weeks. Four weeks after the stent was removed, laparoscopic nephroureterectomy was performed, and the animals were euthanized. Histopathologic analysis of the Surgisis-regenerated segment of the UPJ was performed using hematoxylin and eosin, reticular (collagen), smooth muscle actin, and S-100 (nerve) stains.

RESULTS

All animals tolerated the procedure. The mean operative time was 162 minutes. One pig (Group II) developed pyonephrosis; one pig (Group III) developed significant ascites and was sacrificed 2 week before the end of the experiment. Histopathologic analysis showed complete epithelializaton at 8 weeks. Reticular stain demonstrated abundant collagen matrix in the submucosa. Smooth muscle staining revealed myofibroblastic proliferation within the SIS-regenerated tissue adjacent to disorganized smooth muscle cells. India ink-stained SIS-regenerated tissue did not show smooth muscle cells. The S-100 stain did not demonstrate neurons at 8 weeks; however, in three pigs, peristaltic activity was noted across the UPJ.

CONCLUSION

The use of acellular collagen matrix in the endoscopic management of UPJ obstruction is a promising technique. The abundance of myofibroblasts and absence of abundant smooth muscle regeneration indicates a need to investigate the role of growth factors in SIS regeneration of host tissue.

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.

Endopyelotomy failure is associated with reduced transforming growth factor-beta

PURPOSE

Approximately 15% of patients with ureteropelvic junction obstruction have endopyelotomy failure and require an additional surgical procedure to remove the obstruction. Transforming growth factor-beta (TGF-beta), a cytokine which stimulates mesenchymal cell proliferation and extracellular matrix deposition, increases in the renal pelvis in response to obstruction. However, TGF-beta also is implicated in smooth muscle regeneration and wound healing. To understand the pathophysiology of ureteropelvic junction obstruction and determine why endopyelotomy fails in some obstructed ureteropelvic junctions, TGF-beta expression in obstructed and normal ureteropelvic junction segments was compared.

MATERIALS AND METHODS

Immunohistochemical staining using a rabbit polyclonal anti-TGF-beta was performed on deparafinfized 4 microm. sections of paraffin blocked ureteropelvic junction segments. Human obstructed ureteropelvic junction segments were removed during primary pyeloplasties (11) and secondary pyeloplasties after endopyelotomy failure (11). Normal ureteropelvic junction segments were removed during nephrectomy for purposes unrelated to obstruction (11). Grading on a scale of 0 to 4 was performed by a physician blinded to the source of the specimen.

RESULTS

Mean TGF-beta expression plus or minus standard error of the mean was significantly increased (p <0.02) in obstructed ureteropelvic junctions from primary pyeloplasties (2.6+/-0.7) compared to normal ureteropelvic junctions (1.6+/-0.7), as expected. However, TGF-beta expression in the endopyelotomy failure group (1.8+/-0.6) was not significantly different from that in normal ureteropelvic junctions and was significantly lower (p <0.05) than that in obstructed ureteropelvic junctions from primary pyeloplasties.

CONCLUSIONS

Obstructed ureteropelvic junctions in cases of endopyelotomy failure have decreased expression of TGF-beta compared with other obstructed ureteropelvic junctions. These data suggest that an elevation of TGF-beta in obstructed ureteropelvic junctions may be necessary for successful tissue repair after endopyelotomy.

Physiology and evaluation of ureteropelvic junction obstruction

Ureteropelvic junction (UPJ) obstruction is not a single anatomic entity but rather a set of processes with multiple causes. In the obstructed system, histologic changes are apparent that have implications for healing. The role of crossing vessels In UPJ obstruction and its treatment is of growing interest. Various methods are available to assess the functional characteristics of the UPJ, of which the diuretic renogram, Whitaker perfusion test, and Doppler ultrasound resistive index may be the most useful. The treatment must be individualized according to the patient's symptoms, the status of renal function, and the potential complications of intervention.

