What is a urinary diversion?
Urinary diversion involves bypassing the bladder and creating some type of reservoir out of the bowel for the urine. The types of reservoirs include: a small portion of bowel that acts as a conduit for the urine out of the abdomen to a stoma at the skin (ileal conduit), a high volume reservoir that is attached to the urethra (neo-bladder), or a smaller stoma, which is periodically catheterized to empty a large abdominal urinary reservoir made out of large bowel (right colon pouch). These are described in more detail below.
Who needs urinary diversion?
Urinary diversion is generally indicated when the bladder has severe dysfunction or needs to be removed due to cancer. Some of the conditions that can lead to a neurogenic or dysfunctional bladder are spinal cord injury, radiation damage and neurologic diseases. Sometimes bowel can be used to expand the volume of the bladder (bladder augmentation), and sometimes the bladder is no longer suitable to be used and a urinary diversion needs to be done.
What are the different types of urinary diversion?
The simplest type of urinary diversion is an ileal conduit. This is also often called a urostomy. In this type of diversion a short segment of bowel is separated from the rest of the intestinal tract. The urinary tubes from the kidneys (ureters) are connected to the one end of this segment of bowel and the other end of the bowel is brought out of the skin and a stoma is created. The stoma sits above the skin and urine drains out of the stoma to a bag, which is pasted to the skin around the stoma. The stoma bags are drained when they fill a few times a day. The urinary stoma bags typically stay on the skin about 3-4 days. This type of urinary diversion takes the least amount of time to create and is probably the most reliable. The downside is that patients have to have a stoma and a bag attached to the skin.
Figure: Ileal conduit: the ureters are attached to a conduit or “pipe” of small bowel that comes to the skin and makes a stoma. A stoma bag attaches to the skin to collect the urine.
Figure: The usual stoma site for an ileal conduit. The stoma can also be located on the left side if necessary.
A neo-bladder is when a long segment of bowel is opened and fashioned into a sphere. The sphere is made out of flat pieces of bowel much in the same way a baseball is made out of flat pieces of leather. The urinary tubes from the kidneys (ureters) are connected to this sphere and then the new bladder (or neo-bladder) is sewn to the urethra in the pelvis. A catheter is left in the urethra until healing occurs. Once the catheter is removed the patient urinates mostly by relaxation of the urethral sphincter and pushing with their abdominal muscles. The major problem with this type of urinary diversion is incontinence at night due to sphincter relaxation and inadequate emptying of the neo-bladder. Some patients need to perform catheterization every day to drain out residual urine from the neo-bladder. The majority of patients that undergo this type of urinary diversion are having their bladder removed for bladder cancer. This type of diversion is usually not suitable for patients that need urinary diversion from a neurogenic bladder.
Right colon pouch
In a right colon pouch a piece of the colon is opened up and fashioned into a sphere (or pouch). The urinary tubes from the kidneys are attached to this sphere and a then a narrow tube of bowel is brought from the sphere to the skin. This narrow tube of bowel can be brought to the right lower portion of the abdomen or to the belly button. The narrow lumen of the bowel leading to the stoma and a natural valve in the bowel prevent urinary leakage from the pouch. Because this stoma does not leak urine no external stoma bag is needed. Instead, the patient catheterizes through the small stoma into the pouch when it needs to be drained. The typical volume of a right colon pouch is 500ml and patients need to catheterize about 4-6 times a day. The problems associated with these pouches are scarring of the stoma and occasional leakage of urine from the stoma.
Figure: The section of bowel that is utilized to construct the right colon pouch. The large bowel is folded down to make a sphere and the small bowel segment is tightened over a catheter to make the channel that comes up to the skin.
Figure: The process of folding the colon (large bowel) to make the storage reservoir for urine.
Figure: Creating the catheterizable channel with a surgical stapler. Stiches are also used to tighten the channel. The channel is most often sewn to the base of the belly button.