Urinary Diversion
Kenneth D. Hatch
GENERAL PRINCIPLES
Permanent urinary diversion is necessary when the bladder is removed for treatment of cancer or if there is injury to the lower urinary tract that cannot be repaired such as radiation fistulae. The development of techniques to divert the urine was necessary before exenterative surgery could be utilized. Brunschwig utilized an incontinent “wet colostomy” for urinary and bowel diversion in his original report on results of pelvic exenteration in 1946. The ureters were connected to the large bowel and the urine was mixed with the feces and expelled through the colostomy. This lead to hyperchloremic acidosis, recurrent pyelonephritis and renal failure and it is not used today.
The modern era of urinary diversion began in 1950 when Bricker published his technique of isolating a loop of ileum, closing one end, anastomosing the two ureters to this end, and bringing the other out as a stoma. The small bowel does not absorb electrolytes as efficiently as the sigmoid does so this eliminated the hyperchloremic acidosis. Since the urine and feces were separated it markedly diminished the recurrent pyelonephritis and renal failure that were experienced with the wet colostomy. The popularity of the Bricker ileal loop was aided by the development of watertight stoma appliances.
The Bricker procedure required an anastomosis of the ileum which may fail to heal if the patient had significant radiation fibrosis. This led surgeons to use the nonirradiated transverse colon for the conduit in those patients. The incidence of anastomotic leak from both the bowel anastomosis and the ureterocolonic anastomosis is lower in the transverse colon group. Electrolyte abnormalities were not increased and stoma revisions were decreased. However, the rate of ureteral stricture and loss of renal unit function were not improved.
Further reductions in bowel complications occurred with the use of surgical staplers, which also decreased the operative time, blood loss, and subsequent medical complications. The ileal and transverse colon diversions were incontinent cutaneous diversions requiring an external bag.
Continent cutaneous urinary diversions were popularized in the 1980s in Mainz, Indiana, and Miami as a technique that would allow the woman to eliminate the urostomy bag and catheterize the stoma three to four times per day through a smaller stoma thus improving their body image.
When the ureters are placed directly into a segment of bowel such as the ileal or transverse colon, the peristalsis of the bowel propels the urine out of the bowel conduit and into a bag. The pressure inside the bowel can reach 60 cm of water. This amount of pressure would damage the kidneys. In order to make an internal reservoir for storage of urine the high pressure would have to be eliminated. This was accomplished by detubularizing the segment of bowel in which the ureters would be placed.
The Mainz pouch used the distal ileum, cecum, and a portion of the ascending colon as the reservoir. The continence mechanism included stapling an intussusception at the ileocecal valve. It was used primarily in patients with bladder tumors in patients who had not had high-dose radiation to the ileum. The metal staples at the ileocecal valve lead to formation of stones. For these two reasons it was not widely adopted in gynecologic oncology.
The Miami pouch and the Indiana pouch use the cecum and right colon for the reservoir and the attached distal ileum for the catheterizing arm. The continence mechanism for the Indiana pouch is a tapering of the ileal segment and the ileocecal valve. For the Miami pouch, sutures are also placed around the ileocecal valve for additional continence.
Definition
Cutaneous incontinent diversions use a segment of bowel as a conduit to deliver urine to an external bag.
Cutaneous continent diversions use a segment of detubularized bowel as an internal reservoir and a segment of bowel attached to the skin to allow emptying by catheterization.
Continent diversions use the sigmoid or rectum as a reservoir and expelling the urine through the anus.
Orthotic bladder is a continent diversion using bowel attached to the urethra.
Urinary diversions in gynecologic oncology are almost always cutaneous diversions since the bladder and the rectum are in the radiation field and anastomosis does not heal well.
Differential Diagnosis
These operations will generally be performed as a part of pelvic exenteration or to permanently divert urine from a radiation-induced vesicovaginal fistula. In the case of the pelvic exenteration the bladder will be removed along with most or all of the urethra. For patients with radiation-induced fistulas the bladder will be left in place. Extensive biopsies must be taken to rule out a cancer-caused fistula.
Imaging and Other Diagnostics
Patients with recurrent cancer will have imaging as described in Chapter 23. For those with radiation fistulae, imaging with CT or MRI to evaluate the ureter, bowel and other pelvic structures will identify abscesses, diverticula or obstruction that will prepare the surgeon for any additional surgical complications.
Preoperative Planning
Planning for the patient with recurrent cancer has been addressed in Chapter 23. The patient needing diversion for radiation necrosis will likely have been overdosed with radiation and will have significant damage to the ileum. The surgeon will likely see a white, fibrotic ileum. This loop of bowel must not be used for the diversion as the anastomosis may not heal. The ureter to ileum anastomosis may also not heal. The transverse colon should be used as the alternative segment of bowel. The fibrotic distal ileum also is a contraindication for a continent diversion using the segment of ileum as the cauterizing segment. It may not heal when the stapler is used to narrow it. It is subject to
continued fibrosis and may lead to stricture that would make catheter insertion difficult.
continued fibrosis and may lead to stricture that would make catheter insertion difficult.
Selection of the type of urinary diversion depends upon both patient factors and medical conditions. The patient factors are age and dexterity, comorbidities that interfere with healing, obesity and the patient’s preference. The medical factors are radiation damage to the bowel, condition of the kidneys, and previous bowel operations limiting the necessary length for continent diversion.
Continent diversion should only be performed when GFR is 50 or greater, there is adequate bowel length and vascularity and the patient has adequate dexterity to catheterize three times daily.
The stoma may be placed in the umbilicus to further improve the body image.
Anatomic Considerations
The ileal conduit is the simplest operation for permanent diversion. The segment to be isolated should be at least 15 cm away from the ileocecal valve so that there is adequate absorption of bile salts, vitamin B12 and fat-soluble vitamins. If the terminal ileum has severe radiation damage then the segment of bowel most favored is the transverse colon. Proximal ileum or even jejunum have been used.
The bowel segment chosen should be isoperistaltic and no longer than necessary so that urine is transported to the urinary bag without time for solute to be absorbed.
Ureteral stents should be placed and the ureterointestinal anastomosis should be wide to prevent stenosis.
The transverse colon conduit segment will have the middle colic artery as its blood supply. If it is used for urinary diversion the IMA cannot be sacrificed to enable an LRA to be performed. And a transverse loop colostomy cannot be performed for fecal diversion.
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