Urinary Catheterisation


  • Intermittent
    • Measurement of bladder residual volume.
    • Obtaining uncontaminated urine for microscopy and culture (especially in females or young children).
    • Facilitating adequate bladder emptying (e.g. in conditions associated with atonic bladder).
    • Intravesical installation of drugs (e.g. contrast media in suspected bladder trauma or for micturating cysto-urethrography, instillation of local cytotoxic agents).
    • Urodynamic assessment.
    • Exclusion of urethral or prostatic obstruction in acute renal failure/ anuria
  • Continuous
    • Acute or chronic urinary retention.
    • Accurate measurement of urine output and to aid fluid balance (e.g. postoperatively).
    • Long term (e.g. when TURP is medically contraindicated).


  • Trauma patient with suspected urethral injury as evidenced by:
    • Blood at the urethral meatus
    • High-riding prostate on rectal examination
    • Penile, scrotal, perineal hematoma
    • Radiographic evidence of urethral/bladder trauma (in many centers a gentle attempt at urethral catherisation by an experienced doctor is accepted practice)
  • Postoperative urological patients. Always consult the urologist first if the patient has had bladder neck or prostate surgery.
  • Known stricture or ‘impossible insertion‘ last time.

Choose the correct catheter

  • Lumen
    • Single lumen—these catheters have no balloon and are used for in/out catheterisation
    • Double lumen—two-way catheters have a draining lumen and a balloon inflation lumen and are used for continuous catheterisation
    • Triple lumen (or three-way catheters)—have a draining lumen, a balloon inflation lumen and an irrigation lumen. Insert when blood, clots or debris are to be washed out of the bladder (e.g. post TURP).
  • Size
    • Catheter size refers to the circumference of the catheter, not the luminal diameter and is recorded in French sizes (1 French (F) = 1 Charrière = 0.33 mm).
    • Choose the smallest catheter that will allow adequate urinary drainage. Size 12–14F is usually adequate for males and females. Use size 16–20F if the patient has urine with debris, mucous, blood clots or haematuria, which may occlude smaller lumens. A 22F triple lumen is the standard size for bladder irrigation and ‘washout’. Smaller sizes (6–10F) are available for children.

Handy Hints:

  • In female adults the normal position of the urethra is 2.5cm inferior to the glans clitoris. It may be difficult to find in infants or postmenopausal elderly females. Occasionally the urethral opening recedes superiorly into the vagina and can be found by palpation.
  • Female urethra is 4cm long. The male urethra is 20 cm long – always advance the catheter to the hilt prior to balloon inflation.
  • Do not over- or underfill the catheter balloon, as this will lead to balloon distortion, causing the catheter tip to deviate within the bladder, and can potentially result in bladder wall necrosis.
  • Urine must flow from an inserted catheter before the balloon can be inflated. Urine may not flow initially because of obstruction by lubricating gel. You may be able to expedite flow by gently suctioning the catheter with a syringe, or applying suprapubic pressure to the patient.
  • If the patient is immunosuppressed, or has prosthetic heart valves, catheter insertion may cause a serious bacteraemia and bacterial seeding. Senior advice should be sought with regard to prophylactic antibiotics prior to catheter insertion

CCC 700 6

Critical Care


BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.