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A8. Urethral catheterization: Types, indications, and technique

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
  • Therapeutic
    • 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
  • 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

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