Pelvic Anatomy: Bladder and Viscera

Pelvic Content

• Pelvic viscera includes the gastrointestinal, urinary, and reproductive systems.
• The gastrointestinal system includes the rectum and anal canal.
• The urinary system includes the terminal parts of the ureters, bladder, and proximal part of the urethra.
• The female reproductive system includes the uterus, uterine tubes, ovaries, and proximal vagina.
• The male reproductive system includes the vas deferens, seminal vesicles, prostate, bulbourethral glands.

The Bladder

• Anterior to the rectovesical pouch and seminal vesicles in males, and the uterovesical pouch and anterior vaginal wall in females
• Located in the pelvis when empty, abdominal when full.
• Holds 150-600 ml of urine.
• The apex is directed towards the pubic symphysis; the median umbilical ligament continues from the tip to the umbilicus.
• The base faces postero-inferiorly , where two ureters enter at the top, with oblique slit-like openings to prevent reflux
• The openings are found at the lateral margins of Inter-ureteric crest.
• Contraction of the smooth muscle causes a sphincteric effect
• The urethra drains inferiorly

Suprapubic Catheterization

• A small catheter can be passed in the midline approximately 2 cm above the pubic symphysis to permit drainage.

Anterior Abdominal Wall

• The arcuate line is visible on the posterior surface.
• The median and medial umbilical ligaments run along the surface.
• The inferior epigastric artery and deep circumflex artery are also present.

Neck of the Bladder

• Is the most inferior part, and is a fixed part
• Detrusor muscles form the involuntary internal urethral sphincter in males due to sympathetic innervation
• Supported by:
  • Perineal membrane and associated muscles
  • Levator ani muscles
  • Pubic bones
• Fixed by the pubovesical ligaments in females, with laxity contributing to Stress Incontinence
• Puboprostatic ligaments fix the bladder in males

Blood Supply to the Bladder

• Anterosuperior parts supplied by superior vesical arteries.
• Base and neck supplied by inferior vesical arteries in males, vaginal arteries in females.
• Obturator and inferior gluteal arteries also supply small branches.

Lymphatics of the Bladder

• The superior surface drains to the external iliac lymph nodes.
• The inferior half drains to the internal iliac lymph nodes.
• The neck drains into the sacral (internal iliac) or common iliac lymph nodes.

Bladder Cancer

• The most common tumor of the urinary tract, 1/3 are multifocal.
• 2/3 are superficial and amenable to local treatment
• Tumors spread through bladder wall, and may invade local structures or lymph nodes.
• Treatment is dependent on severity, and may include local resection, chemotherapy, or radical surgical removal of bladder and prostate.

Urethra

• Male urethra is long and bends twice:
  • Pre-prostatic: contains internal urethral sphincter
  • Prostatic: contains prostatic sinus, seminal colliculus.
  • Membranous: contains external urethral sphincter.
  • Spongy: contains corpus spongiosum, openings of bulbourethral glands; bulbar and penile parts.
• Female urethra is short:
  • Passes through pelvic floor and perineum to open into the vestibule
  • Contains para-urethral mucous glands.

Bladder Catheterization

• Easier in females than male due to the difference in the length of the urethra
• Ascending infections of the bladder are more common in women compared to men
• Placement of the catheter in men is made more difficult by the length of the urethra, and the present angles
• This is compensated by aligning the penis as well as possible

Male Reproductive System

Components:

• Testis
• Epididymis
• Ductus deferens
• Ejaculatory ducts
• Urethra and penis

Accessory Glands

• Single prostate
• A pair of seminal vesicles
• A pair of bulbourethral glands

Testes and Epididymis

• The testes develop originally high on the posterior abdominal wall and then descend
• They produce sperms and testosterone (sperms formed in the seminiferous tubules)
• The epididymis is located on the posterolateral sides of the testis and stores newly formed sperms

Testicular Arteries

• Originate high up on the abdominal wall, therefore are retroperitoneal, and cross anterior to the ureters and the illiac arteries

