What is Artificial Urinary Sphincter?
An artificial urinary sphincter is a device that prevents leaking of urine from the urinary bladder. It is placed through surgery in some patients with a condition called stress urinary incontinence.
The urinary tract in a normal person consists of the kidneys, ureters, urinary bladder and the urethra. Urine is produced by the kidneys, passes through the tube-like ureters and is stored in a muscular pouch called the urinary bladder. A muscular sphincter called the internal urethral sphincter located at the neck of the bladder, prevents the urine from leaking out. In addition, the pelvic muscles form an external sphincter, which supports the function of the internal sphincter.
When the bladder fills up, it sends signals via nerves and the spinal cord to the brain giving the person a feeling of fullness. When the person is ready to pass urine, the brain sends signals to the bladder to contract and the urinary sphincters to relax. The urine then passes through a small tubular structure called the urethra and the patient is able to empty the bladder. In females, the urethra is short but in males, it is relatively long and consists of three parts - the prostatic urethra which passes through the prostate, penile urethra which is located in the penis, and the short membranous urethra which connects the two. The penile urethra consists of the lower pendulous part, and the upper bulbous part.
Some people suffer from urinary incontinence. These individuals cannot control passing of urine. This results in urine leakage and possible embarrassment. There are three main types of urinary incontinence:
- Stress urinary incontinence: In stress urinary incontinence, leakage of urine occurs at times when pressure in the abdomen is increased, for example, during coughing, sneezing etc.
- Urge urinary incontinence: In this type of incontinence, leakage follows an urgent urge to empty the bladder.
- Overflow incontinence: This type of incontinence results in dribbling of urine once the bladder is full.
Which Patients Benefit from an Artificial Urinary Sphincter?An artificial urinary sphincter is found to be useful in cases of severe stress urinary incontinence that is not controlled by simpler methods such as tablets and exercise of the perineal muscles.
Stress urinary incontinence commonly occurs in males following surgical removal of the prostate for the treatment of prostate cancer. It can also occur rarely after endoscopic removal of prostate for benign conditions called transurethral resection of prostate (TURP).
Other causes of such incontinence include spinal cord injuries that interfere with signals to and from the bladder, or urethral injury due to pelvic fractures.
Artificial urinary sphincter is also used in females in cases of severe stress incontinence usually after a failed surgical procedure such as sub-urethral sling procedure.
What are the Types of Artificial Urinary Sphincters Available?Several models of artificial urinary sphincters have been manufactured over the years, with improvements introduced in newer models. The most commonly used model is marketed by the American Medical Systems and called AMS 800. This model has been tested extensively since 1980's and has stood the test of time with very low failure rates.
The AMS 800 consists of three main parts, an occlusive cuff that goes around the urethra, a balloon reservoir that is placed in the abdomen and a control pump that is placed in the scrotum in males or the labia in females. The components are connected through two tubing connectors.
The cuff is placed through an open surgical procedure around the urethra. It has fluid in it and when inflated it increases pressure on the urethra and keeps it closed. When the patient wishes to pass urine, he presses the control pump that is located at a convenient point under the skin. This allows the fluid in the cuff to move into the balloon reservoir, thereby releasing the pressure around the urethra and allowing the urine to flow out. The cuff refills on its own with fluid from the balloon reservoir within a few minutes.
Newer artificial sphincters like Flow-Secure, Periurethral Constrictor and ZSI 375 are also available.
The costs of these artificial sphincters are high especially as these may not be covered under some of the health insurance schemes. It is best to check in advance with the insurance provider before getting admitted to the hospital for such a surgery.
What Tests Should be Conducted Before the Procedure?A complete history from the patient and a physical examination are necessary before arriving at a decision to use the artificial urinary sphincter device in the patient. Tests done prior to the procedure include those that are routinely done before any surgical procedure, and those that will ensure that the patient will benefit from the surgery. The tests include:
- Routine tests like hemoglobin levels, blood counts, liver and kidney function tests, ECG for heart function etc. The urine should be tested for any infection.
- Ultrasound and cystoscopy to rule out any structural problems in the bladder. During cystoscopy, a telescope-like instrument is introduced in the urinary bladder, and its inner layer is inspected for any abnormalities.
- Urodynamic testing, which includes tests to evaluate the function of the bladder and the urinary sphincter. There are several types of urodynamic tests available like:
- Uroflometry which measures the speed and amount of urine passed
- A pressure flow study, which studies the pressure in the bladder required to generate urinary flow and the flow rate of the urine
- Voiding cystourethrography, in which a radio-opaque dye is inserted into the bladder, and images are obtained as the patient passes urine
What is the Procedure for the Surgical Insertion of an Artificial Urinary Sphincter?Before the surgical procedure, the patient should be explained everything about the device including how to use it.
The expectations of the patient should also be set; the patient should not expect to be 100% dry following the procedure.
Normal hospital stay can be 3 to 5 days for the procedure.
Antibiotics will generally be prescribed before the procedure to prevent infection.
Medications which prevent clotting of blood will have to be stopped on the advice of the doctor.
Overnight fasting is usually needed prior to the surgery.
The procedure is done under general anesthesia or spinal anesthesia. In spinal anesthesia, the anesthetic is injected into the back, and the patient cannot feel temporarily from waist downwards.
A Foley's catheter is introduced into the urethra.
The approach for the surgery may be through the perineal area, scrotum or the lower abdominal region. Some surgeries are performed through a single incision, while others require more than one incision.
The size of the cuff is determined using a cuff sizer that comes with the device. The cuff is placed either at the bladder neck or around the bulbous urethra.
The pressure regulating balloon is inserted in the lower abdomen. A pouch is created in the scrotum and the control pump is placed in it.
The individual components are connected with the tubing connectors, and the incisions are closed with sutures. The device is left in the inactivated state and should be activated only around six weeks after surgery, once complete healing has occurred.
What are the Post-operative Instructions that should be Given to the Patient?
The patient is instructed to come back around a week following the procedure if sutures have to be removed, and again around five to six weeks later so that the device can be activated. The patient is instructed on how to use the device and is also advised on regular follow-ups. He should carry an Identification Card indicating that he is using the device. This is important because, if catheterization of the urinary bladder is needed in the future, the device needs to be deactivated first.
What are the Benefits and Risks of Artificial Urinary Sphincter?The artificial urinary sphincter improves the quality of life of patient with stress urinary incontinence. The patient is saved from public embarrassment due to urinary leakage. However, the protection may not be 100% and the patient may require the use of a pad as well.
Possible adverse effects of artificial urinary sphincter include the following:
- Erosion of the urethra under the cuff
- Wearing off of the cuff
- Mechanical failure or incorrect size of the cuff, which may require revision surgery