Anatomy
 

The urinary bladder has a more or less spherical shape and is located, at the end of both ureters, down in the abdomen, right behind the pubic bone. The bladder can contain about 400 cc. of urine; while empty it is no larger than a tennisball. Both ureters enter the bladder from the sides. They actually go diagonally through the bladder wall, so they are being squeezed somewhat when the bladder fills; in this way a valve is formed that provides for a one-way flow, prohibiting reflux of urine from the bladder to the kidneys. The openings of the ureters is 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.

Although the bladder is located in the lower abdomen, it is essentially not a part of it: it has nothing to do with the bowels, while it is possible to open the bladder surgically without opening the abdomen. In the male, the anal canal 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 anal canal. The female urethra is, by the way, relatively short (since she doesn't have a penis): only an inch or so.

A couple of blood vessels are connected to the bladder from the sides, ensuring a wealthy blood supply, so that even a few blood vessels can be missed - for instance after an accident - without the bladder getting into trouble. The nerve supply is also abundant; a virtual network of nerve-bundles are connected to the bladder, while even quite a few nerve cells are present to be able to do some on-the-spot regulating of the function of the bladder. 

Functions
 

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. Therefore the bladder is needed for storage of urine, so that we humans do not lose urine all day long. Apparently, this was a feature in the human design needed to carry us through evolution; possibly we would have been easy prey for carnivores had it not been for our bladder to prevent the spreading of vast amounts of human scent.

A second important feature of the bladder is the voiding of stored urine once a suitable spot has been found to do that, i.e. a toilet. In order to get this done as quickly as possible, the bladder wall is equipped with muscle fibers, so that the bladder can shrink itself into the size of a tennisball. Emptying the bladder seems a simple feat, but isn't. Contrary to what many people think, it is not the action of the abdominal wall muscles that empties the bladder. Straining, i.e. using the muscles of the abdomen, is a rather inefficient way to void urine. Straining will enhance the pressure on the bladder contents and thus causes a more powerful flow of urine, but will also squeeze the bladder outlet and enhance the outflow resistance.

That is the reason why nature gave the bladder its own muscle. At the same moment, however, the sphincter around the urethra, that normally closes the outlet to prevent leaking, has to relax: if you don't open the tap, nothing will come out of it.
Fortunately, we do not have to think about those things while passing urine; everything is controlled by nerve cells in the spine and around the bladder. The sensitive spot in the bladder consists of the triangular area between the openings of the ureter and the bladder outlet, the trigone. Once this area gets stretched at a certain degree of bladder filling, your brain gets a signal that the bladder is going to need emptying.

The signals will get stronger while the bladder gets fuller; if you keep resisting (or, after a party will lots of alcohol, don't wake up) the control centre in the spine will take over and will start the voiding procedure: the bladder will empty itself completely. Babies always pass urine this way; it will take a couple of years before the child will have mastered to control the passing of urine. 

Diseases, Signs and Symptoms
 

Diseases of the bladder can be subdivided into a few categories:

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). Benign tumors also exist in the bladder, but they occur only in young adults. Bladder cancer normally shows itself because the fragile tissue often bleeds a bit, causing a redness of the urine. Although this should be an alarming sign, a lot of people do not visit their doctor when the 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 and the patient can be cured. It has a tendency to recur, however, so frequent controls are necessary for years.

If it is not treated in time, the cancer might start penetrating the bladder wall, and might also spread to other parts of the body, like the lymph nodes. This will make treatment more difficult.

The tissue on the inside of the bladder closely resembles the tissues found in the ureters and renal pelvis. X-rays of these organs will therefore also be part of the frequent checkups once a bladder tumor has been found to make sure that no tumor will be missed.

Cystitis.

An infection of the bladder is one of the more frequent sites of infections in humans. Bacteria can easily slip up into the bladder, especially in the female (who has a very short urethra). Normally, these bacteria are washed out of the bladder during voiding, but in some cases (low on drinking, a lot of bacteria, aggressive bacteria, low on resistance after an operation) an infection can arise. The bacteria are mostly coming from ones own bowels, but 'strangers' like gonorrhea can also cause cystitis. In the male, the cystitis is less common, since the urethra is longer and the bladder further away from the outside world. If a man does get an infection of the bladder, it often means that there is something else going on too: bladder stones, enlargement of the prostate, etc. In the male, a cystitis can easily lead to an infection of the prostate or an epididymitis.

Bladder stones 

​

They may originate as kidney stones, pass through the ureter and end up in the bladder although they can form in the bladder.. Compared to the bladder outlet and the urethra, these stones are relatively small and they will normally be washed out quickly, unless, for example, the prostate is enlarged and blocking the exit, so the stone gets stuck in the bladder and grows and can become quite large. Bladder stones are usually 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.

​

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
 

The bladder and its function can be investigated in different ways. Not all possible investigati ons are, of course, necessary. As a rule, the urologist will make a choice to be able to eliminate or confirm possible causes of the patients problems. It is a mistake to think that the latest invention in diagnostic tools will always be the best available. In certain cases additional information can be gathered from a 'new' test, but this is not always so; a CT-scan can be very useful to get an impression of the extent of a kidney tumor, but it can be very difficult to visualize a bladder tumor or a stone, while these are easy to find at cystoscopy.

A few possible examinations will be discussed here; there are more, but that would be impossible on this Page.

