Urinary diversion is a term used the normal structures of the urinary system are bypassed and an opening is being made in the urinary system to divert urine. The flow of urine is diverted through an opening in the abdominal wall. Patients who might require urinary diversion would be those whose bladders were non-functional or needed to be removed due to cancer or injury.

When the entire bladder is removed, another way to store and remove urine from the body is needed. Two options include a urostomy or a continent diversion.  

The word urostomy is made up of "urine" and "ostomy", the latter being Greek for "opening". In creating a urostomy, an artificial opening is created through the surface of the skin, which permits the urine to be excreted from the body while bypassing the bladder. 
 
The ileal loop or conduit is a short (8 inches) segment of small bowel (ileum). It carries the urine from the ureters from each kidney to the skin (stoma), where a flexible bag or appliance collects the urine.  The bag is emptied every 6 hours. The appliance is replaced every 3 to 5 days.
 
Since a urostomy has no nerve supply or muscles, it cannot be controlled as a normally functioning bladder would. A common side effect urostomy patients suffer is urinary infection, and they may have to take a low dose of antibiotics. Urostomy patients should also undergo yearly tests for blood pressure, hemoglobin, and urea levels, as well as checks for stone formation, which can be detected by ultrasound.
 
Patients can lead a normal life, including normal work, physical or sports activities, sex and a social life, normal clothing and diet. Travel is not restricted in any way and bathing and showering can be done with or without the pouch in place. However, patients should try to drink at least 8 to 10 glasses of fluid per day to help decrease the chance of urinary infection.

Continent diversions enable patients to urinate at his or her discretion without the use of any form of appliance or collecting device, as in a urostomy. Continent diversion does not require a bag outside the body. Instead, the surgeon will create a sac by reshaping a long piece of small intestine and attaching it to the ureters, the tubes that lead from the kidneys to the bladder. Urine is emptied when the person places a drainage tube into the hole of the diversion. Newer methods of surgery can route the urine into the urethra, making urination nearly normal.
 
Continent urinary diversion can be broadly divided into two categories: cutaneous and orthotopic.
 
Cutaneous continent diversion refers to the use of the gastrointestinal tract to create a new bladder, which is attached to the skin inside the body. This does not require the use of a collection appliance. However, the patient is required to place a catheter or small plastic tube into their new bladder four to five times a day to empty the reservoir.
 
Orthotopic continent diversion is also known as neobladder and most closely resembles the normal urinary anatomy. This form of continent diversion has been used in both men and women who've had surgery called cystectomy [link to Bladder Cancer module] that removes the bladder. The neobladder or reservoir created in orthotopic continent diversion) is created from a long (24 inches) length of small and/or large bowel to make reservoir to hold the urine.  If the urethra can be saved, the reservoir may be attached to it to allow voiding through the urethra.  This form of diversion requires several months to stretch the neobladder to be able to hold urine for 4 to 6 hours.  Voiding is accomplished with abdominal pressure, so that the urinary stream is slower than with the old bladder.  While daytime control is excellent, patients will often have to get up once at night to empty the neobladder to avoid urine leakage during sleep.  This procedure is more attractive to younger patients, who want to avoid wearing an appliance, but does require a more intense recovery than other procedures. 
           
If the urethra cannot be used, then a narrow tube of bowel connecting the reservoir to the skin is used to drain the reservoir with a catheter every 4 to 6 hours (continent urinary reservoir).  The opening on the skin is small, sometimes covered with a band-aid. Again, the reservoir needs time to be stretched to be able to hold a reasonable amount of urine. 
           
While the major advantage of a neobladder/reservoir is freedom from an external appliance, there are more risks associated with the reservoir in orthotopic diversion compared with cutaneous diversion:
 
Incontinence, particularly at night, as the bowel continues to secrete fluid overnight even when the oral fluid intake is minimal; and the external sphincter is not as active while sleeping.
 
Difficult catheterization when the reservoir gets overfilled from kinking of the catheter passage.
 
Infections, as the bowel surface has many folds and receptor sites for bacteria to attach and grow.
 
Stones may form from the combination of mucous, infections, and hair or other foreign matter introduced with the catheter.
 
Obstruction or blockage of the kidneys may occur from scarring at the entry of the ureter into the small bowel reservoir
 
Metabolic problems from the decrease in the bowel absorptive surface, including vitamin B12 absorption, acidosis (build up of acid in the body), and diarrhea from shortened small bowel (short gut syndrome when over 100 cm is used).
 
Potential cancer risk in the large bowel over many years of exposure to urine and infections, which produce nitrosamines.
 
All patients undergoing anticipated continent urinary diversion should be prepared for the possibility that a traditional urostomy using an ileal conduit or loop might be performed.