Benign prostatic hyperplasia

Definition

    • Lower urinary tract symptoms consequent upon bladder outlet obstruction due to BPH are predominantly due to 2 components

      • A static component related to an increase in benign prostatic tissue narrowing the urethral lumen

      • A dynamic component related to an increase in prostatic smooth muscle tone mediated by alpha-adrenergic receptors

    • Symptoms related to bladder outlet obstruction may also be contributed by bladder over-activity. [1]

Risk Factors

    • Age over 50 years

      • Histological and lower urinary tract voiding symptoms increase with age. [2]

    • Family history

      • Men with an affected family relative, diagnosed with BPH before age 60 years, are at an increased risk.

      • In addition, twin studies indicate a 3.3-fold higher risk in monozygotic twins with affected siblings. [6]

    • Non-Asian race

      • A US study showed that Asian men have smaller prostates at any given age with less need for invasive surgery compared with white or black men. [7]

    • Cigarette smoking

      • A potential causal relation has been associated with lower urinary tract symptoms. [8] [9]

    • Male pattern baldness

      • A potential causal relation has been associated with lower urinary tract voiding symptoms. [8] [9]

    • Metabolic syndrome

      • A potential causal relation has been associated with lower urinary tract voiding symptoms. [10]

Differential diagnosis

    • Overactive bladder

      • Frequent urge to urinate with possible incontinence and nocturia.

  • Prostatitis

      • Fever, suprapubic or low back pain, tender, enlarged prostate gland on rectal examination is more consistent with prostatitis.

    • Prostate cancer

      • Abnormal digital rectal examination with prostate nodules or asymmetry is more consistent with prostate cancer

  • UTI

      • Presence of fever, dysuria, suprapubic or low back pain is more consistent with UTI.

  • Bladder cancer

      • Haematuria, suprapubic pain, bladder spasms with abnormal voiding, history of tobacco abuse, unknown major risk factor is more consistent with bladder cancer.

    • Neurogenic bladder

      • Storage abnormality in patients with involuntary bladder contractions.

      • Usually seen in patients with vascular disease, Parkinson disease, multiple sclerosis or diabetes mellitus with neuropathy. [15]

    • Urethral stricture

      • History of straddle injury or prior urological surgery with obstructive symptoms is more consistent with urethral stricture.

Epidemiology

    • Global differences in epidemiology statistics are somewhat dependent upon how BPH is defined.

    • However, the prevalence of histological BPH does increase with age

      • Afects approximately 42% of men between the ages of 51 and 60 years, and 82% of men between the ages of 71 and 80 years. [2]

    • In 2000, BPH generated $1.1 billion in healthcare costs and accounted for over 4.4 million office visits, 117,000 emergency department visits and 105,000 hospitalizations in the US. [3]

Aetiology

    • Hyperplasia of the epithelial and stromal compartments, particularly in the transitional zone, may be attributed to various factors

      • Including shifts in age-related hormonal changes creating androgen/oestrogen imbalances

    • Changes in prostatic stromal-epithelial interactions that occur with ageing and increases in prostatic stem cell numbers are also aetiological considerations

    • Progression from pathological BPH to clinical BPH (i.e., the presence of symptoms) may require additional factors

      • Such as prostatitis, vascular affects, and changes in the glandular capsule. [4]

Clinical features

    • Storage symptoms

      • Frequency, urgency, and nocturia

    • Voiding symptoms

      • Weak stream, hesitancy, intermittency, straining, incomplete emptying, and post-void dribbling

    • Fever with dysuria

      • Suggestive of complicated UTI

    • Urinary retention

      • Acute complication

Pathophysiology

    • BPH involves hyperplasia of both epithelial and stromal prostatic components.

    • A key characteristic of BPH is increased stromal:epithelial ratio.

    • Over time, prostatic hyperplasia can result in bladder outlet obstruction.