Is there an infection in the body (for example in the kidney, bladder or prostate)??To find this out, the sedimentation rate can be measured and the number of white blood cells (leukocytes).

How about the matter that circulates in the blood and which, in high concentrations could give cause to stone formation? Like urate and calcium.
 

Urine

​

Is there an infection of the bladder present? It is often impossible to find out where the infection is located (kidneys, bladder, prostate). However, sometimes an infection of the kidneys will give itself away because of the enormous amount of white blood cells in the urine. An infection of the bladder is generally less obvious in the urine.

Are red blood cells present in the urine? This could happen in cases of infection, but can also be a sign of cancer of kidneys or bladder.

Is there a lot of calcium or urate (or another known stone-forming substance) in the urine, giving a higher chance on bladder stones?

How about the acidity of the urine? Urine should be slightly acid, which serves as a barrier against infections.

Imaging

 

X-rays.

 

On a normal X-ray a bladder stone is often visible. The bladder itself is usually not visible.

 

Cystogram

During a cystogram the bladder is filled (through a catheter) with a liquid that will show on an ordinary X-ray. Large bladder tumors will be visible in this way, while, after emptying the bladder, it will show whether the bladder is really empty. When an IVU (intravenous urogram) is made, a cystogram is included 'for free'.

Ultrasound

 

Using ultrasound the bladder can be seen very well by way of ultrasonic sound waves (so you cannot hear nor feel them). Also other organs, like the uterus in females, can be seen. The size of the bladder and the quality of emptying can be measured, while bladder stones and large tumors can be visualized.

Cystoscopy 
This means looking into the urethra and bladder using a small tube, 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 in one go. One does also get an impression of the quality of the bladder muscles.

 

Urodynamics

A urodynamic examination is necessary to test the function of the bladder.The bladder is first emptied through a catheter. After another small catheter is inserted into the bladder, it is filled, very gently, with water, while, at the same time the amount of water flowing in an the bladder pressure is measured. In this way information is gathered about the bladder capacity, the sensitivity and the way the bladder is emptied again.

The examination is important to get information about the condition the bladder is in (which is important for the prediction of the outcome of an operation of the prostate) and to find the cause in cases of incontinence.

Treatment 

It is impossible to present all possible therapeutic options for all diseases of the bladder. More frequent forms of treatment will be mentioned.

Cystitis.
Treatment depends on the nature, i.e. cause of the cystitis. If only a cystitis is present, then treatment should be instituted using antibiotics, if possible focussed on the type of bacteria causing the disease. In some cases there is more going on. A bladder stone, impregnated with bacteria, could be present, in which case the stone should also be treated. Or there might be an obstruction of the bladder outlet, because of prostatic enlargement or a urethral stricture. In these cases a residue of urine will often be left in the bladder after voiding, enhancing the chance of recurring infection.
In cases of concurrent prostatitis an intermittent cystitis frequently exists.

Too low an acid content of the urine can also cause recurrent infections.
A frequent cause of infection of the bladder is insufficient urine production, for instance in hot weather. If this cleaning mechanism of the bladder is interrupted, for example because of loss of water in the form of sweat, the bacteria will not be flushed out of the bladder often enough and will get time to multiply.

Bladder stone.
If the stone is not very large (an inch or so) it will generally be possible to crush it by using the cystoscope and flush out the debris. This is not a suitable method for very large stones, which can better be removed during a 'conventional' operation. It should be borne in mind that there might be a cause for the bladder stone, like kidney stones or an enlarged prostate, which should then also be treated.

Bladder Cancer.
 

The treatment of bladder cancer is very much depending on the size of the tumour and whether it is still confined to the inside of the bladder wall or not. The presence of tumor spread to other parts of the body also influences the choice of therapy. If the tumour is confined to the inside of the bladder wall, it can usually be removed by cystoscope through the urethra (TURBT: TransUrethral Resection of Bladder Tumour); afterwards only a small scar will mark the spot. Frequent checkups by cystoscopic examination will be necessary to be able to detect and to remove recurrent tumour early in its development.

If the tumour has grown into the bladder wall, it is generally impossible to remove it through the cystoscope. In those cases, an operative procedure will be necessary to remove a part of the bladder containing the tumour. Often the bladder as a whole will need to be removed and the ureters will be connected to the skin (stoma) via a small isolated part of the small bowel. Occasionally , the bladder can be replaced and reconstructed using bowel. This type of operation is quite demanding on the general health of the patient and will only be done if he or she can take it. If not, radiotherapy can be an alternative. In certain cases additional therapy with chemotherapy or a combination of surgery and radiotherapy may be the best choice.

If tumours recur frequently, frequent rinsing of the bladder with certain chemical agents will often help, although it may not completely cure the tumour.

Incontinence.

The treatment of incontinence also depends on the cause of the disease. If caused by a highly sensitive bladder (there is a problem in postponing urination and the voiding frequency is high), the probable solution will be medical: some medicines will calm the bladder down. If caused by an insufficient sphincter, the there is a choice. Either exercising the sphincter, which will take time and effort of the patient, and will frequently be done under the guidance of a physiotherapist.

If it helps, the effect will last a long time. Or a surgical approach, in which the tissues surrounding the urethra will be stretched tight. The effect will be instantaneous right after the operation, but it does not last forever and will often need a re-do after 5-7 years or so. A lot of patients still opt for a surgical approach, probably because it is easier and gives quicker results. 

Further Reading

The Inner Body - The Urinary Bladder

​