Artificial Urinary Sphincter (AUS)
How the AUS Works and an Overview of the Operation
The AUS is a hydraulically-operated device that circumferentially squeezes the urethra. A doughnut-shaped silicon “cuff” squeezes the urethra and a pump (implanted below the skin in the scrotum) controls the opening of the cuff. The AUS works well for all degrees of incontinence. Dr. Elliott is among the top 1% of American urologists for this procedure.
The AUS cuff is tailored to the size of your urethra. When it is deflated you can urinate freely because it is not squeezing the urethra. When it is inflated, it squeezes the urethra shut. How tightly it squeezes is regulated by a balloon in the abdomen. The thickness of the wall of the balloon determines the pressure that it takes to inflate the balloon. A thicker balloon will mean more pressure. We usually use a 61-70cm H2O balloon. Once the balloon and the cuff are connected by tubing, the pressure in the balloon will equalize across the system and a 61-70 cm H2O balloon will mean the urethra gets squeezed with 61-70 cm H2O. We choose this pressure because a typical blood pressure is 120/80; this ensures that we are below the lowest blood pressure number and that blood flow can continue to get to the urethra under the cuff and keep that urethra healthy, even when it is getting squeezed.
Because the balloon pressure causes the pressurizing of the cuff, a closed cuff is the “default” setting of the AUS device. You pump the device to open it. The pump is connected to the balloon and the cuff. When you squeeze the pump 2-3 times it sucks the fluid out of the cuff and pushes it up into the balloon, allowing you to urinate. The over-inflated balloon then wants to re-equilibrate the pressure in the system, thus re-inflating the cuff. But the fluid flows through a resister in the pump before it can get to the cuff. This resister slows down the fluid flow so that it takes about 1-2 minutes to fully re-inflate the cuff, giving you enough time to empty your bladder.
Thus, just like an external clamp on the penis, the AUS device does not make you urinate, it only blocks the leakage. Thus, when you pump the AUS open you still use your bladder muscle to empty the bladder naturally.
How the AUS Works
Pressure Regulating Balloon
Pump in Scrotum
Overview of the operation
It is composed of 3 parts: (1) a donut-shaped “cuff” that wraps around and compresses the urethra, (2) a balloon that pressurizes the cuff, and (3) a pump that controls the opening of the cuff. The cuff is implanted through an incision in the perineum, just like the sling. The cuff comes in various sizes and we measure the circumference of your urethra during surgery to see which size is right for you. The pump is implanted in the scrotum through an incision in the top of the scrotum. The balloon is implanted into the abdomen, either through the high scrotal incision or through a separate abdominal incision. All the components are connected to each other by tubing and filled with sterile saline. At the end of the procedure, the device is deactivated, and the man continues to leak. The scrotum would be too sore right after surgery to operate the device.
Risks of the AUS implant
The average lifespan of the device is about 7-8 years. When the device stops working, the man almost always becomes incontinent again; it is extremely rare that the device stops working in the “closed” position. About half of the failures are due to urethral atrophy and half are due to mechanical failure of the device. Urethral atrophy means that the urethra shrinks over time; much like a ring that is tight on one’s finger can lead to an hourglass deformity of the finger, the cuff squeezing the urethra for several years can lead to that part of the urethra shrinking. When we implant the AUS, the size of the cuff is chosen to match the size of the urethra; so, as the urethra shrinks over the years, the cuff becomes loose around the smaller urethra. When this happens, one will be able to squeeze the pump like normal, but the man will leak urine. Mechanical failure of the AUS is usually due to a hole developing in the cuff or the balloon and it leaking fluid. The fluid leak causes the AUS to lose its pressure. When this happens, the pump will not operate normally. The pump will either feel flat (or have a large dimple) all the time or will be very slow to fill (lose its dimple) after squeezing it. Urethral erosion occurs in about 5 % of men undergoing AUS surgery. Erosion means that the cuff wears a hole in the urethra. The cuff then gets infected by the urine. Sometimes this happens from having a catheter placed while the cuff is closed. Forcing the catheter through the closed cuff causes a tear in the urethra. It can also happen spontaneously, without catheter placement. Spontaneous erosion probably happens due to an unhealthy urethra (from radiation, older age or hormone therapy) that develops a hole in it after years of getting squeezed by the cuff.
Benefits of the AUS implant
AUS Implant is one of my favorite surgeries because the surgery takes less than an hour, the patient goes home the same day, and curing the urine leakage can have such a dramatic positive impact on a man’s quality of life. Urinary incontinence can prevent people from going out with friends, exercising, and enjoying much of life. An AUS can help a man reengage and live a happier life.
Most men can go home the same day as the operation. They will remain incontinent until they come back to clinic 3 weeks later to have the AUS activated. All the stitches are dissolvable.