This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genito Urinary System, Subject name: Radiology
[{'content': 'Adder head appearance is seen in: \nSelect and explain. \nA. Ureterocoele, B. Duplication of ureter, C. Urethral diverticulum., D. Mega ureter', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a (Ureterocoele) Ref: Bailey, 24th ed, p. 1310Ureterocoele: Cystic enlargement of intramural portion of ureter. Adder heaed appearance in excretory urography is typical.Other important radiographic appearance* Spring onion appearance- Ureterocoele* Spider leg appearance- Polycystic kidney* Flower vase appearance- Horse shoe kidney* Rim sign or crescent sign- Hydronephrosis* Sandy patches, foetal head in pelvis- Schistosomiasis bladder* Golf hole ureter, thimble bladder- TB kidney* Soap bubble appearance- Hydronephrosis* Clubbing of calyces- Hydronephrosis* Meniscus sign- CBD stone* Reverse J sign with hydronephrosis- Retrocaval ureter* Drooping flower appearance- Ectopic ureter* Irregular filling defects, spider leg appearance- Renal cell carcinomaUrographically early filling of the bulbous terminal ureter is noted, a finding that has been referred as a spring onion appearanceSome notes on radiological investigations in urology* Rapid sequence urography is carried out in patients with suspected reno vascular hypertension.* Urethroscopy is confirmatory for stricture of urethra.* Infusion urography-in compromised renal function* Diuretic urography-PUJ obstruction* Micturating cysto urethrography-investigation of choice for VUR and posterior urethral valve.* Retrograde urethrogram is the best to visualize penile urethra.', 'role': 'assistant'}]