Bladder catheterisation refers to insertion of a catheter (a tube) into the urinary bladder to drain urine. The catheter may be inserted into the urethra (urethral catheterisation) or through the skin (suprapubic catheterisation).
Indications
- Diagnostic
- Acquire urinary sample
- Monitor urinary output
- Especially important in critically ill patients
- To allow instillation of diagnostic agents
- To measure internal body temperature
- Therapeutic
- Alleviation of acute or chronic urinary retention
- To allow instillation of therapeutic agents
Types
- Straight catheter
- For acquiring urinary sample
- Inserted into the urethral opening
- Not for indwelling
- Foley catheter or standard balloon catheter
- Most common indwelling urinary catheter
- Has two lumens
- One lumen opens to the end of the catheter and allows urine to flow out
- One lumen opens to a deflated balloon at the end of the catheter
- Saline is injected into the other end, which inflates the balloon inside the bladder and prevents it from being dragged out
- Inserted into the urethral opening
- Contraindications
- Acute prostatitis
- Urethral trauma
- 3-way catheter
- Like a Foley catheter, but has one additional lumen
- This additional lumen is connected to a large bag of saline on one end, and it empties into the bladder
- This provides continuous irrigation of the bladder, which prevents formation of clots
- Used after certain urological surgeries where there is bleeding or for bladder tamponade
- Suprapubic catheter
- Bladder should be full – to prevent going through the bladder, and to prevent the peritoneum from covering the bladder
- Has two lumens, like Foley
- The patient’s haemostasis parameters should be known and considered
- Inserted 2 cm above pubic symphysis
- Indications
- Contraindications to Foley, like urethral trauma, acute prostatitis
- Inability to place Foley
Some catheters have a temperature sensor for continuous measurement of the internal body temperature. Some catheters can be connected to a special apparatus which allows for precise measurement of hourly diuresis.
Technique
- Ask for latex or lidocaine allergy
- Patient lies on their back
- The area of the urethral opening should be disinfected 2 – 3x, working from the centre and outwards
- Cover the patient with sterile isolating sheet, with a hole for genitalia
- Insert lidocaine gel
- This gel lubricates, disinfects, and anaesthetizes the urethra
- Give it a few minutes to take effect
- Insert the catheter into the urethra, keep the kidney bowl at the other end of the catheter
- When urine starts to drain the correct position is achieved
- Inflate the balloon with saline through the other lumen
- This usually requires 5 – 10 mL of saline
- Pull the catheter back until it stops
- Attach a urine collection bag to the urine-draining lumen of the catheter
- Potential difficulties
- The first pubic flexure in men is straightened by elevating the penis during initial insertion
- The perineal flexure is unavoidable
- The female urethral orifice may be difficult to find
- The first pubic flexure in men is straightened by elevating the penis during initial insertion
Catheter size
- Measured in French (Fr)
- 1 Fr = 0,33 mm
- Standard sizes are 14 – 18 Fr
- The smallest size which is adequate for the indication should be used
- Larger sizes have higher risk of erosion or stricture formation
- Larger sizes are used to drain blood clots