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The urinary bladder is part of the urinary system, it collects urine that flows from the kidneys constantly, and after filling it is responsible for its removal. It is worth learning the basics of its structure and physiology, as well as finding out how to diagnose bladder diseases and what are the most common ailments associated with it.

The urinary bladderis a part of the urinary system, which is a muscular sac that can significantly enlarge its size and actively remove accumulated urine.

The capacity of the bladder is from 250 to 500 ml, and in extreme cases it can extend to more than 1 liter.

The bladder is located in the pelvis, behind the symphysis pubis, in front of the uterus in women, and in the rectum in men.

The empty bladder is pyramidal in shape and fits completely into the pelvis, becomes more spherical as it inflates and moves to the abdominal cavity.

Bladder: macroscopic structure

In anatomical structure, we distinguish the following structures of the bladder:

  • top of the bladder - this is the top of the pyramid, facing the pubic symphysis, this is where the median umbilical ligament begins, the developmental remnant of the ureter, it runs along the inner abdominal wall to the navel
  • inferior-lateral surfaces adjacent to the pelvic floor muscles
  • the upper surface facing the abdominal cavity is covered with the peritoneum
  • bottom of the bladder - it lies on the muscles of the pelvic floor, its inner surface is smooth, at the bottom of the bladder there are ureteral openings that drain urine from the kidneys and the inner urethra, i.e. the place of further outflow - these three structures form the apexes the so-called bladder triangle; the bottom of the bladder rests on the prostate gland in men, and on the genitourinary triangle in women
  • the bladder neck is the passage into the urethra, surrounded by fibrous-muscular bands that run to the coccyx and hold the bladder in place - these bands are called pubic-bladder and pubic-prostatic ligaments

The peritoneum from the upper surface passes posteriorly to the anterior surface of the rectum, creating the recto-bladder recess, which is the lowest abdominal recess in men. In women it is the vesico-uterine cavity, i.e.transition of the peritoneum from the bladder to the anterior surface of the uterus.

Vessels reaching the bladder come from the internal iliac artery and they are: the umbilical artery and its branch - the superior bladder artery, as well as the inferior bladder artery and the vaginal artery in women. The outflow of blood takes place through the veins of the bladder plexus to the internal iliac vein.

Nerve fibers run to the bladder from the lower abdominal plexuses and form the so-called bladder spot. Sympathetic fibers come from the sacral ganglia of the sympathetic trunk and run through the inferior mesenteric ganglion and through the hypogastric nerves. Their task is to inhibit the outflow of urine by contracting the internal urethral sphincter.

Parasympathetic innervation comes from the S2-S4 segments of the spinal cord, runs along the pelvic nerves and is responsible for the excretion of urine by the contraction of the bladder muscle. Feeling is caused by the nerves entering the spinal cord at L1 and S2 levels.

The location of the bladder and the fact that with the filling it begins to protrude above the symphysis pubis allows, if catheterization is not possible, to puncture the bladder above the symphysis pubis without disturbing the peritoneum and thus evacuating residual urine.

Bladder: microscopic structure

The wall of the bladder is 2 to 10 mm thick, depending on the filling, and consists of 3 layers:

  • Mucosa and submucosa

The mucosa and submucosa are covered with multilayered transitional epithelium, it is very characteristic and occurs only in the urinary tract. A special feature is the presence of umbellate cells, which form the top layer and cover several cells underneath, another name for it is the urothelial epithelium.

The entire inner surface of the bladder, with the exception of the aforementioned bladder triangle, is folded, particularly strongly around the ureteral orifices.

Mucosa folds act as valves preventing the return of urine to the ureters, they are constructed in such a way that the more the bladder is filled, the more they stick to the ureters, but never block the flow of urine to the bladder.

  • Muscle membrane

The muscle membrane has three layers: longitudinal: inner and outer and middle circular, they are not strictly separated from each other, the muscle fibers rather interpenetrate.

The entire bladder muscle is called the bladder detrusor muscle, which is responsible for emptying the bladder, and the thickened part around the inner opening of the urethra - the internal urethral sphincterurinary.

Each of these components is innervated separately and under normal conditions, when one of them contracts, the other must be relaxed.

  • Outer membrane and peritoneum

Urinary bladder: physiology and role of the bladder

Urine is produced by the kidneys in the amount of approx. 1 ml / kg / h, which is an average of more than 1.5 liters per day, then flows through the ureters to the bladder, where it is stored, and then removed.

Urine draining from the ureters does not increase the pressure in the bladder in direct proportion to its volume, because the structure is stretchy.

The characteristic feature is the plasticity of the bladder muscles, i.e. initially, during filling, tension is created and a slight urge to urinate is felt, as the bladder volume increases, this tension and the need to urinate disappear, and the pressure remains constant.