    • Obstruction has both:

      • a prostatic component due to increased epithelial tissue, particularly in a transition zone

      • a dynamic component due to increases in stromal smooth muscle tone

    • A large number of alpha-adrenergic receptors are present in the prostate capsule, stroma, and the bladder neck.

      • The predominant alpha-1 receptor in prostatic stromal tissue is the alpha-1A receptor.

    • Treatment of symptomatic BPH is mainly accomplished via:

      • reduction of the size of the glandular component

        • following inhibition of the formation of dihydrotestosterone (DHT) by 5-alpha-reductase inhibitors

      • relaxation of smooth muscle tone

        • with alpha-blockers

    • Select surgical intervention (e.g., transurethral resection) alleviates symptoms of urinary obstruction by reduction of prostatic bulk

Investigations

    • urinalysis

      • pyuria (pus in urine)

    • PSA

      • elevation greater than age guideline

    • International Prostate Symptom Score (IPSS)

      • score of 0 to 35 to define severity of symptoms

    • global bother score

      • score 0 to 6 dependent on degree of bother

    • volume charting

      • diary of frequency of voiding

    • ultrasound

      • hydronephrosis, mass, urolithiasis

    • CT abdomen/pelvis

      • mass, hydronephrosis, urolithiasis

    • cystoscopy

      • mass, stone, stricture

    • uroflowmetry

      • less than 20 mL/second

    • urodynamic study

      • abnormal bladder pressure, abnormal bladder voiding

Management

a) conservative

    • watchful waiting

    • behavioural management programme

      • Limitation of fluids

      • bladder training focused on timed and complete voiding

      • treatment of constipation

b) medical

    • Alpha-blockers work through smooth muscle relaxation in the prostate and bladder neck.

      • The predominant receptor type in the prostate and bladder is the alpha-1A receptor

      • Alpha-blockers specific for this receptor are more prostate selective and have less vascular effects

      • Long-acting alpha-1 antagonists include terazosin and doxazosin

      • Alfuzosin is a modified release alpha-1A antagonist

      • Tamsulosin and silodosin are a long-acting sub-type (alpha-1A) selective alpha-blocker

    • 5-alpha-reductase inhibitors work through reduction of serum dihydrotestosterone (DHT)

      • Inhibit DHT formation, reducing prostate volume by 20% to 25%

      • They have been shown to reduce the risk for acute urinary retention and the need for invasive therapy by approximately 50%

      • Finasteride is a type II 5-alpha-reductase inhibitor that reduces serum DHT by 75%

      • Dutasteride is a type I and II 5-alpha-reductase inhibitor with 90% to 95% reduction of serum DHT

c) surgical

    • Minimally invasive therapy

      • photoselective vaporisation

      • transurethral needle ablation

      • transurethral microwave therapy

      • visual laser ablation

      • interstitial laser coagulation

    • Transurethral resection of the prostate (TURP) or transurethral vaporisation (TUVP)

    • Open prostatectomy or holmium laser enucleation (HoLEP)

Prognosis

    • The majority of patients with BPH can expect at least moderate improvement of their symptoms with a decreased bother score and improved quality of life

    • Lower urinary tract symptoms (LUTS), secondary to BPH, may affect sexual wellbeing including erectile function

    • Medical therapy for BPH may also effect sexual function, beneficially and harmfully, so this must be considered on an individual basis

    • Some studies suggest that patients with a low risk for progression may be able to discontinue first-line therapy with alpha-blockers after several months of therapy

      • However, the majority of patients will require ongoing therapy.

    • Clinical progression of BPH (as defined by symptom progression >3 points) occurs in approximately 20% of patients

      • Approximately 2.5% of patients will develop acute urinary retention and another 6% will require invasive therapy over a 5-year time-frame

      • Risk for BPH progression is increased in patients with higher prostate volumes and PSA levels

      • Risk reduction of clinical BPH progression has been demonstrated by 39% in patients on doxazosin and 34% in patients on finasteride

        • Patients on combination therapy had a 66% reduction in clinical BPH progression