Doppler ultrasound of the perineum and the penis shows a large left arterio-cavernous fistula in the perineal region, underlying a small skin bruise behind the left scrotum. The fistula is probably from the dorsal artery of the left penis in the perineal region. Suspected small pseudoaneurysm 3 mm in diameter just proximal to the fistula. High flow in the left corpus cavernosum in the perineal region. More distally in the penis, no significantly increased vascularization in the corpora cavernosa.