Prostate anatomy, structure & function – define BPH & BOO, which terminology?

Kieran JeffersonConsultant Urological Surgeon

Biography

08 - Partner, Warwickshire Urology

06 - Consultant, UHCW

05-06 Fellow in uro-oncology, Bristol

98-05 SpR urology, Southwest deanery

94-98 Basic surgical training, Bristol

90-93 BM BCh, Oxford

87-90 BA (Nat Sci), Cambridge

• Ipsen (Decapeptyl)Paid consultant; principal trial investigator; book sponsorship; meeting sponsorship

• Wyeth/Takeda (Prostap)Trial co-investigator; meeting sponsorship; paid lecturer; book sponsorship

• Glaxo (Dutasteride)Trial co-investigator, meeting sponsorship, paid lecturer

• Astrazeneca (Zoladex)Principal trial investigator; meeting sponsorhip; paid lecturer

• Novartis (Zoledronate)Trial co-investigator; meeting sponsorship

• Sanofi Synthelabo (Docetaxel)Meeting sponsorship; book sponsorship

Potential conflict of interest

What is a prostate?

• prostate = ‘protector’ gr.

• exocrine gland

• reproductive role

Who needs a prostate?

• Phylogenetic conservation in mammals

• Wide variation in ejaculatory volumes• human 3ml, boar 250ml!

• Ejaculate nourishes sperm & ↑ motility• fructose, citrate, spermine, prostaglandins, Zinc

• Optimises fertility • acid-base buffering, antibacterial

Semen

• Spermatozoa (100 million)+ seminal plasma

• Plasma from SVs and prostate

• PSA – serine protease; ? lyses seminal clot

• Seminogelins – coagulation and capacitation

Embryology

• Wolffian ducts form SV, epididymis, vas• requires testosterone (not DHT)

• Prostate develops from urogenital sinus• requires DHT/5-AR• glands bud from urogenital sinus• reciprocal induction

• Stromal-epithelial interaction• endoderm/mesenchyme

Adult prostate

• Androgen dependent (DHT)

• Differentiation vs proliferation vs apoptosis

• Testicular androgens from Leydig Cells

• Prostatic 5-AR converts to DHT

Gross anatomy

• 20g; 3 x 4 x 2 cm• Ovoid; narrow apex and

broad base• Apex continuous with

rhabdosphincter• Inf vesical, int pudendal

and mid rectal arteries• Lymphatic drainage to

obturator/iliac nodes

Sagittal section

• B = bladder; CS = verumontanum; DVC = dorsal venous complex; PS = pubic symphysis;

• pPF/SVF = Denonvilliers’ fascia; R = rectum; RU = rectourethralis; SS = striated (rhabdo) sphincter; VEF = visceral endopelvic fascia

Axial section mid-prostate

• DVC = dorsal vascular complex; ED = ejaculatory ducts

• NVB = neurovascular bundle; PEF/VEF = parietal/visceral endopelvic fascia; PF = prostatic fascia; pPF/SVF = Denonvilliers’ fascia; R = rectum; U = urethra

Axial section at sphincter

• DVC = dorsal venous complex; MDR = median dorsal raphe; NVB = neurovascular bundle; PB = pubis; PPL = puboprostatic ligament

• SS = striated (rhabdo) sphincter; U = urethra; VEF = visceral endopelvic fascia.

McNeal’s Zones

• Transition Zone (TZ; 5-10%)• BPH & excess cancers (20%)• Surrounding stroma

• Central Zone (CZ; 25%)• ? Wolffian Duct origin• surrounds ejaculatory ducts

• Peripheral zone (PZ; 70%)• Most prostate cancers• Most prostatitis

• Anterior fibromuscular stroma (AFS)

McNeal’s Zones

TZ

PZ

TZ

PZ

CZ

Histology

70% glandular structures; 30% stroma

Thin fibromuscular capsule

Surrounds urethra lined with transitional epithelium

Stromal-epithelial interaction

• Details complex (if at all understood)and constantly changing

• Androgen actions on stromal cells trigger paracrine release of growthfactors, which act on epithelial cells, regulating differentiation, proliferationand apoptosis

Nomenclature

• Benign prostatic hyperplasia (BPH)• histological diagnosis• cellular proliferation (epithelium & stroma)• Transition zone predominantly

• Benign prostatic enlargement (BPE)• clinical/radiological diagnosis

• Lower urinary tract symptoms (LUTS)• does not presume cause cf ‘prostatism’

• Bladder outlet obstruction (BOO)• cystometric finding• low flow despite high detrusor pressure

Benign Prostatic Hyperplasia

• Overgrowth of epithelium and stroma

• SM hypertrophy and increased tone

• Predominantly TZ change of unknown aet

• Imbalance of proliferation/apoptosis

• May cause BOO, LUTS and complications

• Near ubiquitous in old men (90% > 80y/o)

LUTS

• Possible to have any combination of LUTS, BPH and BOO

• Reasonable association between LUTS, prostate volume and PSA

• Storage vs voiding symptoms

• IPSS score increases with age

• Degree of bother important

BOO

• No population level stats for cystometric BOO

• Qmax < 10ml/s – likely to have BOO

• Qmax > 15ml/s – unlikely to have BOO

• Flow rates decline with age

Complications of BPH/BOO

• Incomplete bladder emptying/OAB• Bladder stones

– (0.1% per year)

• UTI – unusual in RCTs

• Obstructive uropathy – rare in RCTs; no case in 3000 MTOPs patients in 4 years

• Acute retention of urine– 2% per year in PLESS study

Conclusions

• Prostate essential for reproduction

• BPH is almost universal in older men

• LUTS and complications are common but most men do not experience them

• Degree of enlargement does not equate to severity of LUTS