Benign Prostatic Hyperplasia

Original Author: Toby Noton
Last Updated: March 26, 2019
Revisions: 6

Benign prostate enlargement (BPE) is an enlargement of the prostate gland which is most often due to benign prostatic hyperplasia (BPH). BPH is a histological diagnosis and is characterised by non-cancerous hyperplasia of the glandular-epithelial and stromal tissue of the prostate leading to an increase in its size.

BPH is very common and the risk increases with age; approximately 40% of men over 50 years have evidence of enlargement, rising to 90% of men over 80 years.

BPH is the most common cause of Bladder Outlet Obstruction (BOO) in men and hence can be considered the most common cause of Lower Urinary Tract Symptoms (LUTS) in men*.

*It is important to note that 15-30% of men over 65 have LUTS regardless of BPH


Pathophysiology

The prostate is a gland found in the male reproductive system which produces prostatic fluid.

The exact mechanism of benign prostatic hyperplasia has not been identified. However, it is clear that androgens play a role particularly in the development in the gland during adolescence and the future development of BPH.

Unlike other androgen dependent organs in the body, the prostate converts testosterone to dihydrotestosterone (DHT) using the enzyme 5α-reductase. DHT is more potent and accounts for 90% of androgen in the tissue. Also, unlike other tissues, the prostate retains the ability to respond to testosterone and thus levels of DHT also remain high though life.

Transforming growth factor beta (TGFβ) may also have a role in inducing proliferation and inhibiting apoptosis which leads to a net increase in cells resulting in the size increase seen in BPH. This is termed the ‘static component’.

Additionally there is increased alpha adrenoceptor-mediated prostatic smooth muscle contraction due to hyperplasia. This is termed the ‘dynamic component’.

Figure 1 – The anatomy of the prostate gland


Risk Factors

Age is the primary risk factor for developing BPH. Other risk factors include family history (first degree relatives), Afro Caribbean ethnicity, and obesity


Clinical Features

Patients with benign prostatic hyperplasia will generally present to primary care with lower urinary tract symptoms (LUTS), either voiding symptoms (hesitancy, weak stream, terminal dribbling, or incomplete empyting) or storage symptoms (urinary frequency, nocturia, nocturnal enuresis, or urge incontinence). Other less common symptoms can include haematuria and haematospermia.

A Digital Rectal Examination (DRE) is essential in order to help distinguish BPH from prostate cancer. A firm, smooth, symmetrical prostate is a reassuring sign (a more rounded prostate of greater than two finger widths may indicate enlargement)

As part of the initial assessment, every patient should complete an International Prostate Symptom Score questionnaire.

The International Prostate Symptom Score (IPSS)

The IPSS is a validated screening tool used in the evaluation and quantification of LUTS.

A score of 0-5, with 0 being ‘never’ and 5 being ‘almost always’, is assigned by the patient to each of the following questions. Scores of 0-7 are mild, 8-19 moderate and 20+ severe.

Each question begins with “Over the past month how often have you…”

  1. Had the sensation of not emptying your bladder completely after you finish urinating? (incomplete emptying)
  2. Had to urinate again less than two hours after you finished urinating? (frequency)
  3. Found you stopped and started again several times when you urinated? (intermittency)
  4. Found it difficult to postpone urination? (urgency)
  5. Had a weak urinary stream? (weak stream)
  6. Had to push or strain to begin urination? (straining)
  7. Most typically get up to urinate from the time you went to bed at night until the time you got up in the morning? (nocturia) 

There is one further question rated 0-6 for the following on Quality of Life and is not included in the overall score:

  1. If you were to spend the rest of your life with your urinary condition just the way it is now, how would that make you feel?

Differential Diagnosis

Figure 2 – Histology demonstrating benign prostatic hyperplasia

Common differential diagnoses for benign prostatic hyperplasia include:

  • Prostate cancer: patients may present with LUTS, however an asymmetrical craggy/nodular prostate and raised PSA are indicative of prostate cancer
  • UTI: the addition of dysuria, loin or suprapubic pain, or pyrexia, in the presence of a nitrite- and/or leucocyte-positive urine dip
  • Overactive bladder: although the patient will present with LUTS, bladder ultrasound will show a low post-void residual volume.
  • Bladder cancer: haematuria is likely to be the predominant feature

Investigations

A urinary frequency and volume chart should be completed by all patients with bothersome LUTS.

Bedside urinalysis should always be performed to exclude urinary tract infection. A post-void bladder scan can be helpful in assessing any significant chronic retention present

Depending on the findings from the DRE, a Prostate Specific Antigen (PSA) may be warranted in order to evaluate any malignant pathology, however is often marginally elevated in BPH even in the absence of malignancy.

An ultrasound scan of the renal tract can also be used to calculate the volume of the prostate* alongside assessment of the rest of the renal tract for urinary retention or hydronephrosis. Any prostate >30ml (volume calculated by width x height x length x 0.52) is deemed enlarged.

