How Does A Catheter Work?

Originally published on: June 25th, 2020. Last modified on December 15th, 2021

A catheter drains urine from the bladder into a drainage bag which may be supported at thigh or calf level. The leg drainage bag requires changing every 5 to 7 days depending on manufacturers instructions.

A Belly Bag or a catheter valve may be recommended. Your District Nurse or Continence Advisor will advise you on which type may be appropriate for your needs.

Catheter bag

如果你确实使用了腿部排水袋,那么当它是半到四分之三满的时候就需要排空。Always ensure it does not pull on the catheter.

The bags are usually of 350ml, 500ml, 750ml or 1litre capacity for daytime use (depending on manufacturer). At night an extra 2-litre bag can be fitted easily to the day leg bag to increase the available capacity. These larger night bags mean you don’t have to get up in the night to empty the bag. They should be supported on a catheter drainage bag stand.


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The Catheter in Situ

An indwelling urethral catheter is passed through the urethra (the tube through which urine passes). This is the usual method of draining urine from the bladder when short-term drainage is required (usually less than 30 days).

If you are sexually active it may be possible to be taught to remove your indwelling urethral catheter prior to intercourse and insert a new one afterwards. You may wish to discuss this with your partner. The District Nurse or Continence Advisor will advise you so don’t be embarrassed to discuss this.

Male Catheter
Male catheter in situ
Female catheter
Female catheter in situ

Suprapubic Catheters



Male suprapubic catheter
Male suprapubic catheter
Female subrapubic catheter in situe
Female subrapubic catheter

ASuprapubiccatheter is normally inserted whilst in hospital and may require an overnight stay, however, the routine changes to the catheter can be done at home. Many District Nurses and Continence Advisors are well practised in this procedure.

Some people prefer to cover the site with a dry dressing but this is only necessary for the initial few weeks after insertion or if there is leakage or exudate. The area needs to be kept clean by daily bathing or whilst showering, or by cleansing with soap and water and drying well afterwards.

Leg bags and catheter valves can be used by those assessed for suitability but some users of suprapubic catheters may find the Belly Bag more useful. These are available on prescription, see your Healthcare Professional for information.

male with catheter bag

Please see our additional resources for more information:

You can download our complete Catheter Care Guidehere,or read our FAQ’s session with our very ownCatheter Nurse.


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