The function of the bladder is to stores urine that is produced by the kidneys. A normal bladder is highly compliant and able to store up to 500 ml of urine. Overactive bladder is a problem with bladder storage that causes a sudden urge to urinate due to an involuntary contraction of the bladder muscle. The urge may be difficult to control voluntarily, and overactive bladder may lead to the involuntary loss of urine (incontinence). Overactive bladder is also associated needing to urinate often during the day and at night.
Overactive bladder can lead to a lot of emotional distress and embarrassment, especially when it occurs during social interactions and work schedules.
Overactive bladder affect both men and women and the incidence increases with age. The prevalence of this condition has been found to be approximately 16%.
Overactive bladder is caused by the involuntary contraction of the bladder detrusor muscles. Most of the time there is no specific cause for this condition (Idiopathic overactive bladder). Sometimes this condition can be caused by serious conditions such as:
Overactive bladder is worsened by increased fluid consumption, alcohol, caffeine intake and spicy and acidic foods.
Your doctor will look for clues that might also indicate the contributing factors. These may include urine samples to test for infection, blood and cancer cells and imaging of the bladder with either an ultrasound or CT scan. A cystoscopy, where a small tube with a camera and light is introduced into the bladder, may be required to examine the inside of the lower urinary tract to rule out bladder cancer, especially if there is blood in the urine or there are risk factors for bladder cancer.
Urodynamics may be required to confirm the presence of overactive bladder. This is confirmed by the presence of phasic involuntary bladder muscle contractions which is detected by small pressure monitoring catheters placed into the bladder and rectum. Urodynamics will also obtain other important information about the bladder including the bladder compliance, sensitivity, emptying and whether there are other contributing factors such as obstruction at the level of the bladder opening.
To treat an overactive bladder, your doctor will first suggest behavioural modifications such as pelvic floor exercises, maintaining a healthy weight, controlling fluid intake, scheduled regular voiding and bladder retraining.
Apart from the general behavioural changes, there are medications that dampen and inhibit involuntary contractions of the bladder detrusor muscle. There are several groups of these medications that act on the sympathetic or parasympathetic nervous supply of the bladder to relax the bladder. Possible medications available in Australia include Ditropan, Oxytrol patches, Enablex, Vesicare and Betmiga.
Injections of Botox into the bladder muscle may benefit people who have an overactive bladder that does not respond to other first line medications. Botox last between 3-9 months, and repeat injections is required.
Other possible treatment options include sacral neuromodulation and bladder augmentation.