Given its limited surface area, the use of stomach in urinary tract reconstruction is mostly limited to composite reservoirs (18). However, there are several advantages to utilizing the stomach over other bowel segments. Its lining is the least permeable to urinary solutes, and the secretion of hydrogen chloride produces an acidified urine that helps to reduce bacteriuria (19). The resultant metabolic alkalosis appears to benefit patients with preexisting metabolic acidosis and renal insufficiency. However, acidified urine may itself lead to complications, including the hematuria-dysuria syndrome.

The jejunum has unique absorptive characteristics compared to other segments of small bowel. It lacks the chloride-bicarbonate exchanger present in the ileum, and its relatively permeable membrane allows for rapid efflux of water, sodium, and chloride into the lumen according to their osmotic gradients. Absorption of potassium and urea from urine, coupled with loss of sodium chloride due to its impermeability across jejunal mucosa, can result in a hypochloremic, hyperkalemic metabolic acidosis that can be life-threatening. Of note, the use of jejunum in urinary tract reconstruction is rarely associated with nutrient malabsorption (8).

The ileum and colon are the most commonly employed intestinal segments in urinary diversion. The ileum has a unique absorptive role: the majority of bile acids, fat-soluble vitamins, and folic acid are absorbed here. As a result, removal of >100 cm of ileum can lead to bile acid malabsorption with resultant steatorrhea and vitamin deficiency (20,21). In addition, impaired vitamin B12 absorption in the distal ileum may lead to megaloblastic anemia and the irreversible neurological deficits associated with dorsal column demyelination. Patients who experience symptoms related to fat malabsorption can be treated with cholestyramine, while those with megaloblastic anemia can be treated with vitamin B₁₂ replacement (22).

Hyperchloremic, hypokalemic metabolic acidosis secondary to ammonium chloride reabsorption is the most common metabolic abnormality associated with urinary diversion using either ileum or colon. In patients undergoing IC diversion, metabolic acidosis is reported in 13% to 17% of patients (8,23-25). In part as a result of longer urinary storage times, the incidence of metabolic acidosis in continent cutaneous diversion is higher, with estimates of approximately 24% in patients with an Indiana pouch (23). It should be emphasized that the risk of metabolic acidosis is largely dependent on the patient’s baseline renal function. In a recent study, Kristjansson et al. found that in patients with a GFR >55 mL/min, the increased acid load created by urinary diversion can be sufficiently counterbalanced to avoid severe acidosis (26). Lastly, in urinary diversions that incorporate the ileocecal valve in order to create a continent catheterizable mechanism, chronic diarrhea, and even some degree of fecal incontinence, have been reported as persistent side effects (27).

An isolated ileal diversion was first reported by Seiffert, but only after Bricker’s publication in 1951 did it gain wider acceptance (28,29). At our institution, IC creation is performed based upon patient preference or for those with renal insufficiency (creatinine clearance <40 mL/min), hepatic disease, bulky T4 disease, markedly impaired dexterity, or significant comorbidities that necessitate abbreviated anesthetic time. In comparison to continent diversion, ICs are simpler to construct, resulting in significantly shorter operative times.

Studies comparing the rates of postoperative complications between ICs and continent diversion have reported mixed results. In a comparison of 20 patients undergoing IC diversion to 19 with continent cecal reservoir, Davidsson et al. reported no significant difference in metabolic abnormalities at 15 years after surgery (30). Both groups were found to have a mild metabolic acidosis with respiratory compensation. Using the Nationwide Inpatient Sample, Gore et al. found that the incidence of immediate postoperative complications was not associated with the type of urinary diversion used (31).
However, the researchers were only able to include complications assessed during the initial hospitalization for surgery, thereby excluding any readmissions and associated diagnoses. In contrast, Nieuwenhuijzen et al. reported on the incidence of perioperative complications after various types of urinary diversion (23). They found that late complications occurred in 39% of patients undergoing IC diversion, compared to 63% of patients with an Indiana pouch. Similarly, Knap et al. found that patients undergoing continent diversion were at higher risk of suffering complications requiring cystectomy-related surgical procedures in the future (32). However, they found no difference in perioperative mortality between the two groups.

The modern IC consists of a straight segment of distal ileum taken 15 cm proximal to the ileocecal junction in order to minimize malabsorption of bile acids and vitamin B₁₂ (Fig. 25A.1). The length of bowel needed for the conduit will vary based on mesenteric length, patient body habitus, and available ureteric length. The segment of bowel chosen may be adjusted to ensure adequate vascular supply, as best evaluated intraoperatively with transillumination of the mesentery. Bowel anastomosis is most commonly performed using a stapler, leaving the isolated conduit inferior to the anastomosis. The ileal segment may be irrigated, and its proximal end is closed with a two layer Lembert or Parker-Kerr suture. Using a nonabsorbable stapler for closure of the conduit may lead to stone formation (33).

The left ureter is tunneled through an avascular portion of the sigmoid mesocolon, and the site for its anastomosis is sharply excised in full-thickness fashion at the proximal portion of the conduit. The ureter is spatulated medially. A mucosa-to-mucosa, end-to-side, and tension-free anastomosis is performed with interrupted, absorbable 4-0 sutures, although continuous runs may be substituted. At the halfway point of completing the anastomosis, most surgeons place ureteral stents or feeding tubes for postoperative drainage. Upon completion, the conduit is irrigated in retrograde fashion to ensure a watertight anastomosis.

Following the second ureteroileal anastomosis, the preoperatively marked circular skin site is incised and carried down to the anterior rectus fascia. A cruciate fascial incision is made no larger than two fingers in width, and the conduit is grasped with a Babcock clamp and passed through to the skin. Four interrupted sutures incorporate deep conduit serosa followed by dermis in order to evert the stoma. Some surgeons incorporate fascia in the everting sutures.

