The most important manifestation of arteriovenous fistula is the local appearance of a pulsating mass, which is examined by the following methods: 1. ultrasound: easy and simple, the main method of screening for arteriovenous fistula, which can directly distinguish between arterial and venous blood flow and whether the two ducts are connected; 2. enhanced CT: allows three-dimensional reconstruction, which can completely show the arteries, veins and surrounding vessels; 3. angiography: called the gold standard, which can clearly locate the vessels that lead to the formation of arteriovenous fistula and the number of arteries, veins and fistulas.