Prostate Study Notes

Prostate

Prostate Embryology

  • The prostate develops from epithelial outgrowths from the prostatic segment of the urethra.
  • This outgrowth starts at week 10 during embryo development.

Prostate Location

  • Location:
    • Retroperitoneal Gland
    • Inferior to the urinary bladder
    • Posterior to the symphysis pubis
    • Anterior to the rectum

Prostate Function

  • Function:
    • Exocrine Gland
    • Secretes an alkaline milky substance that makes up approximately 20 to 30% of semen.
    • The alkaline fluid helps sperm live longer in the relatively acidic vagina.

Prostate Anatomy

  • Anatomy:
    • Size: Approximately the size of a walnut.
    • Varies with age; measures approximately 4 x 2 x 3 cm.
    • Around age 40, the prostate gland begins to enlarge.
    • Shape: The prostate is shaped like an inverted rounded pyramid.
    • The “base” is the superior aspect and the widest part, resting against the inferior wall of the urinary bladder.
    • The “apex” is the inferior aspect and the narrowest part of the prostate.
  • Prostate Zones:
    • Peripheral Zone
    • Central Zone
    • Transitional Zone
    • Anterior Fibromuscular Stroma
Peripheral Zone (PZ)
  • Outermost Zone, consisting of approximately 70% of the glandular tissue.
  • Most common area for malignancy to occur.
Central Zone (CZ)
  • Comprises approximately 25% of the prostate gland.
  • Surrounds the ejaculatory ducts.
  • Cancers in this zone are less common but more serious. In many cases, cancer in the CZ spreads to the seminal vesicles.
Transitional Zone (TZ)
  • Smallest Zone of the prostate.
  • Surrounds the prostatic urethra, responsible for many symptoms of an enlarged prostate.
Anterior Fibromuscular Stroma (AFS)
  • Contains muscle and stroma (connective tissue).
  • Does NOT contain any functional glandular tissues.

Blood Supply to the Prostate

  • Arterial Supply:
    • Begins with the Internal iliac artery, which branches into:
    • Inferior vesicle artery, which then branches into two segments:
      • Prostatic artery
      • Capsular artery
  • Venous Drainage:
    • Many tiny veins from the prostate drain into the Dorsal Vein (which drains the penis), eventually contributing to the Venous Plexus which drains into the Internal Iliac Vein.

The Male Urethra

  • In males, the urethra has two primary functions:
    • Excreting fluid waste (urine)
    • Excreting seminal fluid
  • Length: The male urethra is approximately 20 cm long.
    • Extends from the bladder to the tip of the penis.
    • Comparison: The female urethra is approximately 4 cm long, making females more susceptible to urinary tract infections (UTIs).
Sections of the Male Urethra

  • Prostatic Section:

    • Most proximal portion, approximately 2.5 cm in length.
    • Extends from neck of urinary bladder to the mid portion of the prostate, accepting drainage from tiny ducts within the prostate and the ejaculatory ducts.

  • Membraneous Section:

    • Shortest section, measuring approximately 0.5 cm in length.
    • Extends from the inferior aspect of the prostate to the proximal aspect of the penis.

  • Spongy Section:

    • Longest aspect of the urethra, measuring approximately 15 cm in length.
    • Extends the entire length of the penis to the external orifice.

Seminal Vesicles

  • Seminal Vesicles:
    • Paired tubular hypoechoic structures located posteroinferior to the urinary bladder.
    • Approximately 4-5 cm in length.
    • Produce some of the liquid that mixes with sperm to form semen, rich in sugars to nourish sperm.
Seminal Vesicles, Vas Deferens, and Ejaculatory Ducts
  • Fluid from the seminal vesicles empties into the ejaculatory ducts, which are surrounded by the Central Zone of the Prostate.
  • Ejaculatory Ducts:
    • Formed by the union of the vas deferens and the seminal vesicle.
  • Verumontanum:
    • The junction where the ejaculatory duct meets the prostatic urethra.
Vas Deferens
  • A muscular tube that begins at the epididymis, courses superiorly into the pelvic cavity, and terminates posterior to the urinary bladder.
  • Near its end, it becomes dilated into a portion known as the ampulla.
  • Just outside the prostate gland, it narrows and unites with the seminal vesicle, forming the ejaculatory duct.
  • The vas deferens transports mature sperm from the epididymis, propelling them into the prostatic urethra and out of the penis during ejaculation.

