Urinary diversion following cystectomy remains one of the great challenges of radical pelvic surgery because an equivalent replacement for the native bladder has yet to be developed. The bladder is ideally a low-pressure, highly compliant reservoir for the storage of urine with its own intrinsic continence mechanism, sensation, and coordinated, volitional emptying by muscular contraction. In addition, the bladder is generally impermeable, stores sterile urine, and possesses antirefluxing ureters to protect the kidneys and upper tracts from sustained increases in bladder pressure. Recapitulating many of the intrinsic properties of the native bladder and understanding the impact of the choice of bowel segments are paramount to successfully reconstructing the urinary tract. Urinary diversions are broadly divided into 2 main categories: continent and incontinent diversions. In this chapter, we will review the principles, surgical technique, perioperative management, and long-term issues associated with continent cutaneous reservoirs. The other major type of continent diversion, orthotopic urinary diversion is described in Chapter 13.

A continent catheterizable diversion was first described by Gilchrest et al¹ in 1950, but it was not until more than 30 years later when continent cutaneous diversions were routinely performed. Although many different techniques have been described, all are based upon 2 underlying principles: a detubularized, spherical bowel reservoir for storage and a continent, catheterizable stoma for emptying. A variety of continent stomas have been described. The terminal ileum can be tailored and used as a catheterizable limb to take advantage of the nonrefluxing ileocecal valve. The appendix or a tailored segment of bowel can be submucosally tunneled to form a stoma utilizing the principles described by Mitrofanoff.² With the Kock or Mainz pouch, a nipple or flap valve is constructed to provide a new continence mechanism. Continent cutaneous reservoirs are an outstanding option for patients in whom an orthotopic urinary diversion is contraindicated.

The Indiana Pouch, a continent cutaneous diversion based upon the terminal ileum and right colon, was first described in 1985 and uses the nonrefluxing ileocecal valve as the continence mechanism. The right hemicolon is detubularized, folded, and is used to fashion a spherical reservoir. The tapered terminal ileum is matured into a stoma either in the right lower quadrant or umbilicus for catheterization of the pouch. Long-term data from multiple institutions have shown this to be a safe and reliable form of urinary diversion, with continence rates that range from 94% to 98%,³ reoperation rates of 15%, and long-term complications, such as pouch calculi, stomal hernia, stomal stenosis, bowel obstruction, and renal insufficiency, in 17%.⁴ Bochner et al⁵ described a modification to the ileocecal reservoir whereby the ureters are anastomosed into the terminal ileum as a ureteral substitution segment and a flap valve is developed with the in situ appendix as the catheterizable stoma. This technique is especially useful in patients who have undergone preoperative radiation therapy where excessive manipulation of the ureters can result in devascularization and a higher rate of ureterointestinal anastomotic strictures. In addition, this modification can be used in patients that require resection of ureter for tumor ­factors. Both techniques will be described in detail.^3,5

Development of a Low-Pressure System

One of the fundamental principles behind any form of continent urinary diversion is the creation of a low-pressure reservoir. Detubularization of the bowel segment and cross-folding into a sphere forms the maximum capacity reservoir for a given bowel segment and limits the ability of the bowel segment to develop a coordinated and synchronous peristalsis.⁶ The spherical configuration maximizes the radius of the reservoir, which according to Laplace law (pressure = tension/radius) will translate into lower filling and storage pressures. Reconfiguration maximizes capacity, therefore, the overall length of bowel required is more limited and this minimizes the surface area available for reabsorption which may reduce metabolic complications. Overall, the spherical reservoir most closely approximates the native bladder by creating a high-capacity, highly compliant reservoir, while minimizing the surface area available for reabsorption of urine and electrolytes during storage. Reconfiguration interferes with the bowel’s ability to coordinate a contraction thereby minimizing high-pressure peaks. This may not only be important in upper tract preservation but facilitates continence as well.

