Prostate Gland
PROSTATE GLAND: ANATOMY AND ORGANOGENESIS
Context
Prostate gland study includes:
Anatomy and organogenesis
Sonographic examination
Biopsy guidance procedures
Infertility evaluation
Main Uses of TRUS (Transrectal Ultrasound)
Essential for:
Prostate cancer evaluation
Infertility assessment
Chronic pelvic pain syndrome (CPPS)
Congenital prostate abnormalities
Biopsy and treatment guidance
Emerging Technologies:
Contrast-enhanced TRUS
Elastography for assessing tumor stiffness
These techniques show promising results in prostate tumor evaluation
Use of 3D imaging for prostate gland analysis
PHYSIOLOGY OF THE PROSTATE GLAND
Description:
Small, walnut-sized gland in the male reproductive system
Produces 25-30% of semen fluid to nourish and protect sperm
Located below the bladder, surrounding the urethra
Muscle contraction propels fluid into urethra during ejaculation
ANATOMY AND ORGANOGENESIS
Indifferent Stage of Embryogenesis:
All embryos start with:
Two paired ducts:
Mesonephric (Wolffian) ducts
Paramesonephric (Müllerian) ducts
Duct Development:
Mesonephric ducts → develop into male reproductive system
Paramesonephric ducts → develop into female reproductive system
Prostate Development:
Initiates at 11 weeks gestation
Forms as solid outgrowths from the posterior urethra
Outgrowths invade surrounding tissue forming five prostatic lobes
Maturation influenced by testosterone:
Develops in high testosterone levels
Enters dormant state when testosterone decreases
Reactivates growth at puberty with rising testosterone levels
Gross Anatomy
Structure:
Adult prostate is funnel-shaped and exocrine
Surrounded by a fibromuscular capsule (not a true capsule)
Average size in young adults:
Dimensions: 4 × 3 × 2 cm
Weight: ~20 ± 6 g
Composed of glandular and fibromuscular tissue
Orientation:
Base (cephalic portion): connected to bladder neck
Apex (caudal portion): connected to urogenital diaphragm
Structures within the Prostate
Prostatic Urethra: runs centrally through the prostate
Ejaculatory Ducts: formed by the union of seminal vesicle duct and vas deferens
Duct Pathway:
Travels through the central zone and joins urethra at the verumontanum
Verumontanum located at the midpoint of the urethra
Prostatic Utricle:
Small epithelial diverticulum at the apex of the verumontanum
Fetal remnant homologous to the female uterus
Can develop cysts, leading to urinary symptoms
Produces an "Eiffel Tower" appearance on ultrasound
VASCULATURE OF THE PROSTATE
Arterial Supply
Blood supply from internal iliac arteries via prostaticovesical arteries
Arterial Pathway:
Iliac arteries travel toward prostate along bladder surface
Branches into:
Prostatic artery
Inferior vesical artery
Further divides into:
Capsular and urethral arteries
Capsular Arteries:
Located on the prostate surface, supplying ~two-thirds of glandular tissue
Urethral Arteries:
Supply the remaining ~one-third of glandular tissue
Venous Drainage
Prostatic Venous Plexus:
Network of small veins draining blood from the prostate
Joins patterns with veins of the bladder and penis, draining into internal iliac veins
Clinical Significance:
Pathway believed to be a major route for bone metastasis in prostate cancer
Prostate Zones
Anatomic Reference Points
The urethra divides prostate into:
Anterior fibromuscular portion
Posterior glandular portion
Prostate tissue composition:
Glandular tissue: 2/3
Fibromuscular tissue: 1/3
Prostate Zones (Glandular Tissue)
Peripheral Zone
Constitutes 70% of the glandular tissue
Location: posterior, lateral, and apical areas
Duct Drainage: distal urethra
Histology: small, round acini; primary site for prostate cancer
Clinical Importance: 70% of prostate cancers arise here
Central Zone
Accounts for 25% of glandular tissue
Location: at the prostate base, surrounds ejaculatory ducts
Histology: large, irregular acini; resistant to disease
Clinical Importance: Only 5% of prostate cancers arise here
Transition Zone
5% of prostate in young men
Can enlarge due to benign prostatic hyperplasia (BPH)
