An arteriovenous fistula is a surgically created anastomosis between an artery and a vein. Its main use is to dilate a vein for easier access in patients requiring regular haemodialysis.
Examining an AV fistula
Type of fistula
Radiocephalic AV fistula (most): radial artery to cephalic vein at wrist
Brachiocephalic AV fistula = brachial artery to cephalic vein in antecubital fossa
Brachiobasilic transposition AV fistula = brachial artery to transposed basilic vein in upper arm
Signs of inflammation: rash, erythema, swelling
Arm elevation test (for outflow obstruction): fistula should collapse on arm elevation
Presence of collateral veins (suggest venous stenosis)
Hands – compare to other side
Signs of ischaemia (Steal syndrome = vascular insufficiency secondary to AV fistula)
Thrill: a thrill is normal but it shouldn’t be pulsatile
Consistency: should be soft and easily compressible
Augmentation test (for anastomotic stenosis): occlude vein 1-2 cm above anastomosis. If arterial pressure is adequately conducted (i.e. there is no anastomotic stenosis), a pulsation in the vein will be seen. NB: if vein is pulsatile anyway, there is venous outflow stenosis.
Bruit: should be a soft machinery–like rumbling sound (high-pitched = stenosis)
Questions and more details about arteriovenous fistulae