Self-assessment Questions

43 The prostate

• 1. What are the two main common conditions of the prostate which require consideration?

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  Benign enlargement and carcinoma.

• 2. After what age would you suspect to find some degree of enlargement of the prostate gland?

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  Some degree of enlargement of the prostate is extremely common from the age of 45 years onwards, but this enlargement often produces either no or only minor symptoms.

• 3. Which structures constitute the prostate gland?

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  The prostate, like the breast and thyroid, is composed of glandular tissue and stroma, which have periods of activity and involution throughout life under the influences of a changing milieu of hormones. Associated with these periods, the gland may become enlarged, with excessive proliferation of both fibrous and epithelial tissue. Enlargement of the prostate results in encroachment on the prostatic urethra. The median lobe may also enlarge as a rounded swelling overlying the posterior aspect of the internal urinary meatus. The three lobes may then obstruct the urethral lumen, impeding the passage of urine. Occasionally, only the median lobe is enlarged.

• 4. What are the six main pathological consequences of outflow obstruction caused by benign enlargement of the prostate gland?

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  (1) Trabeculation of the bladder: as a result of the obstruction, the bladder hypertrophies and the thickened muscle bands produce trabeculation. (2) Bladder diverticula: form from saccules between muscle bands. (3) Bladder stones form as a consequence of urinary stasis, particularly in diverticula. (4) Urinary infection may occur (especially after catheterization). (5) Hydronephrosis: results from back pressure on the ureters, which may result in renal failure. (6) Renal failure: due to progressive hydronephrosis, resulting in anaemia and uraemia. It is commonly referred to as obstructive nephropathy.

• 5. What are the clinical features of prostatic enlargement? What would you look for on examination?

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  Correct answer:

  There are three types of symptoms that result from prostatic hyperplasia
  (1) Obstructive symptoms consequent upon bladder outflow impedance.
  (2) Irritative symptoms due to the muscular instability of the bladder (detrusor instability).
  (3) Symptoms of the sequelae, such as infection or renal failure. It is important to realize that lower urinary tract infections are not always due to prostatic hyperplasia and bladder outflow obstruction. They may be due to the ageing process of the bladder since they may also occur in females with age.

  Obstructive symptoms. The narrowing of the prostatic urethra by the lateral lobes on each side and the possible median lobe enlargement causes the patient's difficulty in passing urine, with a poor and intermittent stream. There may be difficulty starting (hesitancy), and dribbling at the end of micturition (terminal dribbling). Associated with the prostatic enlargement, there may be partial obstruction and congestion of the prostatic plexus of veins, which may produce haematuria, which occurs at the end of micturition when the bladder contracts around the enlarged intravesical part of the prostate. As a cause of haematuria, bleeding from distended veins should only be diagnosed after exclusion of intravesical and upper tract tumours. Eventually, the bladder is likely to fail to overcome the obstruction and this results in retention of urine. This may be acute, with sudden onset and severe pain, or chronic, in which the bladder gradually becomes distended and the patient develops dribbling overflow incontinence, with little or no pain. It is in the latter group that uraemia is likely to occur. In some instances a complete obstruction then supervenes ('acute on chronic obstruction').

  Symptoms of detrusor instability. Involuntary contractions of the distended bladder result in frequency, urgency and nocturia. Urinary tract infection may exacerbate the symptoms, or precipitate acute retention.

  Symptoms of renal failure. The obstruction to the outflow of the bladder may result in renal failure with drowsiness, headache and impairment of intellect due to uraemia. It is therefore always wise to examine the bladder for enlargement and to determine the blood urea in an elderly man with inexplicable behavioural changes.

  Examination. The patient with an enlarged prostate, if uraemic, is likely to be pale and wasted, with a dry, furred tongue; he may be mentally confused. Examination of the abdomen may reveal a large bladder, which may reach to the umbilicus or even above. The swelling has the typical globular shape of the bladder arising from the pelvis, and is dull to percussion. If there is acute obstruction the bladder will be tender to palpation. On rectal examination the prostate will be enlarged. Typically, in benign enlargement the lateral lobes are enlarged and a sulcus is palpable between them in the midline posteriorly. This is in contrast to carcinoma, which usually involves the posterior part of the gland and obliterates the sulcus with a craggy, hard mass. The size of the prostate may appear to be larger than it really is if the bladder is grossly enlarged and pushes the prostate down towards the examining finger. The gland should therefore be palpated again after catheterization and before operation. Occasionally only the middle lobe is enlarged. In such cases the prostate appears normal in size on rectal examination, in spite of marked symptoms or even retention of urine. The diagnosis is established at cystoscopic examination.

• 6. What are the main obstructive symptoms of prostatic enlargement?

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  Correct answer:

  The narrowing of the prostatic urethra by the lateral lobes on each side and the possible median lobe enlargement causes the patient’s difficulty in passing urine, with a poor and intermittent stream. There may be difficulty starting (hesitancy), and dribbling at the end of micturition (terminal dribbling). Associated with the prostatic enlargement, there may be partial obstruction and congestion of the prostatic plexus of veins, which may produce haematuria, which occurs at the end of micturition when the bladder contracts around the enlarged intravesical part of the prostate. As a cause of haematuria, bleeding from distended veins should only be diagnosed after exclusion of intravesical and upper tract tumours. Eventually, the bladder is likely to fail to overcome the obstruction and this results in retention of urine. This may be acute, with sudden onset and severe pain, or chronic, in which the bladder gradually becomes distended and the patient develops dribbling overflow incontinence, with little or no pain. It is in the latter group that uraemia is likely to occur. In some instances a complete obstruction then supervenes (‘acute on chronic obstruction’).

