This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CT and MRI of the Kidney, Subject name: Radiology
Cobra snake head appearance is seen in - 
Select and explain. 
A. Rectocele, B. Ureterocele, C. Posterior urethral valve, D. Bladder tumour
B: Ureterocele
Answer: B: Ureterocele 
Explanation: Ans. is 'b' i.e., Ureterocele Cobra head sign (Adder head or Snake appearance)o 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.