Transition of renal arteriovenous fistula to arteriocalyceal fistula during embolization.

Selective and superselective renal embolization is a generally accepted technique for treating traumatic or iatrogenic renal arteriovenous fistulas or arteriocalyceal fistulas. Only a minority are pure arteriocalyceal fistulas. During embolization, an arteriovenous fistula may become a frankly bleeding arteriocalyceal fistula, causing massive haematuria and necessitating further embolization.