AVF is the preferred form of access in view of superior patency rates and fewer complications compared with AVG and catheters. According to KDOQI guidelines AVF maturation is considered clinically successful if 6 weeks after the fistula surgery the fistula supports a flow of 600ml/min, is located at a maximum of 6mm in depth. AVF has a high risk of primary failure resulting from early thrombosis and maturation failure
