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
[{'content': 'Adder head is seen in- \nSelect and explain. \nA. Rectocele, B. Ureterocele, C. Posterior urethral valve, D. Bladder tumour', 'role': 'user'}, {'content': "Answer: B \nExplanation: 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.", 'role': 'assistant'}]