Ureteric stricture formation following ureteric instrumentation in patients with a nephrostomy drain in place

OBJECTIVE

To determine what effect the presence of a nephrostomy, left on free drainage, might have on the rate of occurrence of ureteric strictures after ureteric instrumentation.

PATIENTS AND METHODS

Eighteen patients were identified in this unit who had had ureteric instrumentation while a nephrostomy was in place.

RESULTS

Eight of 11 patients in whom the nephrostomy was left open developed ureteric strictures. None of seven patients in whom the lumen was maintained by stenting and/or clamping of the nephrostomy developed strictures. The strictures needed dilatation and stenting in seven patients and the ureter had to be reimplanted in the other.

CONCLUSION

In patients in whom a nephrostomy is in place, the opening should be occluded after ureteric instrumentation or a stent should be inserted if it is to be left on free drainage.

Endopyelotomy: patient selection, results, and complications

The popularity of minimally invasive surgical techniques, such as endopyelotomy, has increased markedly among urologists in recent years. While it was initially thought that this procedure was best utilized in patients with secondary UPJ obstruction, recent evidence suggests that endopyelotomy should be considered in the majority of cases. The primary contraindication to endoscopic incision of the UPJ is a long stricture, although a large redundant renal pelvis and the presence of crossing lower pole vessels are considered by some to be relative contraindications as well. Although the majority of surgeons have used a percutaneous, antegrade approach to endopyelotomy, successful results also have been reported with a ureteroscopic, retrograde technique. With the development of modified ureterotomes and balloon-cutting devices, the retrograde approach eventually may become the preferred method since no skin incision or external drainage are needed. The role of endopyelotomy in children remains undefined. While successful results have been reported in infants, the relative morbidity and long-term success of open pyeloplasty in this age group are excellent, thus limiting the relative advantage of an endoscopic approach. However, there may be a role for endopyelotomy in older children and in those patients with secondary obstruction who have failed open surgery. From a technical standpoint, there are several minor variations in surgical technique and postoperative management that are important. The success rate of endopyelotomy using a cold knife or small electrocautery probe appears to be comparable, and the use of cautery may allow for precise control of minor bleeding thus decreasing the risk of complications. However, larger electrodes may induce greater tissue reaction leading to fibrosis and should be avoided. Postoperatively, most authors prefer a tapered double-pigtail stent which allows for adequate internal drainage while avoiding excessive pressure within the distal ureter. While successful results have been reported with stenting intervals of only four days, it is generally recommended that the stent be left in place for a minimum of six weeks following endoscopic incision of the UPJ. Overall, endopyelotomy is associated with shortened hospitalization, more rapid return to normal activity levels, and decreased morbidity compared with open pyeloplasty. The success rates reported with endopyelotomy approach those achieved with open surgery, and it is likely that an endoscopic approach to UPJ obstruction will assume an increasingly greater role in the future.

Long-term effects of ureteric stent after ureteric dilation

Balloon dilation of the right ureterovesical junction (UVJ) and distal ureter to three times its normal caliber was performed in 12 pigs. A right double-J (D-J) stent was inserted after dilation in 6 pigs. Bilateral upper tract dynamics with different perfusion rates (0.5, 2 and 4 ml. per minute) were recorded before dilation, immediately after dilation, and then 4 and 7 weeks after dilation. Immediate and late antegrade nephrostograms as well as suprapubic cystograms were taken. Grade 3 reflux occurred in 100% of animals at 7 weeks on the dilated, stented ureter and no reflux on the dilated, nonstented ureter. At 7 weeks on the dilated, stented side, significant growth (> 100,000, colonies) of Pseudomonas species was noted in all animals. Creatinine clearance was significantly reduced on the dilated, stented side when compared to the dilated, nonstented side at 7 weeks. Histologic examination of the dilated, stented and dilated, nonstented ureters at 4 weeks revealed a segmental muscular defect with muscular regeneration starting from the edge of the defect, particularly in the innermost region. At 7 weeks, there was a more advanced, but similar, pattern of muscular regeneration in both groups. However, at 7 weeks, metaplastic changes of the ureter and chronic pyelonephritis were evident on the dilated, stented ureter. Electron microscopy showed that myofibroblasts played a major role in the healing process with new muscle formation. At 4 weeks, no significant morphologic difference was found between the dilated, stented and dilated, nonstented ureters. At 7 weeks, however, it appeared that the ureteric stent resulted in damage and deterioration of renal function without affecting muscular regeneration of the ureter. We conclude that the changes observed could be entirely due to the infection associated with the stent rather the stent itself.

