Pelvic Anatomy: Viscera and Bladder

Pelvic Content

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

The Bladder

• Anterior to the rectovesical pouch and seminal vesicles in males.
• Anterior to the uterovesical pouch and the anterior vaginal wall in females.
• It is located in the pelvis when empty and can extend into the abdomen when full.
• It is the most anterior element of the pelvic viscera.
• The terminal parts of the ureters, the bladder itself, and the proximal part of the urethra are the pelvic parts of the urinary system
• The bladder holds about 150-600 ml of urine
• The apex is directed towards the pubic symphysis, with the median umbilical ligament continuing from the tip to the umbilicus.
• The base faces posterior-inferiorly.
• Two ureters enter at the top with oblique slit-like openings to prevent reflux, found at the lateral margins of the inter-ureteric crest.
• Contraction of the detrusor muscle creates a sphincteric effect.
• The urethra drains inferiorly.
• The mucosal lining is smooth and firmly attached to the underlying smooth muscle coat.
• Inferolateral surfaces are supported by the levator ani muscles.
• The superior surface is domed and covered with peritoneum.

Suprapubic Catheterization

• A small catheter is passed in the midline approximately 2 cm above the pubic symphysis to facilitate drainage.

Neck of the Bladder

• The most inferior part of the bladder is fixed.
• In males, detrusor muscles form the involuntary internal urethral sphincter.
• Sympathetic innervation constricts the internal urethral sphincter.
• The bladder supported by the perineal membrane, associated muscles, pubic bones, and tough ligaments.
• Females have pubovesical ligaments, and laxity can contribute to stress incontinence.
• Males have puboprostatic ligaments.

Vessels

• Anterosuperior parts are supplied by the superior vesical arteries.
• The base and neck are supplied by the inferior vesical arteries in males, replaced by the vaginal arteries in females.
• The obturator and inferior gluteal arteries also supply small branches to the bladder.

Lymphatics

• Lymphatics from the superior surface drain to the external iliac lymph nodes.
• Lymphatics from the inferior half drain to the internal iliac lymph nodes.
• Some lymphatics from the neck drain into the sacral (which drains then to internal iliac) or common iliac lymph nodes.

Bladder Cancer

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

Urethra

• Male urethra is longer and bends twice.
• Pre-prostatic, internal urethral sphincter
• Prostatic, prostatic sinus, seminal colliculus
• Membranous, external urethral sphincter
• Spongy, corpus spongiosum, openings of the bulbourethral glands, bulbar and penile parts

Bladder Catheter

• Placement is easier in females.
• Ascending infections of the urinary bladder i.e cystitis more common in women than men because of shorter length of the female urethra
• Placement is more difficult in men because the urethra is longer and has angles that require a penis to be aligned.
• These angles must be compensated for by aligning the penis to prevent perforations.
• Prostatic tissue damage can cause pain and bleeding.

Male Reproductive System

• Major components include the testis, epididymis, ductus deferens, ejaculatory ducts, urethra, and penis.
• Accessory glands include a single prostate, a pair of seminal vesicles, and a pair of bulbourethral glands.

Testes

• The testes develop high on the posterior abdominal wall and then descend.
• Sperm made in the seminiferous tubules.
• They produce sperm and testosterone.
• Epididymis: stores newly formed sperms.
• The epididymis is located on the posterolateral sides of the testis.

Vas Deference and Seminal Vesicles

• Muscular duct which transports spermatozoa from the tail of the epididymis to the ejaculatory duct
• Accessory gland of the male reproductive system
• Part of the spermatic cord
• The secretions increase the volume of semen
• Blind-ended tubular outgrowth from vas deferens
• The duct joins vas deferens joining to form ejaculatory duct in the prostate gland.

Vasectomy

• A method of birth control that can be performed under local anaesthesia is a vasectomy.
• It involves removing a section of the vas (ductus) deferens.
• It involves ligating and/or cauterising the cut ends.

Prostate

• It secretes proteolytic enzymes into the semen for breaking down clotting factors in the ejaculate.
• It surrounds the urethra in the pelvic cavity
• Relationships: posterior to the pubic symphysis, anterior to the rectum, inferior to the urinary bladder.
• The apex of the prostate: along the superior fascia of the deep perineal pouch.
• The inferolateral surfaces: levator ani.

Prostate Anatomy

• Capsule
• Prostatic urethra
• Seminal colliculus
• Bulbourethral glands

Lobes of the Prostate:

• Anterior lobe is anterior to the urethra.
• Median lobe is posterior to the urethra, bounded inferiorly by the ejaculatory ducts, and enlarges into the base of the bladder in benign prostatic hypertrophy.
• Posterior lobe: posterior to the urethra, bounded superiorly by the ejaculatory ducts, can be felt in a digital rectal examination.
• Lateral lobes: right & left

Zones of the Prostate:

• Transitional zone surrounds the proximal and middle urethra.
• Benign prostatic hypertrophy occurs in the transition zone.
• The central zone is posterior to the prostatic urethra and forms the base of the prostate, containing the ejaculatory ducts.
• The peripheral zone surrounds the distal prostatic urethra at the apex and extends posterolaterally to the base, deficient anteriorly.
• About 70% of prostatic tumours occur in the peripheral zone.

Rectal Examination

• Prostate examined with digital rectal examination
• External anal sphincter
• Irregular/hard prostate means malignant
• Males: seminal vesicle, recto-vesical pouch
• Females: posterior wall of the vagina, cervix, rectouterine pouch

Benign Prostatic Hypertrophy (BPH)

• BPH is common in males.
• Clinical features result because they have been compressing prostatic part of the urethra resulting in obstructing urine overflow
• Muscular hypertrophy happens because there is high muscular pressure needed to push the fluids away out of the bladder
• Higher pressure lead to kidneys and ureters dilating which is hydronephrosis

Prostatic Cancer

• Common after the age of 65.
• People with early-stage are ASYMPTOMATIC
• Can happen in peripheral regions of prostate
• Feel prostate with digital exam
• If have ultrasound assess transrectal ultrasonography

Male Pelvic Fascia

• Prostatic fascia dense fascia around the lateral of anterior regions and prostate

  • Contains venous plexus

• Rectovescial septum to separates surface of the bladder for of the rectum

• Peritoneum surface continuous w pelvic inlet of the peritoneum

Blood Vessels-Prostate

• Artery: Prostatic arteries from inferior artery < internal iliac artery

Venous

• drainage drains prostate
• Batson veinsvalveless parallel that connect to deep pelvis

Autonomics to the Urinary Bladder

• Parasympathetic (pelvic splanchnic- S2-4):
  • Pelvic splanchnic
  • Motor bladder contracting
  • Inhibitory to sphincter
• T12-L2 Sympathetic
• Contract sphincter
• innervate vessels
• Pain
  • afferents follow sympathetics