Urge incontinence is the urgent need to pass urine due to untimely contractions of the bladder muscle (detrusor). This occurs day and night, often leading to the passing of urine before the sufferer can reach a toilet. The condition affects women more often than men, and though urge incontinence is less common than stress incontinence, a number of older women suffer from both forms. Treatment ranges from retraining the bladder to medication to relax the bladder muscle and, in severe cases, surgery to increase the bladder's size.
Why Does It Happen?
There are two ways in which urge incontinence may occur:
Detrusor instability – the bladder muscle is unstable and contracts inappropriately, often before the bladder has had a chance to fill. This may be caused by an injury to the spine (leading to altered nerve control of the bladder), by overflow incontinence due to retention of urine1, or by prostate enlargement or inflammation, but in many cases there is no obvious cause.
Sensory incontinence – pain occurs when the bladder is part full, leading to an urgent need to empty it. This pain may be due to urinary tract infection, but in some cases no infection is found.
A detailed history, examination of the vagina in women, and examination of the back passage in both sexes will help to rule out underlying causes of incontinence. Particular attention is paid to urinary tract infection, other bladder problems, the function of the nerves that supply the bladder and 'saddle' area2, and medical conditions and medications that may cause incontinence. Several tests may be performed, and these are detailed in the entry on Stress Incontinence.
Dealing With Urge Incontinence
The simplest form of treatment is bladder retraining, which involves slowly increasing the time between toilet trips. Bladder retraining can be difficult and is best achieved with specialist help, but if successful, which it is in around 85% of cases, it will allow the bladder to contain more urine before the need to pass urine is triggered. Pelvic floor exercises may also help, and are detailed in the entry on Stress Incontinence.
Besides antibiotics for the treatment of urinary tract infections, there are a handful of drugs that may help urge incontinence. The anticholinergic drug oxybutynin can be used to reduce the activity of the bladder muscle, but is often accompanied by side effects such as a dry mouth, blurred vision and constipation. Other medications may also be used, but no medical treatment exists that will completely cure the condition.
In severe cases of urge incontinence that do not respond to medication, surgical interventions may be used. Injection of botulism toxin into the bladder during cystoscopy3 is thought to be effective in around half those treated, with the effect lasting for at least six months. A severely unstable bladder may be cured by a clam ileocystoplasty, a complicated operation in which a section of bowel is cut out while maintaining its blood supply, the bladder is opened like a clam, and the bowel is sewn on to enlarge the size of the bladder. Relatively new possibilities for treatment include electrical stimulation of the sacral nerve via a small pacemaker-like device implanted beneath the skin, and weekly electrical stimulation of the posterior tibial nerve without an implant.
1 Overflow incontinence occurs when urine is retained in the bladder to the point that it is suddenly passed without any feeling of urgency. Overflow incontinence can alter the bladder's perception of fullness, leading to urge incontinence later on.
2 That is to say, the nerves that provide sensation to the area with which one sits upon a saddle.
3 Cystoscopy consists of the dilation of the urethra so that a camera and instruments can be passed through it via a thin tube.