Histology: resembles peripheral zone acini; primary site for BPH
20% of prostate cancers arise here
Periurethral Zone
Less than 1% of glandular tissue
Embedded within prostatic urethra wall
Clinical Significance: site of prostatic calculi formation
SURROUNDING STRUCTURES
Seminal Vesicles: paired structures posterior to superior prostate
Appear empty (curvilinear, hypoechoic) or filled (large ovoid cystic structures)
Ampulla of the Vasa Deferentia: adjacent to seminal vesicles; thick-walled tubular shapes
Ejaculatory Ducts: formed by vas deferens and seminal vesicle junction
*Prostate Relationships:
Anterior: connected to pubic bone
Lateral: covered by levator ani muscles
Posterior: lies anterior to the rectum
CLINICAL ROLE OF PROSTATIC EVALUATION
Advantages of TRUS
High-resolution imaging
Complements digital rectal examination (DRE)
No ionizing radiation
Cost-effective compared to other imaging methods
Dynamic imaging of blood flow
Applications
Biopsy guidance
Complementary to DRE
Indications
Differentiation of cystic vs solid lesions
Abnormal PSA test evaluation
Assessment of inflammatory processes
Male infertility evaluation
Guidance for biopsies
Sonographic Examination
Indications and Contraindications
Indications: evaluation for various urination and ejaculation issues
Contraindications: severe rectal conditions or active prostatitis
CLINICAL USES OF TRUS
Detect irregularities in prostate feel
Identify masses, cysts, calcifications
Evaluate non-palpable lesions
Recent advancements:
Elastography and contrast-enhanced ultrasound improve localization of significant prostate cancer
Multiparametric ultrasound: integrated imaging technique
EVALUATION OF SYMPTOMS
Symptoms include hematospermia, painful ejaculation, dysuria, perineal pain
Detect prostatitis via doppler imaging for increased vascularity
Other conditions:
BPH: enlarged, heterogeneous gland
Cysts/abscesses: simple or complex fluid collections
Ejaculatory duct cysts/masses
INFERTILITY
Sonography evaluates male infertility; less invasive than vasography
Key evaluation targets: normal seminal vesicles and vasa deferentia
Azoospermia:
No sperm in ejaculate (10% cases)
Causes: obstructive lesions, endocrine disorders, testicular defects
Enlarged prostate findings:
Gross enlargement suggests distal duct obstruction; volume for seed implantation must be <45-50 cc
Low ejaculate volume (7% of patients) due to blockage or secretory dysfunction
Infection and subfertility:
Leukocytospermia indicates infection; can impair sperm quality
SCANNING TECHNIQUES
IMAGING APPROACHES TO PROSTATE ULTRASOUND
Historical Method: Transabdominal, limited resolution
Modern Method: Endorectal (TRUS) provides better resolution
EXAMINATION TECHNIQUE
Patient preparation:
Left lateral decubitus position with knees flexed
Bladder should be empty to reduce discomfort
Ultrasound gel applied to probe
Probes: End-fire or side-fire, frequency 9-12 MHz or higher
Pain Control During Biopsy: 2% lidocaine injection near neurovascular bundles
IMAGE ORIENTATION
Endorectal scan orientation is inverted; adjustments in readings per anatomy
Normal prostate appears crescent-shaped
Regular evaluations for capsule continuity and any disruptions indicating pathology
Images taken from base to apex for thorough examination and volume measurement
DOPPLER EVALUATION IN TRUS
Purpose: identify increased vascularity (hyperemia) within lesions
Techniques include color/power Doppler for visualization
Advanced technologies like MicroFlow Imaging enhance small vessel detection without contrast agents
SUMMARY
The prostate gland anatomy, physiology, vascularity, zones, and clinical significance is essential for prostate health evaluation and treatment options.
TRUS plays a crucial role in the diagnosis and management of prostate diseases, including cancer, infertility, and other urinary ailments. Fast advancements in imaging technologies provide a promising future for enhanced detection and treatment strategies.