A 72-year-old man (Mr Johnson) presents to the surgical assessment unit. He has been complaining of a 3-year history of marked lower urinary tract symptoms (LUTS) and a recent history of bed-wetting. He has noticed his urinary flow has diminished significantly over time, and now he just ‘dribbles’. He tells you he spends ‘hours’ in the toilet as it takes him a long time to void. He wakes up five times a night to pass urine. Mr Johnson saw his GP today regarding these symptoms. The GP noticed a large abdominal mass. He felt uncertain about this abdominal mass and hence he referred the patient for your assessment and management. Mr Johnson has an non-significant past medical history.
Examining his abdomen you note him to have a full bladder to the level of the umbilicus. This mass is dull to percussion and painless on palpation. He has not really noticed his bladder become full overtime. Digital rectal examination (DRE) revealed a large benign-feeling prostate, no masses and normal anal tone and sensation. His biochemistry reveals markedly deranged renal function, which is a new finding.
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1 What is Mr Johnson’s likely diagnosis and how would you manage him initially?
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Correct answer:
The likely diagnosis is high pressure chronic retention (HPCR). He is likely to have a large residual volume. He has renal dysfunction resulting from ‘back pressure’ on the kidneys. Your initial management should consist of:
- Insertion of a catheter and record the post void residual
- U&Es initially and daily
- Daily weights (this allows documentation of loss of excess fluid)
- Lying and standing blood pressure. This is looking for a symptomatic postural drop of 20 mmHg
- Hourly urine output
He does not necessarily require IV fluids straight away, as initially the diuresis is a physiological one. He would require IV fluids if the diuresis is prolonged or he becomes symptomatic with postural hypotension.
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2 What investigation would you request and why?
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Correct answer:
A renal tract ultrasound scan is needed to check for bilateral hydro-ureteronephrosis. This usually resolves with catheter drainage and as renal function improves.
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3 On catheterization he has a residual volume of 3 L. Over that day he has significant diuresis. Can you explain the physiological process of this?
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Correct answer:
Initially there is a physiological diuresis with the excretion of retained fluid. This can be followed by a pathological diuresis because of the following:
- Decreased response to collecting ducts to antidiuretic hormone (ADH)
- Increased production atrial natriuretric peptide (ANP)
- Loss of cortico-medullary concentration gradient
- Osmotic diuresis due to increased urea excretion.
Over the next week his renal function improves with catheter drainage and his diuresis stops. Your specialist registrar consents him and lists him for an outpatient transurethral resection of the prostate (TURP) and discharges him home with a catheter in situ.
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4 What are the other indications for TURP?
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Correct answer:
Other than HPCR, the following are indications for TURP:
- Recurrent urinary tract infections
- Recurrent or refractory bouts of urinary retention
- Bladder stones
- Haematuria caused by prostatic bleeding that does not settle with 5-ARIs
- Worsening symptoms despite maximum medical therapy.
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5 If Mr Johnson was multiply comorbid, precluding him from operative intervention, what would his management options be?
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Correct answer:
Clean intermittent self catheterization (CISC) or a long-term catheter (LTC) are the only other management options.