Urodynamic studies can give objective measurements related to reported symptoms, including bladder contractility, flow rate, and storage capacity. The bladder outlet obstruction index (BOOI) can help diagnose obstructive voiding related to BPH*.

*Calculated using maxium flow rate (Qmax) and detrusor pressure at maximum flow rate (Pdet max); BOOI = Pdet max – (2 x Qmax). A BOOI >40 = obstructed, BOOI 20-40 = equivocal, and BOOI <20 = unobstructed

Figure 3 – Hydronephrosis with associated cortical atrophy, which can be seen in long-standing cases of high-pressure chronic retention secondary to BPH


Management

For patients who have an incidental identification of benign prostatic hyperplasia, with no clinical features of the condition nor of any significant complications, many patients can simply be reassured and advised BPH is not a cause for significant concern.

Asking patients to keep a symptom diary, providing a medication review (especially iatrogenic causes of LUTS), and giving suitable lifestyle advice (e.g. moderating caffeine and alcohol intake) are helpful conservative options that can be done for all patients.

Medical Management

Most men with symptomatic BPH should initially be trialled on an α-adrenoreceptor antagonist (α-blockers)*, such as tamsulosin. They act by relax prostatic smooth muscle via blockade of α-adrenoceptors, thus reducing the dynamic component.

They provide a symptomatic benefit within a few days* and their response rate to this treatment is thought to be around 30-40%; those who do respond can expect approximately a 4-point improvement in their IPSS.

*Significant side effects are associated with alpha blockers, such as postural hypotension, asthenia, rhinitis, retrograde ejaculation, and Floppy Iris Syndrome (occurs intra-operatively in those undergoing cataract surgery).

For those that remain symptomatic despite α-adrenoreceptor antagonists, 5α-reductase inhibitors, such as Finasteride, are often then trialled*. They act to prevent the conversion of testosterone to DHT, resulting in a decrease in prostatic volume, thus reducing the static component; it is important to note that 5α-reductase inhibitors also decrease PSA level by 50%.

*Due to the mechanism of action, it can take up to six months to perceive symptomatic benefit from the use of 5α-reductase inhibitors

Surgical Management

Patients who are refractory to medical management or develop a significant sequlae of benign prostatic hyperplasia (e.g. high pressure retention) will be referred for potential surgical management.

A wide range of surgical procedures are available, most commonly of which performed is the TURP procedure.

TransUrethral Resection of the Prostate (TURP)

A TransUrethral Resection of the Prostate (TURP) is the most widely used procedure undertaken to manage BPH, involving endoscopic removal of obstructive prostate tissue using a diathermy loop to increase the urethral lumen size

It has excellent clinical outcomes, many patients having significant clinical improvement within a few months. Complications of TURP include haemorrhage, sexual dysfunction, retrograde ejaculation, and urethral stricture.

Other Techniques

A Holmium Laser Enucleation of the Prostate (HoLEP) procedure involves using a Holmium:YAG laser used to heat and dissect sections of prostate into the bladder. It is becoming increasing more prevalent in use due to excellent outcomes and reduced post-operative complications, its use only being limited due to it being a technically challenging procedure.

Other surgical methods used for BPH include PVP (Photoselective Vaporization of the Prostate), TUVP (Transurethral Vapourization of the Prostate), and TUMT (Transurethral Microwave Thermotherapy). Although used less commonly simple prostatectomy using open or minimally invasive surgical techniques remain an option for patients with large prostates.


Complications

The main complication of BPH is high-pressure retention, where chronic or acute-on-chronic urinary retention results in a post-renal kidney injury. Other complications of the condition include recurrent UTIs or significant haematuria episodes.

TURP Syndrome

TURP syndrome is a rare but potentially life-threatening complication of TURP. TURP using monopolar energy requires use of hypoosmolar irrigation during the procedure which can result in significant fluid overload and hyponatremia as the fluid enters the circulation through the exposed venous beds.

Patients with TURP syndrome present with confusionnausea, agitation, or visual changes and needs urgent management by addressing the fluid overload and carefully reducing the level of hyponatremia. Fortunately, TURP syndrome is increasingly rare due to the use of bipolar energy which uses isotonic irrigation fluids.

Key Points

  • Benign prostatic hyperplasia is very common and the risk of the condition increases with age
  • Urinary flow rate and post-void residual scans can be used in objectively assessing urinary symptoms
  • All patients should be offered advice on lifestyle and discussion of conservative management options
  • There are a vast array of both medical and surgical management options available

Quiz

Question 1 / 4
Which enzyme is responsible for converting testosterone to dihydrotestosterone?

Quiz

Question 2 / 4
Which of the following is NOT a recognised risk factor for developing BPH?

Quiz

Question 3 / 4
Which of the following would classically be classed as a voiding symptom (rather than a storage symptom)?

Quiz

Question 4 / 4
All of the following are recognised risk factors for developing TURP syndrome, except

Results

Medico Digital

Further Reading

The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study
Roehrborn CG et al., European Urology

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