Disorder of the prostate - what is benign prostatic hyperplasia (BPH ) ?

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a histological entity characterized by an increase in both the stromal and glandular elements of the prostate gland, leading to an overall increase in its size. Benign prostatic enlargement is a clinical finding on rectal examination and is not necessarily associated with benign prostatic obstruction of urine flow, as defined by urodynamic studies.

Epidemiology

Benign prostatic hyperplasia is the most common benign tumour in men and the risk of its development increases with age. It is found in 70% of men aged 70 and the prevalence approaches 100% by 80 years of age. It is more common in Western societies than in the Far East; in the USA it is more common in the black population than the white.

Pathology

Benign prostatic hyperplasia arises as nodular growth in the periurethral glands of the transitional zone of the prostate . Histological evidence can be found as early as the fourth decade of life. Development of benign prostatic hyperplasia probably results from an imbalance of growth factors (fibroblast growth factors and transforming growth factor β), oestrogen and increasing sensitivity of the ageing prostate to circulating androgens. Circulating testosterone is converted by the prostatic intracellular enzyme 5α-reductase to dihydrotestosterone (DHT), the major intracellular androgenic metabolite, and is the main stimulant for growth.

Although the symptoms associated with benign prostatic hyperplasia are often attributed to outflow obstruction, the association is not entirely accurate. Relief of symptoms does not always follow after prostatectomy and yet treatments that do not necessarily relieve outflow obstruction can result in improvement of symptoms .It is likely that there are other mechanisms involved. Therefore objective evidence of obstruction is usually acquired prior to surgical treatment.

Scope of disease

The majority of patients with benign prostatic hyperplasia are asymptomatic. A smaller proportion of patients present with symptoms arising directly from urinary flow obstruction (voiding symptoms) or secondary to changes within the detrusor muscle of the bladder as a result of outflow obstruction (storage symptoms). Patients can also develop haematuria, stone formation, acute and chronic retention of urine and secondary renal impairment.

Clinical features

The most common form of presentation is with lower urinary tract symptoms (LUTS). Voiding symptoms include hesitancy (longer time to initiate the urinary flow), poor or intermittent stream of urine, straining, terminal dribbling, haematuria and dysuria. Storage symptoms include frequency of urine, urgency, nocturnal enuresis and incontinence. It is important to note that lower urinary tract symptoms are not specific to benign prostatic hyperplasia and can be caused by urethral strictures, urinary tract infections, bladder cancer, prostate cancer, or detrusor changes associated with aging.

Acute urinary retention is more common in the elderly and characterized by a painful total inability to void. Most patients have minimal urinary symptoms prior to the development of acute retention and on catheterization have a large amount of residual urine (600-1000 mL). Patients with chronic urinary retention may present with storage symptoms and may have a painless, palpable bladder on examination that may be associated with renal impairment.

On examination, the bladder may be palpable. The external genitalia are examined for phimosis, meatal stenosis or urethral induration as alternative causes for obstruction. A rectal examination is performed to assess the consistency and regularity of the prostate gland and to identify nodules suggestive of prostate cancer. The normal prostate feels rubbery, with a palpable median sulcus and discernible lateral margins. Although there is little correlation between the size of the prostate on rectal examination and the degree of obstruction, an enlarged prostate gland on clinical examination is an independent predictor of outcome following treatment.

Initial Investigation

Urinalysis

A midstream specimen of urine should be taken for dipstick analysis, microscopy and culture to exclude infection or haematuria. The presence of haematuria should alert the clinician as to the possible presence of a bladder tumour or stones.

Urea and electrolytes

An elevated serum creatinine level implies renal impairment that can arise from obstruction to urinary flow (obstructive uropathy).

Prostate-specific antigen (PSA)

PSA estimation should be performed if there is a clinical suspicion of prostate cancer, but not routinely as an investigation for the evaluation of lower urinary tract symptoms. An elevated PSA in the range of 3-10 ng/mL is more commonly associated with benign prostatic hyperplasia (60-70%) than with prostate cancer (25-30%).

Further investigations

Urodynamic evaluation

Urodynamics refers to the objective documentation of urinary tract function and provides a rational basis for therapy. Urodynamic assessment for male lower urinary tract symptoms includes an assessment of urine flow rate by non-invasive uroflowmetry .Ultrasound assessment of residual urine and inspection of a detailed frequency-volume micturition diary.

The predictive value of uroflowmetry for the presence of obstruction on pressure-flow studies is indicated in .The outcome of bladder outlet surgery is better in men with a low flow rate than in those with flow rates greater than 15 mL/s. Full pressure-flow evaluation may be required in patients with failed previous surgery or concomitant pathology.

Abdominal film

A plain abdominal KUB film is performed if there is a suspicion of bladder calculi.

Abdominal ultrasound

Abdominal ultrasound is performed to identify hydronephrosis in patients with impaired renal function or a palpable bladder and to detect tumours in patients with haematuria.

Flexible cystoscopy

Flexible cystoscopy is indicated in selected patients with recent onset of storage symptoms or haematuria to exclude a lower urinary tract cancer.

Initial management

Urinary retention

A urinary catheter should be inserted to decompress the bladder and usually results in immediate relief of both acute and chronic retention. A trial without catheter alone is often unrewarding in acute retention, and surgery in the form of transurethral resection is usually indicated for relief of obstruction.

