The vein gradually dilates, distally up to the last valve and proximally up to the vena cava. If the fistula hole is large, the pressure in the vein increases abruptly, and a few weeks after the trauma, a pulsatile mass can be seen locally due to venous distension, much like a pseudoaneurysm. When the fistula is small, the vein at the fistula gradually expands, the vein lining thickens, fibrous tissue proliferates, and an action-like wall forms due to the gradual thickening of the vein wall. How to check for action-like wall? Fistulas between the arteries and veins that are simple are rare, and most traumatic aneurysms, which can be located on the arterial side, the venous side, or between the arteries and veins. In a history of penetrating trauma, the patient may notice a pulsatile mass on his or her own and there is a localized buzzing sound. The diagnosis of arteriovenous fistula should be considered when there is swelling of one limb, varicose veins and venous valve insufficiency, a higher localized skin temperature of the limb than that of the opposite side, and scarring, murmurs, and tremors at the site of injury. Acute arteriovenous fistula patients often have severe multiple trauma or limb me through the injury. When examining the patient, the diagnosis and management of arteriovenous fistula is often delayed because attention is focused on the site of severe bone and soft tissue injuries. Arterial and venous traffic can be divided into direct and indirect. Neighboring veins and arteries injured at the same time, the wound edge is directly opposite each other, within a few days can be directly traffic, known as direct arteriovenous fistula. Such as arterial and venous wound can not be directly on the joint, but in the two between the presence of hematoma, later hematoma mechanization, the formation of through the artery and vein between the sac or tube, said indirect fistula. Fistula of the proximal artery progressive dilatation and elongation; arterial wall initially some thickening, later degenerative changes, smooth muscle fiber atrophy, elastic fiber reduction, wall thinning, and atheromatous plaque formation. If the fistula hole is large, the trunk artery adjacent to the fistula can swell and form an aneurysm. The distal artery shrinks due to decreased blood flow. The vein gradually expands, distally up to the last valve and proximally up to the vena cava. If the fistula is large, the pressure in the vein increases abruptly, and a pulsatile mass, much like a pseudoaneurysm, can be seen locally a few weeks after the trauma due to venous distension. When the fistula is small, the vein gradually expands at the fistula, the vein lining thickens, and the fibrous tissue proliferates, forming an “action-like wall” due to the gradual thickening of the vein wall.