Overactive Bladder Syndrome
What is the bladder?
The bladder is the organ which stores urine produced by the kidneys. It is a muscle in the shape of a bag which can hold a maximum of around 500 millilitres of urine (Fig. 1a and b).
Most people start feeling their bladder is filling when it is half full. In order to empty the bladder, you have to be able to relax. This usually means being in a socially convenient environment, such as a toilet or a private space. The brain will then send a signal to the bladder to start squeezing out the urine.
How often you urinate depends on many factors, but in particular how much you drink. Most people urinate less than 8 times during the day and either not at all or once during the night.
What are overactive bladder symptoms?
Overactive bladder symptoms (OAB) are a collection of urinary storage symptoms. Storage symptoms include:
- The sudden need to urinate and having trouble postponing it
- Any involuntary loss of urine
- The need to urinate more often than usual
- The need to wake up at night to urinate
OAB symptoms are common and can affect both men and women. Between 10 and 20% of people suffer from it at some stage in their lives.
What causes overactive bladder symptoms?
OAB symptoms can have various causes:
- Some people experience sudden and spontaneous contractions of the bladder muscle
- Some people are more sensitive to the feeling of their bladder filling
- In some cases the kidneys produce too much urine at night, which causes nocturia. This may be related to older age or medical conditions which result in more urine being produced at night
- Some people have a smaller bladder which is filled to capacity more quickly, but this is not very common
Terms your doctor may use
- Urgency is a sudden need to urinate which is difficult to postpone. This may be because of fear of urine leakage. It is the most important symptom of OAB.
- Urgency incontinence is leakage of urine which may happen if you cannot reach a toilet in time.
- Urinary frequency is the need to urinate more often than usual, generally more than 8 times a day.
- Nocturia is waking up once or more per night because of the need to urinate.
- LUTS (lower urinary tract symptoms), is a term used for the collection of symptoms which can point to a number of diseases affecting the urinary tract.