Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) or benign prostatic enlargement (BPE) is an extremely common condition in elderly men and is a major cause of bladder outflow obstruction. 

Terminology

The term benign prostatic hypertrophy was formerly used for this condition, but since there is actually an increase in the number of epithelial and stromal cells in the periurethral area of the prostate, not an enlargement of cells, the more accurate term is hyperplasia.

Although the term prostatomegaly is often used interchangeably with BPH, strictly speaking prostatomegaly may refer to any cause of prostatic enlargement. 

Epidemiology

By the age of 60, 50% of men have BPH, and by 90 years of age the prevalence has increased to 90%. As such it is often thought of essentially as a 'normal' part of ageing ¹.

Clinical presentation

Although a degree of prostatomegaly may be completely asymptomatic, the most common presentation is with lower urinary tract symptoms (LUTS) including ^1-4: 

• poor stream despite straining
• hesitancy, frequency and incomplete emptying of the bladder
• nocturia

An enlarged prostate may also be incidentally found on imaging of the pelvis or on digital rectal exam. 

The international prostate symptom score (IPSS) is an 8 question (7 symptom questions + 1 quality of life question) scoring system used in assessing clinical severity, tracking symptoms and aiding management in benign prostatic hyperplasia.

Pathology

Benign prostatic hyperplasia is due to a combination of stromal and glandular hyperplasia, predominantly of the transition zone (as opposed to prostate cancer which typically originates in the peripheral zone).

Androgens (DHT and testosterone) are necessary for the development of BPH, but are not the direct cause for the hyperplasia.

Risk factors

• increasing age
• family history
• race: blacks > whites > asians
• cardiovascular disease
• use of beta-blockers
• metabolic syndrome: diabetes, hypertension, obesity ⁸

Complications

Complications of untreated benign prostatic hyperplasia include ⁴:

• urinary retention
• bladder calculi and bladder diverticula
• recurrent urinary tract infection
• recurrent gross haematuria
• hydronephrosis and hydroureter and eventual renal failure

Markers

• prostate specific antigen (PSA): elevated but non-specific

Radiographic features

Ultrasound

Ultrasound has become the standard first line investigation after the urologist's finger.

• there is an increase in volume of the prostate with a calculated volume exceeding 30 mL (width x height x length x 0.52)
• the central gland is enlarged, and is hypoechoic or of mixed echogenicity
• calcification may be seen both within the enlarged gland as well as in the pseudocapsule (representing compressed peripheral zone)
• post-micturition residual volume is typically elevated
• associated bladder wall hypertrophy and trabeculation due to chronically elevated filling pressures

Fluoroscopy

On IVP, the bladder floor can be elevated and the distal ureters lifted medially (J-shaped ureters or fishhook ureters). Chronic bladder outlet obstruction can lead to detrusor hypertrophy, trabeculation and formation of bladder diverticula.

CT

Not typically used to assess the prostate, BPH is more frequently an incidental finding. Extension above the symphysis pubis was used as a marker on axial imaging, however now that volume acquisition and coronal reformats are standard, the same criteria as on US can be used (>30 mL).

MRI

• enlarged transition zone
• heterogeneous signal with an intact low signal pseudocapsule in the periphery

Treatment and prognosis

Medical management for early disease typically commences with an alpha blocker such as tamsulosin given in combination with a 5-alpha reductase inhibitor such as dutasteride. 

Surgical management for symptomatic patients is typically with a transurethral resection of the prostate (TURP), and careful patient selection is important given the high prevalence of both BPH and lower urinary tract symptoms (LUTS) in this population. Intermittent self catheterisation is an option for those unsuitable for surgery. 

Urodynamic studies and prostate size estimation are often used to guide therapy, although prostate size in isolation is a poor predictor of symptom severity ⁴.