Enterocystoplasty and reflux nephropathy in the canine model

Animal models in urinary diversion

We set out to critically assess the value of animal experimentation in urinary diversion through intestinal segments, as some authors question the effectiveness of animal research, criticising the methodological quality, lack of standardization, inadequate reporting and the few systematic reviews in this field. Based on a comprehensive MEDLINE literature search (MeSH database; search terms: urinary diversion, urinary reservoirs, continent, rat, dog, animal models) we retrieved and evaluated all full-length papers published in English, German, French, and Spanish languages from 1966 to 2011 reporting the use of animal models in the setting of urinary diversion. Studies were stratified according to the addressed research question. Within each category species, gender, number of animals, age at procedure, type of diversion, mortality, length of follow-up, experimental procedure and outcome were recorded and tabulated. In all, 159 articles were judged to be relevant and while there are numerous animal models only a few have been used in more than one study. Animals were used for the systematic study of new surgical techniques (93 articles) or metabolic and functional consequences of urinary reconstruction (66 articles). For the latter purpose, the most often used animal is the rat, whereas the dog model is preferred for technical experimentation. In many studies, the validity of the model is at least questionable. Animal experiments have repeatedly been conducted addressing the same question, often with striking discrepancies in outcome. Animal studies were even performed after a surgical technique had been pioneered in humans. The use of animal models in urinary diversion is far from standardized rendering the results less than ideal for comparison across studies. Due to differences in anatomy and physiology, the applicability of findings in animal experiments to clinical urology is limited. Continued effort is needed to optimise the use of animal models in experimental urology.

Does reflux in orthotopic diversion matter? A randomized prospective comparison of the Studer and T-pouch ileal neobladders

PURPOSE

Orthotopic neobladder reconstruction has become a standard form of urinary diversion in many centers for patients undergoing radical cystectomy for bladder cancer. There is still controversy about the best technique for construction of the neobladder, and especially whether it is necessary to include an antireflux mechanism.

METHODS

We designed a prospective randomized clinical trial comparing two forms of ileal neobladder: the Studer pouch and the T-pouch. The latter includes an extraserosal tunneled afferent limb which prevents reflux from the pouch to the kidneys. The primary endpoint of the study is renal function and anatomy at 3 years following surgery, with secondary endpoints including early and late postoperative complications, renal infections and need for secondary procedures.

RESULTS

To date we have randomized 462 patients over approximately 6 years, with a planned full enrollment of 550 patients. Ten percent of patients have been withdrawn because they did not undergo the planned orthotopic diversion due to a positive urethral margin on frozen section. We expect approximately 70% of patients to be alive and available for follow-up at 3 years, which will give us ample power to detect clinically meaningful differences in the outcome of these two diversions.

CONCLUSION

This trial has been feasible and randomization has been acceptable to most patients. Long-term follow-up of the patients on this trial should be able to definitively answer the question of the importance of an antireflux mechanism in the orthotopic neobladders construction.

A randomized study comparing an antireflux system with a direct ureteric anastomosis in patients with orthotopic ileal neobladders

OBJECTIVE

To assess the benefit of an antireflux system in patients with orthotopic ileal neobladders, as there is controversy about whether reflux prevention offers any advantages.

PATIENTS AND METHODS

We conducted a randomized prospective study between January 2002 and March 2004, on 60 patients (53 men and seven women) with a mean (sd) age of 52.7 (7.3) years, who were candidates for orthotopic neobladders. Patients with comorbidities were excluded. Preoperative evaluation included intravenous urography (IVU), cystoscopic biopsy and radioisotope renography to evaluate the differential glomerular filtration rates (GFRs). Cases with normal kidneys and ureters, and with similar GFRs, were enrolled. Surgery comprised a standard radical cystectomy with pelvic lymphadenectomy. The ureters were randomized to either a direct anastomosis into a 5-cm ileal chimney on one side, or to be implanted using the antireflux serous-lined extramural tunnel on the contralateral side in the same patient. Regular follow-up included IVU and renography every 6 months in cancer-free patients.

