Prostatic hyperplasia is the most common benign condition to affect the prostate, and the treatment of this condition forms a major part of the workload for urological surgeons in Europe and the United States of America. Despite uncertainty about the aetiology and natural history of the disease it is evident that the incidence of benign prostatic hyperplasia increases with age. The doubling time of the hyperplastic gland is slow and it is rare to see patients presenting before the age of 55 years. Berry and his colleagues reviewed the results of five autopsy studies and looked at the prevalence of benign prostatic hyperplasia diagnosed histologically against age. The prevalence begins rising in the fourth decade and approaches 90 per cent by the ninth decade. American men now have a 29 per cent chance of undergoing a transurethral prostatectomy during their lifetime. The economic cost to the National Health Service in the United Kingdom from prostatic surgery lies between £54000000 and £71000000 a year. There is a much lower incidence of benign prostatic hyperplasia in Asia, and in China and Japan it is an uncommon condition.

The function of the prostate remains unclear. It produces about 10 per cent of the seminal fluid, has a beneficial effect on sperm motility, and produces numerous substances such as citric acid, acid phosphatase, prostaglandins, and zinc. The roles of most of these products are not known.

There is considerable evidence for steroid hormone control of prostatic growth. Normal prostatic development is only seen in the presence of functioning testes. Benign prostatic hyperplasia does not occur in castrated males, or pseudohermaphrodites who cannot convert their testosterone to the active metabolite, dihydrotestosterone. The role of oestrogens is controversial but they have been shown to be a stimulant of benign prostatic hyperplasia in the dog model. It is interesting that ageing in men is associated with a gradual decline in testosterone and a concomitant increase in oestrogens. Recently prostatic growth factors have been isolated that stimulate the growth in vitro of fibroblasts and epithelial cells. Benign prostatic hyperplasia originates in the periurethral or transitional zone of the prostate. The periurethral glands and connective tissue stroma undergo hyperplasia and the smooth muscle hypertrophies. These have the effect of enlarging the gland, causing narrowing of the prostatic urethra and obstruction (Fig. 1) 1589.

The clinical features of benign prostatic hyperplasia are caused by prostatic outflow obstruction, although there is no clear relationship between the size of the gland and symptomatology. Increasing outflow resistance commonly causes a mixture of obstructive symptoms (hesitancy, poor stream, a sensation of incomplete voiding due to postmicturition residual urine in the bladder, and ultimately acute or chronic urinary retention). These obstructive symptoms may be mixed with symptoms of detrusor irritation such as urgency, urge incontinence, frequency, and nocturia. It has also been demonstrated that patients with appreciable urinary symptoms due to benign prostatic hyperplasia may experience impairment of their health in many other ways, including disturbance of sleep, lack of energy, interference with employment, sexual function, social life, and holidays.

Symptoms secondary to urinary infection and bladder stones can result from incomplete bladder emptying (Fig. 2) 1590. Occasionally the bladder decompensates leading to chronic urinary retention with overflow. These patients often present with enuresis and little else in the way of obstructive symptoms. The most severe complication from benign prostatic hyperplasia is that of a high pressure chronic retention with renal failure, where symptoms may be minimal, and a poorly emptying bladder with hypertension are often the only clinical features (Figs. 3 and 4) 1591,1592.

A detailed history and full examination, including digital rectal examination are the essential prerequisites to making the diagnosis. The urine should be examined by dipstick and microscopy and culture. Serum creatinine and electrolytes should be checked if there is any suspicion of a chronic retention. If polydipsia is suspected a frequency/volume chart will establish this diagnosis.

Urinary symptoms are notoriously unreliable and unreproducible, so it is helpful to have further objective anatomical and physiological information. The most useful is the urinary flow rate, in which the patient is asked to void into a machine from a ‘comfortably full’ bladder. The flow is converted into a graph tracing (Fig. 5) 1593. A maximum flow rate of less than 10 ml/s from a voided volume of more than 200 ml strongly suggests obstruction.

Ultrasound imaging of the urinary tract gives information on the size of the prostate, the residual volume after micturition, bladder stones, and upper urinary tract dilatation. This investigation has replaced the intravenous urogram (IVU) as the investigation of choice for demonstrating the relevant anatomy in this condition.

