What is a Mitrofanoff?
A Mitrofanoff is a small channel that connects the bladder to the outside of the body. A catheter is used to empty urine from the bladder through the channel, and a one way flap valve is used to maintain urine control.
How is the Mitrofanoff constructed?
To create a Mitrofanoff, the surgeon will make a narrow tube using a piece of your appendix. If you do not have an appendix, your small bowel will be used. The narrow tube is sewn to your skin. The opening is called a stoma, and it is usually placed in the belly button, making it fairly inconspicuous.
If the appendix is short in length or the patient is heavy-set, then the appendix will not reach the belly-button and is instead sewn to the right lower part of the abdomen.
The other end of the narrow tube is connected to the bladder (reservoir) using a tunneling technique to create a flap-valve. (see illustration below).
The bladder should have a large capacity (usually 500 ml) and will need to store urine at low pressures. If the bladder is small, then the capacity of the bladder will have to be increased by patching the bladder with a piece of bowel. This bladder patching surgery is done at the same time as creation of the Mitrofanoff.
The Mitrofanoff is almost never connected to a neobladder made out of bowel, because over time, the flap valve can stop working properly, causing leakage of urine. This does not occur when the Mitrofanoff is connected to the native bladder.
How does the Mitrofanoff work?
As the bladder fills, urine pressure builds up and helps to compress the tunneled channel. As bladder pressure rises, the tunneled channel becomes compressed against the wall of the bladder, creating a one way valve which prevents urine leakage. To drain the bladder, a catheter is passed 4 to 5 times a day through the one-way flap valve. Once the bladder is drained (this usually takes a couple of minutes), the catheter is removed.
What complications can occur with a Mitrofanoff?
Since the appendix or piece of small bowel is utilized to create the channel, there is always a risk of infection after surgery. To decrease this risk of infection a bowel clean-out is always performed a day or two prior to surgery.
The stoma at the skin can become narrow with time and make passing a catheter difficult. This occurs in 30% of adult patients. Correcting the narrowing typically requires a minor outpatient surgical procedure.
Difficult catheterization because of tortuosity or kinks in the channel can also occur, but this is a very rare complication.
In rare instances, the Mirofanoff flap valve cannot work properly and the patient leaks from the stoma. As long as the bladder has sufficient capacity, leakage through the channel is very rare.