Palpation of the Urinary Bladder-Bladder Distention-Urinary Retention-Suprapubic Aspiration-Cystoscopy-Bladder Injuries-Difficulty with Micturition after Spinal Cord Injury-

Palpation of the Urinary Bladder

The full bladder in the adult projects up into the abdomen and may be palpated through the anterior abdominal wall above the symphysis pubis.

Bimanual palpation of the empty bladder with or without a general anesthetic is an important method of examining the bladder. In the male, one hand is placed on the anterior abdominal wall above the symphysis pubis, and the gloved index finger of the other hand is inserted into the rectum. From their knowledge of anatomy, students can see that the bladder wall can be palpated between the examining fingers. In the female, an abdominovaginal examination can be similarly made. In the child, the bladder is in a higher position than in the adult because of the relatively smaller size of the pelvis.

 

Bladder Distention

The normal adult bladder has a capacity of about 500 mL. In the presence of urinary obstruction in males, the bladder may become greatly distended without permanent damage to the bladder wall; in such cases, it is routinely possible to drain 1000 to 1200 mL of urine through a catheter.

Urinary Retention

In adult males, urinary retention is commonly caused by obstruction to the urethra by a benign or malignant enlargement of the prostate. An acute urethritis or prostatitis can also be responsible. Acute retention occurs much less frequently in females. The only anatomic cause of urinary retention in females is acute inflammation around the urethra (e.g., from herpes).

 

Suprapubic Aspiration

As the bladder fills, the superior wall rises out of the pelvis and peels the peritoneum off the posterior surface of the anterior abdominal wall. In cases of acute retention of urine, when catheterization has failed, it is possible to pass a needle into the bladder through the anterior abdominal wall above the symphysis pubis, without entering the peritoneal cavity. This is a simple method of draining off the urine in an emergency.

Cystoscopy

The mucous membrane of the bladder, the two ureteric orifices, and the urethral meatus can easily be observed by means of a cystoscope. With the bladder distended with fluid, an illuminated tube fitted with lenses is introduced into the bladder through the urethra. Over the trigone, the mucous membrane is pink and smooth. If the bladder is partially emptied, the mucous membrane over the trigone remains smooth, but it is thrown into folds elsewhere. The ureteric orifices are slitlike and eject a drop of urine at intervals of about 1 minute. The interureteric ridge and the uvula vesicae can easily be recognized.

 

Bladder Injuries

The bladder may rupture intraperitoneally or extraperitoneally. Intraperitoneal rupture usually involves the superior wall of the bladder and occurs most commonly when the bladder is full and has extended up into the abdomen. Urine and blood escape freely into the peritoneal cavity. Extraperitoneal rupture involves the anterior part of the bladder wall below the level of the peritoneal reflection; it most commonly occurs in fractures of the pelvis when bony fragments pierce the bladder wall. Lower abdominal pain and blood in the urine (hematuria) are found in most patients.

In young children, the bladder is an abdominal organ, so abdominal trauma can injure the empty bladder.

Difficulty with Micturition after Spinal Cord Injury

After injuries to the spinal cord, the nervous control of micturition is disrupted.

The normal bladder is innervated as follows:

■■ Sympathetic outflow is from the first and second lumbar segments of the spinal cord. The sympathetic nerves  inhibit contraction of the detrusor muscle of the bladder wall and stimulate closure of the sphincter vesicae.

■■ Parasympathetic outflow is from the second, third, and fourth sacral segments of the spinal cord. The parasympathetic nerves stimulate the contraction of the detrusor muscle of the bladder wall and inhibit the action of the sphincter vesicae.

■■ Sensory nerve fibers enter the spinal cord at the above segments.

Urinary Bladder- Urinary Bladder relation-Micturition-

Urinary Bladder

The urinary bladder lies immediately behind the pubic bones inside the pelvis. Its function is storage urine and in the adult has a maximum capacity of about 500 mL. The bladder has a strong muscular wall. Its shape and relations vary according to the amount of urine that it contains.

When the bladder is empty  it is pyramidal, having an apex, a base, and a superior and two inferolateral surfaces; it also has a neck. in the adult lies entirely within the pelvis; as the bladder fills, its superior wall rises up into the hypogastric region. In the young child, the empty bladder projects above the pelvic inlet; later, when the pelvic cavity enlarges, the bladder sinks into the pelvis to take up the adult position.

The apex of the bladder points anteriorly and lies behind the upper margin of the symphysis pubis. It is connected to the umbilicus by the median umbilical ligament (remains of urachus). The base, or posterior surface of the bladder, faces posteriorly and is triangular. The superolateral angles are joined by the ureters, and the inferior angle gives rise to the urethra. The two vasa deferentia lie side by side on the posterior surface of the bladder and separate the seminal vesicles from each other. The upper part of the posterior surface of the bladder is covered by peritoneum, which forms the anterior wall of the rectovesical pouch. The lower part of the posterior surface is separated from the rectum by the vasa deferentia, the seminal vesicles, and the rectovesical fascia. The superior surface of the bladder is covered with peritoneum and is related to coils of ileum or sigmoid colon. Along the lateral margins of this surface, the peritoneum passes to the lateral pelvic walls.

