eMedicine Specialties > Urology > Surgery
Urinary Diversions and Neobladders: Treatment
Updated: Dec 9, 2008
Treatment
Medical Therapy
The treatment of urinary diversion is usually limited to the management of complications. These patients have unique problems that require the involvement of the surgeon who has been responsible for the patient's care prior to the date complications occurred.
Initially, the treating physician should focus on the date the patient had the diversion and the type of diversion performed, including the type of bowel segment used. Knowing the chronicity of the problem helps the treating physician stratify the patient as having early or late complications.
Early complications
These complications are best managed by consulting the surgeon who performed the diversion. Most commonly, the treatment is intravenous hydration and possible nasogastric tube placement guided by abdominal radiography and laboratory studies, including metabolic profile, complete blood cell count, urinalysis, and urine culture, if indicated.
If the integrity of the ureteral-bowel anastomosis is suggested to have been compromised, consider performing further imaging studies using ultrasonography, IVP, or nuclear renal scan.
Use ultrasonography judiciously as a diagnostic study because the presence of hydronephrosis does not necessarily indicate obstruction. Some degree of baseline hydronephrosis is not uncommon in patients with refluxing ureteral anastomoses.
Special attention must be given to patients with continent diversion, abdominal distension, and abdominal pain. One of the most catastrophic complications of continent diversion is reservoir rupture and bacterial peritonitis. The examining physician must maintain a low threshold for consulting a urologist and/or performing contrast-enhanced CT scanning of the abdomen and pelvis.
If urinary reservoir rupture goes undiagnosed and untreated, the outcome can be fatal. If a ruptured reservoir is diagnosed, administer broad-spectrum intravenous antibiotics and consult with a surgeon for urgent repair, if indicated. Reservoir rupture may be either an early or late complication of diversion. Particular attention must be given to patients with continent diversion after prior pelvic irradiation because these patients are at a high risk for reservoir rupture.
A continent catheterizable reservoir (ie, the urethra is not attached to the pouch) that is unable to catheterize via the efferent limb is a medical emergency. Ultrasound-guided percutaneous drainage may be required. Blind percutaneous drainage is discouraged because of the risk of injury to the mesenteric vascular pedicle that supplies the reservoir.
Urinoma may be treated with percutaneous drainage and/or stenting of the appropriate urinary segment in an effort to aid in closure of the abnormal communication.
Late complications
Urinary obstruction is best treated in the short term with percutaneous drainage or consultation with a urologist and retrograde drainage.
Prevention is the most effective treatment for vitamin B-12 deficiency. Strongly consider periodic parenteral replacement in patients with a urinary diversion in which ileum was used.
Electrolyte abnormalities are best treated in the short term with intravenous hydration and acidosis correction. The patient should receive lifelong supplementation with oral potassium and/or sodium citrate. Chlorpromazine or nicotinic acid may be given to patients in whom sodium loading may be dangerous.
Administer sodium chloride and thiazide diuretics (the potassium-wasting effect is desirable) to patients with jejunal conduit syndrome.
Diagnosing and treating concomitant pyelonephritis, obstruction, or urinary stasis is important in a patient with metabolic abnormalities; otherwise, the patient is sure to be refractory to treatment.
Secretory diarrhea is initially treated with cholestyramine (4 g PO bid) in an attempt to decrease colonic exposure and to free bile salts. Dietary fat restrictions are recommended for patients with significant steatorrhea (ie, >20 g/d).
Osmotic diarrhea is treated by slowing bowel motility with oral agents (eg, loperamide, diphenoxylate, difenoxin) to decrease transit time.
Surgical Therapy
Urinary diversion is typically performed after radical anterior pelvic exenteration; therefore, the typical patient undergoes surgery for several hours before the diversion is started. Attention must be given to the patient's preoperative state of health and ability to tolerate a potentially long surgical procedure. The surgeon performing the continent urinary diversion must carefully select the patient with this in mind. Most surgeons do not perform continent urinary diversions as rapidly as they perform noncontinent urinary diversions.
Candidates for urinary diversion due to neurologic dysfunction often do not have normal hand motor skills. Preoperatively, this condition must be evaluated carefully. Many patients with spinal cord injuries are excellent candidates for continent catheterizable diversions. For these patients to possess the skill to catheterize their own stomas and to rely on no one else to do so is paramount.
Preoperative Details
Preoperatively, ensure that the patient has undergone a full mechanical and antibiotic bowel preparation. If large-bowel segments are to be used, an air-contrast barium enema is recommended to rule out significant diverticulosis or other conditions that may exclude large bowel for use in urinary diversion.
Inquire about prior abdominal or pelvic radiotherapy, which suggests that the use of small-bowel segments is not appropriate, unless several years have passed since the patient received radiotherapy and the small-bowel segments appear grossly normal at the time of diversion.
