Urinary catheterisation
Aseptic technique, plenty of lidocaine gel, wait for urine before inflating the balloon, and always pull the foreskin back down.
A 78-year-old man has not passed urine for 10 hours after a hip repair. He is uncomfortable and his bladder is palpable to the umbilicus. Bladder scan: 1,100 mL.
A 40-year-old trauma patient has blood at the urethral meatus.
How do you catheterise the first patient, and why shouldn't you pass a urethral catheter in the second?
- IndicationRetention, accurate output monitoring in the sick, surgery, comfort at the end of life.
- Size12–14 Fr for most adults. 16–20 Fr three-way for haematuria and clots.
- Aseptic techniqueClean, sterile gloves, lidocaine gel, wait 3–5 minutes.
- Insert until urine flows, then 2–3 cm moreIn men, all the way to the hub.
- Inflate the balloon only after urine flowsPain on inflation: stop, deflate, advance.
- Replace the foreskinPrevents paraphimosis.
- DocumentResidual volume, size, balloon water, indication, review date.
- Blood at the meatus after trauma
- Failed catheter in retention
- Frank haematuria with clots
- Paraphimosis
- Urine output under 0.5 mL/kg/hour despite fluids
- Urethral injury (forcing)
- False passage
- Balloon inflated in the urethra
- Paraphimosis
- Catheter-associated infection
- Post-obstructive diuresis
| Adult size | 12–14 Fr routine |
| Haematuria | 16–20 Fr three-way, irrigation |
| Balloon | 10 mL sterile water (check the catheter) |
| Lidocaine gel | 11 mL (men), 6 mL (women), wait 3–5 minutes |
| Residual over 400 mL | Retention |
| Hourly output target | At least 0.5 mL/kg/hour |
Check every dose against a current drug reference and your hospital protocol.
On this page
Indications
- Acute or chronic retention.
- Accurate urine output monitoring in the critically ill.
- Perioperative (long operations, epidurals).
- Bladder irrigation for clot retention.
- End-of-life comfort.
Not for: convenience in incontinence.
Contraindications
- Blood at the meatus, a high-riding prostate, or perineal bruising after trauma (suspected urethral injury). Senior and urology, retrograde urethrogram.
- Known urethral stricture without urology advice.
Male catheterisation
- PrepareCatheter pack, sterile gloves, cleaning solution, lidocaine gel, catheter, 10 mL water, bag.
- PositionLying flat, legs slightly apart. Drape.
- CleanRetract the foreskin, clean the glans and meatus.
- GelInstil lidocaine gel slowly into the urethra. Wait 3–5 minutes.
- InsertPenis held upright at 90° to straighten the urethra. Advance gently.
- Resistance at the prostateLower the penis toward the feet; ask the patient to cough or relax.
- UrineAdvance to the hub. Inflate balloon with 10 mL water. Pull back gently. Connect bag.
- Replace the foreskinAlways.
Female catheterisation
- Lying flat, knees bent and apart.
- Separate the labia; clean front to back.
- Meatus is below the clitoris and above the vaginal opening.
- Insert 5–6 cm until urine flows, then 2–3 cm more before inflating.
- If the catheter enters the vagina, leave it as a marker and use a new one.
If it won't pass
More gel, wait, lower the penis, relaxed patient. Try a Coude-tip catheter if trained.
Stop. Don't force. Senior or urology. Suprapubic catheter if bladder is palpable.
Urology. Smaller catheter only on advice.
After catheterisation
- Residual volume: document it. Over 400 mL confirms retention.
- Post-obstructive diuresis: after chronic retention, watch hourly output. Over 200 mL an hour for several hours: check U&E, replace part of the losses.
- Haematuria after decompression is common and usually settles.
- Review the need daily. Remove as soon as possible.
- Trial without catheter (TWOC) after retention: often after starting tamsulosin.
Complications
| Complication | Action |
|---|---|
| Paraphimosis | Reduce the foreskin; compress oedema; urgent urology if stuck |
| Urethral trauma or false passage | Stop, senior, urology |
| Balloon in the urethra | Pain on inflation: deflate, advance further |
| Infection | Treat only if symptomatic; change catheter before taking a sample |
| Bypassing | Check for blockage, constipation, bladder spasm |
| Blocked catheter | Flush; change |
Treatment
See urinary retention and haematuria.
Common mistakes
- Inflating the balloon before urine flows.
- Forgetting to replace the foreskin.
- Forcing past resistance.
- Catheterising a trauma patient with blood at the meatus.
- Sending a urine sample from the bag.
- Leaving catheters in "for convenience".
Frequently asked questions
What size urinary catheter should I use?
12–14 Fr for most adults. A 16–20 Fr three-way catheter for haematuria with clots.
When should a urethral catheter not be passed?
After trauma with blood at the urethral meatus, perineal bruising or a high-riding prostate.