Refluxing vs Antirefluxing Systems

The principle behind constructing nonrefluxing anastomoses is to protect the kidneys and upper tracts from sustained high pressures and to prevent ascending bacteriuria. In its normal state, the ureter creates a dynamic, unidirectional flow of urine from the kidney to the bladder by means of peristalsis with the ureter eventually passing at an oblique angle through the bladder wall to its lumen. The intramural portion of the ureter must be of sufficient length (ureteral length to ureteral diameter ratio of 5:1) to allow for passive compression during bladder filling otherwise vesicoureteral reflux (VUR) can occur.⁷ Numerous investigators have observed a link between vesicoureteral reflux, upper urinary tract infections or pyelonephritis, and renal scarring. Hutch⁸ described increased rates of pyelonephritis in paraplegic patients with VUR, while other investigators noted higher rates of renal scarring and urinary tract infections (UTIs) in children with a history of reflux.⁹

There is significant debate regarding whether the uretero- intestinal anastomoses should be constructed in a nonrefluxing or refluxing manner. This was particularly relevant for patients undergoing ureterosigmoidostomy, which diverts the urine into a high-pressure chronically infected system, but has become less of a concern with the development of lower pressure, high-capacity continent reservoirs. With detubularization of the bowel, peristaltic contractions and pressure transmission to the upper tracts is minimized. Berglund and Kock¹⁰ described the volume and pressure characteristics of various intestinal reservoirs and noted that sustained pressures above 25 to 30 cm of water can lead to renal deterioration. Continent cutaneous reservoirs will typically only have sustained pressures above 25 cm of water for approximately 2 minutes per hour during the day, assuming stored volumes below 500 cc or no more than 60% of reservoir capacity.¹⁰

More recent observations suggest that vesicoureteral reflux is not itself a cause of urinary tract infections. Reflux may deliver colonized urine to the renal pelvis, but it is the sustained stasis of bacteriuria within the upper tracts that is the greater risk factor for pyelonephritis. In children who have reflux and are dysfunctional eliminators, the risk of febrile UTIs or pyelonephritis is significantly higher. Correcting the dysfunctional elimination was one of the most modifiable risk factors for reducing the risk of future infections.¹¹ As a corollary, stasis of colonized urine within the upper tracts, either secondary to an ureterointestinal anastomotic stricture or from poor emptying of the urinary reservoir, may predispose patients with continent diversions to upper tract infections, pyelonephritis, and increase the risk of long-term scarring.

There appears to be a greater risk of gradual renal deterioration from ureterointestinal anastomotic strictures than from reflux of urine into the upper tracts. Nonrefluxing anastomoses are associated with twice the rate of strictures than refluxing anastomoses, irrespective of the type of bowel segment used. Rates of ureterointestinal strictures with a refluxing anastomotic repair range from 1.7% to 3.6% compared with the 13% to 29% described with the LeDuc nonrefluxing anastomosis technique.¹² Approximately one-half of patients with strictures will require surgical intervention, leading some surgeons to conclude that the greater risk to the upper tracts is ureterointestinal anastomotic stricture rather than reflux. In a group of 126 patients followed for more than 25 years with Kock reservoirs, Jonnson et al¹³ concluded that the type of diversion does not significantly impact long-term kidney function as long as any potential strictures are recognized and treated. Refluxing anastomoses are technically simpler to complete and have not been associated with significant rates of upper tract deterioration, thus making them the procedure of choice for ureterointestinal anastomoses.^{3,14,15,16,17}

Development of Continence Mechanism

There are 4 basic continence mechanisms that may be ­utilized in the construction of a continent reservoir. Mitrofanoff described tunneling the appendix beneath the tenia of the adjacent cecum to create a continent, catheterizable limb that is brought to the skin surface. This technique may not be feasible if the caliber and/or length of the appendix are inadequate.² In the Kock pouch, a nipple valve is constructed by intussuscepting a portion of the small bowel into the lumen of the low-­pressure reservoir to serve as the continence mechanism.¹⁸ Due to the complexity of this reconstruction and the relatively high rate of complications with the nipple valve, this technique has not been widely adopted.¹⁹ Expanding upon the flap valve mechanism described by Ghoneim,²⁰ Skinner²¹ adapted the technique to construct a double-T pouch for continent cutaneous diversions which utilizes a serous-lined extramural tunnel instead of intussuscepted small bowel as the flap-valve continence mechanism. The complexity of construction and longer operative times has also limited its widespread adoption. The hydraulic ileal valve, as seen in the Indiana pouch, incorporates the native ileocecal valve, a tapered limb of ileum, and plication sutures at their junction to form the basis of the continence mechanism.³

