The most common cause of acquired aeriovenous fistula is

. Trauma is the most common cause of accquired atreiovenous fistula(AV fistula).most common sites involved are femoral region,brachial region,popliteal region,wrist,aoa-vena canal,abdomen.It may be following road traffic accidents,penetrating wounds,cock fight injury(common in south india).Other causes includes after surgical intervention of major vessels,cimino fistula(AVF created for renal dialysis). Refer page no 219 of SRB's manual of surgery 5th edition.