RESULTS

The mean (sd) follow-up was 23 (9.6) months. There was prolonged urinary leak from a refluxing ureter in one patient that was treated with a temporary percutaneous nephrostomy. Symptomatic pelvic collections required tube drainage in six cases. Six ureters developed early anastomotic strictures (one direct and five antirefluxing), and were treated with endoscopic ureterotomy in three and open revision in three. Serum creatinine levels were normal in all patients throughout the observation period. GFRs were similar in the two groups. The mean GFRs before surgery and at 6, 12, 18, and 24 months after cystectomy were: 55.1, 50.7, 49.4, 52.2 and 53.9 mL/min for the direct side; and 56.1, 53, 52.4, 53.2 and 50.4 mL/min for renal units with antirefluxing implantation. There was a significant deterioration of the GFRs due to anastomotic strictures, from 48.6 (6.7) mL/min before surgery to 31.8 (15.9) mL/min after the revision (P = 0.01).

CONCLUSIONS

The antireflux procedures were associated with a higher incidence of anastomotic strictures than the direct methods and there was a significant deterioration of renal function after obstruction. The long-term follow-up data are awaited.

Techniques for uretero-intestinal reimplantation

PURPOSE OF REVIEW

Uretero-intestinal reimplantation is a crucial component of urinary diversion. Several techniques for refluxing and nonrefluxing uretero-intestinal reimplantation have been established and modified to minimize anastomotic complications and preserve renal function. We review current experience with uretero-intestinal reimplantation in different types of urinary diversion.

RECENT FINDINGS

The basic principles of uretero-intestinal reimplantation are still controversially discussed. Several studies have focused on complications of urinary reflux from direct end-to-side or end-to-end anastomosis, such as pyelonephritis and calculus formation. Strictures at the anastomotic site of nonrefluxing tunneled ureteral reimplantation resulting in hydronephrosis and renal deterioration have led some to question the need for an antirefluxive anastomosis, at least in "low pressure urinary diversion". Alternative surgical procedures aim to avoid reflux and minimize the risk for anastomotic strictures by direct ureteral reimplantation into an intact isoperistaltic afferent ileal segment or the prevalvular ileum, with the ileocaecal valve functioning as an antireflux mechanism.

SUMMARY

A "gold standard" for uretero-intestinal anastomosis in urinary diversion does not yet exist. Further prospective randomized studies are required to identify the best anastomotic techniques for different types of urinary diversion.

Renal function in the setting of urinary diversion

Incorporating bowel into the urinary tract sets the stage for a potentially dangerous situation for the upper part of this tract. Obstruction, reflux and chronic bacteriuria may develop, all of which can all be detrimental. Most reports on renal function have used IVP and serum creatinine only, methods which are inadequate for proper assessment. Long-term follow-up of patients with ileal conduit diversion reveals a high incidence of morphological and/or functional damage to the kidneys. Refluxing techniques for implanting the ureters have usually been employed. In patients with continent cutaneous diversion or orthotopic bladder substitution, some recent publications have shown rather well preserved glomerular filtration rates. Traditionally, antirefluxing ureteric implantation has been used in these patients. There is presently a trend towards refluxing anastomosis in this setting, providing a low pressure pouch has been constructed. However, pressure can be high in such pouches and bacteriuria is common. The consequences for the fate of the upper urinary tract is unknown and caution should be exercised in recommending such techniques. There is clearly a need for prospective randomized controlled studies on the issue of refluxing versus antirefluxing anastomosis in continent urinary reconstruction. Patients with continent or non-continent diversion should have lifelong follow-up with regard to the upper urinary tract.

Bladder, bowel and bugs--bacteriuria in patients with intestinal urinary diversion

The incorporation of intestinal segments into the urinary tract favors bacterial growth of the skin flora, anaerobic bacteria, and uropathogenic strains. The route of infection is ascending; bacteria enter the urethra or the abdominal stoma, which is followed by colonization of the reconstructed lower urinary tract. Bacteriuria is common in all kind of reconstructions; however, urine from neobladder patients with complete emptying is reported to carry bacteria to a lesser extent. Clean intermittent catheterization and residual urine seem to increase the bacterial burden. Patients with augmentation cystoplasties constitute a distinct subgroup in which the remaining part of the bladder tissue is an important determinant of urinary tract susceptibility to infection. The increased rate of bacteriuria in the reconstructed patients indicates a lack of "antibacterial defenses", and the symptom free state of the patients suggests that only a restricted host response is triggered. The role of the specific and inflammatory antibacterial defenses in the reconstructed lower urinary tract remains largely unknown.

