Types of Fistula for Dialysis: AV Fistula, Graft and Catheter Explained

People on haemodialysis need a reliable way to move blood to the dialysis machine and back, several times a week. This connection is called vascular access, and there are three main types: an arteriovenous (AV) fistula, an AV graft and a central venous catheter. An AV fistula, made by joining one of your own arteries to a vein, is the preferred option for long-term dialysis because it usually lasts longest and has the lowest risk of infection and clotting.

This guide explains the types of fistula used for dialysis, how they compare with grafts and catheters, how a fistula is made and matures, and how to look after it.

What Is an AV Fistula and Why Is It Needed for Dialysis?

An AV fistula is a direct connection between an artery and a vein, made by a vascular surgeon, usually in the arm. Blood from the artery flows straight into the vein at high pressure, so over the following weeks the vein becomes larger and its wall becomes thicker.

Ordinary veins are too small and their blood flow too slow for haemodialysis, which needs a high, steady flow of blood through the dialyser. The enlarged fistula vein can carry that flow and can be needled safely at every session. This is also why dialysis staff refer to an "arterial" needle: it draws blood from the high-flow part of the fistula closest to the artery, even though both needles are placed in the enlarged vein.

Types of Vascular Access for Haemodialysis

A permanent catheter (often called a permacath) allows dialysis to start straight away, but because infection risk is higher, most nephrologists recommend a fistula or graft for long-term treatment whenever possible.

Types of AV Fistula for Dialysis

Radiocephalic Fistula (Wrist)

Also called the Brescia-Cimino fistula, this joins the radial artery to the cephalic vein at the wrist. It is usually the first choice because it preserves the upper-arm vessels for future access. It can take longer to mature and may not develop well if the forearm vessels are small.

Brachiocephalic Fistula (Elbow)

This joins the brachial artery to the cephalic vein near the elbow. It generally gives higher blood flow and is easier to needle, but it carries a slightly higher risk of steal syndrome, where too much blood is diverted away from the hand.

Brachiobasilic Transposition Fistula (Upper Arm)

This joins the brachial artery to the basilic vein, which lies deep in the upper arm. The vein is moved (transposed) closer to the skin so it can be needled, which is often done as a second operation. It is used when the cephalic vein is not suitable.

In rare cases, when the arms cannot be used, a fistula or graft may be created in the leg. Before surgery, a doctor examines the arms and usually uses ultrasound vessel mapping to decide which type is most likely to work.

How an AV Fistula Is Made

1. Vessel mapping: an ultrasound scan of the arm checks the size and condition of the arteries and veins.
2. Surgery: the procedure is usually done under local or regional anaesthesia, often as a day procedure. The surgeon makes a small incision and joins the chosen artery and vein.
3. Recovery: the wound heals over one to two weeks. The arm may be swollen or bruised for a few days.
4. Maturation: the vein enlarges over the following weeks before it can be used for dialysis.

Because a fistula needs time to mature, doctors usually recommend creating it several months before dialysis is expected to start.

Fistula Maturation and the Rule of 6s

A fistula usually needs about 6 weeks to 3 months to mature. A widely used guide is the rule of 6s: by about 6 weeks, a mature fistula should be at least about 6 mm wide, no more than about 6 mm below the skin, and carrying a blood flow of about 600 mL per minute. The nephrologist or surgeon confirms maturity by examination and, often, ultrasound. Hand and arm exercises, such as squeezing a soft ball, may be advised to help the fistula develop.

How Fistula Needles Are Used During Dialysis

At each session, a dialysis nurse or technician places two needles in the fistula: one draws blood to the dialyser and the other returns the cleaned blood. Needling sites are rotated along the fistula (the rope-ladder method), or the same spots are used each time to form a tunnel (the buttonhole method), to protect the vessel over the long term.

New fistulas are usually needled with smaller needles first, moving to larger ones as the fistula matures. Dialysis units use sterile, single-use AV fistula needles in a range of sizes; the Vital disposable AV fistula needle set is one example. A numbing cream or spray before needling can reduce discomfort for patients who find it painful.

Caring for Your AV Fistula

1. Check it every day. Feel for the buzzing vibration (the "thrill") over the fistula. If you have been taught how, listen for the whooshing sound (the "bruit") with a stethoscope.
2. Keep the arm clean, and wash it with soap and water before each dialysis session.
3. Protect the fistula arm: no blood pressure measurements, blood tests, injections or drips in that arm.
4. Avoid pressure: no tight sleeves, watches or bangles on the fistula arm, and avoid sleeping on it.
5. Avoid heavy lifting and activities that could injure the arm, unless your doctor has cleared them.
6. After dialysis, apply gentle pressure to the needle sites until bleeding stops, as your dialysis team has shown you.

Warning Signs: When to Contact Your Dialysis Team

Contact your dialysis unit or doctor promptly if you notice any of the following:

1. The thrill or bruit becomes weaker or stops (this can mean the fistula is blocked).
2. Redness, warmth, pus or pain around the fistula, or a fever (possible infection).
3. New or increasing swelling of the arm or hand.
4. A cold, pale, numb or painful hand or fingers (possible steal syndrome).
5. Bleeding from needle sites that does not stop with normal pressure.
6. A bulge that grows quickly or has shiny, thin skin over it.

A blocked or failing fistula can often be treated, for example by angioplasty or surgery, if it is caught early. Do not wait for your next dialysis session.