Comparison of intraluminal pressures in ileal and colonic conduits in children

Radical cystectomy and orthotopic bladder substitution using ileum

Over the past decade, continent urinary diversion, especially orthotopic bladder substitutions, has become increasingly popular following radical cystectomy for bladder cancer. The ultimate goal of orthotopic bladder substitution is to offer patients the best quality of life, similar to that of patients with native bladders. To achieve that purpose, surgeons should be familiar with the characteristics of good candidates for neobladders, the possible intraoperative and postoperative problems related to the surgery, and the solutions to these problems. Postoperative surveillance and instructions given to the patients also contribute to successful, functional results. Here, we reviewed the indications, pitfalls, and solutions for orthotopic bladder substitutions and the patients' quality of life after surgery. When performed properly, orthotopic continent diversion offers good quality of life with few long-term complications. Therefore, we believe it is the best option for the majority of patients requiring cystectomy.

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.

Urinary diversion: ileal conduit to neobladder

PURPOSE

The goals of urinary diversion have evolved from simply diverting the urine through a conduit to orthotopic reconstruction, which provides a safe and continent means to store and eliminate urine with efforts to provide an improved quality of life. We address meaningful points that may help optimize clinical results in patients with an orthotopic bladder substitute.

MATERIALS AND METHODS

The review involved an objective evaluation of the basic science literature of functional, structural and physiological characteristics of gastrointestinal tissue as a substitute for bladder. Potential problems that may be associated with particular parts of the gut for use in reconstruction are discussed. We also summarize the clinical results and complications of orthotopic reconstruction.

RESULTS

In the last 10 years the paradigm for choosing urinary diversion has changed substantially: In 2002 all patients undergoing cystectomy were neobladder candidates. It is critically important to understand the phenomenon of maturation. The motor and pharmacological response of the implanted gut changes dramatically toward that of the bladder. Structural and ultrastructural changes in the ileal mucosa lead to a primitive epithelium similar to urothelium. The need for reflux prevention is not the same as in ureterosigmoidostomy conduit or continent diversion. Reflux prevention in neobladders is even less important than in a normal bladder. When using nonrefluxing techniques, the risk of obstruction is at least twice that after direct anastomosis. Kidney function is not impaired by diversion if stenosis is recognized and managed. Patient health status is more influenced by underlying disease than by diversion. Complications of neobladders are actually similar to or lower than the true rates after conduit formation, in contrast to the popular view that conduits are simple and safe. Some degree of nocturnal leakage is a consistent finding in most reports despite a technically sound operation. The precise pathogenesis of urinary retention requiring clean intermittent catheterization remains uncertain. There are new complications, such as neobladder rupture and mucous tamponade.

CONCLUSIONS

Orthotopic reconstruction has passed the test of time. In these patients life is similar to that in individuals with a native lower urinary tract. Until a better solution is devised orthotopic bladder reconstruction remains the best option for patients requiring cystectomy.

Urodynamic investigation of the ileal conduit: upper tract dilatation and the effects of revision of the conduit

Urodynamic studies of the ileal conduit were performed in 36 patients with normal upper urinary tracts (controls) and in 32 who had progressive upper tract dilatation within 6 years preceding the study. In controls the conduit emptied mainly by means of low pressure, to-and-fro activity. In contrast, high frequency, high amplitude peristaltic activity was found commonly in patients with upper tract dilatation, such activity being consistent with obstruction of the distal conduit. Of the 32 patients with upper tract dilatation 17 underwent reoperation on the conduit as well as postoperative urodynamic studies. Among these 17 patients a decrease was observed in basal pressure in the conduit postoperatively compared to preoperatively (5 +/- 4 and 12 +/- 6 cm. water, p less than 0.001). A decrease also was found postoperatively in the frequency (4 +/- 6 and 36 +/- 28 per hour, p less than 0.001) and amplitude (34 +/- 47 and 61 +/- 28 cm. water, p less than 0.001) of peristaltic activity. Radiological improvement in the appearance of the upper urinary tracts was found in 9 patients (53 per cent) postoperatively. These findings support the hypothesis that upper tract dilatation in certain patients with an ileal conduit may be caused by high pressure activity in the presence of free ureteral reflux. Such abnormalities, which are probably the result of obstruction of the distal conduit, may be detected by means of urodynamic evaluation and may be corrected by revision of the conduit.

The role of the ileal conduit in the development of upper tract dilatation

The purpose of this study was to clarify the role of the conduit in the development of upper tract dilatation after ileal conduit urinary diversion. Twenty-seven patients with a normal upper tract were compared with 17 who had developed upper tract dilatation. Patients were studied by means of a technique to measure pressure and flow under "steady-state" conditions. Pressure activity was classified into two types. Type I pressure activity (frequency 6.2 +/- 3/min; amplitude 4.7 +/- 3 cm H2O) resulted in to-and-fro movement of contrast and the escape into the appliance of small volumes of contrast. In controls, most of the output from the conduit occurred during type I activity (73 +/- 14%). Type III/IV pressure activity resulted in vigorous aboral peristalsis and occurred infrequently in controls (frequency 5 +/- 4/h). In patients with upper tract dilatation, in contrast, type III/IV peristaltic activity occurred frequently (frequency 37 +/- 30/h; P less than 0.001: amplitude 72 +/- 34 cm H2O) and was responsible for most of the output (70 +/- 17%; P less than 0.001). The findings support the hypothesis that high pressure activity in the conduit is an important factor in the aetiology of upper tract dilatation, and they are compatible with the presence in such patients of functionally important obstructions of the distal conduit.

