The urinary bladder is a muscular bag which has a more or less spherical "balloon" shape and is located at the end of both ureters, low down in the abdomen, behind the pubic bone. The bladder normally contains about 400 cc.(12oz) of urine. Both ureters diagonally pass through the bladder wall being squeezed when the bladder fills prohibiting reflux of urine from the bladder to the kidneys. The openings of the ureters are located near the bladder outlet. A triangle is thus formed between the two ureteral openings and the bladder outlet, which is the beginning of the urethra. In the male, the rectum (lower bowel) is right behind the bladder and the prostate is located right under the bladder, around the urethra. In the female the uterus and vagina lie in between the bladder and the rectum. The female urethra is relatively short - only an inch or so, opening between the labial lips. Bladder awareness and emptying are regulated by nerves which are connected to the brain through the lower spine.
Function (What does it do?)
The urinary bladder is a rather simple organ. The urine, produced by the kidneys, is transported by the ureters towards the bladder to be stored there. A second important feature of the bladder is the voiding of stored urine once a suitable place and time has been found. In order to get this done as quickly as possible, the bladder wall is equipped with muscle fibers which contract to pull open the bladder neck and expel urine into the urethra. At the same moment the sphincter muscle around the urethra, that normally closes the outlet to prevent leaking, relaxes and urine flows out of the urethral opening. Fortunately, we do not have to think about those things while passing urine; everything is controlled by nerve cells in the brain, the spine and around the bladder. Stretching of the bladder wall gives the brain a signal that the bladder is going to need emptying. Normally, the brain is able to suppress the bladder contraction until it is convenient to void.
Disease, Signs and Symptoms (what can go wrong?)
Diseases of the bladder can be subdivided into a few categories:
1. Diseases of the bladder itself.
Bladder cancer:
In bladder cancer the tumor arises on the inside of the bladder wall. These tumors are often formed like a mushroom (with a small stem). Bladder cancer normally shows itself because the fragile tissue often bleeds, causing redness of the urine. Although this should be an alarming sign, a lot of people do not visit their doctor when they observe a red discoloration of the urine; unfortunately the bleeding often stops by itself and the urine might not show anything wrong for several weeks or months - the tumor will however not stop growing. While the cancer remains confined to the inside of the bladder wall, it can normally be removed surgically via a cystoscope and the patient can be cured. This condition has a tendency to form new tumors because it is thought that they are caused by an agent (carcinogen) in the urine. Some types of bladder cancer may penetrate the bladder wall, and spread to other parts of the body. This makes treatment more difficult.
Cystitis:
Bladder infections occur commonly in humans. Bacteria can easily move up into the bladder, especially in the female (who has a very short urethra). Normally, these bacteria are flushed out during voiding; but in some cases (low oral fluid intake, aggressive forms of bacteria, after sex and lowered immunity states) an infection can arise. The bacteria mostly come from the bowel, colonizing the genital area and the urethral opening. In the male, cystitis is less common, since the urethra is longer and the bladder further away from the outside. An infection of the bladder in males, is often associated with bladder stones, enlargement of the prostate, scarring with narrowing of the urethra and other abnormalities of the urinary system. Cystitis can easily lead to an infection of the prostate (prostatitis) or epididymitis.
Bladder Stones:
They may originate as kidney stones, passing down the ureter into the bladder. Usually, these stones are small and will be washed out quickly, unless, for example, the prostate is enlarged and blocking the exit, so that the stone lodges in the bladder and grows. Bladder stones are found more in men. A bladder stone can be impregnated with bacteria, causing a persistent infection of the bladder, that will only be cured after removal of the stone.
2. Diseases concerning bladder function.
On the one hand, the bladder muscle can be too weak, causing incomplete emptying of the bladder during voiding. On the other hand, the bladder might get too active, causing frequent urination or incontinence (or the bladder sphincter might be too weak, which can also cause incontinence).
Examinations (What can we check?)
Routine urinalysis: A simple dipstick coated with different reagents can analyze many substances found in the urine in a minute or less. This includes a urine acidity test, a check for protein, sugar, red and white blood cells. More specialized dipstick tests can determine abnormal function of the liver and can indicate abnormal cell constituents which may indicate a tumor in the urinary tract. Microscopic examination of the urine takes about five minutes to perform and this can determine the presence of infection, bleeding or excess crystals in the urine seen in some stone formers.
Urine cytology: The urine sediment is examined by a Pathologist by special techniques and stains to check for abnormal cells which may uncover a tumor.
Xrays: A bladder stone is often visible on a plain X-ray. The bladder itself is usually not visible.
During a Cystogram the bladder is filled (through a catheter) with a liquid that will show on an ordinary X-ray. The size, shape, supports, degree of emptying and reflux of dye up the ureters can be determined.
A CT or MRI scan is very useful to examine the tissues of and around the bladder and may be performed if other more simple tests are insufficient to diagnose a particular problem.
Using Ultrasound the bladder can be seen very clearly. Also other organs, like the uterus and ovaries may be seen. The size of the bladder and the quality of emptying can be measured, while bladder stones and large tumors may be visualized.
Cystoscopy means looking into the urethra and bladder using a small telescope, which can be made of metal (rigid) or plastics (flexible). This is perhaps the most important examination of the bladder, since even very small bladder tumors or stones can be found, while the urethra and prostate can be inspected.
A Urodynamic examination may be necessary to test the function of the bladder. The bladder is first emptied through a catheter. Another small catheter is inserted into the bladder, filling it with water or gas, while, at the same time the bladder pressure is measured. In this way information is gathered about the bladder capacity, the sensitivity of the bladder and an assessment of the continence(the ability to hold urine) mechanisms. This examination is important to get information about the condition of the bladder and is a predictor of the outcome of surgery to restore continence.
What is Urology?