The stone obstructing the VUJ is well seen by ultrasound in this case. It results in dilatation of the pelvicalceal system and the ureter in the left side .The ureter is seen dilated at its proximal part and its distal part, posterior to the bladder .

• the stone shown as echogenic focus in greyscale (B-mode) with a posterior acoustic shadow
• when color Doppler is used, a twinkling artifact is produced by the stone