Only after exceeding a certain volume, usually around 400ml, pressure increases and nerve fibers sensitive to stretching transmit a stimulus to the brain, which is interpreted as the need to empty the bladder.

During urination (voiding), the urethral sphincter and perineal muscles relax, and the urinary detrusor muscle contracts, so it is an active process.

The bladder has the following roles, resulting from its construction:

  • urine collection
  • urine output
  • preventing the flow of urine into the ureters

Diagnostics of bladder diseases

In the case of suspected abnormalities of the bladder, we have a wide range of tests to check both its function and structure. The most frequently used tests are:

  • cytometry - evaluates the relationship between bladder volume and intravesical pressure
  • uroflowmetry - assesses the efficiency of the detrusor muscle and its synchronization with the relaxation of the urethral sphincter
  • voiding cystography - after administering the contrast to the bladder, the examined person must urinate, during which time a series of X-rays is taken, which can assess both the contours of the bladder mucosa and the presence of any obstacles in the outflow of urine
  • assessment of residual urine after voiding
  • cystoscopy - in this examination, the doctor looks at the inside of the bladder by inserting a small camera through the urethra, and can also perform minor procedures this way
  • abdominal ultrasound - during this examination, a visual assessment of the bladder is possible, but it is necessary that it is filled for examination
  • computed tomography and magnetic resonance imaging of the cavityabdominal and pelvic - tests performed less frequently, however, allow for an accurate assessment of the anatomy of the bladder
  • urine general examination - enables the evaluation of the presence of protein in the urine, the initial diagnosis of haematuria, and is also used in the case of infection
  • urine culture - a test for complicated and recurrent infections

Read also:

  • Urodynamic examination - what does it look like? How to prepare?

Diseases of the bladder

There are several groups of bladder diseases: birth defects, infections, cancer and functional disorders.

  • What does a visit to the urologist look like?

Some diseases, such as urinary incontinence, although closely related to the bladder, are the result of disorders of its innervation rather than diseases of this organ itself. Similarly, urolithiasis, deposits are formed in the kidneys, their presence in the bladder does not indicate its pathology, it is the result of the process of stone excretion.

  • Birth defects

The congenital anomalies include: - bladder malformation - this is most often a fatal defect, because it prevents urine drainage, which causes kidney failure - bladder eversion - this is the lack of the front wall of the bladder and integuments, the bladder is then open to the cavity amniotic, the defect is surgically correctable under appropriate conditions - bladder diverticula - it is a mild defect, usually asymptomatic

  • Bladder infections

Urinary tract infections affect not only the bladder, but also the urethra and kidneys. The latter are especially dangerous and can even be life-threatening. Urinary tract infections related to the bladder include:

  • uncomplicated cystitis
  • asymptomatic bacteriuria
  • non-bacterial cystitis
  • recurrent cystitis in a woman
  • urinary tract infection in a pregnant woman

Urinary tract infection is the presence of microbes in the urinary tract above the bladder sphincter, which should normally be sterile.

Bacteria can exist physiologically only in the urethra, in order to maintain this state, our body has developed a number of defense mechanisms, such as appropriate urine reaction, removal of urine remaining in the urethra, or specific epithelium.

Urinary tract infections are much more common in women, mainly due to the shorter urethra.

  • Bladder infections in women

The pathogens that cause cystitis arethe most common bacteria:Escherichia coliandStaphylococcus saprophyticus , less frequentlyChlamydia trachomatis ,Neisseria gonorrhoeaeand viruses, especially fungi.

The presence of microorganisms can be demonstrated in a general urine examination or in the urine culture, however, most often a urinary tract infection is diagnosed on the basis of an interview and a medical examination.

Treatment is based on the elimination of microorganisms from the urinary system, most often with the use of an antibiotic, and by appropriate support of own immune mechanisms, such as acidification of urine, frequent voidions to prevent urinary retention and the development of pathogens in the bladder.

It is also very important to treat risk factors, e.g. urinary tract defects and prevent infections, which include: increasing the amount of fluids drunk, urinating immediately after feeling pressure, using Lactobacillus preparations and antibiotic prophylaxis in the case of very frequent relapses .

  • Uncomplicated cystitis

Uncomplicated cystitis is an infection that occurs in a woman who has a normal urogenital system, without disturbing defense mechanisms.

Symptoms are pollakiuria, burning and pain when urinating, sometimes hematuria.

The treatment is antibiotic therapy.

Recurrent cystitis occurs in about 15% of women and is usually temporarily related to sexual intercourse. The basis of the procedure is prophylaxis.