Vas Deferens

• The internal spermatic facia contains cremasteric muscle
• The body contains the internal spermatic facia
• The head is the entry point
• Testis covered by Tunica albuginea , Tunica vaginalis

Vas Deference and Seminal Vesicles

• Vas (ductus) deference: muscular duct that transports spermatozoa from the tail of epididymis to the ejaculatory duct
  • Located in the Spermatic Cord
  • Joins by the duct of seminal vesicle to form the ejaculatory duct
• Seminal Vesicles
  • Accessory gland of the reproductive system
  • Joins vas deference to form ejaculatory duct
  • Secretions increase the volume of semen
  • The duct of the seminal vesicle joins the ductus deferens to form the ejaculatory duct within the prostate gland.

Vasectomy

• Is a method of birth control
• Requires a local anaesthetic
• Involves removing a section of the vas (ductus) deferens, then ligating and/or cauterising the cut ends

Prostate

• Is a accessory gland that is posterior to the pubic symphysis
• It surrounds the urethra in the pelvic cavity, and anterior to the rectum
• It's base is inferior to the urinary bladder, and located along the deep perineal pouch
• Has inferolateral surfaces, called Levator ani

Prostatic Fuction

• Secretes proteolytic enzymes into the semen which assists with breaking down clotting factors in the ejaculate, liquefying it
• Apex: Along the superior fascia of the deep perineal pouch
• Inferolateral surfaces: Supported by the levator ani

Prostate Anatomy

• Capsule: Is a membrane forming the exterior of the prostate
• Contains prostatic urethra, in addition to the seminal colliculus
• Prostate glands ducts drain into this structrure

Lobes of the Prostate

• Anterior: anterior to the urethra;
• Median: posterior to the urethra, bounded inferiorly by the ejaculatory ducts (enlarges into the base of the bladder);
• Posterior: posterior to the urethra, bounded superiorly by the ejaculatory ducts; felt in digital rectal exam;
• Lateral: right and left

Zones of the Prostate

• Transitional zone: proximal and middle urethra, site of benign prostatic hypertrophy
• Central zone: posterior to the prostatic urethra, forms the base of the prostate, contains the ejaculatory ducts
• Peripheral zone: distal prostatic urethra at the apex of the prostate that extends posterolaterally, often the site of prostatic tumours (70%)

Rectal Examination

• Prostate palpation is possible during the practice in both males and women
• A malignant prostate is hard and irregular
• This allows palpation of males: Seminal vesicle, recto-vesical pouch
• This allows palpation of females: posterior wall of the vagina, cervix, rectouterine pouch

Benign Prostatic Hypertrophy

• Common in older men and is is defined as:
  • >50% at the age of 60 years
  • >75% at the age of 80 years
• Results from compression of the Prostatic Urethra = results in:
• Muscular Hypertrophy of the bladder
• Retrograde back pressure
• Hydroureter and -nephrosis
• Can be resolved with Transurethral Resection of Prostate (TURP) = remove prostate tissue to improve urine flow

Prostate Cancer

• Common in men of the age of 60, and more common in the 2 decades before that
• Defined as adenocarcinoma
• Occurs in most adults, can either be early stage asymptomatic of cause frequency, hesitancy, and urgency or hematuria
• Occurs in the peripheral regions of the prostate
• Can be tested through digital rectal exam via a biopsy

Imaging

• The prostatic zones are used in imaging
• The structure can be seen during an MRI
• Cancer zones contain low signal intensity
• Peripherhal regions contain high signal intensity

Male Pelvic Fascia

• Condensation of fascia surrounds the prostatic fascia and lateral region of the prostate, which contains the venous plexus.
• The rectovesical lines fascia, and separates the prostrate for the base of the ladder from the rectum
• Visceral peritoneum passes over the top of the bladder, around the peritoneum and seminal vesicles

Prostate Vessels

• Blood is supplied by Prostatic Arteries: originate from the interior vesicle artery (<< internal arteries)
• Connects the vertebral venous plexuses
• Also contains the inferior and superior vesicle artery
• and the Middle rectal artery