• 7. What are the main symptoms of detrusor instability in people with prostatic enlargement?

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  Correct answer:

  Involuntary contractions of the distended bladder result in frequency, urgency and nocturia. Urinary tract infection may exacerbate the symptoms, or precipitate acute retention.

• 8. What are the main symptoms of renal failure in a person with prostatic enlargement?

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  Correct answer:

  The obstruction to the outflow of the bladder may result in renal failure with drowsiness, headache and impairment of intellect due to uraemia. It is therefore always wise to examine the bladder for enlargement and to determine the blood urea in an elderly man with inexplicable behavioural changes.

• 9. What would you look for on examination of a patient with prostatic obstruction?

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  Correct answer:

  The patient with an enlarged prostate, if uraemic, is likely to be pale and wasted, with a dry, furred tongue; he may be mentally confused. Examination of the abdomen may reveal a large bladder, which may reach to the umbilicus or even above. The swelling has the typical globular shape of the bladder arising from the pelvis, and is dull to percussion. If there is acute obstruction the bladder will be tender to palpation. On rectal examination the prostate will be enlarged. Typically, in benign enlargement the lateral lobes are enlarged and a sulcus is palpable between them in the midline posteriorly. This is in contrast to carcinoma, which usually involves the posterior part of the gland and obliterates the sulcus with a craggy, hard mass. The size of the prostate may appear to be larger than it really is if the bladder is grossly enlarged and pushes the prostate down towards the examining finger. The gland should therefore be palpated again after catheterization and before operation. Occasionally only the middle lobe is enlarged. In such cases the prostate appears normal in size on rectal examination, in spite of marked symptoms or even retention of urine. The diagnosis is established at cystoscopic examination.

• 10. What would you feel for on rectal examination of the prostate or a man with outflow obstruction?

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  Correct answer:

  On rectal examination the prostate will be enlarged. Typically, in benign enlargement the lateral lobes are enlarged and a sulcus is palpable between them in the midline posteriorly. This is in contrast to carcinoma, which usually involves the posterior part of the gland and obliterates the sulcus with a craggy, hard mass. The size of the prostate may appear to be larger than it really is if the bladder is grossly enlarged and pushes the prostate down towards the examining finger. The gland should therefore be palpated again after catheterization and before operation. Occasionally only the middle lobe is enlarged. In such cases the prostate appears normal in size on rectal examination, in spite of marked symptoms or even retention of urine. The diagnosis is established at cystoscopic examination.

• 11. How would investigate a person with prostatic enlargement and outflow obstruction?

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  (1) 24 hour frequency/volume chart. The patient records when he passes urine, and how much he passes in a 24 hour period.
  (2) Serum urea and creatinine to identify renal failure.
  (3) Haemoglobin is estimated, since uraemia inhibits the bone marrow and leads to anaemia.
  (4) Prostate-specific antigen (PSA) is a sensitive indicator of prostatic carcinoma, and has superseded measurement of acid phosphatase. A PSA concentration of below 0.4ng/mL is normal. Refinements in PSA include measurements of the free/total PSA ratio, which is over 0.15 in normal men.
  (5) Urinalysis for the presence of leucocytes. Culture is performed if urinalysis is positive: an infected renal tract severely complicates prostatic disease. Most patients with prostatic disease do not have an infected urine until the bladder and urethra have been instrumented.
  (6) Urine flow rate assessment. A void volume of at least 200mL is required for meaningful assessment of maximal flow rate. A maximum flow rate of less than 10 mL/s indicates obstructed flow or weak bladder contractility. A flow rate of over 15mL/s is unlikely to be obstructed. Urodynamics (pressure flow assessment) can be used to distinguish outflow obstruction from poor detrusor contraction, which will not improve following surgery.
  (7) Ultrasound scan will demonstrate bladder enlargement, hydronephrosis and hydroureter. Following voiding it can be used to estimate the amount of residual urine in the bladder. Normally there is none; however, in the presence of bladder outflow obstruction the bladder cannot be completely emptied. Ultrasound has replaced the intravenous urogram in the routine investigation of patients with outflow obstruction.

• 12. What is the normal value for free/total prostate-specific antigen ratio?

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  Correct answer:

  This is over 0.15 in normal men.

• 13. What is the role of urodynamics in the assessment of urine flow rate in men with prostatic hypertrophy?

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  Correct answer:

  A void volume of at least 200mL is required for meaningful assessment of maximal flow rate. A maximum flow rate of less than 10mL/s indicates obstructed flow or weak bladder contractility. A flow rate of over 15mL/s is unlikely to be obstructed. Urodynamics (pressure flow assessment) can be used to distinguish outflow obstruction from poor detrusor contraction, which will not improve following surgery.