A flow rate study and ultrasound should be sufficient to establish the diagnosis in the majority of cases. Formal urodynamic assessment is indicated in the younger age group or where irritative symptoms predominate.

The aims of treating benign prostatic hyperplasia are to improve the quality of life by removing outflow obstruction and restoring easy micturition. It has been suggested that symptomatic patients should be offered the choice of immediate treatment or watchful waiting, on the basis that the patient's preferences should be the dominant factor in the decision to recommend intervention in the absence of the risk of mortality. Many different therapies are available for the treatment of benign prostatic hyperplasia. These include a range of drug therapies and surgical techniques. The options range from watchful waiting to open prostatectomy and are discussed in more detail below.

These include &agr;-blockers, which act by relaxing the smooth muscle of the prostate and bladder neck which receives innervation via &agr;&sub1;-adrenergic receptors. Postural hypotension is a common side-effect of these drugs but is minimized by taking the first dose at night. Those of a younger age group or those patients with small prostate glands seem to benefit most from &agr;-blockade.

Evidence suggesting that functioning testes are necessary in the development of benign prostatic hyperplasia has led a number of investigators to assess the role of hormonal treatments. Androgen withdrawal has been shown to cause regression of benign prostatic hyperplasia, but the side-effects of loss of libido and potency make it unacceptable in the treatment of this disease. Attempts have therefore been made to develop a 5&agr;-reductase inhibitor which blocks the conversion of testosterone to dihydrotestosterone. It is hoped that this will cause regression of the prostate while maintaining testosterone levels and avoiding unacceptable side-effects. While the role of these drug treatments remains to be established, in the foreseeable future they are unlikely to replace surgical treatment as a long-term option in many cases of benign prostatic hyperplasia.

There are a variety of surgical options in the treatment of benign prostatic hyperplasia although transurethral prostatectomy at the present time remains the gold standard by which other methods should be evaluated. Transurethral prostatectomy (TURP) has increased in popularity over the last three decades with the development of the resectoscope and this operation led to a marked reduction in postoperative morbidity and length of hospital stay compared with the open prostatectomy. In 1989/90 some 93 per cent of all prostatectomies performed in National Health Service hospitals in the United Kingdom were performed transurethrally and this figure rose to 98 per cent when prostate surgery performed by specialist urological surgeons was evaluated.

The widespread introduction of transurethral prostatectomy without its rigorous assessment in randomized controlled trials has led to recent debate about its effectiveness and the risks relative to the previously conventional open procedure. Some studies have suggested a higher mortality in patients undergoing a transurethral prostatectomy over those undergoing open surgery. However more recent work has suggested that this difference may be due to difficulties in adjusting adequately for comorbidity.

It has been found that 78 per cent of patients experience improvement of symptoms after a prostatectomy and 74 per cent are happy with the result. It would certainly appear that outcomes are related to the severity of the symptoms, with those patients experiencing the most severe symptoms preoperatively experiencing the greatest improvement postoperatively.

The incidence of complications following transurethral prostatectomy varies between different series but larger studies have reported an immediate postoperative morbidity rate of 18 per cent, with haemorrhage, clot retention, failure to void after catheter removal, and urinary tract infection being the common complications. Total incontinence is very rare although minor degrees of incontinence are much more common and the incidence of urinary tract infection in the 3 months following surgery has been reported as high as 25 per cent. The incidence of retrograde ejaculation is variable but all patients should be warned of this before surgery. Transurethral syndrome is an unusual complication following transurethral resection and is characterized by raised blood pressure, bradycardia, mental confusion, and nausea. It is thought to be due to intoxication with the irrigating solution and is related to the length of time of the procedure. The operative mortality following transurethral prostatectomy ranges from 0.2 to 1 per cent, the most common cause of death following surgery being due to cardiovascular complications.

Transurethral prostatectomy is not without its complications and these together with a trend towards less invasive surgery have led to increasing pressure on urological surgeons to search for alternative measures to treat benign prostatic hyperplasia. At the present time there are a number of other alternatives to transurethral prostatectomy which will be discussed below.

