As a foundation doctor, you’ll frequently be asked to review patients with urinary retention. This article offers a simple and structured approach to assessment and management of urinary retention, along with tips for difficult catheterisations.
Contents
Key Definitions
- Urinary retention: Inability to pass urine.
- Acute urinary retention = painful.
- Chronic urinary retention = painless.
- High pressure chronic retention: = >1L with hydronephrosis and deranged renal function.
- Post obstructive diuresis: Excessive excretion of urine (>200mls/hour).
- TWOC: Trial without catheter.
- False passage: Iatrogenic, abnormal urethral tract.
- Suprapubic catheter (SPC): Inserted through the lower abdomen into the bladder.
- Nephrostomy: Percutaneous tube into the renal pelvis. [1,2]
Volumes to keep in mind (rough guide)
- Typical bladder volume = 500mls.
- Urge to void = 250mls.
- Post void residual (adults) < 50mls.
- Post void residual (elderly) < 100mls.
- Post void residual > 200mls is abnormal. [1,3]
Image showing rough bladder volumes. Image from https://www.embracephysio.sg/normal-bladder-habit-curiosities-urine-the-right-place/
Bleep: Patient not passing any urine!
Approach
- Approach as if AKI assessment (pre-rental, intrinsic, post renal).
- Fluid balance.
- Bladder scan.
- Pain/no pain.
- Creatinine.[1,4]
When to catheterise
- Acute urinary retention = emergency and requires urgent catheterisation.
- Chronic urinary retention = Catheter not necessarily required unless unless there are symptoms, complications, or risk of renal damage. [1,4]
What size of catheter
- Typical size for male and female:
- Female 14Fr.
- Male 16Fr.
- Tip: Smaller size catheters can sometimes be more difficult to insert because their increased flexibility makes them harder to guide. [1,4]
Which type of catheter
- 2-way (Foley): Two ports: drainage + balloon.
- 3-way: Three ports: Drainage + ballon + Extra port for irrigation (e.g. clot retention, haematuria).
- Special catheters: Coudé/Tiemann tip: Curved tip for difficult insertions (e.g. enlarged prostate, strictures). [1,5]
2-way vs 3 way catheter. Image from https://x.com/Daniel_Urologia/status/1591225945327030272
Coudé vs straight tip catheter. Image from https://quizlet.com/931333787/nur-325-final-exam-flash-cards/
How long to keep catheter
- Ultimately, catheter stays until indication for insertion has been treated (e.g If infection related, TWOC once infection has been treated).
- Short-term catheters last up to 4 weeks.
- Long-term cathteters last up to 12 weeks. [6]
Urethral Catheterisation – Step by Step
Preparation
- Confirm indication, explain, obtain verbal consent.
- Chaperone present.
- Gather kit: catheter pack, appropriate catheter, 0.9% saline, sterile water (10ml), instillagel, gloves, drainage bag.
Aseptic technique
- Wash hands, sterile gloves, set up sterile field.
- Clean genitalia (retract foreskin in men, part labia in women).
Anaesthetic/lubrication
- Instillagel into urethra (wait 3–5 mins).
Insertion
- Advance catheter slowly until urine flows and fully inserted to the Y junction of the catheter.
- Inflate balloon with 10ml sterile water.
- Attach drainage bag and secure catheter.
- Replace foreskin in men to avoid paraphimosis.
Documentation
- Date/time, indication, catheter type/size, balloon volume, residual volume/urine appearance, aseptic technique.
- If discharging with catheter district nurses need to be notified. [7]
Tips!
- Plenty of instillagel.
- Males – straighten penis 90 degrees to the patient. Advance to membranous urethra then level out. This helps straighten the urethras natural curvature.
- Feel the change in resistance at different parts of the urethra – more experience the better.
- Female – know your anatomy and have appropriate positioning/access.
Be aware!
- Inflating balloon in urethra can cause trauma/stricture.
- Forceful advancement against resistance can cause false passage.
- Poor lubrication or asepsis can cause infection/trauma.
- Not considering patient’s anatomy or prior insertion.
Difficult catheterisation escalation pathway
- Standard 14–16Fr 2-way Foley.
- Coudé/Tiemann – single attempt.
- Flexible cystoscopy ± guidewire catheterisation.
- Suprapubic catheter (if urethral route fails/contraindicated).
Summary
- AUR is a common urological emergency.
- Immediate management = urethral catheterisation.
- Always investigate and treat the underlying cause.
- Do NOT inflate balloon until catheter fully inserted + urine draining.
- Typical sizes: Female 14Fr and Male 16Fr.
- Smaller catheters may be harder to insert (too flexible).
- Escalation for difficult catheterisation: Foley > Coudé/Tiemann > Flexible cystoscopy ± guidewire > Suprapubic.
References
[1] Reynard, J., Brewster, S. and Biers, S. (2016a) Oxford Handbook of Urology. Oxford: Oxford University Press.
[2] Leslie, S.W., Sajjad, H. and Sharma, S. (2020) Postobstructive Diuresis, PubMed. Treasure Island (FL): StatPearls Publishing. Available at: https://www.ncbi.nlm.nih.gov/books/NBK459387/.
[3] Walton, T. (2010) Benign prostate hyperplasia. Available at: https://www.baus.org.uk/_userfiles/pages/files/professionals/bsot/TJW-Benign-prostate-hyperplasia.pdf?fbclid=IwAR2NU-HMvWlJE78CBNiBcio3-H-sYmqCb8cm03Lv81pY2hc913M-OeExw3U.
[4] Diagnosis and management of Bladder Cancer. Available at: https://www.baus.org.uk/_userfiles/pages/files/professionals/sections/BladderCancer-Nov2017.pdf (Accessed: 10 October 2025).
[5] Bianchi, A. (2023) Difficult Foley Catheterization, StatPearls [Internet]. Available at: https://www.ncbi.nlm.nih.gov/books/NBK564404/ (Accessed: 10 October 2025).
[6] NHS: Living with a Urinary catheter (no date) NHS choices. Available at: https://www.nhs.uk/tests-and-treatments/urinary-catheters/living-with/ (Accessed: 10 October 2025).
[7] Male Catheterisation – OSCE Guide | Geeky Medics. Available at: https://geekymedics.com/penile-catheterisation-osce-guide/ (Accessed: 10 October 2025).
Written by Conall Quigley (FY2)
Edited by Joseph Latham (CT3)