With chronic retention, the residual volume on catheterization may be in excess of 3 L, and a brisk diuresis may follow decompression. In this setting (5% of patients) fluid replacement with intravenous normal saline may be required.

Expectant management

Patients with mild symptoms may not require treatment. Over 5 years, 30% of patients with benign prostatic hyperplasia will experience progression of their symptoms, whilst 50% will remain static, and 20% will improve. Approximately 10% will experience an episode of acute retention. Patients need to be kept under follow-up to identify those with progressive disease.

Medical management

Drugs are aimed at reducing prostatic and bladder neck smooth muscle tone (α-adrenergic antagonists) or prostatic gland volume (5α-reductase inhibitors).

α-Adrenergic antagonists

Bladder outflow obstruction due to benign prostatic hyperplasia is partly due to the dynamic effect of the tone of the prostate smooth muscle mediated via α-adrenoreceptors. α-Adrenergic antagonists (e.g. alfuzosin, tamsulosin) lead to objective and subjective improvement in approximately 80%.

5α-Reductase inhibitors

5α-Reductase inhibitors (e.g. finasteride) block the conversion of testosterone to dihydrotestosterone and reduce prostate size with minimal effect on potency and libido. The use of finasteride is associated with symptomatic improvement (which may take from 6-9 months), with fewer patients undergoing surgery (10% to 5%) and developing acute urinary retention (7% to 3%) at 4 years.1 The main clinical use is in the reduction of the risk of acute retention of urine in elderly unfit men and in those with a markedly enlarged prostate.

Combination therapy

It has recently been reported that the use of both doxazosin and finasteride results in significantly greater improvement in symptoms than either agent alone.

Surgical management

Indications for surgical treatment include acute urinary retention, renal failure associated with hydronephrosis, recurrent urinary tract infection, recurrent haematuria and persistent symptoms.

Transurethral incision of prostate

Transurethral incision (bladder neck incision) is performed if there is bladder outflow obstruction due to benign prostatic hyperplasia with a resectable prostatic weight of less than 30 g. The bladder neck is divided with a single or double incision at the 7 or 5 o' clock position as far distally as the verumontanum. The results are comparable to transurethral resection.

Transurethral resection of the prostate

Transurethral resection of the prostate (TURP) is the standard surgical treatment for benign prostatic obstruction. It involves resection of the hyperplastic prostatic tissue from the bladder neck as far distally as the verumontanum. The prepared patient is anaesthetized with general or spinal anaesthetic and placed in stirrups. A resectoscope is inserted with diathermy attached. A formal cystoscopy is performed to exclude bladder lesions. The prostate is 'shaved' away in strips using the resecting loop, and haemostasis is performed. Resected 'chips' are evacuated from the bladder using an Ellik's evacuator. The specimen is sent for histology to exclude cancer. After sufficient tissue has been removed, a large (24 F) three-way catheter is carefully inserted and bladder irrigation attached. The catheter may be removed after a few days, when the haematuria has settled.

The success rate for symptomatic relief is 85%. Generally this procedure is safe, although it has an overall mortality of around 1% and morbidity due to transurethral resection syndrome (see below), haemorrhage, sepsis, clot retention, stricture formation (3%), urinary incontinence (1%), erectile dysfunction (15%), and retrograde ejaculation (90%).

CLINICAL ALERT

Transurethral resection syndrome is due to absorption and breakdown of glycine (used as an irrigant) resulting in hypervolaemia and dilutional hyponatraemia. Clinically patients develop restlessness and confusion followed by convulsions, cardiac arrhythmia and pulmonary oedema. Mortality associated with transurethral resection syndrome is 50%. Measures to reduce the risk of transurethral resection syndrome include limiting the resection time to less than 1 hour, abandoning the procedure if there is excessive bleeding, and reducing the pressure of the irrigant in the bladder by lowering the level of the irrigation fluid. If the development of transurethral resection syndrome is suspected, resection should be discontinued, haemostasis obtained rapidly, the irrigant switched off and the patient transferred to a high-dependency unit for invasive monitoring together with cardiopulmonary support and the cautious use of diuretics or fluid restriction

Open retropubic prostatectomy

Open surgery via a lower midline or Pfannenstiel incision should be considered for patients with very large prostates (estimated resectable prostatic size greater than 80 g). This approach is preferred to TURP for large prostates because it is quicker and has a reduced risk of transurethral resection syndrome, as there is no need for irrigation with glycine.

Minimally invasive therapies

Due to the morbidity of TURP there has been considerable interest recently in the development of alternative, less invasive therapies. These include transurethral microwave thermal therapy (TUMT), transurethral needle (radiofrequency) ablation of the prostate (TUNA), high-intensity focused ultrasound (HIFU) and the insertion of self-retaining intraurethral stents (for patients with poor life expectancy or those who are unfit for surgery).

Prognosis

Drug treatment is associated with symptomatic improvements in the majority. Approximately 10% of patients will eventually require surgery.



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Comments 1 comment

MJ Franc 4 years ago

Great information, it makes perfect sense too.Lovely video as well.Very well presented ..Thanks a lot for sharing..:)

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