Effect of stent duration on ureteral healing following endoureterotomy in an animal model

Ureteral strictures were created in 18 minipigs. Six weeks after stricture inducement, endourologic incision with a balloon cutting device was performed and a 7 F internal polyurethane stent was placed. After this step, 14 pigs remained in the study and were randomized into three different groups depending upon the time when the stent was removed: 1, 3 or 6 weeks. Twelve weeks after stricture incision, the pigs were killed, the status of the incised ureteral segment was evaluated histologically, and a healing score was determined. There were no statistically significant overall differences among the mean values of the overall healing score throughout the three different groups. However, when the one-week and the six-week groups (p < .05) were compared with respect to strictures requiring more than one incision due to stricture length greater than 2 centimeters, a more favorable outcome occurred in the 1 week group. Based on these findings it may be reasonable to remove ureteral stents as early as 1 week after endoureterotomy and endopyelotomy.

Histology of ureter after unsuccessful endoscopic intubated incision

Endoscopic intubated ureterotomy is used increasingly for treatment of ureteral stricture. In 3 patients with recurrent stricture after this procedure the area of ureterotomy was excised after 69, 78 and 83 days, and cut in cross section to examine the scar for muscle regeneration. A segmental scar was found consisting of collagen-rich connective tissue with few fibroblasts. Scarce smooth muscle fibers were dispersed within the scar, mostly at the edge of incision but without a regular structure.

Ureteronephroscopic endopyelotomy

The percutaneous nephrostomy tract has provided urologists with antegrade access to the upper urinary tract. Via this approach ureteropelvic junction obstruction has been treated with an endoscopically controlled incision with a cold knife. While less invasive than an open operation, we have noted significant discomfort from the 24 to 32F percutaneous tract. Accordingly, we sought to achieve the same results by using a less invasive approach, that is retrograde ureteronephroscopic endopyelotomy. A total of 10 patients (9 women and 1 man) with 5 primary and 5 secondary ureteropelvic junction obstructions underwent ureteroscopic endopyelotomy with a 3 or 5F Greenwald cutting electrode passed through a 12F rigid, 10.8F flexible or 9.8F flexible deflectable ureteronephroscope. Preoperatively, ureteropelvic junction obstruction was documented by a furosemide washout renal scan and/or a Whitaker test in 8 of 10 patients. In 2 patients an excretory urogram or retrograde pyelography was diagnostic. Duration of the procedure averaged 180 minutes (245 minutes with a concurrent Whitaker test). At the conclusion of the procedure a 7/14F indwelling ureteral stent was placed. The nephrostomy tube was removed after 3 days and average hospital stay was 5 days. The ureteral stents were routinely left in place for 6 weeks. Followup in 10 patients averaged 12 months. Flank pain was largely resolved in all patients. A followup Whitaker test, excretory urogram or renal scan ultimately has demonstrated decreased or no obstruction in 9 of 10 patients. In summary, early results with retrograde ureteronephroscopic endopyelotomy, specifically in female patients, appear to be promising. Morbidity is minimal and efficacy is satisfactory given the favorable objective response noted in 90% of the patients.

