Frequently asked questions: catheters, urine drainage bags and incontinence.

SMTL are frequently asked for advice on problems with catheters and drainage bags. This document lists the "frequently asked question" we encounter.


Should I use a larger size catheter if the patient is leaking around the catheter?

No. Leakage around the catheter has a number of causes:

  • Blocked catheters
  • Cholinergic drugs
  • Large catheters
  • Large balloons

Catheters which are too big for the patient can cause spasm which expels urine around the catheter base. Increasing the size of the catheter is commonly thought to be a solution, as many professionals reason that a larger catheter will "block the gap".

However, a larger catheter will only increase the likelihood of spasm, and therefore leakage. In many cases, using a smaller catheter will solve the problem, assuming it is caused by catheter size.

Using large balloons (such as 30ml balloons) or over-inflating balloons can also cause this problem.

How long can I leave a urinary catheter in-situ?

Always follow the manufacturers advice, which can differ between manufacturers.

In general,

  • Uncoated latex:
    Plain latex catheters can be used for up to 7 days.
  • Silicone treated latex:
    Silicone treated latex should not be confused with silicone coated latex. Silicone treated latex catheters are usually plain latex catheters which have been dipped into silicone lubricant. The silicone lubricant has little or no protective effect, and the catheters should be treated as uncoated latex catheters.
  • Silicone coated latex catheters, hydrogel-coated latex catheters, all-silicone catheters, 100% silicone catheters, silicone-elastomer coated catheters:
    All of these catheters are classified as long term catheters, and can usually be used for up to 12 weeks.
  • Plastic catheters:
    Some Foley (2-way) catheters are made of plastic. However, they usually have a latex balloon. Depending on the manufacturer, these may be classed as short term (7 days), or short to medium term (7-28 days).

Why has my patients urine drainage bag turned purple?

Tryptophan (L_Tryptophan) is an antidepressant drug which is used rarely these days. It decomposes in the gut to form indoxyl sulphate, which is then absorbed and secreted in the patients urine.

Once the indoxyl suphate comes into contact with air, it is oxidised to insoluble indigo, producing a heavy purple discolouration of the components in the drainage system, including the drainage bag.

(Sources: British National Formulary and booklet "Guidelines for the management of the catheterised patient", produced by the Infection Control Dept., Memorial Hospital, Darlington, County Durham, and sponsored by Bard (1984, reprinted 1987).)

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