Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is an idiopathic but common benign condition which affects older men. The prevalence increases with age and it affects 70% of males > 60 years. It is characterised by a slowly growing prostate which compresses the urethra and causes chronic lower urinary tract obstruction, causing lower urinary tract symptoms (LUTS). It can be managed with medicines or surgical removal.

Etiology

• Multifactorial
• Sensitization of the prostate to androgens and oestrogens
• Higher oestrogen/testosterone ratio in elderly

Pathophysiology

• BPH originates from the transitional zone of the prostate
• BPH -> chronic bladder outlet obstruction -> LUTS
• There is no increased risk for prostate cancer

Clinical features

• Lower urinary tract symptoms like urinary urgency, frequency, incontinence, hesitancy, poor stream, etc.

Complications

• Recurrent urinary tract infection (due to the chronic urinary obstruction)
• Bladder stone
• Severe urinary tract obstruction

Diagnosis

• Diagnosis of BPH is clinical
  • Based on presence of LUTS in absence of other causes of LUTS
  • BPH does not require prostate biopsy
• International prostate symptom score (IPSS)
  • A questionnaire used to screen for, diagnose, and follow up symptoms of BPH
  • Points given from answers, the sum ranges from 0 – 35
  • The sum gives the severity of symptoms
• Urine analysis
  • If pyuria -> infection, which can cause similar symptoms
  • If haematuria -> can be tumor or ureter stone
• PSA
  • To look for co-existing prostate cancer
• Ultrasound
  • Can see stones, tumor, dilation of upper urinary tract
  • Can see prostate size
  • Can look for residual urine
  • Can see thickened bladder wall (detrusor hypertrophy)
• DRE
  • Symmetrically enlarged
  • Smooth (no nodules)
  • Firm
  • Nontender
  • Rubbery texture
• Uroflowmetry
  • Low peak flow, prolonged duration

Management

Behavioural modifications

• Restrict fluid intake before bedtime to prevent nycturia
• Reduce intake of diuretics like coffee, alcohol
• Urinating in sitting position

Medical therapy

• For voiding symptoms
  • Alpha-blockers
    • Tamsulosin, alfuzosin
    • Relax smooth muscle in bladder neck
    • Can cause hypotension, retrograde ejaculation
  • 5-alpha-reductase inhibitors
    • Finasteride, dutasteride
    • Decrease size of prostate
    • Takes 6 months for effect to set in
    • Can cause sexual dysfunction, gynecomastia
• For storage symptoms
  • Antimuscarinics
    • Oxybutynin, darifenacin
    • Decrease detrusor tone, increase bladder capacity
    • Can cause constipation, dry mouth, cognitive dysfunction (in elderly)
  • β-3 agonists
    • Mirabegron (Betmiga®)
    • Decrease detrusor tone, increase bladder capacity
    • More expensive
    • Does not have side effects of antimuscarinics

Surgical therapy

• Indications
  • Severe LUTS
  • BPH with complications
• Transurethral resection of the prostate (TUR-P)
  • Gold standard for BPH
  • Only if the prostate is not very large (< 80 g)

An instrument called a resectoscope is similar to a cystoscope and can be used to perform transurethral resection of the bladder (TUR-B) or prostate (TUR-P). This is done under spinal or general anaesthesia. The resectoscope has a camera like a cystoscope but is thicker, and has a metallic loop on the end. The metallic loop is a monopolar cautery, which is used to resect the bladder, or the prostate from the inside of the urethra. During TUR one obtains histological samples for pathological examination.

TUR-B is indicated for as a procedure which is both diagnostic and therapeutic for all stages of bladder cancer. TUR-P is indicated for severe benign prostatic hyperplasia instead of prostatectomy. It is not used for prostate cancer.

During TUR-P, the prostate capsule is not removed. The remaining cavity will be epithelialized after a few months.

TUR syndrome

During cystoscopy the bladder is continously irrigated with fluids. During cauterization bleeding and thermal burns occur, which is washed out with fluid. In some cases, a monopolar resectoscope is used because it is cheaper than a bipolar one. To prevent burns, the fluid used to irrigate must be non-conductive, usually distilled ion-free water or glycine-based solutions. Some of this water can be absorbed, causing hypotonicity and potentiallly haemolysis. Absorbed glycine can also cause CNS problem. This usually only occurs after prolonged irrigation, and so TUR is usually kept shorter than 1 hour to reduce the risk.

Nowadays one can use bipolar resectoscope with physiological saline solution (which is also conductive and is isotonic) to prevent TUR syndrome, but this fluid is more expensive. One can also use bipolar cautery, as this eliminates the need for non-conductive fluids.

• Simple prostatectomy
  • For large prostates (> 80g)
  • Only central and transitional zones are removed
    • Peripheral zone remains
  • Most commonly transvesically
    • Entry suprapubically
    • Operation is called transvesical adenectomy or Freyer prostatectomy
  • Can also be accessed through the perineum or the lower abdomen (retropubic)
• Newer methods
  • Laser ablation
  • Radioablation
  • Thermal ablation
• Radical prostatectomy is NOT used for BPH, only prostate cancer!