The incidence of post-operative urinary tract infection in patients with ureteric stents

Despite the many advantages provided by the ureteric stent, it produces a foreign body reaction and increases the risk of infection. We undertook a study on the rate of infection in a group of paediatric patients with ureteric stents; 40 ureteric stents, 6 to 9 F, were used in 36 children undergoing the following procedures: 18 pyeloplasties, 20 antireflux ureteric reimplantation and 2 uretero-rectal anastomoses. Only patients with sterile urine pre-operatively were included in the study. All received antibiotic cover in the post-operative period. Positive urine cultures were found in only 3 patients (7.5%). In spite of this low incidence, the urine specimens collected from all children 1 month after removal of the stent showed a much higher incidence of infection. It was concluded that ureteric stenting is a safe procedure with a low rate of infection provided that antibiotic cover is given.

Percutaneous pyeloplasty

The indication for and the technique of the percutaneous operation on strictures at the ureteropelvic junction are reported on 120 patients. The results of evaluation of 66 followed-up cases are presented. The new method proves to be superior to open surgery in secondary (acquired) stenoses with a success rate of 89 per cent, whereas in congenital stenosis the success rate was 75 per cent. However, if this simple and safe technique does fail, open plastic surgery still can be performed.

Functional and histological restitution in the urinary tract after Nd:YAG laser coagulation

Current development in endourologic equipment has made possible the endoscopic application of the Nd:YAG laser in the treatment of urothelial tumors of the whole urinary tract. The clinical results are rather promising. We controlled with various methods the healing processes of 14 rabbit ureters after Nd:YAG laser treatment as to morphological repair and physiological function. The ureters were irradiated transrenally with an energy of 60 J coagulating all wall layers. Healing of the laser lesions nearly to normal in all animals was observed 4 to 6 weeks after treatment. The prevailing histological and physiological changes in the ureter are extremely slight and do not disturb the normal ureteral function. The results show the complete healing process of the ureter after laser coagulation and make the application of Nd:YAG laser in the upper urinary tract much more predictable.

Complications following ureteroscopy

We report 4 cases of ureteral injury and stricture formation following ureteroscopic stone manipulation. Possible etiologies of stricture formation and our methods of managing them are discussed. The complications of ureteroscopy have been reported only rarely and the ureteroscopist should be aware that the procedure is not always benign.

Ureteroscopic pyelolysis for pelviureteric junction obstruction

The development of endourological techniques for the treatment of upper urinary tract disease has concentrated mainly on the endoscopic treatment of upper urinary tract stones. The relief of pelviureteric junction obstruction (PUJ) by percutaneous pyelolysis has recently been reported and the use of the flexible uretero-pyeloscope has also been described. We describe the use of a rigid uretero-renoscopy to relieve strictures causing secondary pelviureteric junction obstruction in two cases.

Percutaneous pyelolysis: indications, complications and results

The results of percutaneous pyelolysis in 28 patients are presented. There were 18 successful and 10 unsuccessful cases. The indications for the procedure are defined in the light of this analysis.

The diagnosis and management of spontaneous rupture of the ureter

Spontaneous rupture of the ureter is rare. It usually is associated with calculous disease and most often occurs in the upper ureter. The surgical management includes drainage of the urinoma and proximal nephrostomy drainage with urinary reconstruction if necessary. Even with good surgical management secondary nephrectomy sometimes is required. The clinical course of 2 patients is described and the literature is summarized.

Ureteral strictures following ureterolithotomy

Ureteral strictures occurring after ureterolithotomy may not be recognized until obstruction or recurrent stone impaction occurs in the area. We describe our treatment of this problem in 9 patients. Management varied from conservative treatment in patients having no discernible renal function on the affected side to various forms of reconstruction or reimplantation, depending upon the situation and site of the stricture. All patients were followed for a minimum of 2 years without complications. The etiopathogenesis and other methods of treatment available for this problem are discussed.

Management of simple ureterolithotomy closure

Two methods of ureterotomy closure, loose adventitial closure and an unsutured incision, were evaluated and compared in 89 cases of simple ureterolithotomy. The loose adventitial closure was associated with a significantly shorter period of postoperative urinary drainage and a lower incidence of ureteral narrowing found at follow-up urographic examination.