Bladder catheterisation

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

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