Definition of AV fistula (arteriovenous fistula)

AV fistula (arteriovenous fistula): an abnormal connection between an artery and a vein. This causes blood to flow directly from the artery into the vein, bypassing the capillaries that are located downstream of the fistula, resulting in a diminished blood supply. AV fistulas can occur anywhere in the body, but are common in the legs. Sometimes, an AV fistula is surgically created for hemodialysis access. Recently, nonsurgical, percutaneous procedures are being used to create AV fistulas for dialysis access.