prostate Flashcards
Describe the lobar anatomy of the prostate
○ Base (Superior) part of the gland is in contact with the urinary bladder
○ The apex (inferior) provides the exit for the urethra at the urogenital diaphragm
○ Posteriorly, the prostate lies against the rectum
○ Anteriorly, the gland is adjacent to the pubic bone
○ Consists of a small anterior fibromuscular region and a larger posterior glandular region
○ Fibromuscular region is located anterior to the prostatic urethra
○ Most pathology is situated in the glandular region
○ Glandular tissue consists of compound tubuloalveolar glands surrounded by smooth muscle fibres
Describe zonal anatomy of the prostate
○ Four zones:
§ Peripheral
§ Central
§ Transitional
§ Periurethral
○ Peripheral zone is the largest- 70% of the glandular prostate
§ Lateral and posterior to the distal prostatic urethra
○ Central zone makes up 20% of the glandular tissue, situated superiorly adjacent to the seminal vesicles and bladder
§ Ejaculatory ducts pass through this zone
○ Transitional zone makes up 5% of the tissue
§ Lateral aspect of the prostatic urethra superior to the verumontanum
§ Lies superiorly and lateral to the central zone and inferior to the fibromuscular
○ Periurethral zone encompasses the urethra and makes up the last 5%
Where does BPH originate from?
Exclusively from the inner gland
95% from the transitional zone
5% from periurethral glands or tissues
What is the normal size of the prostate?
Normal max diameter is 4cm
Volume varies with age, between 20-33cc
What is endorectal prostate U/S and biopsy?
Due to close proximity, better detail is obtained
Careful assessment of normal anatomy, benign prostatic hyperplasia, inflammatory processes and detection and staging of cancer
Method of choice for intervention
○ Biopsies
○ Aspirations
○ Treatment of cancer with guidance of implantation of iodine 125
Aspiration of intraprostatic cysts
How are patients prepared for biopsy?
Pre-examination enema
Broad spectrum antibiotics
Informed consent
Transrectal scan is usually performed by the radiologist or urologist
Patient is usually in the left lateral decubitus position with the knees drawn up to their chest
How is a prostate biopsy performed?
Exclude any obstructive lesions
Transducers should be at least 5MHz, preferably 7.5MHz to obtain maximum resolution and detail
Use sterile coupling gel and a suitable cover
Use B-mode to assess the prostate and measure it
Assess seminal vesicles for size, symmetry, cysts or calculi
Sagittal and transverse images of the following structures:
○ Seminal vesicles
○ Prostate
○ Bladder base and peri-prostatic areas
○ Any palpable or sonographically suspicious lesions
Colour Doppler interrogation
Prostate cancer is more hypervascular compared to normal prostatic glandular tissue
What are the ways biopsies are performed?
Biopsies can be performed by transperineal or transrectal approaches
○ Transrectal is better tolerated and more accurate
Biopsies can be performed of suspicious lesions or in a systemic approach
Systemic approach is where the prostate is divided into 6 segments and a random sample is taken from each (Sextant biopsy)
What are complications of prostate biopsy?
Excessive bleeding
rectal haematoma
post-procedural infection
Describe the normal ultrasound appearance of the prostate
Seminal vesicles are hypoechoic structures superior to the prostate
Prostate has the appearance of a symmetrical, heterogeneous organ with medium level echoes
In trans, it appears as a semilunar shape near the base and more rounded near the apex
Fibromuscular region appears hypoechoic compared to the rest of the gland
Periurethral tissue appears hypoechoic, not easily distinguishable from fibromuscular stroma
Central and transitional zones cannot be distinguished
Peripheral zone appears more hyperechoic and homogeneous
What clinical symptoms is BPH associated with?
Bladder outlet obstruction
Difficulty initiating void
nocturia
weak urine stream
What is the result of prolonged bladder outlet obstruction?
marked hypertorphy of the bladder wall, trabeculation of bladder muscle, retention of urine
leads to urinary infections
reflux of urine
hydronephrosis
what is BPH
BPH is clearly defined as a well-rounded and symmetrical enlargement of the central gland with inner glandular tissue becoming hypoechoic in comparison to the compressed peripheral zone
Often no sonographic distinction between central and peripheral glands
Can have distinct nodules
○ Mimic carcinoma
○ Often well-delineated and hyperechoic to surrounding tissue
○ Can be single or multiple
Calcifications are common within the enlarged prostate and appear as isolated hyperechoic areas with acoustic shadowing
○ Usually benign pathology
Cysts are uncommon, simple cysts are ignored generally unless compressing the urethra
What is prostatitis?
Transmission of infections from the bladder or urethra
Post-surgical catheterisation of the urethra is a common cause
Describe the sonographic appearance of acute prostatitis?
Acute prostatitis:
○ Limited B-mode findings
○ May demonstrate hypoechoic rim around the prostate or periurethral areas
○ Focal/diffuse hypoechoic areas may be seen
○ Colour Doppler to assess hyperaemia
Diffuse hyperaemia is indicative of prostatitis
Focal areas of vascularity can be indicative of carcinoma