Dilatation of the prostatic urethra has been practised for many centuries using metal sounds; in the mid-nineteenth century metal dilators were designed with the specific purpose of rupturing the prostate gland and the bladder neck. While successful in relieving obstruction they were associated with significant morbidity and their use was abandoned. Transurethral dilatation of the prostate involves positioning a balloon catheter carefully in the prostatic urethra and inflating it to a predetermined size to cause rupture of the anterior commissure and widening of the prostatic urethral lumen, thereby relieving obstruction. Several studies have shown it to be a safe procedure and it has been suggested that it is most effective in younger patients with moderate symptoms without median lobe enlargement of the prostate and residual urine capacity less than 150 ml. While a number of patients seem to benefit from the procedure there appears to be a high relapse rate.

This technique was initially reported by Orandi in 1973 and involves an incision in the capsule of the prostate in the seven o'clock and five o'clock position opening up the prostatic urethra and forming a groove or tunnel through which voiding can take place. The technique does not involve resection of prostatic tissue and for this reason is said to carry less morbidity and a shorter operating time. The long-term follow-up rate shows symptomatic relief in 80 per cent of patients although its use is not recommended with a prostate gland of over 35 g in weight.

Heat can be selectively delivered to the prostate by microwave probes placed in the rectum or in the prostatic urethra. The depth of penetration of the microwave is dependent on the frequency and the heating of the tissue results from polarization of the small molecules in the oscillating electromagnetic field. Conventionally hyperthermia consists of raising the body temperature to between 42 and 45°C. More recently the concept of thermotherapy has been introduced where the prostate is heated higher than 45°C in order to produce more definite tissue changes in the prostate. Hyperthermia treatments require several sessions lasting 30 to 60 min; thermotherapy requires a single treatment lasting 1 h. These treatments can be performed on an outpatient basis with minimal morbidity but although good symptomatic responses have been reported there is very little improvement in the minimal flow rate. Complications include haematuria, urinary tract infection, and rectal pain and 20 per cent of patients may need catheterization for up to 7 days.

This technique appears to be effective in certain groups of patients but requires a prolonged period of catheterization, making it less attractive than are other options.

Ultrasonic aspiration of tissues has been reported in a variety of different surgical procedures and, following the development of an endoscopic ultrasonic aspirator by Wuchinich, aspiration of the prostate has become practical. The instrument combines fragmentation, irrigation, and aspiration of tissues high in water content whilst sparing those tissues with high collagen levels such as prostatic capsule. Some encouraging results have been reported although the procedure is not without its complications. It would appear that up to 85 per cent of patients maintain antegrade ejaculation following the procedure.

The first stent used for prostatic obstruction was described in 1980 by Fabian and since then a variety of temporary and permanent prostatic stents have been developed. Many have the advantage that they can be introduced under local anaesthetic although the potential for dislodgement, calcification, and infection, and interference in sexual function remain.

This is probably the treatment for benign prostatic hyperplasia that holds the greatest promise for the future. The term laser prostatectomy embraces two distinct techniques, contact and non-contact Nd:YAG lasers. The use of the Nd:YAG laser was first described in the treatment of localized prostatic carcinoma, and subsequently the development of the transurethral ultrasound-guided laser induced prostatectomy system was described using a non-contact laser which, under ultrasound guidance, produced sloughing of the prostatic tissue by coagulative necrosis. Following treatment the urinary flow improves over several weeks and initial results suggest that this improvement may match that obtained from a conventional transurethral prostatectomy. The mechanism of non-contact laser prostatectomy is similar in many respects to microwave hyperthermia and cryosurgery which rely primarily on thermal coagulation and delayed sloughing of the tissue.

Using the contact laser technique the laser probe directly touches and immediately vaporizes the prostatic tissue, the net result being the immediate removal of obstructing tissue in a manner equivalent to transurethral prostatectomy. Improvement in the urinary stream is usually prompt although the contact method is more time-consuming than the non-contact technique. The potential advantages of laser prostatectomy over conventional transurethral prostatectomy are in terms of postoperative morbidity and economic costs. It is anticipated that reduced bleeding may lead to the reduction requirement for transfusion and the possibility of avoiding catheterization. If this proves to be the case selected patients may be treated in this way in a day surgery unit.

Benign prostatic hyperplasia continues to account for a major part of the workload of urological surgeons. This is likely to increase with the increasing age of the population and will continue to present a challenge for urological surgeons to develop new and effective ways of managing the disease. No doubt new drug therapies will be developed for patients in whom watchful waiting is not an option, but the most exciting surgical development at the present time would appear to be in the development of laser prostate surgery.

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