According to international guidelines, native arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis. Evaluation and choice of blood vessels suitable for AVF creation have been carried out for decades exclusively through the physical examination of the upper limbs. However, it provides useful information exclusively on the superficial venous system, whereas arterial system can be examined only through the palpation of the arterial pulses and the patency of the palmar arch with the Allen test. The use of Doppler ultrasound (DUS) has increased the number of patients that are eligible for AVF. It allows an accurate measurement of arterial and venous diameters and the capacity of the feeding artery to dilate, therefore optimizing the search for vessels suitable for surgical intervention (preoperative vascular mapping). Furthermore, color Doppler imaging (CDI) has improved the survival of native AVF by increasing the early diagnosis of complications (postoperative surveillance). Access flow assessment in the feeding artery (usually the brachial) by DUS is a well-known predictor of vascular access outcomes. Vessel diameter measurement could also be useful to detect and follow venous stenosis, which represents one of the main causes of AVF failure. CDI is the only imaging technique able to provide both morphological and functional information about native vascular access and it is the only tool directly available to the nephrologist.
