Management (general and specific)
Catheterisation
Urethral catheterisation is the usual method employed in the UK4. Suprapubic catheterisation (SPC) is usually reserved for when this fails. Suprapubic catheterisation is possible using several techniques4. US guidance is an extremely useful adjunct to utilising either Bonanno catheters or the more conventional balloon catheter.
Unguided SPCs are contraindicated when there is a past history of bladder cancer, a history of haematuria or a suspicion of clot retention. These are the red flags of bladder cancer and one would wish to avoid seeding and spreading along the track that is used to insert the catheter.
Its important to document post catheterisation residual volume (RV), features of prostate examination, renal function, catheter type and gauge (14 or 16 French gauge) and ease of introduction in the case notes, as they assist in determining further management. Consent should be recorded in the notes.
Post obstructive diuresis can be a problem after relief of retention. Most commonly accepted definitions are a urine output of greater than 200mL/hr for two consecutive hours or greater than three litres over a 24-hour period. Some patients can pass as much as 8-20 L/day. Cardiac failure or renal insufficiency patients, especially if they have marked peripheral oedema, are at high risk. Severe dehydration and postural hypotension can occur. Hourly urine outputs must be recorded and should be less than 200 ml/h as a general rule. High risk patients for this condition are often found to have a RV>1000 ml and impaired renal function. Careful fluid balance assessment, electrolyte monitoring and judicious fluid replacement (preferentially via oral route) is used to manage post obstruction diuresis, which should settle within 24-48 hours.
Up to 70% of men will have recurrent retention within one week if the bladder is simply drained16.