Seminal Fluid

  • Semen Composition:
    • Contains fluid from the following structures:
    • Epididymis
    • Seminal vesicles
    • Prostate gland
    • Vas deferens
    • Seminal fluid helps sperm swim towards the ovum while keeping them nourished and protected.

Imaging the Prostate

  • The prostate can be imaged using two approaches:
    • Transabdominal
    • Transrectal (TRUS)
Transabdominal Imaging
  • Requirements:
    • Full urinary bladder required.
    • Patient placed supine.
    • Proper draping techniques used.
  • Technique:
    • The probe is angled approximately 30 degrees caudal using the bladder as a window.
    • Slight compression may be used to ensure the inferior portion of the prostate is not obscured.
Volume Measurement
  • Volume measurement requires three measurements: height, width, and length.
  • Two measurements taken in the sagittal scan plane, one in the transverse scan plane.
  • Both the urinary bladder and seminal vesicles are also imaged and volume measurements obtained in sagittal and transverse planes, both pre- and post-void.
Transrectal Imaging (TRUS)
  • Patient Positioning:
    • Patient lies in a lateral decubitus position, facing away from the sonographer and the machine, with knees bent towards the chest.
  • Technique:
    • A small amount of urine in the bladder ideal for identification.
    • Patient relaxes and “bears down” to open the sphincter as the transducer is slowly inserted.
    • Imaging is done in sagittal and transverse planes; volume taken by measuring height and length in sagittal plane and width in transverse plane.

Prostate Pathology

  • Prostate-Specific Antigen (PSA):
    • PSA is a protein produced by the prostate and can be measured with a blood test.
    • Elevated PSA can indicate:
    • Benign Prostatic Hyperplasia (BPH)
    • Prostate Cancer
    • Prostatitis
Normal PSA Ranges:
  • Normal ranges of PSA increase as men age:
    • Men under 50: PSA < 2.5 ng/ml
    • Men between 50-59: PSA < 3.5 ng/ml
    • Men between 60-69: PSA < 4.5 ng/ml
    • Men older than 70: PSA < 6.5 ng/ml
Benign Prostatic Hyperplasia (BPH)
  • Definition:
    • Hyperplasia: An increase in the number of normal cells in the tissues of an organ (prostate).
    • BPH is a non-malignant enlargement of the prostate gland, common as men age.
Diagnosis of BPH
  • Can be detected by:
    • Digital Rectal Exam
    • Blood Test (PSA Levels)
    • Cystoscopy
    • Ultrasound Examination (TRUS or transabdominal)
    • Biopsy (Transrectal ultrasound-guided prostate biopsy is common.)
Clinical Symptoms of BPH
  • Symptoms usually begin in a man's 40s and progress slowly, often causing noticeable symptoms after age 50.
  • Common Symptoms:
    • Urinary Frequency
    • Nocturia
    • Urinary Urgency
    • Weak Urinary Flow
    • Dysuria
Symptoms Explanation
  • Pressure from the enlarged prostate can make it harder to initiate urination, leading to weaker flow and potential dribbling. Patients may feel as though they haven't fully emptied their bladder.
More Serious Problems Included in BPH
  • Urinary stasis, urinary tract infections, complete blockage of urethra, renal infection, and renal failure.
Sonographic Findings of BPH
  • Enlarged prostate gland, possible cysts, heterogeneous echotexture, possible post-void residual, possible calcifications.