Reflux, stricture and glomerular filtration rate after two antireflux techniques in continent urinary reconstruction using the right colon

In the present study the incidence of reflux, stricture formation and changes in glomerular filtration rate in patients with the submucosal tunnel or the Camey-Le Duc technique of ureteric implantation into the caecum/detubularized right colon used for continent cutaneous diversion/orthotopic bladder substitution was investigated. Reflux was found in two renal units and ureterointestinal stenosis occurred in five renal units after submucosal tunnel ureteric implantation. After Camey-Le Duc ureteric implantation, one renal unit showed reflux and none had stenosis of the ureterointestinal anastomosis during follow-up. Mean glomerular filtration rate (ml/min/1.73 m2) fell from 98 to 85 in the submucosal tunnel group and from 88 to 81 in the Camey-Le Duc group after mean follow-ups of 9 and 5 years, respectively. Both methods of ureteric implantation in this study were effective in preventing reflux, and renal function was well preserved in both groups. The absence of ureterointestinal strictures in the Camey-Le Duc group is encouraging and indicates that this is a reliable method for reflux prevention.

Renal function up to 16 years after conduit (refluxing or anti-reflux anastomosis) or continent urinary diversion. 1. Glomerular filtration rate and patency of uretero-intestinal anastomosis

OBJECTIVE

To evaluate the glomerular filtration rate (GFR) and incidence of anastomotic stenosis in patients with urinary diversion by ileal or colonic conduit (refluxing or anti-reflux uretero-intestinal anastomosis) or with a continent caecal reservoir.

PATIENTS AND METHODS

All conduit urinary diversions performed from 1977 to 1984 were randomized by type (ileal or colonic) and by the method of ureteric implantation (with or without anti-reflux technique). In continent caecal reservoirs anti-reflux implantation was used for both ureters. Total and separate GFR were measured pre-operatively and after a mean follow-up of 123 months (range 36-198) with 51Cr-EDTA and scintillation renography.

RESULTS

Of the 56 evaluable patients, 18 had an ileal and 20 a colonic conduit, and 18 had a continent reservoir. The total mean GFR fell from 88 to 71 mL/min in the ileal group, from 84 to 65 mL/min in the colonic group and from 100 to 85 mL/min in the reservoir group. Separate GFR did not differ significantly between kidneys with and without reflux protection in the patients with a conduit diversion. Strictures occurred in 15 uretero-intestinal anastomoses and were unrelated to the mode of ureteric implantation (in the conduit groups). Renal function improved after ureteric reimplantation in six of seven kidneys, but after balloon dilatation in only one of five.

CONCLUSION

GFR fell moderately in all three groups, with no significant intergroup difference, and the continent caecal reservoir compared favourably with conduit diversion. The fall in separate GFR did not differ significantly between kidneys with and without reflux protection. Surgical exploration of uretero-intestinal stenosis is recommended if renal function is threatened.

Enterocystoplasty in renal transplantation candidates: urodynamic evaluation and outcome

In anticipation of renal transplantation 11 patients with end stage renal disease and small volume, poorly compliant bladders underwent enterocystoplasty. The etiology of bladder dysfunction included myelodysplasia in 4 patients, posterior urethral valves in 4 and vesicoureteral reflux in 3. Mean patient age at the time of bladder augmentation was 16.4 years (range 10 to 28). Detubularized bowel segments were used in all patients and included ileum in 7, ileocecal segment in 3 and sigmoid in 1. Urodynamic evaluation before and after enterocystoplasty demonstrated marked improvement in bladder capacity and compliance. These 11 patients have received 13 renal transplants with an 85% graft survival at a mean followup of 30.1 months. No bladder ruptures or other perioperative complications have occurred. All patients remain continent on clean intermittent catheterization. Our experience suggests that enterocystoplasty is a safe and effective method of restoring lower urinary tract function in the patient with end stage renal disease and a small, noncompliant bladder.