Selection Criteria for Continent Diversions

When considering the creation of a continent diversion, it is of paramount importance to have a motivated patient with realistic expectations regarding the functional outcomes and limitations of the reconstruction. Patients undergoing continent cutaneous diversions must physically be able to catheterize themselves on a routine basis. Those patients who are less concerned with body image, those who are socially isolated or prone to poor follow-up, and those with advanced age or significant comorbidities may be better served with a noncontinent urinary diversion.²²

Absolute contraindications to continent urinary diversion are impaired renal function and severe hepatic dysfunction due to the metabolic complications associated with reabsorption of urine and electrolytes during periods of storage. There must be adequate renal function to address this reabsorption. Patients with creatinine levels higher than 2.0 mg/dL or glomerular filtration rates lower than 35 mL/minute are not optimal candidates for continent diversion. Reabsorption of urinary components by the ileum and colon may lead to severe systemic electrolyte abnormalities in patients with limited renal function. In addition, free water loss occurs within continent reservoirs, which may lead to dehydration in those patients with impaired renal concentrating ability. Patients with severe hepatic dysfunction are at risk for hyperammonemia due to an impaired ability to process the ammonia absorbed by the reservoir.

Relative contraindications to continent cutaneous diversion are inflammatory bowel disease, an inability or unwillingness to self-catheterize, mental impairment, and prior colon cancer history if the colon is to be used for reconstruction. All patients who undergo continent urinary diversion need to receive detailed preoperative counseling and teaching regarding the planned reconstructive procedure. Patients must be aware that although the goal of reconstruction is to provide an acceptable substitute for the native bladder, there are inherent differences with continent diversions that the patient must be willing to accept long term.

Although any segment of bowel can be utilized to construct a urinary reservoir, factors such as the patient’s renal function, history of prior abdominal surgery or radiation therapy, and the type of reconstruction planned will greatly impact the surgeon’s choice of bowel segment. Each bowel segment has its own relative advantages and disadvantages including metabolic sequelae when used for urinary diversion.

The stomach is the least permeable and is associated with the lowest rates of bacteriuria of all intestinal segments due to the secretion of hydrochloric acid.²³ However, it is associated with a hypochloremic metabolic alkalosis secondary to the loss of protons and chloride in the urine. Those patients with impaired renal function may not be able to excrete sufficient bicarbonate to buffer this metabolic derangement. The secretion of excess acid in the urine may cause hematuria-dysuria syndrome in some patients. Typically, there is not an adequate volume of stomach than can be removed to form a complete urinary diversion; most commonly, the stomach is used in composite diversions or in children where it is utilized as an augment to the bladder. In addition, there are often limitations to the blood supply that limits the usefulness of stomach in pelvic urinary reconstruction.

The jejunum is not typically used for urinary diversion due to the high rates of symptomatic metabolic derangements observed with this bowel segment. Patients experience jejunal-conduit syndrome as a result of increased sodium and chloride excretion combined with potassium and hydrogen reabsorption. Patients develop a hyponatremic, hypochloremic, hyperkalemic metabolic acidosis that is associated with water loss and dehydration. The risk of metabolic derangements increases the more proximal the segment of jejunum used for the diversion. While the jejunum has the theoretical advantage of being less likely to have been within radiation fields administered to the pelvis, the relative disadvantages outweigh this theoretical benefit limiting its utility for diversions.