Transurethral Resection of Prostate (TURP)

  • TURP: A surgical procedure to treat BPH by removing tissue from the prostate.
Prostatitis
  • Prostatitis is described as an infection of the prostate or inflammation without infection (idiopathic).
  • Can affect men of all ages.
Categories and Treatments for Prostatitis
  1. Acute bacterial
  2. Chronic bacterial
  3. Prostatodynia
  4. Asymptomatic inflammatory
  • Treatments vary:
    • Categories 1 & 2: Antibiotics and pain relievers.
    • Category 3: Symptom relief.
    • Category 4: No treatment necessary.
Clinical Symptoms of Prostatitis
  • Painful, difficult and/or frequent urination, hematuria, groin pain, fever, body aches, and penile discharge.
Prostate Cysts
  • Symptoms can occur depending on the size and location of cysts:
    • Seminal vesicle cysts may cause painful ejaculation, dysuria, and infertility.
    • Ejaculatory duct cysts: Small cysts may be asymptomatic while larger ones can cause perineal pain, dysuria, hematospermia, and ejaculatory pain.

Prostate Cancer

  • Most common form of cancer in men (besides skin cancer), with 1 in 41 men dying from it.
  • Treatment options include surgery, radiation, hormone therapy, and chemotherapy; some men may opt for watchful waiting.
Adenocarcinoma
  • Most common form of prostate cancer, particularly in African American males over 50; typically slow-growing and found within the peripheral zone (PZ).
Clinical Symptoms
  • Prostate cancer is often asymptomatic but can have early signs:
    • Frequent urination, frequent pain in the lower back, hips, or upper thighs, weak urine flow, difficulty having an erection, blood in urine or semen.
Sonographic Findings
  • Enlarged prostate, hypoechoic mass, possible calcifications, and hypervascularity.
Ultrasound Guided Prostate Biopsy
  • A procedure to remove samples of suspicious tissue from the prostate.
  • Performed using a fine needle to collect tissue samples, typically 6-12 samples sent for analysis.
  • Preoperative Preparation:
    • Patients may need to stop medications that increase bleeding risk, perform a cleansing enema, and take antibiotics pre-procedure.
Outcome Expectations for Biopsy
  • Patients are advised to rest, avoiding excessive walking or lifting on the day of the procedure.

Metastases

  • Common metastasis pathways for prostate cancer include diffusion to bone (particularly the spine), lymphatic pathways to other organs, and direct invasion into the rectum and bladder.
Treatment for Malignancy
  • Treatment options for prostate cancer include:
    • Radiation therapy, brachytherapy, chemotherapy, cryosurgery, hormonal therapy, high-intensity focused ultrasound (HIFU), and radical prostatectomy.
    • Pitfalls: These treatments can lead to complications like incontinence and impotency.

Penile Ultrasound

  • Used to evaluate conditions affecting the penis, including erectile dysfunction, plaques (e.g., Peyronie's disease), fibrosis, lumps, and cancer.
Erectile Dysfunction (ED)
  • Doppler ultrasound can assess problems related to blood flow during erection; injections may be used to induce an erection during testing.
Penile Fracture
  • Defined as a tear in the tunica albuginea, which can occur from vigorous intercourse.
  • Emergency treatment is required to prevent complications like erectile dysfunction.
  • An ultrasound can locate the tear and assess for urethral injury.
Penile Tumors
  • Less than 1% of cancers in males; associated with poor hygiene and chronic inflammation (e.g., smegma accumulation under phimotic foreskin).
  • Squamous cell carcinoma is the most common type, originating typically on the glans or prepuce.
Penile Anatomy
  • The penis comprises skin, neurovascular structures, and erectile bodies (corpus spongiosum and corpus cavernosa), with each structure serving a key role in sexual function.
Components of Ejaculate
  • Composed of sperm, seminal plasma (which nourishes and protects sperm), and lubricating mucus.
Clinical Correlations
  • Circumcision, penile fractures, and their anatomical and physiological implications.