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Please note: This page is intended for healthcare professionals only. It is designed as a general educational guide and does not replace local guidance, senior clinical advice, or individual clinical judgement. Patients should not use this page as medical advice and should seek advice from an appropriate healthcare professional.

Catheters & Troubleshooting

About catheters

Not all catheters are the same. They differ in size, tip shape, number of channels, material and drainage setup. Knowing these differences helps you choose the right catheter and, troubleshoot common problems.

1Number of channels / ports

1 port = clean intermittent self-catheterisation (CISC)

  • Doesn’t have a balloon to retain in bladder
  • Also called “In-and-Out” catheter
  • Indications: low-pressure chronic retention / incomplete bladder emptying for any reason (see here) – as a permanent or temporary solution while awaiting surgery
  • Patient factors:
    • Are compliant and motivated
    • Good hand dexterity and vision
    • Have mental capacity

2-way catheter

  • The standard catheter
  • Has 2 channels – drainage and balloon port

3-way catheters

  • Key Features:
    • Three ports – drainage, balloon port, irrigation inlet
      • Continuous irrigation is key for the management of patients admitted with haematuria and clots.
    • Larger diameter (typically 18 – 24Ch) to allow clot drainage
    • Larger balloon capacity (20-50mL)
      • Usually inflate to 20-30mL
      • 50mL can be used to improve haemostasis after TURP by tamponading the prostatic fossa (only done if instructed by SpR/consultant)
  • Common Indications:
    • Post-operatively (eg. TURBT, BPH surgery)
    • Significant haematuria or clot retention needing irrigation + bladder washouts
Catheter port count — 1-way, 2-way and 3-way
2-way catheter — drainage and balloon inflation channels

2Catheter tips

Straight Tipped Catheters = standard tips

  • Straight rigid or semi-rigid tip
  • Two drainage holes (eyes) near the tip

Open Tipped Catheters

  • In addition to side holes has an open end (no tip)
  • Designed to allow the easy passage of guidewires, facilitate greater drainage of thick fluid, debris and clots.
  • Can be more traumatic to urethra if inserted blindly due to the open tip brushing against the wall of the lumen.

Curved Tipped Catheters

  • Often called Coudé or Tiemann tip
  • Key Features:
    • Has an angled tip (typically 30 – 45 degree curve)
    • Often with stiffer construction for easier navigation
    • Often has a marking or stripe indicating the direction of the curve
  • Aim → mimics the anatomy of proximal male urethra giving greater ability to navigate past enlarged prostate or high bladder neck.
  • There are multiple iterations of curved tipped catheters – but all work similarly for navigating prostatic obstruction.
Catheter tips — straight, open and Tiemann

3Material

Material Typical use / key point
Latex Flexible and cheap, but avoid if latex allergy. Usually short-term only unless coated.
PTFE-coated latex Short-term indwelling catheter, often up to 28 days depending on product/local policy.
Hydrogel-coated latex Softer coating, more comfortable than plain latex; still avoid in latex allergy.
100% silicone Latex-free, commonly used for long-term catheters, often up to 12 weeks depending on product/local policy. Wider internal lumen for same Charrière size.
Silver/alloy or antimicrobial-coated Used in some settings to reduce catheter-associated infection risk, but not routine everywhere.
PVC / plastic Often used for intermittent catheters rather than long-term indwelling Foley catheters.

4Sizes

  • Catheters come in a range of sizes - from 6–26 Ch/Fr.
  • Size is measured using the Charrière/French scale – it refers to the outer diameter of the catheter: 1 Ch/Fr = 0.33 mm.
  • The colour of the balloon port universally corresponds to the relevant Ch/Fr size (see below)
Catheter colour and French size chart
  • Used by size:
    • For routine adult → 12–18 Ch
    • Haematuria and clots → ideally larger sizes, usually 20–24 Ch
  • Remember that a 3-way catheter has an additional irrigation channel, so an 18 Ch 3-way catheter will have a smaller drainage lumen than an 18 Ch 2-way catheter.

5Drainage options

Free drainage = a bag

  • Leaving a catheter on free drainage is typically the best option in the following instances:
    • High pressure chronic retention
    • Frequent/high volume build-up of sediment/debris
    • Frequent episodes of haematuria
    • Recurrent UTIs
    • Reduced/immobility
  • Many patients continue carrying out normal daily activities.
  • Bag types:
    • Leg bag – short or long. Usually has 500mL capacity.
    • Night bag – usually has 2L capacity.
    • Urometer – used in hospitals for output monitoring
  • Leaving an indwelling catheter on free drainage for very long periods may result in a reduction in patients’ bladder capacity and loss of detrusor function, which may impair their ability to be successfully TWOC’d.

Flip-flow valve

  • Suitable for compliant patient with preserved vision, hand dexterity and mental capacity.
  • Acts as a tap, which can be turned off and on to allow the bladder to fill while maintaining continence and for bladder emptying at a time of the patient’s choosing
Flip-flow catheter valve
 

Catheterisation techniques (normal + others)

 

Catheter troubleshooting