Discuss several options of urinary diversion with each patient preoperatively. This discussion allows the freedom to exercise intraoperative decisions that suit the technical demands of each individual case.
Intraoperative Details
The surgeon should be very familiar with the intended procedure. Occasionally, altering the original plan and performing an alternative type of diversion secondary to individual patient anatomy is necessary.
No matter what type of diversion is planned, basic principles of abdominal surgery apply. Thoroughly irrigate the bowel contents after isolating the limb that will be used for diversion. The bowel reanastomosis should be widely patent and should be performed along the antimesenteric segments.
Debate exists regarding which type of ureteral anastomosis should be performed. Each type has its merits and disadvantages. The Wallace anastomosis allows for widely patent ureteral orifices, which are less likely to become obstructed. This procedure also allows for reflux of urine, which theoretically may predispose patients to long-term reflux nephropathy.
A nonrefluxing anastomosis significantly diminishes the risk of reflux nephropathy; however, it is also more prone to stricture and obstruction, which ultimately may lead to reoperation and repair.
To reduce urinary reflux, the authors prefer the Wallace type of anastomosis with a properistaltic segment of nondetubularized ileum.
Detubularizing continent reservoirs and reconstructing them in a more spherical shape is of paramount importance. This procedure allows for greater capacity and, most importantly, for reduced storage pressure.
In the case of neobladder construction, test the limb that will be isolated for diversion for mesenteric mobility prior to disrupting bowel continuity. Traction on stay sutures in the bowel segment allows the surgeon to determine whether placing the intended neobladder in the pelvis for the urethral anastomosis will be difficult. If difficulty is experienced, the surgeon may counter-incise the mesenteric peritoneum, mobilize the mesenteric pedicle to the root, and, in extreme cases, re-flex the operating table to decrease the distance between the pubic symphysis and the umbilicus.
Stents are recommended to bridge the ureteral anastomosis. When a neobladder is constructed, a urethral Foley catheter and suprapubic tube are left in place. When a continent catheterizable reservoir is constructed, a stenting catheter is left in place in the efferent limb and a suprapubic tube is placed through a separate portion of the reservoir and brought out through a stab incision in the skin. Noncontinent diversion is drained by ureteral stents only.
Postoperative Details
The length of time drainage tubes should stay in place varies according to individual practice. The authors prefer to stent the ureteral anastomosis for 2 weeks. The urethral Foley catheter is left in place for 2 weeks before removal. The suprapubic tube is then clamped and the reservoir, cycled with postvoid residuals, is checked. At the third postoperative week, the suprapubic tube is removed. Typically, an IVP is performed at 6 weeks postoperatively; renal ultrasonography is performed if the patient is allergic to intravenous contrast agents.
Complications
Early complications
These include postoperative ileus or bowel obstruction, which, as a group, is more common in continent diversions. Other early complications may include ureter-bowel anastomotic leak, acute pyelonephritis, and urinoma.
Late complications
Metabolic disturbances may result from the interaction of urine with the absorptive surface of the bowel used for the procedure.
Complications due to technical error and/or patient healing factors manifest most often as ischemic strictures. Technical errors that lead to stricture are caused by tension at the anastomotic site, inadvertent ligation of the vascular supply to the graft, and overzealous ureteral mobilization. In addition to avoiding excessive ureteral mobilization, surgeons must use electrocautery judiciously in their surgical dissection.
Patient comorbidities (eg, peripheral vascular disease, chronic obstructive pulmonary disease, infection) also contribute to altered healing and probably increase the overall incidence of complications. Unique metabolic derangements may occur because of urine contact with the absorptive surface area of the bowel mucosa.
Jejunal segments
Jejunal segments pose the most medically challenging metabolic abnormality with regard to urinary diversion. The decreased number of tight mucosal junctions allows for more water and electrolyte loss. Dehydration results in aldosterone secretion and urine delivery to the jejunal segment that is low in sodium and has an elevated potassium concentration. The jejunum responds by absorbing more potassium and exchanging sodium and water, exacerbating the dehydration and resulting in further aldosterone production. Aldosterone production perpetuates a cycle that is extremely refractory to treatment. The net effect in 27% of patients is a hyperkalemic, hyponatremic, hypochloremic metabolic acidosis, known as the jejunal conduit syndrome.
Ileal and colonic segments
Patients in whom ileal and colonic segments were used may develop hyperchloremic metabolic acidosis, which is likely caused by increased ammonium and chloride absorption by the bowel segment from the urine. Because of the poor absorptive capacity of colonic segments, these patients tend to develop hypokalemia more often than those in whom small-bowel segments were used. Patients with sepsis or decreased hepatic functional reserve who develop ammonia hyperabsorption by the bowel segment are at risk for hyperammonemia and encephalopathy.