What is post-obstructive diuresis?
A large urine output after relieving chronic retention. Monitor hourly output and electrolytes.
What should you do if there is pain when inflating the balloon?
Stop and deflate. The balloon may be in the urethra; advance further until urine flows.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A catheterised man has a painful swollen foreskin that won't move over the glans. What is it?
Answer: Paraphimosis. Always replace the foreskin after catheterisation; reduce paraphimosis urgently.
- Hydrocele: No.
- Balanitis: Infection.
- Priapism: Erection.
- Phimosis: Foreskin can't retract, not stuck back.
2. A man has blood at the urethral meatus after a pelvic fracture. What should be done?
Answer: Call urology. Suspected urethral injury: urology, possibly suprapubic catheter.
- Insert a 20 Ch catheter: No.
- Give antibiotics only: No.
- Insert a catheter carefully: Can worsen urethral injury.
- Ignore it: No.
3. Which catheter is used for clot retention?
Answer: Three-way 20–22 Ch. A three-way catheter allows bladder irrigation.
- 12 Ch two-way: Too small for clots.
- 8 Ch feeding tube: No.
- Condom catheter: No.
- Suprapubic always: Not first.
4. After urethral catheterisation, an elderly man’s retracted foreskin can’t be pulled forward and the glans is swollen and painful. What is the first step?
Answer: Manual reduction after reducing oedema. Paraphimosis is a urological emergency: the retracted foreskin forms a constricting band, causing venous congestion, oedema and potentially arterial compromise of the glans. Reduce oedema (ice, compression, osmotic agents like sugar, puncture technique), then manually reduce under analgesia/penile block; dorsal slit if fails; elective circumcision later. Prevent by always replacing the foreskin after catheterisation or examination.
- Leave it — resolves spontaneously: Paraphimosis does not resolve on its own and risks glans ischaemia.
- Circumcision immediately in all: Manual reduction comes first.
- Apply heat packs: Heat increases swelling.
5. A 70-year-old catheterised man on a medical ward has a painful, swollen glans with a tight band of foreskin behind it. The foreskin was left retracted after catheter care 6 hours ago. What is this and what is needed?
Answer: Paraphimosis — urgent reduction. Paraphimosis occurs when a retracted foreskin cannot be returned, constricting the glans and causing swelling and risk of ischaemia. It is a urological emergency. Reduce it manually after analgesia and compressing the swelling; if that fails, a dorsal slit is needed. Always return the foreskin after catheter insertion or care.
- Phimosis — elective circumcision: Can’t retract — not an emergency.
- Balanitis — antifungal cream: Balanitis is infection of the glans; this is constriction by a retracted foreskin, so cream will not help.
- Oedema — observe: Observation risks glans ischaemia; paraphimosis needs prompt reduction.
6. Why is the mucosa of the bladder trigone smooth, unlike the rest of the bladder?
Answer: It derives from the mesonephric ducts. The trigone forms from the incorporated ends of the mesonephric ducts into the bladder wall, and its mucosa is firmly bound to the underlying muscle, so it stays smooth even when the bladder is empty. The rest of the bladder comes from the urogenital sinus (endoderm), and its loosely attached mucosa forms folds (rugae). The trigone lies between the two ureteric openings and the internal urethral orifice.
- It lacks a detrusor layer completely: Muscle is present beneath it.
- It has no blood supply of its own: It has a blood supply.
- It is covered by peritoneum: Peritoneum covers the superior surface only.
- It is lined by keratinised epithelium: Lined by transitional epithelium.
7. During a transurethral resection of the prostate, the surgeon resects from the bladder neck down to, but not beyond, the seminal colliculus (verumontanum). Why is this the distal limit?
Answer: The external sphincter lies just distal to it. The seminal colliculus is a raised mound on the posterior wall of the prostatic urethra, with the prostatic utricle in the middle and the ejaculatory ducts opening on each side. Just distal to it, the urethra becomes membranous and passes through the external urethral sphincter. Resecting beyond the verumontanum risks injuring this sphincter and causing permanent incontinence, which is why it is the key distal landmark in TURP. The bladder neck (internal sphincter) is resected, which causes retrograde ejaculation.
- The ureteric orifices open beside it: The ureteric orifices are in the bladder trigone, far proximal.
- The inferior vesical artery enters there: Its branches enter at the bladder neck at 5 and 7 o'clock.
- The ejaculatory ducts would bleed heavily: Their opening is not the reason for the limit.
- The prostatic utricle is lined by cancer cells: The utricle is a normal Müllerian remnant.
References and dose sources
- Lidocaine (lignocaine) dosing: Drugs.com: Lidocaine dosage (see also our lidocaine (lignocaine) dose page)
- Tamsulosin dosing: Drugs.com: Tamsulosin dosage (see also our tamsulosin dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.