Dialysis access

Haemodialysis cleans your blood through a machine, which needs a strong, reliable flow of blood several times a week. Normal arm veins are too small and slow for this.

An arteriovenous (AV) fistula solves the problem. In a short operation, an artery in your arm is joined directly to a nearby vein. The extra blood flow makes the vein grow larger and thicker over the following weeks, so it can be needled easily for dialysis.

A fistula made from your own vessels is usually the preferred access because it tends to last longer and has fewer infections than a graft or a dialysis catheter (a plastic tube in a neck vein). Planning it early, before dialysis is urgent, makes a real difference.

You may need an AV fistula if your kidney doctor expects you to start haemodialysis in the coming months, or if you are already on dialysis through a catheter.

You may also need to be seen if an existing fistula or graft is not working well, for example:

Weak thrill (the buzzing you feel over the fistula) or poor flow during dialysis

Prolonged bleeding after the needles are removed

Swelling of the arm, hand or face

A fistula that has not grown enough to be used

The most common causes of a failing fistula are narrowing of the vein and clotting. Low blood pressure, dehydration and pressure on the arm can make clotting more likely.

The first step is vein mapping: a duplex Doppler scan of both arms that measures the size and health of the arteries and veins. It takes about 15–30 minutes and shows the best place for the fistula, usually in the non-dominant arm, as far down the arm as the vessels allow.

Protect your veins from now on. Ask that blood tests and drips are taken from the back of the hand or from the other arm, and avoid blood pressure cuffs on the arm planned for access.

Bring your latest kidney blood tests, your medicines list and any previous access reports. Wear a short-sleeved or loose top. The team will tell you whether any blood thinners need adjusting before surgery.

The options, from most to least preferred for most patients, are:

AV fistula: your own artery is joined to a vein at the wrist or elbow. It is done under local anaesthesia and usually takes 60–90 minutes, and you go home the same day.

AV graft: when the veins are not suitable, a soft synthetic tube connects the artery and vein under the skin. It can usually be used sooner than a fistula but needs more maintenance.

Dialysis catheter: a tube in a large neck vein, used when dialysis is needed urgently or other options are not possible.

To keep access working, problems are treated early:

Fistuloplasty: a balloon passed through a needle widens a narrowed segment.

Clot removal: a blocked fistula or graft can sometimes be reopened if treated quickly.

The arm may be sore and a little swollen for a few days. Keep it raised on a pillow, keep the dressing dry and move your fingers often. Gentle hand exercises, such as squeezing a soft ball, may be advised once the wound has settled.

A fistula needs time to mature, usually several weeks and sometimes a few months. Follow-up visits, often with a Doppler scan, check that it is growing well before it is used for dialysis.

Look after your fistula every day:

Feel for the thrill each morning and evening

No blood pressure cuffs, blood tests or drips on that arm

Avoid tight sleeves, watches and sleeping on the arm

Keep the skin clean and do not carry heavy bags on that arm

Ideally, you should be seen months before dialysis is expected to start, so the fistula has time to mature and you can avoid a neck catheter. Ask your kidney doctor about referral early.

Contact the clinic the same day if:

The thrill is weaker or you cannot feel it at all: a clot treated early can sometimes be cleared

The dialysis team reports poor flow or high pressures

Bleeding after dialysis lasts much longer than usual

The skin over the fistula becomes red, hot or painful

Seek emergency care if:

The fistula bleeds heavily: press firmly on it with a clean cloth and call for help

The skin over the fistula becomes thin, shiny or starts to break down

Your hand becomes cold, pale, numb or very painful