Picture of the bladder
The urinary bladder is a muscular sac in the pelvis, just above and behind the pubic bone. When empty, the bladder is about the size and shape of a pear.
Urine is made in the kidneys, and travels down two tubes called ureters to the bladder. The bladder stores urine, allowing urination to be infrequent and voluntary. The bladder is lined by layers of muscle tissue that stretch to accommodate urine. The normal capacity of the bladder is 400 to 600ml.
During urination, the bladder muscles contract, and two sphincters (valves) open to allow urine to flow out. Urine exits the bladder into the urethra, which carries urine out of the body. Because it passes through the penis, the urethra is longer in men (20cm/8in) than in women (3.8cm/1½in).
- Cystitis: Inflammation or infection of the bladder causing pain or discomfort.
- Urinary stones: Stones (calculi) may form in the kidney and travel down to the bladder. If calculi block urine flow through the bladder, they can cause severe pain.
- Bladder cancer: A tumour in the bladder is usually discovered after blood is noticed in the urine. Cigarette smoking and workplace chemical exposures cause most cases of bladder cancer.
- Urinary incontinence: Involuntary urination, which may be chronic, is known as urinary incontinence. It can result from a variety of causes.
- Overactive bladder: The bladder muscle (detrusor) contracts involuntarily, causing some urine to leak out. Detrusor overactivity is a common cause of urinary incontinence.
- Haematuria: Blood in the urine is referred to as haematuria - it may be benign, or may be caused by a serious condition such as bladder cancer.
- Urinary retention: When urine does not exit the bladder normally due to obstruction or suppressed bladder muscle activity, the bladder may swell to hold more than a litre of urine.
- Cystocele: Weakened pelvic muscles (usually from childbirth) allow the bladder to press on the vagina, and problems with urination can result.
- Bed-wetting (nocturnal enuresis): Bed-wetting is defined as recurrent involuntary passage of urine during sleep by a child five years of age or older who has never achieved night-time dryness.
- Dysuria (painful urination): This is pain or discomfort during urination that is usually due to infection or inflammation of the bladder or external genitals.
- Urinalysis: This basic test on a sample of urine is done when looking for problems of either the bladder or kidneys. Urinalysis may also be performed to help in the diagnosis of other conditions such as diabetes mellitus or pregnancy. The first part of the test is a dipstick urinalysis, which uses a test stick impregnated with chemicals. When the stick is dipped into urine, the chemicals change colour based on the substances in the urine. If this is abnormal the urine should be looked at under a microscope and tested in a laboratory.
- Cystoscopy: A narrow tube is passed through the urethra into the bladder that has a light, camera and other tools to allow a doctor to diagnose and treat bladder problems.
- Urodynamic testing: A series of urination tests, usually done in a hospital out-patient department, that check urine flow, pressure, bladder capacity and other measurements, which can help identify bladder problems.