As the bladder fills, it becomes ovoid, and the superior surface bulges upward into the abdominal cavity. The peritoneal covering is peeled off the lower part of the anterior abdominal wall so that the bladder comes into direct contact with the anterior abdominal wall.

The inferolateral surfaces are related in front to the retropubic pad of fat and the pubic bones. More posteriorly, they lie in contact with the obturator internus muscle above and the levator ani muscle below.

The neck of the bladder lies inferiorly and rests on the upper surface of the prostate. Here, the smooth muscle fibers of the bladder wall are continuous with those of the prostate. The neck of the bladder is held in position by the puboprostatic ligaments in the male; these are called the pubovesical ligaments in the female. These ligaments are thickenings of the pelvic fascia.
When the bladder fills, the posterior surface and neck remain more or less unchanged in position, but the superior surface rises into the abdomen The mucous membrane of the greater part of the empty bladder is thrown into folds that disappear when the bladder is full. The area of mucous membrane covering the internal surface of the base of the bladder is called the trigone. Here, the mucous membrane is always smooth, even when the viscus is empty, because the mucous membrane is firmly adherent to the underlying muscular coat. The superior angles of the trigone correspond to the openings of the ureters, and the inferior angle to the internal urethral orifice. The ureters pierce the bladder wall obliquely, and this provides a valvelike action, which prevents a reverse flow of urine toward the kidneys

as the bladder fills. The trigone is limited above by a muscular ridge, which runs from the opening of one ureter to that of the other and is known as the interureteric ridge. The uvula vesicae is a small elevation situated immediately behind the urethral orifice, which is produced by the underlying median lobe of the prostate.

The muscular coat of the bladder is composed of smooth muscle and is arranged as three layers of interlacing bundles known as the detrusor muscle. At the neck of the bladder, the circular component of the muscle coat is thickened to form the sphincter vesicae.

 

Micturition

Micturition is a reflex action that, in the toilet-trained individual, is controlled by higher centers in the brain. The reflex is initiated when the volume of urine reaches about 300 mL; stretch receptors in the bladder wall are stimulated and transmit impulses to the central nervous system, and the individual has a conscious desire to micturate. Most afferent impulses pass up the pelvic splanchnic nerves and enter the 2nd, 3rd, and 4th sacral segments of the spinal cord. Some afferent impulses travel with the sympathetic nerves via the hypogastric plexuses and enter the first and second lumbar segments of the spinal cord. Efferent parasympathetic impulses leave the cord from the second, third, and fourth sacral segments and pass via the parasympathetic preganglionic nerve fibers through the pelvic splanchnic nerves and the inferior hypogastric plexuses to the bladder wall, where they synapse with postganglionic neurons. By means of this nervous pathway, the smooth muscle of the bladder wall (the detrusor muscle) is made to contract, and the sphincter vesicae is made to relax. Efferent impulses also pass to the urethral sphincter via the pudendal nerve (S2, 3, and 4), and this undergoes relaxation. Once urine enters the urethra, additional afferent impulses pass to the spinal cord from the urethra and reinforce the reflex action. Micturition can be assisted by contraction of the abdominal muscles to raise the intra-abdominal and pelvic pressures and exert external pressure on the bladder. In young children, micturition is a simple reflex act and takes place whenever the bladder becomes distended. In the adult, this simple stretch reflex is inhibited by the activity of the cerebral cortex until the time and place for micturition are favorable. The inhibitory fibers pass downward with the corticospinal tracts to the 2nd, 3rd, and 4th sacral segments of the cord. Voluntary control of micturition is accomplished by contracting the sphincter urethrae, which closes the urethra; this is assisted by the sphincter vesicae, which compresses the bladder neck. Voluntary control of micturition is normally developed during the second or third year of life.

Urinary Bladder-Uterus

Urinary Bladder

In adults, the empty bladder is a pelvic organ and lies posterior to the symphysis pubis. As the bladder fills, it rises up out of the pelvis into the abdomen, where it can be palpated through the anterior abdominal wall above the symphysis pubis (Fig. 6.23). The peritoneum covering the distended bladder becomes peeled off from the anterior abdominal wall so that the front of the bladder is in direct contact with the abdominal wall (see page 272).

In children, until the age of 6 years, the bladder is an abdominal organ even when empty because the capacity of the pelvic cavity is not great enough to contain it. The neck of the bladder lies just below the level of the upper border of the symphysis pubis.

Uterus

the fundus of the uterus can be palpated at the end of the 2nd month of pregnancy, through the lower part of the anterior abdominal wall. With the progressive enlargement of the uterus, the fundus rises above the level of the umbilicus and reaches the region of the xiphoid process by the 9th month of pregnancy. Later, when the presenting part of the fetus, usually the head, descends into the pelvis, the fundus of the uterus also descends.