Explain the need for and method of catheterisation to the patient. Use the smallest catheter—in practical terms usually a 12 Ch, with a 10-mL balloon. For longer catheterisation periods (weeks) use a Silastic catheter to limit tissue reaction, thereby reducing risk of a catheter-induced urethral stricture. If you suspect clot retention (a history of haematuria prior to the episode of retention), use a three-way catheter (20 Ch or greater) to allow evacuation of clots and bladder irrigation to prevent subsequent catheter blockage.
The technique is aseptic. One gloved hand is sterile, the other is 'dirty'. The dirty hand holds the penis or separates the labia to allow cleansing of the urethral meatus; this hand should not touch the catheter. Use sterile water or sterile cleaning solution to 'prep' the skin around the meatus.
Apply lubricant jelly to the urethra. Traditionally this contains local anaesthetic [e.g., 2% lignocaine (lidocaine)], which takes between 3 and 5 minutes to work. However, a randomised,
168 J. REYNARD AND N. COWAN
placebo-controlled trial showed that 2% lignocaine was no more effective for pain relief than anaesthetic-free lubricant (Birch et al. 1994), suggesting that it is the lubricant action that prevents urethral pain. If using local anaesthetic lubricant, warn the patient that it may 'sting.' Local anaesthetic lubricant is con-traindicated in patients with allergies to local anaesthetics and in those with urethral trauma, where there is a (theoretical) risk of complications arising from systemic absorption of lignocaine. When instilling the lubricant jelly, do so gently, as a sudden, forceful depression of plunger of syringe can rupture the urethra! In males, 'milk' the gel toward the posterior urethra, while squeezing the meatus to prevent it from coming back out of the meatus.
Insert the catheter using the sterile hand, until flow of urine confirms it is in the bladder. Failure of urine flow may indicate that the catheter balloon is in the urethra. Intraurethral inflation of the balloon can rupture the urethra. If no urine flows, attempt aspiration of urine using a 50-mL bladder syringe (lubricant gel can occlude eye-holes of catheter). Absence of urine flow indicates either that the catheter is not in the bladder or, if the indication for the catheterisation is retention, that the diagnosis is wrong (there will usually be a few millilitres of urine in the bladder even in cases where the absence of micturition is due to oliguria or anuria, so complete absence of urine flow usually indicates the catheter is not in the bladder). If the catheter will not pass into the bladder, and you are sure that the patient is in retention, proceed with suprapubic catheterisation.