In obese patients or those with short mesenteries, a loop end urostomy, or Turnbull stoma, may be fashioned over a temporary support bar. Several studies have demonstrated a reduced incidence of stomal stenosis associated with the Turnbull, although at the cost of an increased risk of developing a parastomal hernia (34,35). Additional maneuvers for gaining conduit length include separating the distal bowel from its mesentery, although this may increase the risk of ischemia and mucosal sloughing. The sigmoid mesentery tunnel may also be widened, and the angle at which the left ureter traverses the sigmoid mesocolon can be manipulated. Some have described creating an ileocecal conduit prior to isolating the conduit limb in order to gain even further length, although this has the disadvantage of removing the ileocecal valve from gastrointestinal continuity.

The colon conduit is an alternative for patients with a history of extensive pelvic radiation or inflammatory bowel disease in whom the ileum is identified as damaged and not usable in
a urinary diversion. A transverse colon conduit is ideal in the patient undergoing total pelvic exenteration, as it avoids the necessity of a bowel anastomosis. In addition, the creation of a nonrefluxing ureterointestinal anastomosis is simplified by tunneling the ureter beneath the taenia of the colon.

Unique to conduit constructions are stomal complications, the incidence of which may be as high as 15% (36). These include parastomal hernias, stenosis, and prolapse. Risk factors for stomal complications include high BMI, especially in elderly patients. A series of 30 patients with history of pelvic radiation who underwent transverse colon conduit diversion reported no cases of bowel or urinary anastomotic leaks; stable or improved renal function in 80%; and a reoperation rate of 20% (37). A large, prospective randomized trial comparing a two-layer sewn to a stapled colon to colon anastomosis found no difference in complication rates (38). In this study, the time needed for completion of the anastomosis was reduced by approximately 10 minutes when stapled, but rates of leak and fistula formation were comparable (39). For patients undergoing ileal or gastric resection, the incidence of bowel obstruction may be as high as 10%, and for colonic resections 5% (24).

As patients live longer lives after radical cystectomy, it is important to be aware of the long-term sequelae of urinary diversion. Madersbacher et al. examined the long-term incidence of complications in 131 patients who underwent IC diversion between 1971 and 1995 (40). At a median follow-up of 96 months, they found that 66% of patients developed a complication related to the IC. Stomal complications, including parastomal hernia, stenosis, and recurrent bleeding or skin irritation, occurred in 24% of patients. Bowel-related complications occurred in 24%, with obstruction being the most common (12% of patients). Upper tract complications also appear to be somewhat common on long-term follow-up, especially in patients with specific comorbidities. At a median follow-up of 91 months, Yang et al. found that of 100 evaluable patients, 14% were found to have radiologic changes in the upper tracts, and 10% developed abnormal serum creatinine levels (41). However, all of these patients had specific comorbidities that may have contributed to the above changes, including diabetes, chronic pyelonephritis, and ureteroileal anastomotic stricture.

Direct anastomosis of the ureter or renal pelvis to the skin avoids the need for a bowel conduit. This technique is largely reserved for pediatric patients when used as a temporary diversion until more definitive bladder reconstruction can be attempted. In addition, it is sometimes used for palliation in patients with extensive pelvic malignancy. Complications resulting from these diversions include stenosis of the ureter at the anastomotic site, as well as significant cutaneous irritation from contact with urine.

Since Gilchrist first introduced the concept of a continent cutaneous pouch in the 1950s using the cecum as a reservoir and the ileocecal valve as a continence mechanism, there has been a marked evolution in this form of diversion (42). The differences between the various techniques are significant: some, like the double-T pouch, are surgically complex and accessible only to experienced reconstructive surgeons, while others employ more common techniques available to many urologists.

Improvements on the catheterizable pouch have focused on two main aspects: prevention of reflux into the upper tracts, and establishing an effective continence mechanism. Surgeons have long sought to create an effective antireflux mechanism at the uretero-intestinal anastomosis in order to prevent the transmission of elevated pressures and bacteria into the upper tracts. However, many of the techniques employed have been found to be associated with an increased risk of anastomotic strictures (43,44). In addition, the actual benefit of preventing bacteriuria in the upper tracts is unclear, and, as a result, there has been a recent trend toward creating refluxing anastomoses (45).

Any catheterizable pouch must include an effective continence mechanism that prevents leakage of urine while still allowing easy catheterization at regular intervals. The type of diversion chosen, and the segment of bowel employed, in large part determines the type of continence mechanism that may be used. One of the most important breakthroughs in ensuring continence came not in the form of a new surgical technique, but rather in the realization that the high intraluminal pressures created by peristalsis could be disrupted. The concept of detubularization had been reported by Goodwin et al. in the 1950s, and in the 1960s, Ekman and Kock applied it to the construction of an ileostomy (46,47). Essentially all present-day continent urinary diversions involve detubularization of the chosen bowel segment, with subsequent closure into a Heineke-Mikulicz configuration.

There are several postoperative complications specific to catheterizable pouches. The most common are associated with the stoma itself, and usually present as inability to catheterize. Wiesner et al. recently compared the incidence of channel-related complications in 401 cutaneous ileocecal pouch diversions using either an instussuscepted ileal nipple or an in situ, submucosally embedded appendix. Thirty-six percent of patients developed a stomal complication that required intervention. Stomal stenosis was most common, occurring in 17% of patients with an ileal nipple and 32% of patients with an appendiceal channel (48). The authors reported that most of these complications were addressed with endoscopic procedures without need for extensive surgical revision. Similar results have been reported by Gerharz et al. (49,50).