Continent reservoirs
Increased bowel surface area or contact time with urine results in greater solute reabsorption and more pronounced abnormalities. Patients with continent reservoirs, which have both a greater surface area for absorption and prolonged contact times with urine, have a higher incidence of metabolic abnormalities. Additionally, creatinine is not a good measure of the glomerular filtration rate (GFR) in a patient who received a continent diversion. Varying amounts of urinary creatinine are reabsorbed by the bowel segment used to store urine; therefore, elevated serum levels of creatinine may not accurately predict the GFR.
Vitamin B-12 deficiency
Vitamin B-12 is an essential nutrient that cannot be synthesized by humans. The human liver is the major site of vitamin B-12 storage, and most stores can last approximately 3 years without replacement. The terminal ileum is the exclusive site of vitamin B-12 absorption in humans. Most urinary diversions in which ileum is used are performed in a way to compensate for the physiology of vitamin B-12 absorption; however, more than 50 cm of resection appears to be the critical length at which abnormal B-12 absorption may be expected.
With the addition of intrinsic factor, Pannek et al demonstrated that 20 of 25 (80%) patients with more than 50 cm of ileum who underwent resection for continent diversion demonstrated abnormal Schilling test results.3 Patients with shorter limbs of ileum are not immune to vitamin B-12 deficiency and/or megaloblastic anemia; symptoms may take longer to manifest. Long-term follow-up studies in patients with shorter ileal segments demonstrate a 25-28% incidence of complications from vitamin B-12 deficiency. Patients in whom more than 50 cm ileum is resected are at increased risk for vitamin B-12 deficiency, which usually does not become clinically apparent for at least 2 years.
Metabolic Disturbances Associated With DiversionOpen table in new window
Table
| Bowel Segment | Sodium (Serum) | Potassium (Serum) | Chloride (Serum) | Bicarbonate (Serum) | Clinical Presentation | Comments |
|---|---|---|---|---|---|---|
| Jejunum | Low | Elevated | Low | Low | Lethargy, vomiting, severe dehydration, weakness | Severe and refractory hyperkalemia with lack of efficacy of aldosterone; avoid using this bowel segment for diversion |
| Ileum | Low/Normal | Normal | Elevated | Low | Anorexia, weight loss, polydipsia, fatigue | Must encourage oral salt replacement and hydration; ileum preferred segment for diversion |
| Colon |
| Bowel Segment | Sodium (Serum) | Potassium (Serum) | Chloride (Serum) | Bicarbonate (Serum) | Clinical Presentation | Comments |
|---|---|---|---|---|---|---|
| Jejunum | Low | Elevated | Low | Low | Lethargy, vomiting, severe dehydration, weakness | Severe and refractory hyperkalemia with lack of efficacy of aldosterone; avoid using this bowel segment for diversion |
| Ileum | Low/Normal | Normal | Elevated | Low | Anorexia, weight loss, polydipsia, fatigue | Must encourage oral salt replacement and hydration; ileum preferred segment for diversion |
| Colon |
Rupture of reservoir
One of the most devastating complications is rupture of the reservoir, which is most common in continent diversions. Hypercontinence of the catheterizable reservoir often leads to an elevated storage pressure and results in rupture. A less common etiology is partial herniation or volvulus of a noncontinent conduit, resulting in rupture of the proximal strangulated portion. Bacterial peritonitis invariably results when a bowel segment used for diversion ruptures. This condition is a surgical emergency that requires exploration, repair, and broad-spectrum intravenous antibiotics; therefore, a patient with a continent diversion and abdominal pain should be presumed to have a ruptured reservoir until proven otherwise. The risk of bacterial peritonitis and increased morbidity should prompt consultation with a urologist early in patient care.
Other complications
- Secretory and/or osmotic diarrhea
- Stomal stenosis, dermatitis, prolapse, retraction, and parastomal hernias (incidence, 15-40%)
- Poor drainage of conduit or reservoir
- Retention in the continent reservoir
- Volvulus and retention in conduit (rare)
- Urinary lithiasis (especially in patients with secretory diarrhea and chronic dehydration)
- Recurrent symptomatic infections
- Ureterosigmoidostomy - Adenocarcinoma, urosepsis, ureteral stenosis, and/or hydronephrosis
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References
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Further Reading
Keywords
urinary diversion, neobladder, urinary tract diversion, urinary conduit, orthotopic diversion, continent catheterizable diversion, ostomy, stoma, ureteroproctostomy, ureterosigmoidostomy, rectal bladder, ileal loop, ileal neobladder, Koch pouch, Indiana pouch, continent diversion, noncontinent diversion, continent urinary diversion, noncontinent urinary diversion, continent urinary tract diversion, noncontinent urinary tract diversion, cutaneous ureterostomy, neobladder diversion, continent catheterizable diversion, urinary system diversion
