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Renal Exam

The Arteriovenous Fistula



An anastomosis between an artery and vein in the arm, created in order to dilate the vein for use in haemodialysis.
  • Look For

  • Location of fistula - radiocephalic (forearm) / brachiocephalic (AC fossa), upper arm transposed basilic fistula
  • Skin - rash, depigmentation, scars, ulceration
  • Inflammation - erythema, swelling, tenderness
  • Distal ischaemia - pain, pallor, pulselessness, paralysis, paraesthesia, poikilothermia Steal syndrome - vascular insufficiency
  • Feel For

  • Consistency - soft, easily compressible
  • Thrill - soft, continuous palpable thrill
  • Hyperpulsatility - outflow obstruction
  • Auscultate For

  • Normal bruit - soft, low-pitched hum
  • High-pitched bruit Stenosis

Augmentation Test

  • Test For

  • Inflow stenosis
  • How to Perform

  • Use a finger to occlude outflow from the fistula a few centimetres from the anastomosis.
  • Interpretation

  • Normal - the fistula becomes hyperpulsatile, and the thrill disappears.
  • Inflow stenosis - the fistula remains weakly pulsatile
  • Accessory vein - the fistula becomes hyperpulsatile, and the thrill persists..

Arm Elevation Test

  • Test For

  • Outflow stenosis
  • How to Perform

  • Elevate the arm and look for collapse of the fistula.
  • Interpretation

  • Normal - the fistula collapses
  • Outflow stenosis - the part proximal to the stenosis will collapse and the distal part will remain distended

Extra Credit

  • Complications of AV Fistula

  • Aneurysm
  • Failure to mature
  • Haematoma
  • Stenosis - inflow or outflow
  • Thrombosis
  • Steal syndrome - ischaemia distal to the fistula
  • Infection
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