AV Fistula / Graft Surveillance

1. 1

   Patient supine, arm extended. Linear probe (5–12 MHz). Palpate access for thrill before scanning.

2. 2

   Begin at the arterial anastomosis: document PSV and waveform. Turbulence here is normal.

3. 3

   Sweep along the juxta-anastomotic vein (most common stenosis site). Flag any focal PSV elevation.

4. 4

   Continue sweep along the access vein to the outflow — document PSV at regular intervals and at any stenosis.

5. 5

   Volume flow: measure brachial artery PSV and diameter. Volume flow = π × r² × TAMEAN × 60. Normal mature fistula >600 mL/min.

6. 6

   Assess aneurysmal segments: measure largest diameter. Note pseudoaneurysms (pulsatile sac with yin-yang flow).

7. 7

   Check for steal: Doppler at radial artery distal to anastomosis — retrograde flow = steal syndrome.

• Arterial anastomosis — Doppler
• Venous outflow — Doppler sweep
• Mid-access — Doppler
• Juxta-anastomotic vein segment
• Outflow vein to central veins
• Brachial artery inflow — Doppler + volume flow

• Brachial artery volume flow (mL/min)
• PSV at anastomosis and outflow
• Stenosis PSV ratio
• Access vein diameter and depth
• Thrombus

• Volume flow <500 mL/min predicts access failure
• PSV ratio >2:1 at stenosis = hemodynamically significant
• Aneurysms common — measure largest diameter
• Central stenosis presents as diffuse arm swelling + high pressures

Volume flow calculation: π × r² × TAMEAN × 60. A flow >600 mL/min indicates maturation. Surveillance every 3–6 months reduces thrombosis risk.