Acute urinary retention

Question 1

What are some causes of acute urinary retention?

Answer 1

BPH with possible prostate infection, bladder overdistension, excessive fluid intake or alcohol

Question 2

What are the 2 main categories of acute urinary retention?

Answer 2

• Spontaneous
• Precipitated - non-prostate related surgery, catheterization or urethral instrumentation, anaethesia, medication with sympathomimetic or anticholinergic effects

Question 3

How is painful acute urinary retention managed?

Answer 3

• Catheter
• If painful retention with <1L residue and normal serum electrolytes, then trial without catheter (TWOC) during same admission
• Prescribing a uroselective a-blocker (Tamsulosin) before TWOC improves chance of voiding success

Question 4

What is post-obstructive diuresis?

Answer 4

This is an increase in volume of urine produced by the kidneys following obstruction

Question 5

Describe the pathophysiology of post-obstruction diuresis

Answer 5

Obstruction causes a build up of fluid in the kidneys which causes retention of urea, sodium and water

When the obstruction is removed, the body rids this quickly, causing diuresis

This is often present in patients with chronic bladder outflow obstruction in association with uraemia, oedema, CCF and hypertension

Question 6

How is post-obstruction diuresis managed?

Answer 6

It is important to monitor fluid balance and be aware if urine output is > 200ml/hour

This will usually resolve in 24-48 hours but in severe cases, may require IV fluid and sodium replacement