What causes OAB?
Under normal circumstances, urine, which is made in the kidneys, drains into the bladder and the bladder is relaxed, so as it fills it expands like a balloon. During this time, urine is prevented from flowing out of the bladder by the muscles of the urinary sphincter and pelvic floor.
When the bladder is full and you want to pass urine, the muscles at the bladder outlet relax and the bladder contracts, so that urine flows out of the urethra and the bladder is emptied.
In people with OAB, the bladder contracts abnormally and frequently, so that there is a feeling of needing to pass urine even though the bladder is not yet full. The bladder contractions may also force urine out of the bladder, especially, if for any reason, the muscles at the bladder outlet are weak.
Because normal bladder function is dependent on many factors, including proper communication of the nerves with the central nervous system and proper functioning of the bladder and urinary tract itself, there are a number of factors that may cause or contribute to symptoms of OAB. Some medications may also contribute to symptoms of OAB.
Examples of factors that may cause or contribute to symptoms of OAB are listed below.6
| Conditions of the lower urinary tract | Conditions of the nervous system | Other illnesses | Functional or behavioural conditions | Medications |
|---|---|---|---|---|
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Adapted from Floridashealth.com7
Factors that may be associated with an increased risk for OAB and/or incontinence include:1,5
- Obesity
- Chronic cough
- Previous pregnancy and childbirth
- Having had a large baby, or a forceps or breech delivery
- Previous urinary tract or gynaecological surgery
- Constipation
- Older age