The ileum and colon are associated with the fewest electrolyte disturbances, have the greatest amount of redundancy, are easily mobilized to any portion of the abdomen or pelvis, and typically possess excellent blood supplies. Both segments are associated with the same metabolic abnormalities due to the absorption of ammonium chloride resulting in a hyperchloremic metabolic acidosis. Patients with impaired renal function are more susceptible to developing severe metabolic abnormalities and can develop lethargy, anorexia, weight loss, and long term are at risk for bone demineralization leading to osteopenia. Symptomatic metabolic acidosis can be treated with alkalinizing agents, maintaining good hydration, and minimizing dwell time of urine stored within the continent diversion. The terminal ileum is responsible for absorption of bile salts, fat-soluble vitamins (K, A, D, and E), and the absorption of vitamin B12. If excessive lengths of ileum are used for diversion, patients can develop steatorrhea, vitamin B12 deficiency, and dehydration. When the ileocecal valve is removed from bowel continuity, there is an increased risk of diarrhea due to the increased fluid load delivered to the colon.

Drugs excreted unchanged in the urine and absorbed by the urinary reservoir can be problematic, especially in those patients receiving adjuvant chemotherapy. Methotrexate toxicity has been described in patients with urinary diversions due to absorption.^24,25 To minimize the reabsorption of excreted drugs and/or metabolites, patients undergoing chemotherapy should have their reservoir or neobladder drained with a Foley catheter during treatment. Those patients taking phenytoin, theophylline, lithium, and certain antibiotics excreted in an active form into the urine should be closely monitored.^26,27,28

A thorough understanding of the patient’s medical and surgical history is necessary when deciding upon the type of diversion planned after complete urinary bladder resection. As discussed, those patients with renal or severe hepatic insufficiency are not candidates for continent diversions. Adjuvant or a remote history of radiation therapy may influence the segment of bowel selected and the type of diversion planned. Patients should be assessed with respect to manual dexterity and be both willing and able to self-catheterize. Preoperative counseling and education by a wound-ostomy nurse is standard practice in our clinic. All patients are marked prior to surgery for the possible stoma site in the case of intraoperative conversion to an incontinent diversion. Preoperative cardiovascular risk assessments are completed and patients undergo outpatient bowel preparation with an oral polyethylene glycol solution particularly if a colon-based reservoir is planned. Preparation for a small bowel-based reservoir does not require formal bowel preparation.

Continent Cutaneous Reservoir ­(Indiana Pouch)

The ascending colon and terminal ileum are isolated from the enteric tract. A 25- to 30-cm length of right colon is needed for the reservoir, and in some patients this may require taking a portion of the proximal transverse colon. A 7- to 10-cm segment of terminal ileum beyond the ileocecal valve is taken with the right colon and used as the catheterizable limb of the pouch (Figure 12-1). A deep division within the mesentery between the terminal superior mesenteric artery and ileocolic arterial branches facilitates mobility to the reservoir segment. Bowel continuity is restored in the standard fashion and the cecum and ascending colon are opened anteriorly along the antimesenteric border between the colonic tenia. Removal of the appendix is not required but advocated by many surgeons.³ The appendix could be removed routinely by the authors if it is not to be used as a catheterizable limb. The terminal ileum is tapered over a 14 French red rubber catheter placed through the ileum into the open pouch. Babcock clamps are placed serially along the antimesenteric border of the ileum to hold the excess ileum to be removed away from the catheter. A straight gastrointestinal anastomosis (GIA) stapler is placed in the groove between the red rubber catheter and the Babcock clamps and the excess ileum is removed with the stapling device. Stapling is stopped just prior to reaching the ileocecal valve to avoid damage to the continence mechanism (Figure 12-2). Interrupted Lembert sutures are used to plicate the funnel-shaped terminal ileum at the ileocecal valve to bolster and support the continence mechanism. Classically, 3 to 4 Lembert sutures are required and placed along the cecum to tighten the ileocecal junction; however, additional sutures may be used to buttress the mechanism. The sutures are placed closest to the ileocecal valve initially and ­subsequent sutures moving away from the ileocecal valve should be placed wider than the previous to narrow the ileocecal junction (Figure 12-3). This portion of the reconstruction is done with the pouch open to allow for visualization of the internal aspect of the ileocecal junction and to allow for direct inspection of the catheter moving in and out of the pouch.