A fistula is formed when an artery is joined to a vein. This is done under the skin, usually at the wrist or elbow. A fistula requires a minor surgical operation, performed under local or general anesthetic.

Since blood pressure in arteries is higher than in veins, when a fistula is formed the vein enlarges. It usually takes about 6 weeks from the operation for the fistula to "Mature" that is, to grow and strengthen. It is then ready to be used for dialysis.

When the fistula is mature, the arm in which it is formed can be used as usual, although patients should protect the arm with the fistula from knocks and pressure so as to keep it in good working order.

Specifically, patients should avoid :

• Wearing tight clothing or a wristwatch on the arm with the fistula
  
  
• Having blood pressure taken on the arm with the fistula
  
  
• Having blood samples taken from the arm with the fistula (except during haemodialysis treatment, or with the renal unit's approval)
  
  
• Sleeping on the fistula arm.
  
  
• Carrying heavy shopping bags on the fistula arm

Patients should check that the fistula is working every day -they are shown how to do this- and advise the renal unit immediately if they are worried that the fistula may not be working.

Some patients particularly children or those with diabetes have blood vessels that are not strong enough for a fistula, and will need a permanent catheter for haemodialysis access. (A mature fistula ready for dialysis. Two needles are inserted into the fistula for each dialysis session )