Reconstruction of the lower urinary tract: observations on bowel dynamics and the artificial urinary sphincter

In 14 patients the lower urinary tract was reconstructed using bowel and the artificial urinary sphincter. Of these patients 11 underwent augmentation cystoplasty. The ileocecal segment was used in 4, cecum in 4 and ileum in 3. Total reconstruction of the lower urinary tract was done using the sigmoid colon in 2 patients and an ileocecocolonic segment in 1. Significant bowel contractions were seen in all segments of the large bowel, including the ileocecal segment, which resulted in urinary incontinence in 3 patients with the artificial urinary sphincter and reflux in 3. The ileal cup-patch technique consistently produced low bladder pressures with excellent compliance and an adequate volume. Because of the unpredictable bowel contractions observed in the ileocecal, sigmoid and cecal segments we recommend that augmentation cystoplasty be performed using the cup-patch technique. This procedure will ensure the virtual absence of bowel contractions, and is associated with excellent compliance and capacity.

Early observations on 31 adults with non-refluxing colon conduits

A colonic segment with tunneled ureterocolic anastomoses was used for non-refluxing urinary diversion in 31 adults during the last 3 1/2 years. Half of the patients had undergone diversions previously. These pre-existing diversions had been associated with significant urologic complications. The remainder of the patients had a variety of benign and malignant diseases. After the non-refluxing colonic diversion all upper tracts remained stable or improved except in 3 patients in whom 4 ureterocolic anastomoses developed silent stenosis. Of 10 patients who had pre-existing refluxing diversion and episodic acute pyelonephritis 7 had no recurrences. No patient with sterile urine became infected and 18 of 24 patients with persistently infected urine improved. The anatomic versatility of the colon that allows the benefits of a low pressure system and unidirectional urine flow makes the non-refluxing colon conduit an advantageous alternative in adults requiring urinary diversion.

Stomal obstruction of ileal conduits in children: a urodynamic study

In an attempt to diagnose stomal obstruction before radiological evidence is present, urodynamic perfusion studies were done on 40 children with ileal conduit diversion. Residual urine, capacity, resting pressure and mean emptying pressure were recorded after perfusion of the conduit with normal saline at 10 ml. per minute. Emptying pressure appeared to be the most sensitive parameter of obstruction. Residual urine may be normal in early obstruction and may be increased in the presence of normal emptying pressures in atonic conduits.

Pressure studies and dynamics of ileal conduits in children

The pressures generated in the ileal conduits of 20 children and their relation to conduit ureteral reflux are investigated. The resting pressure in the ileal conduits was generally low but peaks of high pressure were observed occasionally. Reflux occurred mostly at low pressure. Whether reflux occurred at any one moment depended on the position of the peristaltic wave in the ureter at that time. There was no consistent relationship between the conduit pressures and deterioration of the upper renal tract.

Ileal conduits in children at the Massachusetts General Hospital from 1955 to 1970

The 45 ileal conduits performed on children at the Massachusetts General Hospital from 1955 to 1963 are reviewed and compared to the 45 ileal conduits performed from 1964 to 1970. Late complications involving the conduits occurred in 60 per cent of the early group and in 51 per cent of the late group. Of the renal units judged normal pyelographically preoperatively in the early group 77 per cent went on to at least some deterioration, while 62 per cent of the late group judged normal later deteriorated. Combining all renal units, 34 per cent remained unchanged, 26 per cent improved and 41 per cent showed some degree of deterioration after ileal conduit urinary diversion. The late complication and renal deterioration rates seem to increase progressively with time. There was no apparent urinary obstruction in 13 per cent of the renal units that deteriorated. Theoretical and experimental considerations indicate the reflux of infected urine as the etiology of the renal deterioration. Because of the late complications and the unacceptably high rate of renal deterioration we no longer perform ileal conduits in children. Instead every effort is made to reconstruct the urinary tract or if urinary diversion is necessary, a colon conduit with non-refluxing ureterocolonic anastomoses is performed.

Pressure measurements in ileal conduits

To study the dynamic properties of ileal conduits and to attempt to diagnose obstruction at an early point in time, that is prior to the development of conduit or upper urinary tract dilatation, a continuously perfused catheter technique was used to measure pressures within the conduit during filling and emptying, and to measure the resistance to flow at the stomal level. The mean values of residual urine, resting pressure, voiding pressure and stomal profile pressure were significantly higher in obstructed than in non-obstructed conduits. However, there was an overlap between values in each parameter, thus necessitating analysis of the entire pressure data in any given case. The data also show that even a small increase in residual urine above normal, 4.0 plus or minus 0.9 cc, may be an indication of early obstruction and that stomal caliber does not necessarily correlate with the degree of obstruction.

Sigmoid conduit urinary diversion

The courses of 11 patients with sigmoid conduit urinary diversion following total pelvic exenteration were reviewed in detail and the results presented. The sigmoid conduit appears to be a safe alternative to the ileal conduit for urinary diversion, and offers in addition the possible advantage of an effective antirefluxing ureterocolic anastomosis.

Urinary diversion: the physiological rationale for non-refluxing colonic conduits

In order to make an accurate comparison between ileal and colonic conduits, and ileal conduit was created from one kidney and a non-refluxing colonic conduit from the other kidney in 16 adult mongrel dogs. Colonic loops do not reflux, have equal resting pressures and rate of emptying when contrasted with ileal conduits, and carry a lower incidence of stomal complications. Colonic conduits respond more favourably to acute occlusion and produce a significantly lower rate of pyelonephritis at 3 months. These factors suggest that colonic conduits offer a definite advantage for long-term urinary diversion.