Editing Intestinal Segments and Urinary Diversion (section)

== Selecting the segment of intestine ==

* '''Intestinal segments used most often for urinary tract reconstruction (2):'''
*#'''Ileum''' 
*#'''Colon'''
*#* '''Jejunum is usually not used for reconstruction of the urinary system because it may result in severe electrolyte imbalance'''
*#** Although the same electrolyte abnormalities are possible with either ileum or colon, nutritional problems (Vitamin B12 deficiency and bile acid salt absorption) are less with colon when compared to ileum as long as the ileocecal valve is left intact

=== Ileal Conduit ===
* Simplest type of conduit diversion to perform; fewest intraoperative and immediate postoperative complications

==== Contraindications (3): ====
# '''Short bowel syndrome'''
# '''Inflammatory small bowel disease'''
# '''History of extensive pelvic irradiation''' where the ileum may have been affected

==== Summary of steps ====
* '''A segment 10-15 cm in length is selected 10-15 cm from the ileocecal valve'''. The cecum and ileal appendage (i.e., that portion of the distal ileum fixed to the retroperitoneum) are mobilized. The ileal mesentery is transilluminated, and a major arcade to the segment selected identified. With a mosquito clamp, the mesentery immediately beneath the bowel is penetrated, and the bowel is encircled with a vessel loop. An area at the base of the mesentery that is to one side of the feeding vessel is selected, and a second vessel loop is placed through the mesentery. At this juncture, the peritoneum overlying both sides of the mesentery is incised from bowel vessel loop to the base of mesentery vessel loop. With mosquito clamps, the tissue is clamped, severed, and tied with 4-0 silk. A portion of mesentery 2 cm in length is cleaned away from the bowel beneath the mesenteric incision. This procedure is repeated at the other end of the selected segment. The base of the mesentery should be as wide as possible and the mesenteric windows not excessive (in general about 5 cm in length) to prevent ischemia of the segment. Allen clamps are placed across the bowel in an angled fashion such that the antimesenteric portion is shorter than the mesenteric portion. (Some prefer to transect the bowel with an anastomotic stapler.) Thus a triangular piece of bowel is removed and discarded.
* The isolated ileal segment is placed caudad, and an ileoileostomy is performed as described earlier. The mesenteric window of the ileoileostomy is closed with interrupted 3-0 silk sutures. The isolated segment is then flushed with copious amounts of saline until the irrigant is clear, at which point the ureters are brought out the retroperitoneum in the right lower quadrant. To accomplish this, the left ureter must be brought over the great vessels and posterior to the sigmoid mesentery to the rent in the posterior peritoneum. This may be done by mobilizing the cecum cephalad to identify the right ureter. The left ureter may be identified by incising the line of Toldt of the left descending colon (Fig. 97-35). This dissection allows anastomosis of the ileal segment as proximally as needed to the ureter. Indeed, the ileum may be anastomosed directly to the renal pelvis on both sides if necessary (see Fig. 97-35C). After a cystectomy, the ureters are identified caudad to the iliac vessels and may be conveniently traced cephalad similar to the previous description. The ureteroileal anastomoses are performed as described previously. These anastomoses are stented
* The base of the conduit is fixed to the retroperitoneum in the right lower quadrant by suturing the posterior peritoneum to the conduit, thus effectively retroperitonealizing the ureterointestinal anastomosis.

=== Colon Conduit ===
* '''Commonly used colon conduits: transverse, sigmoid, and ileocecal'''

==== Transverse colon ====
* '''Used in patients with prior extensive pelvic irradiation or when an intestinal pyelostomy needs to be performed.'''

==== Sigmoid conduit ====
* '''Good choice in patients undergoing a pelvic exenteration who will have a colostomy since no bowel anastomosis needs to be made.'''
* '''Contraindications:'''
** '''When the internal iliac artery has been ligated and the rectum has been left in situ'''
** '''Extensive pelvic irradiation'''

==== Ileocecal conduit ====
* '''Advantages:'''
** '''Provides a long segment of ileum when long segments of ureter need replacement'''
** '''Provides colon for the stoma'''

==== Contraindications (3): ====
# '''Presence of inflammatory large bowel disease'''
# '''Disease of segement being considered'''
# '''Severe chronic diarrhea'''

=== Jejunal Conduit ===
* '''Advantages'''
** '''Avoids irradiated bowel and ureter'''
* '''Disadvantage:'''
** '''May result in severe electrolyte imbalance'''
*** '''Rarely used except when neither colon or ileum can be used'''

=== Stomach Conduit ===
* '''Rarely indicated; may be considered when the use of other intestinal segments in a patient with a decreased amount of intestine would result in serious nutritional problems'''
* '''Advantages (5):'''
*# '''Electrolyte imbalances rarely occur in patients with normal renal function, although a hypochloremic, hypokalemic, metabolic alkalosis has been described'''
*#* '''Less permeable to urinary solutes'''
*#* '''Has a net excretion of chloride and hydrogen ions rather than a net absorption of them, effectively reversing the acidosis of renal insufficiency; may be preferred option in patients with pre-existing metabolic acidosis or renal dysfunction'''
*# '''Not associated with malabsorption; may be preferred option in patients with short bowel syndrome'''
*# '''Not usually in field of radiation, may be preferred option in patients with previous pelvic radiation'''
*# '''Produces less mucus'''
*# '''Acidic pH reduces bacterial colonization'''
* '''Complications specific to stomach conduit'''
** '''Early:'''
*** '''Gastric retention'''
**** '''Caused by atony of the stomach or edema of the anastomosis'''
*** '''Hemorrhage'''
**** '''Most commonly originating from the anastomotic site'''
*** '''Hiccups'''
**** '''Secondary to gastric distention'''
*** '''Pancreatitis'''
**** '''As a consequence of intraoperative injury.'''
*** '''Gastroduodenal and gastroureteral leaks'''
**** '''Have been reported, occasionally resulting in a fatal outcome'''
** '''Late:'''
*** '''Dumping syndrome'''
*** '''Steatorrhea'''
*** '''Small stomach syndrome'''
*** '''Increased intestinal transit time'''
*** '''Bilious vomiting'''
*** '''Afferent loop syndrome'''
*** '''Hypoproteinemia'''
*** '''Hematuria-dysuria syndrome (from the excreted acid)'''
*** '''Severe metabolic alkalosis associated with respiratory distress'''
**** '''The syndrome of severe metabolic alkalosis in patients who have had a gastrocystoplasty is most likely to occur in patients who have elevated gastrin levels'''
*** '''Megaloblastic or iron deficiency anemia'''
*** '''Severe ulcerative complications'''
**** '''Rare'''
**** '''Long-term histamine (H2) or proton-pump inhibition should be considered for these patients.'''

=== Ileal vesicostomy ===
* Uses spatulated ileum and a generous transverse cystotomy to decompress the bladder and to allow an appliance to be used on the abdomen. 
*Particularly well suited to spinal cord injury patients or those with significant neurologic disease.  
**Patients who are particularly good candidates are those with significant detrusor–external sphincter dyssynergia.
*Concept is that patients with a neurogenic bladder have an easier job of caring for themselves with an abdominal stoma.