  • Complicated urinary tract infection

This is any urinary tract infection in a man or woman with impaired urinary outflow (anatomical or functional) or in a woman with impaired defense mechanisms.

Risk factors are: urine retention, diabetes, urolithiasis. It manifests itself similarly to uncomplicated, but each such diagnosis requires thorough diagnostics.

Depending on the severity of the disease, treatment is carried out on an outpatient basis or in a hospital, first of all, the infection should be eliminated, and then, if possible, risk factors should be removed.

  • Non-bacterial cystitis

The so-called non-bacterial cystitis manifests itself typically for urinary tract infections.

The most common causes are fungal and chlamydial infections, standard tests do not allow the determination of the infectious agent. Appropriate antimicrobial treatment is used in the therapy.

  • Asymptomatic bacteriuria

It occurs when, despite the presence of a certainincreased amount of bacteria there are no symptoms of infection. This condition does not require treatment, except for pregnant women and people who undergo urological procedures.

The presence of a catheter in the bladder is also associated with a higher risk of infectious complications.

The mere presence of bacteria in the urine of a catheterized person is not an indication for treatment, as removal of the catheter clears the infection. Therapy is started in the event of symptoms.

  • Bladder tumors

The most common growths in this organ are papilloma and bladder cancer.

The first one is a benign neoplasm originating in the transitional epithelium, manifested by hematuria. Treatment consists of removing the papilloma, usually by cystoscopy, but unfortunately it tends to recur.

Bladder cancer is malignant, just as papilloma comes from the epithelium that lines the urinary tract.

Symptoms are: hematuria, pollakiuria, painful urge to urinate, urinary retention.

Cystoscopy with specimen collection allows you to make a reliable diagnosis, imaging tests with computed tomography allow you to assess the advancement of the neoplasm.

Surgical methods are the procedure of choice in this diagnosis, depending on the stage, you can perform transurethral radical electroresection of the tumor or radical cystectomy (removal of the bladder with surrounding organs), in the most advanced cases the treatment is radiotherapy or chemotherapy.

  • Functional disorders

Malfunctioning of the bladder is most often caused by damage to its innervation, which leads to contraction disorders.

Depending on which fibers are broken, the bladder becomes either stretched and shrinks poorly or shrunken with overgrown walls.

In the case of spinal cord rupture, the detrusor muscle and the urethral sphincter are simultaneously paradoxically stimulated, i.e. two opposite reactions, resulting in a smaller bladder and a thicker wall, this condition is called spastic bladder of neurogenic aetiology.

One of the bladder innervation disorders is the so-called overactive bladder, in its course there are mainly urgent pressures, i.e. a sudden, unrestrained urge to urinate resulting from too high nervous excitability of the detrusor muscle, as a result of urgent pressure there are also pollakiuria and urinary incontinence.

  • Interstitial Cystitis

This diagnosis is made afterexclusion of other causes of pelvic pain, e.g. bacterial cystitis or kidney stones.

Pain in the pelvic region while filling the bladder is characteristic for interstitial cystitis, but it subsides when emptying the bladder, moreover, there is pollakiuria and small amounts of urine.

The onset of the disease is sudden, then the symptoms disappear and then recur again after a few months. The cause of the disease has not been clearly defined so far, so treatment of this ailment is difficult.

Sometimes interstitial cystitis is treated as a group of symptoms rather than a separate disease entity.

  • Urinary incontinence

As already mentioned, urinary incontinence is not always associated with abnormal bladder function. There are many reasons:

  • obesity
  • traumatic births
  • hormonal disorders
  • operations
  • comorbidities, e.g. diabetes

There are three basic types of urinary incontinence:

  • exercise
  • urgent pressures (mentioned earlier)
  • overflow incontinence

The first of them is caused by the insufficiency of the urethral sphincter and is manifested by urinating (even small amounts) during exercise, coughing, laughing, the bladder muscle function is normal here.

Overflow incontinence is caused by an outflow obstruction, such as an enlarged prostate. The bladder is full and stretched, and urine leaks out unknowingly.

Urinary incontinence can also be temporary and result from urinary tract infections or side effects of medication.

Rare bladder diseases are fistulas or detrusor failure.

The urinary bladder, despite its seemingly simple structure, is quite a complex organ with a number of adaptation mechanisms to its role.

It is very important in the process of urine excretion, being responsible not only for its storage in appropriate, pathogen-free conditions, but also actively involved in the process of voiding.

Diseases of the bladder are very common, such as infections in women.

Urinary incontinence, on the other hand, is not always a disease of the bladder itself, but it is nevertheless extremely troublesome and often it is impossible to completely eliminate the problem.

The scale of this ailment is very large, it is estimated that even half of women over 65 have this problem.

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Category:

Urology and Nephrology