<prompt> Adder head is seen in-RectoceleUreterocelePosterior urethral valveBladder tumour  <response>: Ans. is b i.e., ureterocele Cobra head sign Adder head or Snake appearanceo The cobra head sign is characterized by bulbous dilatation of distal end of the ureter with a surrounding radiolucent halo, seen within the contrast material enhanced bladder on intravenous urograms IVP,o The cobra head sign is classically seen with an intravesical orthotopic ureteroceleo A cobra - shaped distal end of a ureter may be seen with incomplete distal ureteral obstruction caused by a tumor or stone. This appearance is termed as pseudoureterocele. 